WorldWideScience

Sample records for stress rupture tests

  1. Liquid salt environment stress-rupture testing

    Science.gov (United States)

    Ren, Weiju; Holcomb, David E.; Muralidharan, Govindarajan; Wilson, Dane F.

    2016-03-22

    Disclosed herein are systems, devices and methods for stress-rupture testing selected materials within a high-temperature liquid salt environment. Exemplary testing systems include a load train for holding a test specimen within a heated inert gas vessel. A thermal break included in the load train can thermally insulate a load cell positioned along the load train within the inert gas vessel. The test specimen can include a cylindrical gage portion having an internal void filled with a molten salt during stress-rupture testing. The gage portion can have an inner surface area to volume ratio of greater than 20 to maximize the corrosive effect of the molten salt on the specimen material during testing. Also disclosed are methods of making a salt ingot for placement within the test specimen.

  2. Nondestructive Evaluation and Monitoring Results from COPV Accelerated Stress Rupture Testing, NASA White Sands Test Facility (WSTF)

    Science.gov (United States)

    Saulsberry Regor

    2010-01-01

    Develop and demonstrate NDE techniques for real-time characterization of CPVs and, where possible, identification of NDE capable of assessing stress rupture related strength degradation and/or making vessel life predictions (structural health monitoring or periodic inspection modes). Secondary: Provide the COPV user and materials community with quality carbon/epoxy (C/Ep) COPV stress rupture progression rate data. Aid in modeling, manufacturing, and application of COPVs for NASA spacecraft.

  3. Bayes Analysis and Reliability Implications of Stress-Rupture Testing a Kevlar/Epoxy COPV Using Temperature and Pressure Acceleration

    Science.gov (United States)

    Phoenix, S. Leigh; Kezirian, Michael T.; Murthy, Pappu L. N.

    2009-01-01

    Composite Overwrapped Pressure Vessels (COPVs) that have survived a long service time under pressure generally must be recertified before service is extended. Flight certification is dependent on the reliability analysis to quantify the risk of stress rupture failure in existing flight vessels. Full certification of this reliability model would require a statistically significant number of lifetime tests to be performed and is impractical given the cost and limited flight hardware for certification testing purposes. One approach to confirm the reliability model is to perform a stress rupture test on a flight COPV. Currently, testing of such a Kevlar49 (Dupont)/epoxy COPV is nearing completion. The present paper focuses on a Bayesian statistical approach to analyze the possible failure time results of this test and to assess the implications in choosing between possible model parameter values that in the past have had significant uncertainty. The key uncertain parameters in this case are the actual fiber stress ratio at operating pressure, and the Weibull shape parameter for lifetime; the former has been uncertain due to ambiguities in interpreting the original and a duplicate burst test. The latter has been uncertain due to major differences between COPVs in the database and the actual COPVs in service. Any information obtained that clarifies and eliminates uncertainty in these parameters will have a major effect on the predicted reliability of the service COPVs going forward. The key result is that the longer the vessel survives, the more likely the more optimistic stress ratio model is correct. At the time of writing, the resulting effect on predicted future reliability is dramatic, increasing it by about one "nine," that is, reducing the predicted probability of failure by an order of magnitude. However, testing one vessel does not change the uncertainty on the Weibull shape parameter for lifetime since testing several vessels would be necessary.

  4. Effect of transient liquid phase (TLP) bonding on the ductility of a Ni-base single crystal superalloy in a stress rupture test

    International Nuclear Information System (INIS)

    Liu, J.D.; Jin, T.; Zhao, N.R.; Wang, Z.H.; Sun, X.F.; Guan, H.R.; Hu, Z.Q.

    2008-01-01

    A Ni-base single crystal superalloy was transient liquid phase (TLP) bonded using a Ni-Cr-B amorphous foil at 1230 deg. C for 8 h. Stress rupture tests of the TLP joint and a matrix sample were carried out at 982 deg. C/248 MPa and 1010 deg. C/248 MPa. The microstructures and fracture surfaces were studied using scanning electron microscopy (SEM). Transmission electron microscopy (TEM) investigations were performed after creep rupture testing to examine the deformation substructures. The results show that the stress rupture ductility of TLP joints is significantly decreased compared to the matrix sample. This reduction of the ductility of TLP joints can be attributed to solid solution strengthening by boron atoms, subgrain boundaries formed in the bonding zone and the concentration of creep cavities formed during the last stage of the stress rupture test

  5. Composite Overwrap Pressure Vessels: Mechanics and Stress Rupture Lifting Philosophy

    Science.gov (United States)

    Thesken, John C.; Murthy, Pappu L. N.; Phoenix, S. L.

    2009-01-01

    The NASA Engineering and Safety Center (NESC) has been conducting an independent technical assessment to address safety concerns related to the known stress rupture failure mode of filament wound pressure vessels in use on Shuttle and the International Space Station. The Shuttle s Kevlar-49 (DuPont) fiber overwrapped tanks are of particular concern due to their long usage and the poorly understood stress rupture process in Kevlar-49 filaments. Existing long term data show that the rupture process is a function of stress, temperature and time. However due to the presence of load sharing liners and the complex manufacturing procedures, the state of actual fiber stress in flight hardware and test articles is not clearly known. Indeed nonconservative life predictions have been made where stress rupture data and lifing procedures have ignored the contribution of the liner in favor of applied pressure as the controlling load parameter. With the aid of analytical and finite element results, this paper examines the fundamental mechanical response of composite overwrapped pressure vessels including the influence of elastic plastic liners and degraded/creeping overwrap properties. Graphical methods are presented describing the non-linear relationship of applied pressure to Kevlar-49 fiber stress/strain during manufacturing, operations and burst loadings. These are applied to experimental measurements made on a variety of vessel systems to demonstrate the correct calibration of fiber stress as a function of pressure. Applying this analysis to the actual qualification burst data for Shuttle flight hardware revealed that the nominal fiber stress at burst was in some cases 23 percent lower than what had previously been used to predict stress rupture life. These results motivate a detailed discussion of the appropriate stress rupture lifing philosophy for COPVs including the correct transference of stress rupture life data between dissimilar vessels and test articles.

  6. Composite Overwrap Pressure Vessels: Mechanics and Stress Rupture Lifing Philosophy

    Science.gov (United States)

    Thesken, John C.; Murthy, Pappu L. N.; Phoenix, Leigh

    2007-01-01

    The NASA Engineering and Safety Center (NESC) has been conducting an independent technical assessment to address safety concerns related to the known stress rupture failure mode of filament wound pressure vessels in use on Shuttle and the International Space Station. The Shuttle's Kevlar-49 fiber overwrapped tanks are of particular concern due to their long usage and the poorly understood stress rupture process in Kevlar-49 filaments. Existing long term data show that the rupture process is a function of stress, temperature and time. However due to the presence of load sharing liners and the complex manufacturing procedures, the state of actual fiber stress in flight hardware and test articles is not clearly known. Indeed non-conservative life predictions have been made where stress rupture data and lifing procedures have ignored the contribution of the liner in favor of applied pressure as the controlling load parameter. With the aid of analytical and finite element results, this paper examines the fundamental mechanical response of composite overwrapped pressure vessels including the influence of elastic-plastic liners and degraded/creeping overwrap properties. Graphical methods are presented describing the non-linear relationship of applied pressure to Kevlar-49 fiber stress/strain during manufacturing, operations and burst loadings. These are applied to experimental measurements made on a variety of vessel systems to demonstrate the correct calibration of fiber stress as a function of pressure. Applying this analysis to the actual qualification burst data for Shuttle flight hardware revealed that the nominal fiber stress at burst was in some cases 23% lower than what had previously been used to predict stress rupture life. These results motivate a detailed discussion of the appropriate stress rupture lifing philosophy for COPVs including the correct transference of stress rupture life data between dissimilar vessels and test articles.

  7. The stress rupture properties of austenitic steel weld metals

    International Nuclear Information System (INIS)

    Wood, D.S.

    Elevated temperature stress rupture data on Mo containing and Mo free austenitic weld metals have been collected from French, Dutch, German and UK sources and the results analysed. The stress rupture strength of Mo containing weld metal is significantly higher than that of Mo free weld metal. At 10,000h the rupture strength of Mo containing weld metal is higher than that of Type 316 steel whereas the Mo free weld metal is about 20% lower than that of Type 304 steel. Austenitic weld metal can give low stress rupture ductility values. It is concluded that there are insufficient data to permit reliable extrapolations to long times and it is recommended that long term tests are performed to overcome this situation

  8. Stress Rupture Life Reliability Measures for Composite Overwrapped Pressure Vessels

    Science.gov (United States)

    Murthy, Pappu L. N.; Thesken, John C.; Phoenix, S. Leigh; Grimes-Ledesma, Lorie

    2007-01-01

    Composite Overwrapped Pressure Vessels (COPVs) are often used for storing pressurant gases onboard spacecraft. Kevlar (DuPont), glass, carbon and other more recent fibers have all been used as overwraps. Due to the fact that overwraps are subjected to sustained loads for an extended period during a mission, stress rupture failure is a major concern. It is therefore important to ascertain the reliability of these vessels by analysis, since the testing of each flight design cannot be completed on a practical time scale. The present paper examines specifically a Weibull statistics based stress rupture model and considers the various uncertainties associated with the model parameters. The paper also examines several reliability estimate measures that would be of use for the purpose of recertification and for qualifying flight worthiness of these vessels. Specifically, deterministic values for a point estimate, mean estimate and 90/95 percent confidence estimates of the reliability are all examined for a typical flight quality vessel under constant stress. The mean and the 90/95 percent confidence estimates are computed using Monte-Carlo simulation techniques by assuming distribution statistics of model parameters based also on simulation and on the available data, especially the sample sizes represented in the data. The data for the stress rupture model are obtained from the Lawrence Livermore National Laboratories (LLNL) stress rupture testing program, carried out for the past 35 years. Deterministic as well as probabilistic sensitivities are examined.

  9. Effect of heating method on stress-rupture life

    Science.gov (United States)

    Bizon, P. T.; Calfo, F. D.

    1977-01-01

    The effect of radiant(furnace), resistance(electric current), burner(hot gas stream), and a combination of resistance and burner heating on intermediate time (100 to 300 hr) stress-rupture life and reduction of area was evaluated. All heating methods were studied using the nickel-based alloy Udimet 700 while all but burner heating were evaluated with the cobalt-based alloy Mar-M 509. Limited test results of eight other superalloys were also included in this study. Resistance heated specimens had about 20 to 30 percent of the stress-rupture life of radiant heated specimens. The limited burner heating data showed about a 50 percent life reduction as compared to the radiant heated tests. A metallurgical examination gave no explanation for these reductions.

  10. LWR primary coolant pipe rupture test rig

    International Nuclear Information System (INIS)

    Yoshitoshi, Shyoji

    1978-01-01

    The rupture test rig for primary coolant pipes is constructed in the Japan Atomic Energy Research Institute to verify the reliability of the primary coolant pipes for both PWRs and BWRs. The planned test items consisted of reaction force test, restraint test, whip test, jet test and continuous release test. A pressure vessel of about 4 m 3 volume, a circulating pump, a pressurizer, a heater, an air cooler and the related instrumentation and control system are included in this test rig. The coolant test condition is 160 kg/cm 2 g, 325 deg C for PWR test, and 70 kg/cm 2 g, saturated water and steam for BWR test, 100 ton of test load for the ruptured pipe bore of 8B Schedule 160, and 20 lit/min. discharge during 20 h for continuous release of coolant. The maximum pit internal pressure was estimated for various pipe diameters and time under the PWR and BWR conditions. The spark rupturing device was adopted for the rupture mechanics in this test rig. The computer PANAFACOM U-300 is used for the data processing. This test rig is expected to operate in 1978 effectively for the improvement of reliability of LWR primary coolant pipes. (Nakai, Y.)

  11. Stress analysis of a rupture disk

    International Nuclear Information System (INIS)

    Werne, R.W.

    1975-04-01

    The results of an elastic stress analysis of the rupture disk for an internal pressure of 45.5 MPa (6600 psi) indicate that the maximum von Mises stresses occur in the membrane and are on the order of 483 to 690 MPa (70,000 psi). This far exceeds the yield of the membrane material of 207 MPa (30,000 psi). These high stresses are expected since the membrane is designed to burst at that design pressure. The von Mises stresses in the rest of the body are less than 138 MPa (20,000 psi). An elastic-plastic analysis of the membrane alone subjected to the 45.5 MPa (6600 psi) pressure indicates that it becomes plastically unstable, i.e., it continues to deform under constant load. A second load case with a constant 6.9 MPa (1000 psi) pressure throughout the entire body (i.e., after release of pressure by burst of the membrane) was analyzed. The results indicate that the elastic von Mises stresses are less than 26.7 MPa (3880 psi) throughout the body. (U.S.)

  12. Investigation on Stress-Rupture Behavior of a Chopped-Glass-Fiber Composite for Automotive Durability Design Criteria

    Energy Technology Data Exchange (ETDEWEB)

    Ren, W

    2001-08-24

    Practical and inexpensive testing methods were developed to investigate stress-rupture properties of a polymeric composite with chopped glass fiber reinforcement for automotive applications. The material was tested in representative automotive environments to generate experimental data. The results indicate that environments have substantial effects on the stress-rupture behavior. The data were analyzed and developed into stress-rupture design criteria to address one of the durability aspects of the material for automotive structural applications.

  13. Investigation on Stress-Rupture Behavior of a Chopped-Glass-Fiber Composite for Automotive Durability Design Criteria; FINAL

    International Nuclear Information System (INIS)

    Ren, W

    2001-01-01

    Practical and inexpensive testing methods were developed to investigate stress-rupture properties of a polymeric composite with chopped glass fiber reinforcement for automotive applications. The material was tested in representative automotive environments to generate experimental data. The results indicate that environments have substantial effects on the stress-rupture behavior. The data were analyzed and developed into stress-rupture design criteria to address one of the durability aspects of the material for automotive structural applications

  14. Global catalog of earthquake rupture velocities shows anticorrelation between stress drop and rupture velocity

    Science.gov (United States)

    Chounet, Agnès; Vallée, Martin; Causse, Mathieu; Courboulex, Françoise

    2018-05-01

    Application of the SCARDEC method provides the apparent source time functions together with seismic moment, depth, and focal mechanism, for most of the recent earthquakes with magnitude larger than 5.6-6. Using this large dataset, we have developed a method to systematically invert for the rupture direction and average rupture velocity Vr, when unilateral rupture propagation dominates. The approach is applied to all the shallow (z earthquakes of the catalog over the 1992-2015 time period. After a careful validation process, rupture properties for a catalog of 96 earthquakes are obtained. The subsequent analysis of this catalog provides several insights about the seismic rupture process. We first report that up-dip ruptures are more abundant than down-dip ruptures for shallow subduction interface earthquakes, which can be understood as a consequence of the material contrast between the slab and the overriding crust. Rupture velocities, which are searched without any a-priori up to the maximal P wave velocity (6000-8000 m/s), are found between 1200 m/s and 4500 m/s. This observation indicates that no earthquakes propagate over long distances with rupture velocity approaching the P wave velocity. Among the 23 ruptures faster than 3100 m/s, we observe both documented supershear ruptures (e.g. the 2001 Kunlun earthquake), and undocumented ruptures that very likely include a supershear phase. We also find that the correlation of Vr with the source duration scaled to the seismic moment (Ts) is very weak. This directly implies that both Ts and Vr are anticorrelated with the stress drop Δσ. This result has implications for the assessment of the peak ground acceleration (PGA) variability. As shown by Causse and Song (2015), an anticorrelation between Δσ and Vr significantly reduces the predicted PGA variability, and brings it closer to the observed variability.

  15. Thompson Test in Achilles Tendon Rupture

    Directory of Open Access Journals (Sweden)

    Spencer Albertson

    2016-07-01

    Full Text Available HPI: A 26-year old male presented to the emergency department after experiencing the acute onset of left ankle pain while playing basketball. Upon jumping, he felt a “pop” in his left posterior ankle, followed by pain and difficulty ambulating. His exam was notable for a defect at the left Achilles tendon on palpation. The practitioner performed a Thompson test, which was positive (abnormal on the left. Significant Findings: The left Achilles tendon had a defect on palpation, while the right Achilles tendon was intact. When squeezing the right (unaffected calf, the ankle spontaneously plantar flexed, indicating a negative (normal Thompson test. Upon squeeze of the left (affected calf, the ankle did not plantar flex, signifying a positive (abnormal Thompson test. The diagnosis of left Achilles tendon rupture was confirmed intraoperatively one week later. Discussion: The Achilles tendon (also: calcaneal tendon or heel cord is derived from the medial and lateral heads of the gastrocnemius muscle, as well as the soleus muscle. Rupture of the Achilles tendon most commonly occurs in the distal tendon, approximately 2-6 cm from its attachment to the calcaneal tuberosity, in an area of hypovascularity known as the “watershed” or “critical” zone.1-3 The Thompson test (also: Simmonds-Thompson test, described by Simmonds in 1957 and Thompson in 1962, is done while the patient is in the prone position, with feet hanging over the end of a table/gurney, or with the patient kneeling on a stool or chair.4-5 Squeezing the calf of an unaffected limb will cause the ankle to plantar flex, but squeezing the calf of a limb with an Achilles tendon rupture will cause no motion. The sensitivity of the Thompson’s test for the diagnosis of a complete Achilles tendon rupture is 96-100% and the specificity is 93-100%, but data is limited.6-8

  16. Nuclear stress test

    Science.gov (United States)

    ... Persantine stress test; Thallium stress test; Stress test - nuclear; Adenosine stress test; Regadenoson stress test; CAD - nuclear stress; Coronary artery disease - nuclear stress; Angina - nuclear ...

  17. Influence of composition on precipitation behavior and stress rupture properties in INCONEL RTM740 series superalloys

    Science.gov (United States)

    Casias, Andrea M.

    Increasing demands for energy efficiency and reduction in CO2 emissions have led to the development of advanced ultra-supercritical (AUSC) boilers. These boilers operate at temperatures of 760 °C and pressures of 35 MPa, providing efficiencies close to 50 pct. However, austenitic stainless steels typically used in boiler applications do not have sufficient creep or oxidation resistance. For this reason, nickel (Ni)-based superalloys, such as IN740, have been identified as potential materials for AUSC boiler tube components. However, IN740 is susceptible to heat-affected-zone liquation cracking in the base metal of heavy section weldments. To improve weldability, IN740H was developed. However, IN740H has lower stress rupture ductility compared to IN740. For this reason, two IN740H modifications have been produced by lowering carbon content and increasing boron content. In this study, IN740, IN740H, and the two modified IN740H alloys (modified 1 and 2) were produced with equiaxed grain sizes of 90 ìm (alloys IN740, IN740H, and IN740H modified 1 alloys) and 112 µm (IN740H modified 2 alloy). An aging study was performed at 800 °C on all alloys for 1, 3, 10, and 30 hours to assess precipitation behavior. Stress rupture tests were performed at 760 °C with the goal of attaining stress levels that would yield rupture at 1000 hours. The percent reduction in area was measured after failure as a measure of creep ductility. Light optical, scanning electron, and transmission electron microscopy were used in conjunction with X-ray diffraction to examine precipitation behavior of annealed, aged, and stress rupture tested samples. The amount and type of precipitation that occurred during aging prior to stress rupture testing or in-situ during stress rupture testing influenced damage development, stress rupture life, and ductility. In terms of stress rupture life, IN740H modified 2 performed the best followed by IN740H modified 1 and IN740, which performed similarly, and IN740

  18. Creep rupture of mild steel compact tension test pieces

    International Nuclear Information System (INIS)

    Priddle, E.K.

    1978-10-01

    Creep rupture lives have been determined for compact tension and unnotched tensile test pieces of mild steel at 450 0 C. Three sizes of compact tension specimens were used in which the ratios of reference stress to elastic stress intensity factor were 2.76, 4.78 and 6.6 (msup(-1/2)). The analysis of results in terms of either initial reference stress or stress intensity was unable to reduce the data to a single failure curve. An empirical correlation was found between rupture time and a reference stress/crack length combination where t = 2.46 x 10 20 sub(σref) sup(-8.96) asup(-1.56) (units hours, MPa and metres). This equation has no valid application to materials or specimens other than those from which it was derived. Reported data for 1/2Cr Mo V and 2 1/4Cr Mo steels at 565 0 C were also correlated by this approach. (author)

  19. The Inclusion of Arbitrary Load Histories in the Strength Decay Model for Stress Rupture

    Science.gov (United States)

    Reeder, James R.

    2014-01-01

    Stress rupture is a failure mechanism where failures can occur after a period of time, even though the material has seen no increase in load. Carbon/epoxy composite materials have demonstrated the stress rupture failure mechanism. In a previous work, a model was proposed for stress rupture of composite overwrap pressure vessels (COPVs) and similar composite structures based on strength degradation. However, the original model was limited to constant load periods (holds) at constant load. The model was expanded in this paper to address arbitrary loading histories and specifically the inclusions of ramp loadings up to holds and back down. The broadening of the model allows for failures on loading to be treated as any other failure that may occur during testing instead of having to be treated as a special case. The inclusion of ramps can also influence the length of the "safe period" following proof loading that was previously predicted by the model. No stress rupture failures are predicted in a safe period because time is required for strength to decay from above the proof level to the lower level of loading. Although the model can predict failures during the ramp periods, no closed-form solution for the failure times could be derived. Therefore, two suggested solution techniques were proposed. Finally, the model was used to design an experiment that could detect the difference between the strength decay model and a commonly used model for stress rupture. Although these types of models are necessary to help guide experiments for stress rupture, only experimental evidence will determine how well the model may predict actual material response. If the model can be shown to be accurate, current proof loading requirements may result in predicted safe periods as long as 10(13) years. COPVs design requirements for stress rupture may then be relaxed, allowing more efficient designs, while still maintaining an acceptable level of safety.

  20. Anisotropic stress rupture properties of the nickel-base single crystal superalloy SRR99

    International Nuclear Information System (INIS)

    Han, G.M.; Yu, J.J.; Sun, Y.L.; Sun, X.F.; Hu, Z.Q.

    2010-01-01

    The influence of orientation on the stress rupture properties of a single crystal superalloy SRR99 was investigated at temperatures of 760 and 1040 deg. C. It is found that the creep anisotropic behaviour is pronounced at the lower temperature of 760 deg. C and the stress rupture life ranks in the order [0 0 1] > [1 1 1] > [0 1 1]. Despite the anisotropy of stress rupture life is evidently reduced at the higher temperature, the [1 1 1] orientation exhibits the longest life. At 760 deg. C, EBSD (electron back scattered diffraction) was adopted to measure the lattice rotation and the deduced results indicate that the dominant slip systems are {1 1 1} during stress rupture test. At 1040 deg. C, the ranking order of the stress rupture life is [1 1 1] > [0 0 1] > [0 1 1] and the single crystal close to [0 1 1] orientation still shows the poorest life. In the [0 0 1] and [1 1 1] samples, regular γ' raft structure is formed compared with [0 1 1] samples. Further observations made by TEM investigations reveal the underlying deformation mechanisms for crystals with orientations near [0 0 1], [0 1 1] and [1 1 1] under two test conditions.

  1. Creep and rupture of an ODS alloy with high stress rupture ductility. [Oxide Dispersion Strengthened

    Science.gov (United States)

    Mcalarney, M. E.; Arsons, R. M.; Howson, T. E.; Tien, J. K.; Baranow, S.

    1982-01-01

    The creep and stress rupture properties of an oxide (Y2O3) dispersion strengthened nickel-base alloy, which also is strengthened by gamma-prime precipitates, was studied at 760 and 1093 C. At both temperatures, the alloy YDNiCrAl exhibits unusually high stress rupture ductility as measured by both elongation and reduction in area. Failure was transgranular, and different modes of failure were observed including crystallographic fracture at intermediate temperatures and tearing or necking almost to a chisel point at higher temperatures. While the rupture ductility was high, the creep strength of the alloy was low relative to conventional gamma prime strengthened superalloys in the intermediate temperature range and to ODS alloys in the higher temperature range. These findings are discussed with respect to the alloy composition; the strengthening oxide phases, which are inhomogeneously dispersed; the grain morphology, which is coarse and elongated and exhibits many included grains; and the second phase inclusion particles occurring at grain boundaries and in the matrix. The creep properties, in particular the high stress dependencies and high creep activation energies measured, are discussed with respect to the resisting stress model of creep in particle strengthened alloys.

  2. Pseudodynamic Source Characterization for Strike-Slip Faulting Including Stress Heterogeneity and Super-Shear Ruptures

    KAUST Repository

    Mena, B.; Dalguer, L. A.; Mai, Paul Martin

    2012-01-01

    . (2004), we propose new relationships for PD models for moderate‐to‐large strike‐slip earthquakes that include local supershear rupture speed due to stress heterogeneities. We conduct dynamic rupture simulations using stochastic initial stress

  3. (stress) testing

    African Journals Online (AJOL)

    However, maximal HR was significantly higher in all groups during their sporting activities than during stress testing in the laboratory (P < 0.01). Conclusions. Maximal HR in veteran athletes during specific sporting activities was significantly higher than that attained during a routine sECG. This finding was not sport-specific, ...

  4. Tensile Stress Rupture Behavior of a Woven Ceramic Matrix Composite in Humid Environments at Intermediate Temperature

    National Research Council Canada - National Science Library

    LaRochelle, Kevin J

    2005-01-01

    Stress rupture tests on the Sylramic(TM) fiber with an in-situ layer of boron nitride, boron nitride interphase, and SiC matrix ceramic matrix composite were performed at 550 degrees C and 750 degrees C with 0.0, 0.2...

  5. Assessment of Creep Deformation, Damage, and Rupture Life of 304HCu Austenitic Stainless Steel Under Multiaxial State of Stress

    Science.gov (United States)

    Sahoo, K. C.; Goyal, Sunil; Parameswaran, P.; Ravi, S.; Laha, K.

    2018-03-01

    The role of the multiaxial state of stress on creep deformation and rupture behavior of 304HCu austenitic stainless steel was assessed by performing creep rupture tests on both smooth and notched specimens of the steel. The multiaxial state of stress was introduced by incorporating circumferential U-notches of different root radii ranging from 0.25 to 5.00 mm on the smooth specimens of the steel. Creep tests were carried out at 973 K over the stress range of 140 to 220 MPa. In the presence of notch, the creep rupture strength of the steel was found to increase with the associated decrease in rupture ductility. Over the investigated stress range and notch sharpness, the strengthening was found to increase drastically with notch sharpness and tended toward saturation. The fractographic studies revealed the mixed mode of failure consisting of transgranular dimples and intergranular creep cavitation for shallow notches, whereas the failure was predominantly intergranular for relatively sharper notches. Detailed finite element analysis of stress distribution across the notch throat plane on creep exposure was carried out to assess the creep failure of the material in the presence of notch. The reduction in von-Mises stress across the notch throat plane, which was greater for sharper notches, increased the creep rupture strength of the material. The variation in fracture behavior of the material in the presence of notch was elucidated based on the von-Mises, maximum principal, and hydrostatic stresses. Electron backscatter diffraction analysis of creep strain distribution across the notch revealed localized creep straining at the notch root for sharper notches. A master curve for predicting creep rupture life under the multiaxial state of stress was generated considering the representative stress having contributions from both the von-Mises and principal stress components of the stress field in the notch throat plane. Rupture ductility was also predicted based on the

  6. On the initiation of sustained slip-weakening ruptures by localized stresses

    KAUST Repository

    Galis, Martin; Pelties, C.; Kristek, J.; Moczo, P.; Ampuero, J.- P.; Mai, Paul Martin

    2014-01-01

    stressed beyond the static frictional strength. The physical properties of the asperity (size, shape and overstress) may significantly impact rupture propagation. In particular, to induce a sustained rupture the asperity size needs to exceed a critical

  7. Effects on stress rupture life and tensile strength of tin additions to Inconel 718

    Science.gov (United States)

    Dreshfield, R. L.; Johnson, W.

    1982-01-01

    Because Inconel 718 represents a major use of columbium and a large potential source of columbium for aerospace alloys could be that of columbium derived from tin slags, the effects of tin additions to Inconel 718 at levels which might be typical of or exceed those anticipated if tin slag derived columbium were used as a melting stock were investigated. Tin was added to 15 pound Inconel 718 heats at levels varying from none added to approximately 10,000 ppm (1 wt%). Limited 1200 F stress rupture testing was performed at stresses from 68,000 to 115,000 psi and a few tensile tests were performed at room temperature, 800 and 1200 F. Additions of tin in excess of 800 ppm were detrimental to ductility and stress rupture life.

  8. Rupture disc opening property for using pipe rupture test in JAERI

    International Nuclear Information System (INIS)

    Kato, Rokuro

    1983-03-01

    In the Mechanical Strength and Structure Lab of JAERI there are being performed pipe break tests which are a postulated instantaneous guillotine break of the primary coolant piping in nuclear power plants. The test being performed are pipe whip tests and jet discharging tests. The bursting of the rupture disc is initiated by an electrical arc and is concluded by the internal pressure. Because the time characteristics during the opening of the rupture disc affects the dynamic thrust force of the pipe, it is necessary to measure these time characteristics. However, it is difficult to measure the conditions during this continuous opening because at the same time of the opening the high temperature and high pressure water is flashing. Therefore, the rupture disc opening was postulated on the measuring of the effective opening characteristics with electric contraction terminals which were attached to the inner surface of the test pipe downstream of the rupture disc and were extended toward the pipe centerline in a ring whose area is about 60 % of the area of the pipe flow sectional area. The measurement voltage was recorded when the data recorder was started in sequence with the electrical arc release from a trigger signal. As a result, it is evident that under high temperature and high pressure water the effective opening time is delayed by a few milliseconds. (author)

  9. Shakedown Tests for Refurbished and Upgraded Frames and Initiation of Alloy 709 Creep Rupture Tests

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hong [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Moser, Jeremy L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Hawkins, Charles S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lara-Curzio, Edgar [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-09-01

    This report describes the shakedown tests conducted on the upgraded frames, and initiation of creep rupture tests on refurbished frames. SS316H, a reference material for Alloy 709, was used in shakedown tests, and the tests were conducted at 816 degree C under three stress levels to accumulate 1% creep strain. 1/4” gage diameter specimen design was used. The creep rupture tests on Alloy 709 were initiated at 600 degree C under 330 MPa to target 1,500 h rupture time. 12 specimens with 3/8” gage diameter were prepared from the materials with 6 heat treatment conditions, 2 from each. The required mechanical load under 330MPa was calculated to be 5,286 lb for the 3/8” gage diameter specimen. Among the ART frames, 7 frames are equipped with 10,000 lb load cell including #5 to 8 and #88 to 90, and can be used. 7 tests were thus started in this stage of project, and remaining 5 will be continued whenever any of the 7 tests is completed.

  10. Rupture tests with reactor pressure vessel head models

    International Nuclear Information System (INIS)

    Talja, H.; Keinaenen, H.; Hosio, E.; Pankakoski, P.H.; Rahka, K.

    2003-01-01

    In the LISSAC project (LImit Strains in Severe ACcidents), partly funded by the EC Nuclear Fission and Safety Programme within the 5th Framework programme, an extensive experimental and computational research programme is conducted to study the stress state and size dependence of ultimate failure strains. The results are aimed especially to make the assessment of severe accident cases more realistic. For the experiments in the LISSAC project a block of material of the German Biblis C reactor pressure vessel was available. As part of the project, eight reactor pressure vessel head models from this material (22 NiMoCr 3 7) were tested up to rupture at VTT. The specimens were provided by Forschungszentrum Karlsruhe (FzK). These tests were performed under quasistatic pressure load at room temperature. Two specimens sizes were tested and in half of the tests the specimens contain holes describing the control rod penetrations of an actual reactor pressure vessel head. These specimens were equipped with an aluminium liner. All six tests with the smaller specimen size were conducted successfully. In the test with the large specimen with holes, the behaviour of the aluminium liner material proved to differ from those of the smaller ones. As a consequence the experiment ended at the failure of the liner. The specimen without holes yielded results that were in very good agreement with those from the small specimens. (author)

  11. Ceramic Composite Intermediate Temperature Stress-Rupture Properties Improved Significantly

    Science.gov (United States)

    Morscher, Gregory N.; Hurst, Janet B.

    2002-01-01

    Silicon carbide (SiC) composites are considered to be potential materials for future aircraft engine parts such as combustor liners. It is envisioned that on the hot side (inner surface) of the combustor liner, composites will have to withstand temperatures in excess of 1200 C for thousands of hours in oxidizing environments. This is a severe condition; however, an equally severe, if not more detrimental, condition exists on the cold side (outer surface) of the combustor liner. Here, the temperatures are expected to be on the order of 800 to 1000 C under high tensile stress because of thermal gradients and attachment of the combustor liner to the engine frame (the hot side will be under compressive stress, a less severe stress-state for ceramics). Since these composites are not oxides, they oxidize. The worst form of oxidation for strength reduction occurs at these intermediate temperatures, where the boron nitride (BN) interphase oxidizes first, which causes the formation of a glass layer that strongly bonds the fibers to the matrix. When the fibers strongly bond to the matrix or to one another, the composite loses toughness and strength and becomes brittle. To increase the intermediate temperature stress-rupture properties, researchers must modify the BN interphase. With the support of the Ultra-Efficient Engine Technology (UEET) Program, significant improvements were made as state-of-the-art SiC/SiC composites were developed during the Enabling Propulsion Materials (EPM) program. Three approaches were found to improve the intermediate-temperature stress-rupture properties: fiber-spreading, high-temperature silicon- (Si) doped boron nitride (BN), and outside-debonding BN.

  12. Design prediction for long term stress rupture service of composite pressure vessels

    Science.gov (United States)

    Robinson, Ernest Y.

    1992-01-01

    Extensive stress rupture studies on glass composites and Kevlar composites were conducted by the Lawrence Radiation Laboratory beginning in the late 1960's and extending to about 8 years in some cases. Some of the data from these studies published over the years were incomplete or were tainted by spurious failures, such as grip slippage. Updated data sets were defined for both fiberglass and Kevlar composite stand test specimens. These updated data are analyzed in this report by a convenient form of the bivariate Weibull distribution, to establish a consistent set of design prediction charts that may be used as a conservative basis for predicting the stress rupture life of composite pressure vessels. The updated glass composite data exhibit an invariant Weibull modulus with lifetime. The data are analyzed in terms of homologous service load (referenced to the observed median strength). The equations relating life, homologous load, and probability are given, and corresponding design prediction charts are presented. A similar approach is taken for Kevlar composites, where the updated stand data do show a turndown tendency at long life accompanied by a corresponding change (increase) of the Weibull modulus. The turndown characteristic is not present in stress rupture test data of Kevlar pressure vessels. A modification of the stress rupture equations is presented to incorporate a latent, but limited, strength drop, and design prediction charts are presented that incorporate such behavior. The methods presented utilize Cartesian plots of the probability distributions (which are a more natural display for the design engineer), based on median normalized data that are independent of statistical parameters and are readily defined for any set of test data.

  13. Rupture

    CERN Multimedia

    Association du personnel

    2006-01-01

    Our Director-General is indifferent to the tradition of concertation foreseen in our statutes and is "culturally" unable to associate the Staff Association with problem-solving in staff matters. He drags his heels as long as possible before entering into negotiations, presents "often misleading" solutions at the last minute which he only accepts to change once a power struggle has been established. Faced with this rupture and despite its commitment to concertation between gentlemen. The results of the poll in which the staff is invited to participate this week. We therefore need your support to state our claims to the Governing Bodies. The Staff Association proposes a new medium of communication and thus hopes to show that it is ready for future negotiations. The pages devoted to the Staff Association are presented in a more informative, reactive and factual manner and in line with the evolution of the social situation at CERN. We want to establish strong and continuous ties between the members of CERN and ou...

  14. Effect of Environment on the Stress- Rupture Behavior of a C/SiC Composite Studied

    Science.gov (United States)

    Verrilli, Michael J.; Kiser, J. Douglas; Opila, Elizabeth J.; Calomino, Anthony M.

    2002-01-01

    Advanced reusable launch vehicles will likely incorporate fiber-reinforced ceramic matrix composites (CMC's) in critical propulsion and airframe components. The use of CMC's is highly desirable to save weight, improve reuse capability, and increase performance. One of the candidate CMC materials is carbon-fiber-reinforced silicon carbide (C/SiC). In potential propulsion applications, such as turbopump rotors and nozzle exit ramps, C/SiC components will be subjected to a service cycle that includes mechanical loading under complex, high-pressure environments containing hydrogen, oxygen, and steam. Degradation of both the C fibers and the SiC matrix are possible in these environments. The objective of this effort was to evaluate the mechanical behavior of C/SiC in various environments relevant to reusable launch vehicle applications. Stress-rupture testing was conducted at the NASA Glenn Research Center on C/SiC specimens in air and steam-containing environments. Also, the oxidation kinetics of the carbon fibers that reinforce the composite were monitored by thermogravimetric analysis in the same environments and temperatures used for the stress-rupture tests of the C/SiC composite specimens. The stress-rupture lives obtained for C/SiC tested in air and in steam/argon mixtures are shown in the following bar chart. As is typical for most materials, lives obtained at the lower temperature (600 C) are longer than for the higher temperature (1200 C). The effect of environment was most pronounced at the lower temperature, where the average test duration in steam at 600 C was at least 30 times longer than the lives obtained in air. The 1200 C data revealed little difference between the lives of specimens tested in air and steam at atmospheric pressure.

  15. Composite Stress Rupture NDE Research and Development Project (Kevlar[R] and Carbon)

    Science.gov (United States)

    Saulsberry, Regor

    2010-01-01

    The objective was to develop and demonstrate nondestructive evaluation (NDE) techniques capable of assessing stress rupture related strength degradation for carbon composite pressure vessels, either in a structural health monitoring (SHM) or periodic inspection mode.

  16. Extreme of random field over rectangle with application to concrete rupture stresses

    DEFF Research Database (Denmark)

    Ditlevsen, Ove Dalager

    2000-01-01

    to time consuming simulation procedures. This paperrevives a conceptually simple approach that gives surprisingly good results in particular for wide band typesof random processes and fields. The closed form formulas obtained for smooth Gaussian fieldsover rectangles contain size effects both with respect...... to the area of the rectangle and the side lengths of therectangle. Published rupture stress data for plain concrete beams illustrate the applicability of the derivedclosed form extreme value distributions as models for distributions of rupture stresses related to weakest linkmechanisms....

  17. The predictive role of health-promoting behaviours and perceived stress in aneurysmal rupture.

    Science.gov (United States)

    Lee, Mi-Sun; Park, Chang G; Hughes, Tonda L; Jun, Sang-Eun; Whang, Kum; Kim, Nahyun

    2018-03-01

    To examine the roles of two modifiable factors-health-promoting behaviours and perceived stress-in predicting aneurysmal rupture. Unruptured intracranial aneurysm detection produces significant stress and anxiety in patients because of the risk of rupture. Compared to nonmodifiable risk factors for rupture such as age, gender and aneurysm size/location, less attention has been given to modifiable risk factors. Two modifiable factors, health-promoting behaviours and perceived stress, have hardly been examined as potential predictors of rupture. This study used a cross-sectional design. We assessed 155 patients with intracranial aneurysms-that is, subarachnoid haemorrhage (n = 77) or unruptured intracranial aneurysm (n = 78)-to examine (i) baseline characteristics (patient and aneurysmal factors), (ii) health-related factors (lifestyle habits and health-promoting behaviour) and (iii) perceived stress levels (psychological stress and physical stress). Patient records provided medical histories and aneurysmal factors; other data were collected using a structured questionnaire addressing lifestyle habits, the Health-Promoting Lifestyle Profile-II to measure health-promoting behaviour and the Perceived Stress Questionnaire to measure perceived-psychological stress and perceived-physical stress levels. Bivariate analysis indicated that aneurysm rupture risk was associated with female gender, aneurysm size/location, defecation frequency, hyperlipidaemia, sedentary time, low Health-Promoting Lifestyle Profile-II mean scores and high perceived-psychological stress scores. After adjusting for known risk factors, the mean Health-Promoting Lifestyle Profile-II and perceived-psychological stress scores remained robust predictors of rupture. Furthermore, known risk factors combined with these scores had greater predictive power than known risk factors alone. Health-promoting behaviour and psychological stress are promising modifiable factors for reducing risk of aneurysmal

  18. The stress-rupture behavior of tubes made from austenitic stainless steels and Ni-based alloys subjected to internal pressure

    International Nuclear Information System (INIS)

    Schaefer, L.; Kempe, H.

    1983-12-01

    The report outlines the stress-rupture results obtained on tubes tested as possible fuel rod cladding tubes for fast breeder reactors cooled with sodium, steam or gas. For the rupture elongations of some specimens showing a pronounced burst, higher values than in earlier reports are now indicated because of better evaluation techniques. The choice and comparisons of materials are explained, the calculations of stresses and strains are described, and reference is made to the own studies carried out to date of the parameters influencing creep-rupture behaviour. Minor modifications of the composition of an alloy and of the mechanical-thermal treatment of materials, respectively, are seen to produce clearcut changes in the stress-rupture properties. (orig.) [de

  19. Viscoelastic characterization of carbon fiber-epoxy composites by creep and creep rupture tests

    International Nuclear Information System (INIS)

    Farina, Luis Claudio

    2009-01-01

    One of the main requirements for the use of fiber-reinforced polymer matrix composites in structural applications is the evaluation of their behavior during service life. The warranties of the integrity of these structural components demand a study of the time dependent behavior of these materials due to viscoelastic response of the polymeric matrix and of the countless possibilities of design configurations. In the present study, creep and creep rupture test in stress were performed in specimens of unidirectional carbon fiber-reinforced epoxy composites with fibers orientations of 60 degree and 90 degree, at temperatures of 25 and 70 degree C. The aim is the viscoelastic characterization of the material through the creep curves to some levels of constant tension during periods of 1000 h, the attainment of the creep rupture envelope by the creep rupture curves and the determination of the transition of the linear for non-linear behavior through isochronous curves. In addition, comparisons of creep compliance curves with a viscoelastic behavior prediction model based on Schapery equation were also performed. For the test, a modification was verified in the behavior of the material, regarding the resistance, stiffness and deformation, demonstrating that these properties were affected for the time and tension level, especially in work temperature above the ambient. The prediction model was capable to represent the creep behavior, however the determination of the equations terms should be considered, besides the variation of these with the applied tension and the elapsed time of test. (author)

  20. Stress-rupture lifetimes of organic fiber-epoxy strands and pressure vessels

    International Nuclear Information System (INIS)

    Hahn, H.T.; Chiu, I.L.; Gates, T.L.

    1979-01-01

    Long-term behavior of filament-wound pressure vessels were tested, Kevlar 49 epoxy strands were studied in stress-rupture for more than a year. Because the strands are the smallest structural unit in filament winding, their behavior directly controls the performance of vessels. Five different stress levels were studied: 86, 80, 74, 68, and 50% of the mean ultimate tensile strength (UTS). At each stress level, approximately one-hundred strands were hung in a room maintained at 22 to 24 0 C and below 20% relative humidity. Failure times were automatically recorded by a data acquisition system. Lifetimes were analyzed statistically using a two-parameter Weibull distribution. The maximum-likelihood method was used to estimate the parameters. The shape parameter, which is a measure of scatter and failure-rate change, increased with decreasing stress level. Less scatter and increasing failure rates were observed at lower stresses. There was no sign of an endurance limit down to 68% UTS. At 50% UTS no failure had yet occurred after 9000 h. The strand data were compared with data on lifetimes of pressure vessels wound with the same fiber and epoxy. The strands had slightly longer characteristic lifetimes, except at 86% UTS, and slightly less scatter, except at 68% UTS. The results of this study indicate that strands can provide valuable information about the long-term performance of filament-wound pressure vessels

  1. Strain Measurement during Stress Rupture of Composite Over-Wrapped Pressure Vessel with Fiber Bragg Gratings Sensors

    Science.gov (United States)

    Banks, Curtis E.; Grant, Joseph; Russell, Sam; Arnett, Shawn

    2008-01-01

    Fiber optic Bragg gratings were used to measure strain fields during Stress Rupture (SSM) test of Kevlar Composite Over-Wrapped Pressure Vessels (COPV). The sensors were embedded under the over-wrapped attached to the liner released from the Kevlar and attached to the Kevlar released from the liner. Additional sensors (foil gages and fiber bragg gratings) were surface mounted on the COPY liner.

  2. Creep and stress rupture behaviour of zircaloy-2 and Zr-2.5% Nb alloy tubes at 573 K

    International Nuclear Information System (INIS)

    Laha, K.; Bhanu Sankara Rao, K.; Chandravathi, K.S.; Mannan, S.L.

    1992-01-01

    Zirconium alloys are extensively used for coolant tubes of pressurised heavy water reactors. The choice of these materials is based on their good corrosion resistance in water, low capture cross section for thermal neutrons and good mechanical properties. In this paper the results of an investigation performed on the creep and rupture behaviour of indigenously produced zircaloy-2 and Zr-2.5% Nb alloy are presented. Samples for creep testing were cut longitudinally from finished pressure tubes. Creep rupture tests were carried out in air under constant load conditions at 300 C employing five stress levels in the range 300-360 MPa. Zr-2.5% Nb alloy displayed higher rupture lives at all stress levels compared to zircaloy-2. Steady state creep rate of Zr-2.5%Nb was lower than that zircaloy-2 at identical stress levels. In the stress range of the experiments, the dependence of the steady state creep rate (ε s ) on applied stress (σ) for both the alloys could be represented by a power law, ε s =A σ n The stress sensitivity (n) for Zr-2.5% Nb was lower than that of zircaloy-2. For both the alloys the time to creep rupture t r was found related to the steady state creep rate through the modified Monkman-Grant relation (ε s ) α . t r = constant. Similar value of α was obtained for both the materials. Zr-2.5%Nb exhibited higher ductility (% elongation to rupture) compared to zircaloy-2 at stress levels ≥ 320 MPa. At lower stresses significant difference in ductility was not noticed. Percentage reduction in area was lower in Zr-2.5%Nb at all stress levels indicating better resistance for necking. The time for onset of tertiary was longer for Zr-2.5% Nb alloy. The proportion of life spent by Zr-2.5% Nb in steady state creep regime was higher compared to that of zircaloy-2. Metallographic investigations on longitudinal sections in both the alloys showed large number of intragranular pores close to the fracture surface. A few number of cracks which are characteristic of

  3. Directly Estimating Earthquake Rupture Area using Second Moments to Reduce the Uncertainty in Stress Drop

    Science.gov (United States)

    McGuire, Jeffrey J.; Kaneko, Yoshihiro

    2018-06-01

    The key kinematic earthquake source parameters: rupture velocity, duration and area, shed light on earthquake dynamics, provide direct constraints on stress-drop, and have implications for seismic hazard. However, for moderate and small earthquakes, these parameters are usually poorly constrained due to limitations of the standard analysis methods. Numerical experiments by Kaneko and Shearer [2014,2015] demonstrated that standard spectral fitting techniques can lead to roughly 1 order of magnitude variation in stress-drop estimates that do not reflect the actual rupture properties even for simple crack models. We utilize these models to explore an alternative approach where we estimate the rupture area directly. For the suite of models, the area averaged static stress drop is nearly constant for models with the same underlying friction law, yet corner frequency based stress-drop estimates vary by a factor of 5-10 even for noise free data. Alternatively, we simulated inversions for the rupture area as parameterized by the second moments of the slip distribution. A natural estimate for the rupture area derived from the second moments is A=πLcWc, where Lc and Wc are the characteristic rupture length and width. This definition yields estimates of stress drop that vary by only 10% between the models but are slightly larger than the true area-averaged values. We simulate inversions for the second moments for the various models and find that the area can be estimated well when there are at least 15 available measurements of apparent duration at a variety of take-off angles. The improvement compared to azimuthally-averaged corner-frequency based approaches results from the second moments accounting for directivity and removing the assumption of a circular rupture area, both of which bias the standard approach. We also develop a new method that determines the minimum and maximum values of rupture area that are consistent with a particular dataset at the 95% confidence

  4. Time-Dependent Stress Rupture Strength Degradation of Hi-Nicalon Fiber-Reinforced Silicon Carbide Composites at Intermediate Temperatures

    Science.gov (United States)

    Sullivan, Roy M.

    2016-01-01

    The stress rupture strength of silicon carbide fiber-reinforced silicon carbide composites with a boron nitride fiber coating decreases with time within the intermediate temperature range of 700 to 950 degree Celsius. Various theories have been proposed to explain the cause of the time-dependent stress rupture strength. The objective of this paper is to investigate the relative significance of the various theories for the time-dependent strength of silicon carbide fiber-reinforced silicon carbide composites. This is achieved through the development of a numerically based progressive failure analysis routine and through the application of the routine to simulate the composite stress rupture tests. The progressive failure routine is a time-marching routine with an iterative loop between a probability of fiber survival equation and a force equilibrium equation within each time step. Failure of the composite is assumed to initiate near a matrix crack and the progression of fiber failures occurs by global load sharing. The probability of survival equation is derived from consideration of the strength of ceramic fibers with randomly occurring and slow growing flaws as well as the mechanical interaction between the fibers and matrix near a matrix crack. The force equilibrium equation follows from the global load sharing presumption. The results of progressive failure analyses of the composite tests suggest that the relationship between time and stress-rupture strength is attributed almost entirely to the slow flaw growth within the fibers. Although other mechanisms may be present, they appear to have only a minor influence on the observed time-dependent behavior.

  5. On the initiation of sustained slip-weakening ruptures by localized stresses

    KAUST Repository

    Galis, Martin

    2014-12-10

    Numerical simulations of dynamic earthquake rupture require an artificial initiation procedure, if they are not integrated in long-term earthquake cycle simulations. A widely applied procedure involves an \\'overstressed asperity\\', a localized region stressed beyond the static frictional strength. The physical properties of the asperity (size, shape and overstress) may significantly impact rupture propagation. In particular, to induce a sustained rupture the asperity size needs to exceed a critical value. Although criteria for estimating the critical nucleation size under linear slip-weakening friction have been proposed for 2-D and 3-D problems based on simplifying assumptions, they do not provide general rules for designing 3-D numerical simulations. We conduct a parametric study to estimate parameters of the asperity that minimize numerical artefacts (e.g. changes of rupture shape and speed, artificial supershear transition, higher slip-rate amplitudes). We examine the critical size of square, circular and elliptical asperities as a function of asperity overstress and background (off-asperity) stress. For a given overstress, we find that asperity area controls rupture initiation while asperity shape is of lesser importance. The critical area obtained from our numerical results contrasts with published theoretical estimates when background stress is low. Therefore, we derive two new theoretical estimates of the critical size under low background stress while also accounting for overstress. Our numerical results suggest that setting the asperity overstress and area close to their critical values eliminates strong numerical artefacts even when the overstress is large. We also find that properly chosen asperity size or overstress may significantly shorten the duration of the initiation. Overall, our results provide guidelines for determining the size of the asperity and overstress to minimize the effects of the forced initiation on the subsequent spontaneous

  6. Status of prototype rupture disc testing in the large leak test rig

    International Nuclear Information System (INIS)

    Amos, J.C.

    1979-09-01

    The prototype CRBRP double membrane rupture disc assembly is being performance tested in conjunction with the LLTR Series II Large Leak Program. In May 1979, the double membrane disc assembly was inadvertently activated during sodium system pressure instrument calibration. This experience indicated that the rupture disc burst at essentially the design burst pressure when a gradually increasing state pressure was applied. The area of membrane opening was found to be about 25 to 30% of the cross-sectional area. In July 1979, the disc assembly was again tested (this time in a single membrane configuration) in conjunction with the first LLTR Series II Test A-1a (inert gas injection). Test data indicated that the disc burst in about 35 ms at essentially the design burst pressure with an opening of about 30% of the cross-sectional area. The pressure immediately downstream of the disc dropped below atmospheric pressure following the rupture tube event (releasing high pressure nitrogen into sodium) for about 1.5 seconds before increasing to a maximum of 30 psig. This behavior raises a question on the adequacy of a downstream pressure device for rapid sensing of disc rupture and initiating plant shutdown following a large SWR event. 14 figures

  7. Effect of Environment on Stress-Rupture Behavior of a Carbon Fiber-Reinforced Silicon Carbide (C/SiC) Ceramic Matrix Composite

    Science.gov (United States)

    Verrilli, Michael J.; Opila, Elizabeth J.; Calomino, Anthony; Kiser, J. Douglas

    2002-01-01

    Stress-rupture tests were conducted in air, vacuum, and steam-containing environments to identify the failure modes and degradation mechanisms of a carbon fiber-reinforced silicon carbide (C/SiC) composite at two temperatures, 600 and 1200 C. Stress-rupture lives in air and steam containing environments (50 - 80% steam with argon) are similar for a composite stress of 69 MPa at 1200 C. Lives of specimens tested in a 20% steam/argon environment were about twice as long. For tests conducted at 600 C, composite life in 20% steam/argon was 20 times longer than life in air. Thermogravimetric analysis of the carbon fibers was conducted under similar conditions to the stress-rupture tests. The oxidation rate of the fibers in the various environments correlated with the composite stress-rupture lives. Examination of the failed specimens indicated that oxidation of the carbon fibers was the primary damage mode for specimens tested in air and steam environments at both temperatures.

  8. Improvement of stress-rupture property by Cr addition in Ni-based single crystal superalloys

    International Nuclear Information System (INIS)

    Chen, J.Y.; Feng, Q.; Cao, L.M.; Sun, Z.Q.

    2011-01-01

    Research highlights: → Cr improved the stress-rupture life of single crystal superalloys significantly. → Cr increased the Re partitioning ratio and resulted in more negative misfit. → Mechanism for improving the stress-rupture life by Cr addition is addressed here. - Abstract: The effects of Cr addition on the microstructure and stress-rupture property have been investigated in three experimental Ni-based single crystal superalloys containing various levels of Cr addition (0-5.7 wt.%). The Re partitioning ratio increased and the lattice misfit became more negative with increasing the Cr addition in both dendrite core and interdendritic region. The changes of elemental partitioning behaviors and the lattice misfit show good agreement with the change of γ' morphology. Cr addition increased the stress-rupture life at 1100 deg. C/140 MPa significantly due to higher γ' volume fraction, more negative lattice misfit and a well rafting structure as well as less width of γ channels. High Cr addition (5.7 wt.%) increased the degree of Re and Cr supersaturation in the γ phase and promoted the formation of topologically close-packed (TCP) phases significantly under thermal exposure and creep deformation at 1100 deg. C.

  9. Ruptured eardrum

    Science.gov (United States)

    ... eardrum ruptures. After the rupture, you may have: Drainage from the ear (drainage may be clear, pus, or bloody) Ear noise/ ... doctor to see the eardrum. Audiology testing can measure how much hearing has been lost. Treatment You ...

  10. Pseudodynamic Source Characterization for Strike-Slip Faulting Including Stress Heterogeneity and Super-Shear Ruptures

    KAUST Repository

    Mena, B.

    2012-08-08

    Reliable ground‐motion prediction for future earthquakes depends on the ability to simulate realistic earthquake source models. Though dynamic rupture calculations have recently become more popular, they are still computationally demanding. An alternative is to invoke the framework of pseudodynamic (PD) source characterizations that use simple relationships between kinematic and dynamic source parameters to build physically self‐consistent kinematic models. Based on the PD approach of Guatteri et al. (2004), we propose new relationships for PD models for moderate‐to‐large strike‐slip earthquakes that include local supershear rupture speed due to stress heterogeneities. We conduct dynamic rupture simulations using stochastic initial stress distributions to generate a suite of source models in the magnitude Mw 6–8. This set of models shows that local supershear rupture speed prevails for all earthquake sizes, and that the local rise‐time distribution is not controlled by the overall fault geometry, but rather by local stress changes on the faults. Based on these findings, we derive a new set of relations for the proposed PD source characterization that accounts for earthquake size, buried and surface ruptures, and includes local rise‐time variations and supershear rupture speed. By applying the proposed PD source characterization to several well‐recorded past earthquakes, we verify that significant improvements in fitting synthetic ground motion to observed ones is achieved when comparing our new approach with the model of Guatteri et al. (2004). The proposed PD methodology can be implemented into ground‐motion simulation tools for more physically reliable prediction of shaking in future earthquakes.

  11. Improvement of stress-rupture life of GTD-111 by second solution heat treatment

    International Nuclear Information System (INIS)

    Yang, Caixiong; Xu, Yulai; Zhang, Zixing; Nie, Heng; Xiao, Xueshan; Jia, Guoqing; Shen, Zhi

    2013-01-01

    Highlights: ► The second solution heat treatment promoted the solution of γ–γ′ eutectic into γ matrix. ► The volume fraction of γ′ increases significantly after adding the second solution heat treatment. ► The improved stress-rupture life is primarily due to the increased volume fraction of γ′ phase. -- Abstract: An added second solution heat treatment was conducted to investigate its effects on the microstructures and stress-rupture properties of GTD-111. The microstructures were analyzed by scanning electron microscope after each step of heat treatments. The stress-rupture life of GTD-111 dramatically increases from about 180 to 288 h at 871 °C/310 MPa after adding a second solution heat treatment. The added second solution heat treatment promoted the solution of γ–γ′ eutectic into γ matrix, and facilitated the nucleation and precipitate of the secondary γ′ particles. The distribution of γ′ phase becomes much denser, the width of γ matrix channel is also reduced, and the volume fraction of γ′ phase significantly increases from about 29.3% to 44.2%. The improved stress-rupture life is primarily due to the increased volume fraction of γ′ phase. The carbides mainly consist of MC and a small amount of M 23 C 6 , which may prevent the dislocation moving and/or grain boundary sliding, and further improve the stress-rupture properties of GTD-111.

  12. Steam line rupture experiments with the PPOOLEX test facility

    International Nuclear Information System (INIS)

    Laine, J.; Puustinen, M.

    2008-07-01

    The results of the steam line rupture experiment series in 2007 with the scaled down PPOOLEX test facility designed and constructed at Lappeenranta University of Technology are reported. The test facility is a closed stainless steel vessel divided into two compartments, dry well and wet well. Air was blown into the dry well compartment and from there through a DN200 blowdown pipe to the condensation pool. Altogether five experiments, each consisting of several blows (tests), were carried out. The main purpose of the experiment series was to study the initial phase of a postulated steam line break accident inside a BWR containment. Specifically, thermal stratification in the dry well compartment and ejection of water plug from the blowdown pipe were of interest. In addition, the effect of counterpressure on bubble dynamics was studied. A temperature difference of approximately 15 deg. C between the upper and lower part of the dry well was measured. In the wet well gas space, a temperature difference of more than 30 deg. C was registered. These were measured during the compression period of the tests. Towards the end of the tests the temperature differences tended to disappear. To get a more detailed picture of temperature distribution in the wet well, especially close to the water level, a dense net of measurements is required in future experiments. In longer experiments, heat conduction to structures and heat losses to surroundings should also be taken into account. Ejection of water plugs from the blowdown pipe did not cause notable loads to the structures due to the suppressing effect of the dry well compartment. The maximum measured pressure pulse at the pool bottom was only 10 kPa and the maximum strain amplitude at the pool bottom rounding was negligible both in axial and circumferential direction. As the counterpressure of the system increased, but the flow rate remained the same, the maximum size of the air bubbles at the blowdown pipe outlet got smaller and

  13. Steam line rupture experiments with the PPOOLEX test facility

    Energy Technology Data Exchange (ETDEWEB)

    Laine, J.; Puustinen, M. (Lappeenranta Univ. of Technology, Nuclear Safety Research Unit (Finland))

    2008-07-15

    The results of the steam line rupture experiment series in 2007 with the scaled down PPOOLEX test facility designed and constructed at Lappeenranta University of Technology are reported. The test facility is a closed stainless steel vessel divided into two compartments, dry well and wet well. Air was blown into the dry well compartment and from there through a DN200 blowdown pipe to the condensation pool. Altogether five experiments, each consisting of several blows (tests), were carried out. The main purpose of the experiment series was to study the initial phase of a postulated steam line break accident inside a BWR containment. Specifically, thermal stratification in the dry well compartment and ejection of water plug from the blowdown pipe were of interest. In addition, the effect of counterpressure on bubble dynamics was studied. A temperature difference of approximately 15 deg. C between the upper and lower part of the dry well was measured. In the wet well gas space, a temperature difference of more than 30 deg. C was registered. These were measured during the compression period of the tests. Towards the end of the tests the temperature differences tended to disappear. To get a more detailed picture of temperature distribution in the wet well, especially close to the water level, a dense net of measurements is required in future experiments. In longer experiments, heat conduction to structures and heat losses to surroundings should also be taken into account. Ejection of water plugs from the blowdown pipe did not cause notable loads to the structures due to the suppressing effect of the dry well compartment. The maximum measured pressure pulse at the pool bottom was only 10 kPa and the maximum strain amplitude at the pool bottom rounding was negligible both in axial and circumferential direction. As the counterpressure of the system increased, but the flow rate remained the same, the maximum size of the air bubbles at the blowdown pipe outlet got smaller and

  14. Weathering effects on tensile and stress rupture strength of glass fiber reinforced vinylester and epoxy thermoset pipes

    Science.gov (United States)

    Nizamuddin, Syed

    Glass fiber reinforced vinylester (GFRE) and epoxy (GFRE) pipes have been used for more than three decades to mitigate corrosion problems in oil fields, chemical and industrial plants. In these services, both GFRV and GFRE pipes are exposed to various environmental conditions. Long-term mechanical durability of these pipes after exposure to environmental conditions, which include natural weathering exposure to seasonal temperature variation, sea water, humidity and other corrosive fluids like crude oil, should be well known. Although extensive research has been undertaken, several major issues pertaining to the performance of these pipes under a number of environmental conditions still remain unresolved. The main objective of this study is to investigate the effects of natural weathering, combined natural weathering with seawater and crude oil exposure, for time periods ranging from 3 to 36 months respectively, on the tensile and stress rupture behavior of GFRV and GFRE pipes. Ring specimens are machined from GFRV and GFRE pipes and tested before and after exposure to different weathering conditions prevalent in the eastern region (Dhahran) of Saudi Arabia and present under service conditions. The natural weathering and combined natural weathering with crude oil exposure of GFRV specimens revealed increased tensile strength even after 36 months of exposure when compared with that of the as received samples. However, the combined natural weathering with seawater exposure of GFRV samples revealed better tensile behavior till 24 months of exposure, and after 36 months their tensile strength was seen to be below that of the as received GFRV samples. The stress rupture behavior of natural weather exposed GFRV samples showed an improvement after 12 months of exposure and it decreased after 24 and 36 months of exposure when compared with the as received GFRV samples. The combined natural weathering with crude oil and seawater exposure of GFRV sample revealed improved

  15. What Is Stress Testing?

    Science.gov (United States)

    ... would during exercise. You can then have the stress test. The medicine may make you flushed and anxious, but the effects go away as soon as the test is over. The medicine also may give you a headache. While you're exercising or getting medicine to ...

  16. In-reactor creep rupture of 20% cold-worked AISI 316 stainless steel

    International Nuclear Information System (INIS)

    Lovell, A.J.; Chin, B.A.; Gilbert, E.R.

    1981-01-01

    Results of an experiment designed to measure in-reactor stress-to-rupture properties of 20% cold-worked AISI 316 stainless steel are reported. The in-reactor rupture data are compared with postirradiation and unirradiated test results. In-reactor rupture lives were found to exceed rupture predictions of postirradiation tests. This longer in-reactor rupture life is attributed to dynamic point defect generation which is absent during postirradiation testing. The in-reactor stress-to-rupture properties are shown to be equal to or greater than the unirradiated material stress-to-rupture properties for times up to 7000 h. (author)

  17. A Critique of a Phenomenological Fiber Breakage Model for Stress Rupture of Composite Materials

    Science.gov (United States)

    Reeder, James R.

    2010-01-01

    Stress rupture is not a critical failure mode for most composite structures, but there are a few applications where it can be critical. One application where stress rupture can be a critical design issue is in Composite Overwrapped Pressure Vessels (COPV's), where the composite material is highly and uniformly loaded for long periods of time and where very high reliability is required. COPV's are normally required to be proof loaded before being put into service to insure strength, but it is feared that the proof load may cause damage that reduces the stress rupture reliability. Recently, a fiber breakage model was proposed specifically to estimate a reduced reliability due to proof loading. The fiber breakage model attempts to model physics believed to occur at the microscopic scale, but validation of the model has not occurred. In this paper, the fiber breakage model is re-derived while highlighting assumptions that were made during the derivation. Some of the assumptions are examined to assess their effect on the final predicted reliability.

  18. Pipe rupture test results; 6 in. pipe whip test under BWR LOCA conditions

    International Nuclear Information System (INIS)

    Kurihara, Ryoichi; Yano, Toshikazu; Ueda, Shuzo; Isozaki, Toshikuni; Miyazaki, Noriyuki; Kato, Rokuro; Miyazono, Shohachiro

    1983-02-01

    A series of pipe rupture tests has been performed in JAERI to demonstrate the safety of the primary coolant circuits in the event of pipe rupture, in nuclear power plants. The present report summarizes the results of 6 in. pipe whip tests (RUN 5605, 5606), under BWR LOCA conditions (285 0 C, 6.8 MPa), which were performed in August, 1981. The test pipe is made of Type 304 stainless steel and its outer diameter is 6 in. and its thickness is 11.1 mm. The restraints are made of Type 304 stainless steel and its diameter is 16.0 mm. Two restraints were set on the restraint support with clearance of 100 mm. Overhang length was varied as the parameter in these tests and was 300 mm or 700 mm. The following results are obtained. (1) The deformations of a pipe and restraints are limited effectively by shorter overhang length of 300. However, they become larger when the overhang length is 700 mm, and the pipe deforms especially at the setting point of restraints. (2) Velocity at the free end of pipe becomes about 30 m/sec just after the break. However, velocity at the setting point of restraint becomes about only 4 m/sec just after the break. (3) It seems from the comparison between the 4 in. tests and 6 in. tests that the maximum restraint force of 6 in. tests is about two times as large as that of 4 in. tests. (author)

  19. Nonexercise cardiac stress testing

    International Nuclear Information System (INIS)

    Vacek, J.L.; Baldwin, T.

    1989-01-01

    Many patients who require evaluation for coronary artery disease are unable to undergo exercise stress testing because of physiologic or psychological limitations. Drs Vacek and Baldwin describe three alternative methods for assessment of cardiac function in these patients, all of which have high levels of diagnostic sensitivity and specificity. 23 references

  20. The stress-tenogram in the diagnosis of ruptures of the lateral ligament of the ankle

    International Nuclear Information System (INIS)

    Evans, G.A.; Frenyo, S.D.

    1979-01-01

    The stress-tenogram is a radiological technique for the investigation of injuries to the lateral ligament of the ankle, and combines the information previously provided by inversion and anterior stress radiographs, and the peroneal tenogram. It is designed to differentiate between stable and unstable ankles, and between isolated ruptures of the anterior talofibular ligament and combined tears of the anterior talofibular and calcaneofibular ligaments. A high degree of diagnostic accuracy has been confirmed at operative repair in a group of thirty-two patients. (author)

  1. Effects of phosphorus on the δ-Ni3Nb phase precipitation and the stress rupture properties in alloy 718

    International Nuclear Information System (INIS)

    Sun, W.R.; Guo, S.R.; Hu, Z.Q.; Park, N.K.; Yoo, Y.S.; Choe, S.J.

    1998-01-01

    The effects of phosphorus on the phase transformation and stress rupture properties of alloy 718 were investigated. The nucleation of δ-phase, which does not contain phosphorus, was suppressed by the enrichment of phosphorus at grain boundaries. A low level of phosphorus resulted in the formation of faults-containing film-like δ-phase along the grain boundaries, while a higher level of phosphorus favored the long lath-like δ-phase precipitation. Phosphorus greatly prolonged the stress rupture life of the alloy in the range of 0.0008-0.013 wt.%, while it reduced the stress rupture life in the range of 0.013-0.049 wt.%. The effect of phosphorus on the stress rupture properties was closely related to its interaction with oxygen. Phosphorus atoms, in the range of 0.0008-0.013 wt.%, enhanced the resistance to oxygen intrusion along the grain boundaries, protected the grain boundaries from decohesion by oxygen atoms and oxidation, and subsequently prolonged the rupture life of the alloy. The protection effect of P is clearly demonstrated by the phenomenon that the crack initiation site was shifted from the surface to the center in the stress-ruptured samples with increasing addition of P. Over 0.013 wt.%, the protection effect of phosphorus is excessive and phosphorus began to display its inherent effect of damaging the grain boundary strength: the stress rupture life of the alloy was reduced accordingly. Maximum stress rupture life was thus obtained at ∼0.013 wt.% P. (orig.)

  2. Critique of the Ford-Andresen film rupture model for aqueous stress corrosion cracking

    International Nuclear Information System (INIS)

    Hall, M.M.

    2009-01-01

    The Ford-Andresen film rupture model for aqueous stress corrosion cracking has obtained a prominent position in the nuclear reactor industry. The model is said to have superior predictive capabilities because it is derived from a fundamental understanding of the film rupture-repassivation mechanism of crack advance. However, a critical review shows that there are conceptual and mathematical problems with the Ford-Andresen model development; there are inconsistencies among the stated and implied assumptions, the crack tip current density expression lacks the necessary dependence on crack tip strain rate and the fundamental proportionality that exists between crack tip strain rate and crack growth rate is overlooked and omitted from the model development. Consequently, the Ford-Andresen model must be considered neither phenomenologically nor fundamentally supported.

  3. A Modified Split Hopkinson Pressure Bar Approach for Mimicking Dynamic Oscillatory Stress Fluctuations During Earthquake Rupture

    Science.gov (United States)

    Braunagel, M. J.; Griffith, W. A.

    2017-12-01

    Past experimental work has demonstrated that rock failure at high strain rates occurs by fragmentation rather than discrete fracture and is accompanied by a dramatic increase in rock strength. However, these observations are difficult to reconcile with the assertion that pulverized rocks in fault zones are the product of impulsive stresses during the passage of earthquake ruptures, as the distance from the principal slip zones of some pulverized rock is too great to exceed fragmentation transition. One potential explanation to this paradox that has been suggested is that repeated loading over the course of multiple earthquake ruptures may gradually reduce the pulverization threshold, in terms of both strain rate and strength. We propose that oscillatory loading during a single earthquake rupture may further lower these pulverization thresholds, and that traditional dynamic experimental approaches, such as the Split Hopkinson Pressure Bar (SHPB) wherein load is applied as a single, smooth, sinusoidal compressive wave, may not reflect natural loading conditions. To investigate the effects of oscillatory compressive loading expected during earthquake rupture propagation, we develop a controlled cyclic loading model on a SHPB apparatus utilizing two striker bars connected by an elastic spring. Unlike traditional SHPB experiments that utilize a gas gun to fire a projectile bar and generate a single compressive wave on impact with the incident bar, our modified striker bar assembly oscillates while moving down the gun barrel and generates two separate compressive pulses separated by a lag time. By modeling the modified assembly as a mass-spring-mass assembly accelerating due to the force of the released gas, we can predict the compression time of the spring upon impact and therefore the time delay between the generation of the first and second compressive waves. This allows us to predictably control load cycles with durations of only a few hundred microseconds. Initial

  4. Elevated temperature design of KALIMER reactor internals accounting for creep and stress-rupture effects

    International Nuclear Information System (INIS)

    Koo, Gyeong Hoi; Yoo, Bong

    2000-01-01

    In most LMFBR (Liquid Metal Fast Breed Reactor) design, the operating temperature is very high and the time-dependent creep and stress-rupture effects become so important in reactor structural design. Therefore, unlike with conventional PWR, the normal operating conditions can be basically dominant design loading because the hold time at elevated temperature condition is so long and enough to result in severe total creep ratcheting strains during total service lifetime. In this paper, elevated temperature design of the conceptually designed baffle annulus regions of KALIMER (Korea Advanced Liquid Metal Reactor) reactor internal structures is carried out for normal operating conditions which have the operating temperature 530 deg. C and the total service lifetime of 30 years. For the elevated temperature design of reactor internal structures, the ASME Code Case N-201-4 is used. Using this code, the time-dependent stress limits, the accumulated total inelastic strain during service lifetime, and the creep-fatigue damages are evaluated with the calculation results by the elastic analysis under conservative assumptions. The application procedures of elevated temperature design of the reactor internal structures using ASME code case N-201-4 with the elastic analysis method are described step by step in detail. This paper will be useful guide for actual application of elevated temperature design of various reactor types accounting for creep and stress-rupture effects. (author)

  5. Oxidative stress damage-associated molecular signaling pathways differentiate spontaneous preterm birth and preterm premature rupture of the membranes.

    Science.gov (United States)

    Dutta, Eryn H; Behnia, Faranak; Boldogh, Istvan; Saade, George R; Taylor, Brandie D; Kacerovský, Marian; Menon, Ramkumar

    2016-02-01

    In women with preterm premature rupture of the membranes (PPROM), increased oxidative stress may accelerate premature cellular senescence, senescence-associated inflammation and proteolysis, which may predispose them to rupture. We demonstrate mechanistic differences between preterm birth (PTB) and PPROM by revealing differences in fetal membrane redox status, oxidative stress-induced damage, distinct signaling pathways and senescence activation. Oxidative stress-associated fetal membrane damage and cell cycle arrest determine adverse pregnancy outcomes, such as spontaneous PTB and PPROM. Fetal membranes and amniotic fluid samples were collected from women with PTB and PPROM. Molecular, biochemical and histologic markers were used to document differences in oxidative stress and antioxidant enzyme status, DNA damage, secondary signaling activation by Ras-GTPase and mitogen-activated protein kinases, and activation of senescence between membranes from the two groups. Oxidative stress was higher and antioxidant enzymes were lower in PPROM compared with PTB. PTB membranes had minimal DNA damage and showed activation of Ras-GTPase and ERK/JNK signaling pathway with minimal signs of senescence. PPROM had higher numbers of cells with DNA damage, prosenescence stress kinase (p38 MAPK) activation and signs of senescence. Samples were obtained retrospectively after delivery. The markers of senescence that we tested are specific but are not sufficient to confirm senescence as the pathology in PPROM. Oxidative stress-induced DNA damage and senescence are characteristics of fetal membranes from PPROM, compared with PTB with intact membranes. PTB and PPROM arise from distinct pathophysiologic pathways. Oxidative stress and oxidative stress-induced cellular damages are likely determinants of the mechanistic signaling pathways and phenotypic outcome. This study is supported by developmental funds to Dr R. Menon from the Department of Obstetrics and Gynecology at The University of

  6. Prediction of long time creep rupture properties of welded joints using the results of short duration creep crack incubation tests

    Energy Technology Data Exchange (ETDEWEB)

    Hosseini, E.

    2013-07-01

    This dissertation submitted to the Swiss Federal Institute of Technology ETH in Zurich examines the applicability of the LICON methodology for the prediction of long-time creep rupture strength of a dissimilar metal weld. The LICON methodology is an approach for predicting the lifetime of materials under creep loading conditions. It predicts long-time uniaxial creep strength using the results from several short duration creep crack incubation tests in conjunction with the outcome of a mechanical analysis on the test-piece. This study has re-examined the previous application of the LICON methodology for 9%Cr and 1CrMoV steels. It has shown that application of the original Lion method (based on reference stress solutions) for certain materials is not appropriate. This study therefore proposes a new development for the Lion approach which uses finite-element analysis to account for the generated multiaxial stress states within welded uniaxial test-pieces.

  7. Prediction of long time creep rupture properties of welded joints using the results of short duration creep crack incubation tests

    International Nuclear Information System (INIS)

    Hosseini, E.

    2013-01-01

    This dissertation submitted to the Swiss Federal Institute of Technology ETH in Zurich examines the applicability of the LICON methodology for the prediction of long-time creep rupture strength of a dissimilar metal weld. The LICON methodology is an approach for predicting the lifetime of materials under creep loading conditions. It predicts long-time uniaxial creep strength using the results from several short duration creep crack incubation tests in conjunction with the outcome of a mechanical analysis on the test-piece. This study has re-examined the previous application of the LICON methodology for 9%Cr and 1CrMoV steels. It has shown that application of the original Lion method (based on reference stress solutions) for certain materials is not appropriate. This study therefore proposes a new development for the Lion approach which uses finite-element analysis to account for the generated multiaxial stress states within welded uniaxial test-pieces

  8. Stress Rupture and Precipitation Behavior of TP310HCbN(HR3C for Supercritical Boilers

    Directory of Open Access Journals (Sweden)

    FANG Xu-dong

    2017-06-01

    Full Text Available Using persistent experiment method, combined with Gleeble,hardness analysis, SEM, EDS, TEM and other analytical methods, the hot deformation, stress rupture and precipitation behavior of TP310HCbN heat resistance steel was analysed at 650℃ and 700℃, the results show that:the change of the hardness is not obviously under two different stress rupture temperature; with stress rupture time prolongs, TP310HCbN heat-resistant steel intragranular precipitates from granular into rod-shaped, and presence of wormlike NbCrN rich precipitates and dislocation interactions; Taiyuan Iron and Steel production of TP310HCbN heat-resistant steel at 650/700℃-100000h extrapolation lasting strength meet the standard requirements.

  9. Investigation into Mechanism of Floor Dynamic Rupture by Evolution Characteristics of Stress and Mine Tremors: A Case Study in Guojiahe Coal Mine, China

    Directory of Open Access Journals (Sweden)

    Guangjian Liu

    2018-01-01

    Full Text Available In order to explore the mechanism of floor dynamic rupture, the current study adopts a thin plate model to further investigate the condition of floor failure. One of the possible explanations could be floor buckling due to high horizontal stress and dynamic disturbance ultimately leading to rapid and massive release of elastic energy thus inducing dynamic rupture. Seismic computed tomography and 3D location were employed to explore the evolution characteristics of floor stress distribution and positions of mine tremors. In the regions of floor dynamic rupture, higher P-wave velocity was recorded prior to the dynamic rupture. On the contrary, relatively lower reading was observed after the dynamic rupture thus depicting a high stress concentration condition. Meanwhile, evolution of mine tremors revealed the accumulation and subsequent release of energy during the dynamic rupture process. It was further revealed that dynamic rupture was induced due to the superposition of static and dynamic stresses: (i the high static stress concentration due to frontal and lateral abutment stress from coal pillar and (ii dynamic stress from the fracture and caving of coal pillar, hard roof, and key stratum. In the later part of this study, the floor dynamic rupture occurrence process would be reproduced through numerical simulations within a 0.6 sec time frame. The above-mentioned findings would be used to propose a feasible mechanism for prewarning and prevention of floor dynamic rupture using seismic computed tomography and mine tremors 3D location.

  10. Evaluation of tube rupture simulation test (TRUST-1) for FBR steam generators

    Energy Technology Data Exchange (ETDEWEB)

    Hayashida, Yoshihiko; Hamada, Hirotsugu [Power Reactor and Nuclear Fuel Development Corp., Oarai, Ibaraki (Japan). Oarai Engineering Center

    1996-06-01

    The intermediate water leak in an FBR Steam Generator (SG) causes a high temperature and corrosive sodium-water reaction jet. In such cases, it is necessary to evaluate the wastage and overheating rupture behavior of heat transfer tubes. Especially, in the large SG that aims at high temperature of sodium and high temperature/pressure of water, the establishment of the rational evaluation method is important. In this paper, as a basic experiment to make clear the phenomenon of overheating rupture, tests and analysis of Tube Rupture Simulation Test-1 (TRUST-1) were conducted. TRUST-1 simulates the overheating rupture of the tube made of Mod.9Cr-1Mo steel by nitrogen gas pressurization and quick induction heating. The result of TRUST-1 are as follows: (1) The breaking strength predicted by the internal pressure is larger than the tensile strength of the tube material. (2) The margin of the breaking strength from the tensile strength of the tube material has a tendency of decreasing with the heating rate, especially in the lower temperature region. (3) Using an theoretical formula that is deduced from the steady creep model and appropriate experimental coefficients that are determined by the test data, the breaking strength can be reasonably evaluated. (author)

  11. The creep and stress-rupture behaviour under internal pressure of tubes made from austenitic stainless steel X8 CrNiMoNb 1616 (Material No. 1.4981)

    International Nuclear Information System (INIS)

    Schaefer, L.; Polifka, F.; Kempe, H.

    1979-05-01

    Creep and stress rupture tests have been performed at 600, 650, 700 and 750 0 C on tubes made from three different heats from the austenitic stainless steel X8 CrNiMoNb 1616 (Material No. 1.4981). The tubes were loaded by internal pressure and the tangential (hoop) creep strain was measured continuously. The results are presented in form of creep curves, stress-time to rupture curves and curves for a creep limit. The average and minimum creep rates as a function of the applied stress have been evaluated and are described with a creep law analogous to Norton's creep law. An interpolation and extrapolation of the stress-rupture-strength and the creep strength are possible using the time-temperature-parameter-plot after Larson and Miller. (orig.) [de

  12. Modelling ground rupture due to groundwater withdrawal: applications to test cases in China and Mexico

    Science.gov (United States)

    Franceschini, A.; Teatini, P.; Janna, C.; Ferronato, M.; Gambolati, G.; Ye, S.; Carreón-Freyre, D.

    2015-11-01

    The stress variation induced by aquifer overdraft in sedimentary basins with shallow bedrock may cause rupture in the form of pre-existing fault activation or earth fissure generation. The process is causing major detrimental effects on a many areas in China and Mexico. Ruptures yield discontinuity in both displacement and stress field that classic continuous finite element (FE) models cannot address. Interface finite elements (IE), typically used in contact mechanics, may be of great help and are implemented herein to simulate the fault geomechanical behaviour. Two main approaches, i.e. Penalty and Lagrangian, are developed to enforce the contact condition on the element interface. The incorporation of IE incorporation into a three-dimensional (3-D) FE geomechanical simulator shows that the Lagrangian approach is numerically more robust and stable than the Penalty, thus providing more reliable solutions. Furthermore, the use of a Newton-Raphson scheme to deal with the non-linear elasto-plastic fault behaviour allows for quadratic convergence. The FE - IE model is applied to investigate the likely ground rupture in realistic 3-D geologic settings. The case studies are representative of the City of Wuxi in the Jiangsu Province (China), and of the City of Queretaro, Mexico, where significant land subsidence has been accompanied by the generation of several earth fissures jeopardizing the stability and integrity of the overland structures and infrastructure.

  13. Does the Lever Sign Test Have Added Value for Diagnosing Anterior Cruciate Ligament Ruptures?

    Science.gov (United States)

    Lichtenberg, Miranda C.; Koster, Christiaan H.; Teunissen, Lennart P.J.; Oosterveld, Frits G.J.; Harmsen, Annelieke M.K.; Haverkamp, Daniel; Hoornenborg, Daniel; Berg, Robert P.; Bloemers, Frank W.; Faber, Irene R.

    2018-01-01

    Background: Diagnosing an anterior cruciate ligament (ACL) rupture based on a physical examination remains a challenge for both surgeons and physical therapists. The lever sign test was developed to overcome the practical limitations of other tests and to optimize diagnosis. An evaluation of the measurement properties of the lever sign test is needed to make adequate interpretations in practice. Purpose: To evaluate the reliability and diagnostic value of the lever sign test. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: A total of 94 patients were recruited between November 2014 and July 2016. Patients were included if they were at least 16 years old, suffered from knee trauma, and had indications for knee arthroscopic surgery. Lever sign, anterior drawer, Lachman, and pivot-shift test outcomes were examined by an orthopaedic/trauma surgeon and a physical therapist. A test-retest design was used to investigate interrater reliability. Moreover, the lever sign test outcomes, alone and in combination with the other diagnostic tests, were compared with arthroscopic results, which served as the gold standard for the test’s diagnostic value. Results: The lever sign test and pivot-shift test had kappa values exceeding 0.80 for interrater reliability. The kappa values for the anterior drawer test and Lachman test were 0.80 and 0.77, respectively. The lever sign test showed the highest specificity (100%) and the lowest sensitivity (39%) when compared with the other 3 tests. Moreover, its positive and negative predictive values were 100% and 65%, respectively, while an accuracy of 71% was calculated. Clustering the lever sign test parallel with the other 3 tests resulted in the highest accuracy of 91%. Conclusion: The lever sign test appears to have high interrater reliability and is the most specific test, showing a maximal positive predictive value. A positive lever sign test result indicates an ACL rupture. These results support the added value

  14. Storage of spent fuels: implementation of a research program on the risk of waste container rupture due to stress corrosion induced by fission products

    International Nuclear Information System (INIS)

    Parise, M.; Walle, E.; Foct, J.

    2001-01-01

    The following topics were dealt with: research programm on stress corrosion of spent fuel casks materials due to fission products, such as iodine, chemical interactions with zirconium, chemical aspects of stress corrosion, rupture risk assessment

  15. Experiment data report for semiscale Mod-1 test S-28-2 (steam generator tube rupture test)

    International Nuclear Information System (INIS)

    Patton, M.L.; Sackett, K.E.

    1977-10-01

    Recorded test data are presented for Test S-28-2 of the Semiscale Mod-1 steam generator tube rupture test series. These tests are among several Semiscale Mod-1 experiments conducted to investigate the thermal and hydraulic phenomena accompanying a hypothesized loss-of-coolant accident in a pressurized water reactor (PWR) system. Test S-28-2 was conducted from initial conditions of 15 936 kPa and 558 K to investigate the response of the Semiscale Mod-1 system to a depressurization and reflood transient following a simulated double-ended offset shear of the broken loop cold leg piping. During the test, cooling water was injected into the cold leg of the intact and broken loops to simulate emergency core coolant injection in a PWR. For Test S-28-2, accumulator injection into the intact loop hot leg was provided to simulate simulate the rupture of six steam generator tubes

  16. Accelerated Stress-Corrosion Testing

    Science.gov (United States)

    1986-01-01

    Test procedures for accelerated stress-corrosion testing of high-strength aluminum alloys faster and provide more quantitative information than traditional pass/fail tests. Method uses data from tests on specimen sets exposed to corrosive environment at several levels of applied static tensile stress for selected exposure times then subsequently tensile tested to failure. Method potentially applicable to other degrading phenomena (such as fatigue, corrosion fatigue, fretting, wear, and creep) that promote development and growth of cracklike flaws within material.

  17. Five Tubes Rupture at Cold Side of Steam Generator Simulation Test Report Using the ATLAS

    International Nuclear Information System (INIS)

    Kang, Kyoung Ho; Park, Hyun Sik; Cho, Seok

    2010-12-01

    In this study, a postulated SGTR event of the APR1400 was experimentally investigated with the ATLAS. In order to simulate a double-ended rupture of five U-tubes in the APR1400, the SGTR-CL-02 test was performed with the ATLAS. The main objectives of this test were not only to provide a physical insight into the system response of the APR1400 during the SGTR but also to produce integral effect experimental data to validate the safety analysis code. In the present report, major thermal-hydraulic phenomena such as the system pressures, the collapsed water levels, and the break flow rate were presented and discussed. Compared to the case of a single U-tube rupture test, opening frequency of the MSSVs in the intact steam generator (SG-2) was highly reduced after 500 seconds in the present SGTR-CL-02 test. Large discharge of the primary inventory resulted in rapid depressurization of the primary system and consequently early injection of the SIP. Supply of cold ECC water by the SIPs reduced the energy transfer to the secondary side compared with the single U-tube rupture case. Less heat transfer to the secondary side had more influence on the secondary pressure of the affected steam generator than the break flow. This integral effect test data will be used to evaluate the prediction capability of existing safety analysis codes of the MARS and the RELAP5 as well as the SPACE code

  18. Five Tubes Rupture at Hot Side of Steam Generator Simulation Test Report Using the ATLAS

    International Nuclear Information System (INIS)

    Kang, Kyoung Ho; Park, Hyun Sik; Cho Seok

    2010-12-01

    In this study, a postulated SGTR event of the APR1400 was experimentally investigated with the ATLAS. In order to simulate a double-ended rupture of five U-tubes in the APR1400, the SGTR-HL-05 test was performed with the ATLAS. The main objectives of this test were not only to provide a physical insight into the system response of the APR1400 during the SGTR but also to produce integral effect experimental data to validate the SPACE code. In the present report, major thermal-hydraulic phenomena such as the system pressures, the collapsed water levels, and the break flow rate were presented and discussed. On the contrary to the case of a single U-tube rupture test, the MSSV of the intact steam generator was not opened any more after 1500 seconds in the present SGTR-HL-05 test. Large discharge of the primary inventory resulted in rapid depressurization of the primary system and consequently early injection of the SIP. Supply of cold ECC water by the SIPs reduced the energy transfer to the secondary side compared with the single U-tube rupture case. Less heat transfer to the secondary side had more influence on the secondary pressure of the affected steam generator than the break flow. This integral effect test data will be used to evaluate the prediction capability of existing safety analysis codes of the MARS and the RELAP5 as well as the SPACE code

  19. Experiment data report for Semiscale Mod-1 test S-28-3 (steam generator tube rupture test)

    International Nuclear Information System (INIS)

    Gillins, R.L.; Sackett, K.E.

    1977-10-01

    Recorded test data are presented for Test S-28-3 of the Semiscale Mod-1 steam generator tube rupture test series. These tests are among several Semiscale Mod-1 experiments conducted to investigate the thermal and hydraulic phenomena accompanying a hypothesized loss-of-coolant accident in a pressurized water reactor (PWR) system. Test S-28-3 was conducted from initial conditions of 15621 kPa and 555 K to investigate the response of the Semiscale Mod-1 system to a depressurization and reflood transient following a simulated double-ended offset shear of the broken loop cold leg piping. During the test, cooling water was injected into the cold leg of the intact and broken loops to simulate emergency core coolant injection in a PWR. Twelve steam generator tube ruptures were simulated by a controlled injection from a heated accumulator into the intact loop hot leg

  20. Experiment data report for Semiscale Mod-1 Test S-28-1 (steam generator tube rupture test series)

    International Nuclear Information System (INIS)

    Collins, B.L.; Coppin, C.E.; Sackett, K.E.

    1977-10-01

    Recorded test data are presented for Test S-28-1 of the Semiscale Mod-1 steam generator tube rupture test series. These tests are among several Semiscale Mod-1 experiments conducted to investigate the thermal and hydraulic phenomena accompanying a hypothesized loss-of-coolant accident in a pressurized water reactor (PWR) system. Test S-28-1 was conducted from initial conditions of 15 767 kPa and 557 K to investigate the response of the Semiscale Mod-1 system to a depressurization and reflood transient following a simulated double-ended offset shear of the broken loop cold leg piping. During the test, cooling water was injected into the cold leg of the intact and broken loops to simulate emergency core coolant injection in a PWR. Sixty steam generator tube ruptures were simulated by a controlled injection from a heated accumulator into the intact loop hot leg

  1. Experiment data report for semiscale Mod-1 test S-28-4 (steam generator tube rupture test)

    International Nuclear Information System (INIS)

    Esparza, V.; Sackett, K.E.

    1977-10-01

    Recorded test data are presented for Test S-28-4 of the Semiscale Mod-1 steam generator tube rupture test series. These tests are among several Semiscale Mod-1 experiments conducted to investigate the thermal and hydraulic phenomena accompanying a hypothesized loss-of-coolant accident in a pressurized water reactor (PWR) system. Test S-28-4 was conducted from initial conditions of 15 646 kPa and 557 K to investigate the response of the Semiscale Mod-1 system to a depressurization and reflood transient following a simulated double-ended offset shear of the broken loop cold leg piping. During the test, cooling water was injected into the cold leg of the intact and broken loops to simulate emergency core coolant injection in a PWR. Thirty steam generator tube ruptures were simulated by a controlled injection from a heated accumulator into the intact loop hot leg

  2. Credibility and Crisis Stress Testing

    Directory of Open Access Journals (Sweden)

    Li Lian Ong

    2014-02-01

    Full Text Available Credibility is the bedrock of any crisis stress test. The use of stress tests to manage systemic risk was introduced by the U.S. authorities in 2009 in the form of the Supervisory Capital Assessment Program. Since then, supervisory authorities in other jurisdictions have also conducted similar exercises. In some of those cases, the design and implementation of certain elements of the framework have been criticized for their lack of credibility. This paper proposes a set of guidelines for constructing an effective crisis stress test. It combines financial markets impact studies of previous exercises with relevant case study information gleaned from those experiences to identify the key elements and to formulate their appropriate design. Pertinent concepts, issues and nuances particular to crisis stress testing are also discussed. The findings may be useful for country authorities seeking to include stress tests in their crisis management arsenal, as well as for the design of crisis programs.

  3. Rehabilitation of the gas pipeline that had a rupture in service caused by SCC (Stress Corrosion C raking); Rehabilitacion al servicio de un gasoducto que ha sufrido una ruptura en servicio por SCC

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Fernando; Carzoglio, Eduardo; Hryciuk, Pedro [TGN - Transportadora de Gas del Norte S.A. (Argentina). Depto. de Integridad

    2003-07-01

    TGN had a rupture in service on Gasoducto Troncal Norte. After initial evaluation of the causes of the rupture it was concluded that it had been caused by Stress Corrosion Cracking (SCC). Subsequent investigation in the area of the rupture revealed that colonies of cracks, typical of SCC were found in pipes located near the rupture. In order to put back in service the pipeline in a safety condition, SCC mitigation activities were performed. A decision was made to conduct a hydro test along approximately 30 kilometers of pipe. The stages of the works, the problems faced and the solutions found are dealt with, as well as the conclusions reached upon completion of the works which allowed a better understanding of SCC phenomenon. The methodology for the identification of those areas susceptible to SCC is also described. (author)

  4. Predicting creep rupture from early strain data

    International Nuclear Information System (INIS)

    Holmstroem, Stefan; Auerkari, Pertti

    2009-01-01

    To extend creep life modelling from classical rupture modelling, a robust and effective parametric strain model has been developed. The model can reproduce with good accuracy all parts of the creep curve, economically utilising the available rupture models. The resulting combined model can also be used to predict rupture from the available strain data, and to further improve the rupture models. The methodology can utilise unfailed specimen data for life assessment at lower stress levels than what is possible from rupture data alone. Master curves for creep strain and rupture have been produced for oxygen-free phosphorus-doped (OFP) copper with a maximum testing time of 51,000 h. Values of time to specific strain at given stress (40-165 MPa) and temperature (125-350 deg. C) were fitted to the models in the strain range of 0.1-38%. With typical inhomogeneous multi-batch creep data, the combined strain and rupture modelling involves the steps of investigation of the data quality, extraction of elastic and creep strain response, rupture modelling, data set balancing and creep strain modelling. Finally, the master curves for strain and rupture are tested and validated for overall fitting efficiency. With the Wilshire equation as the basis for the rupture model, the strain model applies classical parametric principles with an Arrhenius type of thermal activation and a power law type of stress dependence for the strain rate. The strain model also assumes that the processes of primary and secondary creep can be reasonably correlated. The rupture model represents a clear improvement over previous models in the range of the test data. The creep strain information from interrupted and running tests were assessed together with the rupture data investigating the possibility of rupture model improvement towards lower stress levels by inverse utilisation of the combined rupture based strain model. The developed creep strain model together with the improved rupture model is

  5. Stress Tests and Vulnerability Assessment

    International Nuclear Information System (INIS)

    Wallner, A.; Lorenz, P.

    2012-01-01

    After the accident in Fukushima, nuclear safety as topic in anti-nuclear work has gained importance within the Joint Project countries. Therefore, nuclear safety and in particular the activities of the European stress tests were chosen to be the main focus of the Joint Project 2011/2012 as well as the common theme of the national projects. This brochure describes: A) Vulnerability Assessment A critical review of the EU Nuclear Stress Tests in Bulgaria, Hungary, Romania and Ukraine is presented in chapter 1. The review details the main weaknesses identified within the stress tests. Important shortcomings not mentioned in the stress tests reports are also discussed. These evaluations do not claim to be exhaustive, but the findings contribute to a more comprehensive understanding of safety and risk of nuclear power plants in Europe. B) Transparency of the stress tests In chapter 2 the experience of the Joint Project NGOs concerning transparency of the stress tests is presented. The information is not meant to be an evaluation of the transparency of the stress tests in general – such an evaluation is not possible within the scope of this brochure. The evaluation aims to show activities concerning stress tests and how they were conceived by the JP NGOs. Some recommendations for improvement are given. C) Safety focus Within the main topic “nuclear safety” of the Joint Project 2011/2012 the NGOs of each JP country selected a special safety relevant topic, which is/was of particular interest in their country: Bulgaria: The short story of Belene NPP – The victory – Key points of the campaign against the nuclear power plant Romania: Risks of the CANDU reactor design Czech Republic: Results of the conference “Power Plant Load Testing: Safety Inspection or Propaganda?“ Slovakia: Safety deficits of the NPP Mochovce These safety relevant issues are discussed in separate sections within the brochure at hand. (author)

  6. Stress Tests and Vulnerability Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Wallner, A. [Austrian Institute of Ecology, Vienna (Austria); Lorenz, P. [ed.; Becker, O. [eds.; Weber, U. [Austrian Institute of Ecology, Vienna (Austria)

    2012-07-01

    After the accident in Fukushima, nuclear safety as topic in anti-nuclear work has gained importance within the Joint Project countries. Therefore, nuclear safety and in particular the activities of the European stress tests were chosen to be the main focus of the Joint Project 2011/2012 as well as the common theme of the national projects. This brochure describes: A) Vulnerability Assessment A critical review of the EU Nuclear Stress Tests in Bulgaria, Hungary, Romania and Ukraine is presented in chapter 1. The review details the main weaknesses identified within the stress tests. Important shortcomings not mentioned in the stress tests reports are also discussed. These evaluations do not claim to be exhaustive, but the findings contribute to a more comprehensive understanding of safety and risk of nuclear power plants in Europe. B) Transparency of the stress tests In chapter 2 the experience of the Joint Project NGOs concerning transparency of the stress tests is presented. The information is not meant to be an evaluation of the transparency of the stress tests in general – such an evaluation is not possible within the scope of this brochure. The evaluation aims to show activities concerning stress tests and how they were conceived by the JP NGOs. Some recommendations for improvement are given. C) Safety focus Within the main topic “nuclear safety” of the Joint Project 2011/2012 the NGOs of each JP country selected a special safety relevant topic, which is/was of particular interest in their country: Bulgaria: The short story of Belene NPP – The victory – Key points of the campaign against the nuclear power plant Romania: Risks of the CANDU reactor design Czech Republic: Results of the conference “Power Plant Load Testing: Safety Inspection or Propaganda?“ Slovakia: Safety deficits of the NPP Mochovce These safety relevant issues are discussed in separate sections within the brochure at hand. (author)

  7. Ultrasound elastography of the lower uterine segment in women with a previous cesarean section: Comparison of in-/ex-vivo elastography versus tensile-stress-strain-rupture analysis.

    Science.gov (United States)

    Seliger, Gregor; Chaoui, Katharina; Lautenschläger, Christine; Jenderka, Klaus-Vitold; Kunze, Christian; Hiller, Grit Gesine Ruth; Tchirikov, Michael

    2018-06-01

    The purpose of this study was to assess, if the biomechanical properties of the lower uterine segment (LUS) in women with a previous cesarean section (CS) can be determined by ultrasound (US) elastography. The first aim was to establish an ex-vivo LUS tensile-stress-strain-rupture(break point) analysis with the possibility of simultaneously using US elastography. The second aim was to investigate the relationship between measurement results of LUS stiffness using US elastography in-/ex-vivo with results of tensile-stress-strain-rupture analysis, and to compare different US elastography LUS-stiffness-measurement methods ex-vivo. An explorative experimental, in-/ex-vivo US study of women with previous CS was conducted. LUS elasticity was measured by point Shear Wave Elastography (pSWE) and bidimensional Shear-Wave-Elastography (2D-SWE) first in-vivo during preoperative examination within 24 h before repeat CS (including resection of the thinnest part of the LUS = uterine scar area during CS), second within 1 h after operation during the ex-vivo experiment, followed by tensile-stress-strain-rupture analysis. Pearson's correlation coefficient and scatter plots, Bland-Altman plots and paired T-tests, were used. Thirty three women were included in the study; elastography measurements n = 1412. The feasibility of ex-vivo assessment of LUS by quantitative US elastography using pSWE and 2D-SWE to detect stiffness of LUS was demonstrated. The strongest correlation with tensile-stress-strain analysis was found in the US elastography examination carried out with 2D-SWE (0.78, p break point - as a surrogate marker for the risk of rupture of the LUS after CS - is linearly dependent on the thickness of the LUS in the scar area (Coefficient of correlation: 0.79, p even at less stroke/strain than would be expected by their thickness. This study confirms that US elastography can help in determining viscoelastic properties of the LUS in women with a previous CS. The

  8. Coupling effects of tungsten and molybdenum on microstructure and stress-rupture properties of a nickel-base cast superalloy

    Directory of Open Access Journals (Sweden)

    Tongjin Zhou

    2018-02-01

    Full Text Available In order to comprehensively understand the forming mechanism of abnormal phases solidified in a nickel-base cast superalloy with additives of tungsten and molybdenum, the coupling effects of W and Mo on the microstructure and stress-rupture properties were investigated in this paper. The results indicated that the precipitation of primary α-(W, Mo phase depended tremendously on the amount of W and Mo addition. When the total amount of W and Mo was greater than 5.79 at%, α-(W, Mo phase became easily precipitated in the alloy. With increasing of Mo/W ratio, the dendrite-like α-(W, Mo phases were apt to convert into small bars or blocky-like phases at the vicinities of γ′/γ eutectic. The morphological changes of α-(W, Mo phase can be interpreted as the non-equilibrium solidification of W and Mo in the alloy. Since the large sized α-(W, Mo phase has detrimental effects on stress-rupture properties in as-cast conditions, secondary cracks may mainly initiate at and then propagate along the interfaces of brittle phases and soft matrix. During exposing at 1100 ℃ for 1000 h, the α-(W, Mo phases transformed gradually into bigger and harder M6C carbide, which results in decreasing of stress-rupture properties of the alloy. Finally, the alloy with an addition of 14W-1Mo(wt% maintained the longest stress lives at high temperatures and therefore it revealed the best microstructure stability after 1100 ℃/1000 h thermal exposure. Keywords: Superalloy, Tungsten and molybdenum, Cast, Microstructure, Stress-rupture properties

  9. Comparison of extrapolation methods for creep rupture stresses of 12Cr and 18Cr10NiTi steels

    International Nuclear Information System (INIS)

    Ivarsson, B.

    1979-01-01

    As a part of a Soviet-Swedish research programme the creep rupture properties of two heat resisting steels namely a 12% Cr steel and an 18% Cr12% Ni titanium stabilized steel have been studied. One heat from each country of both steels were creep tested. The strength of the 12% Cr steels was similar to earlier reported strength values, the Soviet steel being some-what stronger due to a higher tungsten content. The strength of the Swedish 18/12 Ti steel agreed with earlier results, while the properties of the Soviet steel were inferior to those reported from earlier Soviet creep testings. Three extrapolation methods were compared on creep rupture data collected in both countries. Isothermal extrapolation and an algebraic method of Soviet origin gave in many cases rather similar results, while the parameter method recommended by ISO resulted in higher rupture strength values at longer times. (author)

  10. Improved austenitic stainless steel for high temperature applications. [Improved stress-rupture properties

    Science.gov (United States)

    Not Available

    This invention describes a composition for an austenitic stainless steel which has been found to exhibit improved high temperature stress rupture properties. The composition of this alloy is about (in wt. %): 12.5 to 14.5 Cr; 14.5 to 16.5 Ni; 1.5 to 2.5 Mo; 1.5 to 2.5 Mn; 0.1 to 0.4 Ti; 0.02 to 0.08 C; 0.5 to 1.0 Si; 0.01 maximum, N; 0.02 to 0.08 P; 0.002 to 0.008 B; 0.004-0.010 S; 0.02-0.05 Nb; .01-.05 V; 0.005-0.02 Ta; 0.02-0.05 Al; 0.01-0.04 Cu; 0.02-0.05 Co; .03 maximum, As; 0.01 maximum, 0; 0.01 maximum, Zr; and with the balance of the alloy being essentially iron. The carbon content of the alloy is adjusted such that wt. % Ti/(wt. % C+wt. % N) is between 4 and 6, and most preferably about 5. In addition the sum of the wt. % P + wt. % B + wt. % S is at least 0.03 wt. %. This alloy is believed to be particularly well suited for use as fast breeder reactor fuel element cladding.

  11. Biomechanical rupture risk assessment of abdominal aortic aneurysms based on a novel probabilistic rupture risk index.

    Science.gov (United States)

    Polzer, Stanislav; Gasser, T Christian

    2015-12-06

    A rupture risk assessment is critical to the clinical treatment of abdominal aortic aneurysm (AAA) patients. The biomechanical AAA rupture risk assessment quantitatively integrates many known AAA rupture risk factors but the variability of risk predictions due to model input uncertainties remains a challenging limitation. This study derives a probabilistic rupture risk index (PRRI). Specifically, the uncertainties in AAA wall thickness and wall strength were considered, and wall stress was predicted with a state-of-the-art deterministic biomechanical model. The discriminative power of PRRI was tested in a diameter-matched cohort of ruptured (n = 7) and intact (n = 7) AAAs and compared to alternative risk assessment methods. Computed PRRI at 1.5 mean arterial pressure was significantly (p = 0.041) higher in ruptured AAAs (20.21(s.d. 14.15%)) than in intact AAAs (3.71(s.d. 5.77)%). PRRI showed a high sensitivity and specificity (discriminative power of 0.837) to discriminate between ruptured and intact AAA cases. The underlying statistical representation of stochastic data of wall thickness, wall strength and peak wall stress had only negligible effects on PRRI computations. Uncertainties in AAA wall stress predictions, the wide range of reported wall strength and the stochastic nature of failure motivate a probabilistic rupture risk assessment. Advanced AAA biomechanical modelling paired with a probabilistic rupture index definition as known from engineering risk assessment seems to be superior to a purely deterministic approach. © 2015 The Author(s).

  12. Scintigraphic ventriculography and stress testing

    International Nuclear Information System (INIS)

    Goris, M.L.; Hung, J.; Debusk, R.F.

    1982-01-01

    Scintigraphic stress ventriculography yields information which is complex and defies description by the difference in ejection fraction between rest and maximum exercise only. The complexity results in part from the ''derived'' nature of the ejection fraction measurement, which is physiologically secondary to stroke volume and end-diastolic volume. Furthermore, the nature of the stress test in which the pulse (stress) is not independent from the response forces an analysis which considers ''when'' as much as ''what'' happens. Automation in data processing, however, has made oversimplification unnecessary and allows a more exhaustive but correct analysis

  13. Testing the stress shadow hypothesis

    Science.gov (United States)

    Felzer, Karen R.; Brodsky, Emily E.

    2005-05-01

    A fundamental question in earthquake physics is whether aftershocks are predominantly triggered by static stress changes (permanent stress changes associated with fault displacement) or dynamic stresses (temporary stress changes associated with earthquake shaking). Both classes of models provide plausible explanations for earthquake triggering of aftershocks, but only the static stress model predicts stress shadows, or regions in which activity is decreased by a nearby earthquake. To test for whether a main shock has produced a stress shadow, we calculate time ratios, defined as the ratio of the time between the main shock and the first earthquake to follow it and the time between the last earthquake to precede the main shock and the first earthquake to follow it. A single value of the time ratio is calculated for each 10 × 10 km bin within 1.5 fault lengths of the main shock epicenter. Large values of the time ratio indicate a long wait for the first earthquake to follow the main shock and thus a potential stress shadow, whereas small values indicate the presence of aftershocks. Simulations indicate that the time ratio test should have sufficient sensitivity to detect stress shadows if they are produced in accordance with the rate and state friction model. We evaluate the 1989 MW 7.0 Loma Prieta, 1992 MW 7.3 Landers, 1994 MW 6.7 Northridge, and 1999 MW 7.1 Hector Mine main shocks. For each main shock, there is a pronounced concentration of small time ratios, indicating the presence of aftershocks, but the number of large time ratios is less than at other times in the catalog. This suggests that stress shadows are not present. By comparing our results to simulations we estimate that we can be at least 98% confident that the Loma Prieta and Landers main shocks did not produce stress shadows and 91% and 84% confident that stress shadows were not generated by the Hector Mine and Northridge main shocks, respectively. We also investigate the long hypothesized existence

  14. Code Assessment of SPACE 2.19 using LSTF Steam Generator Tube Rupture Test

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Minhee; Kim, Seyun [KHNP CRI, Daejeon (Korea, Republic of)

    2016-10-15

    The SPACE is a best estimated two-phase three-field thermal-hydraulic analysis code used to analyze the safety and performance of pressurized water reactors. As a result of the development, the 2.19 version of the code was released through the successive various verification and validation works. The present work is on the line of expanding the work by Kim et al. In this study, results produced by the SPACE 2.19 code were compared with the experimental data from JAERI's LSTF Test Run LSTF SB-SG-06 experiment simulating a Steam Generator Tube Rupture (SGTR) transient. In order to identify the predictability of SPACE 2.19, the LSTF steam generator tube rupture test was simulated. To evaluate the computed results, LSTF SB-SG-06 test data simulating the SGTR and the RELAP5/ MOD3.1 are used. The calculation results indicate that the SPACE 2.19 code predicted well the sequence of events and the major phenomena during the transient, such as the asymmetric loop behavior, reactor coolant system cooldown and heat transfer by natural circulation, the primary and secondary system depressurization by the pressurizer auxiliary spray and the steam dump using the intact loop steam generator relief valve.

  15. Creep-rupture tests on chromium-containing conventional and ODS steels in oxygen-controlled Pb and air at 650 °C

    International Nuclear Information System (INIS)

    Yurechko, Mariya; Schroer, Carsten; Wedemeyer, Olaf; Skrypnik, Aleksandr; Konys, Jürgen

    2014-01-01

    Highlights: • Generally superior creep performance of ODS steels with 12–14% Cr is indicated. • Strength of 9Cr-ODS at 650°C approaches conventional 9Cr steels at decreasing load. • ODS steels show brittle primary and ductile residual fracture. • Apparent link between secondary creep rate and fracture mode of ODS steels. • Clear impact of liquid Pb at low load, corresponding to long time-to-rupture. - Abstract: Conventional martensitic steels with 9 mass% chromium (Cr), namely T91 and P92, and ODS steels with 9, 12 and 14 mass% Cr, respectively, were subjected to creep-rupture tests in stagnant oxygen-controlled lead (Pb) at 650 °C and c o = 10 −6 mass% dissolved oxygen. The 9Cr conventional steels were tested in the liquid metal at static engineering stress in the range from 75 to 200 MPa. 12 and 14Cr ODS were tested at 190–400 MPa, and 9Cr ODS at 75–300 MPa. Reference tests in stagnant air were carried out in the same stress ranges. The ODS steels with 12 or 14 mass% Cr, mainly tested in oxygen containing Pb, clearly exhibit a change in the stress-dependence of secondary creep rate and appearance of fracture surface at 330–400 MPa. No such change has been observed for 9Cr ODS so far. The conventional martensitic steel P92 shows a significant drop in creep strength accompanied by reduced necking and a change from ductile to brittle fracture when tested in Pb at 75 MPa (time-to-rupture t R = 13,090 h)

  16. Advantages of the experimental animal hollow organ mechanical testing system for the rat colon rupture pressure test.

    Science.gov (United States)

    Ji, Chengdong; Guo, Xuan; Li, Zhen; Qian, Shuwen; Zheng, Feng; Qin, Haiqing

    2013-01-01

    Many studies have been conducted on colorectal anastomotic leakage to reduce the incidence of anastomotic leakage. However, how to precisely determine if the bowel can withstand the pressure of a colorectal anastomosis experiment, which is called anastomotic bursting pressure, has not been determined. A task force developed the experimental animal hollow organ mechanical testing system to provide precise measurement of the maximum pressure that an anastomotic colon can withstand, and to compare it with the commonly used method such as the mercury and air bag pressure manometer in a rat colon rupture pressure test. Forty-five male Sprague-Dawley rats were randomly divided into the manual ball manometry (H) group, the tracing machine manometry pressure gauge head (MP) group, and the experimental animal hollow organ mechanical testing system (ME) group. The rats in each group were subjected to a cut colon rupture pressure test after injecting anesthesia in the tail vein. Colonic end-to-end anastomosis was performed, and the rats were rested for 1 week before anastomotic bursting pressure was determined by one of the three methods. No differences were observed between the normal colon rupture pressure and colonic anastomotic bursting pressure, which were determined using the three manometry methods. However, several advantages, such as reduction in errors, were identified in the ME group. Different types of manometry methods can be applied to the normal rat colon, but the colonic anastomotic bursting pressure test using the experimental animal hollow organ mechanical testing system is superior to traditional methods. Copyright © 2013 Surgical Associates Ltd. Published by Elsevier Ltd. All rights reserved.

  17. Stress testing in financial institutions

    Directory of Open Access Journals (Sweden)

    Mirković Vladimir

    2014-01-01

    Full Text Available In 2000 the Basle Committee on the Global Financial System defined stress testing as 'a generic term describing various techniques used by financial firms to gauge their potential vulnerability to exceptional but plausible events'. Exceptional events refer to one-off or recurring events with far-reaching consequences for the concerned financial institution and the financial sector s stability overall. Such unexpected (exceptional events include, for instance: bankruptcy in Argentina in 2001, stock markets collapse ('Black Monday' on 19 October 1987, or the fall of the energy giant Enron in 2001. The adoption of the new Basle Accord (better known as Basle II in 2001 envisaged the implementation of stress tests for the identification of events and future changes in economic circumstances that could cause some unfavorable effects on banks' credit exposure, along with the assessment of banks' ability to survive in the new circumstances. Negative experiences from the past, having undermined the stability of financial systems worldwide, made a decisive impact on regulators at all levels to additionally consider the issue of increasing the financial system's resistance to the occurrence of unexpected - exceptional events. To this end, the introduction of stress tests was the turning point in the process of increased banking systems' resistance to shocks. This paper primarily deals with stress testing methodology and bank risk measurement techniques, along with the main results of conducted tests, directly impacting the entire financial system.

  18. 77 FR 3408 - Annual Stress Test

    Science.gov (United States)

    2012-01-24

    ...-2011-0029] RIN 1557-AD58 Annual Stress Test AGENCY: Office of the Comptroller of the Currency (``OCC... certain companies to conduct annual stress tests pursuant to regulations prescribed by their respective... stress test as prescribed by this proposed rule. In addition to the annual stress test requirement, such...

  19. Eccentric pressurized tube for measuring creep rupture

    International Nuclear Information System (INIS)

    Schwab, P.R.

    1981-01-01

    Creep rupture is a long term failure mode in structural materials that occurs at high temperatures and moderate stress levels. The deterioration of the material preceding rupture, termed creep damage, manifests itself in the formation of small cavities on grain boundaries. To measure creep damage, sometimes uniaxial tests are performed, sometimes density measurements are made, and sometimes the grain boundary cavities are measured by microscopy techniques. The purpose of the present research is to explore a new method of measuring creep rupture, which involves measuring the curvature of eccentric pressurized tubes. Theoretical investigations as well as the design, construction, and operation of an experimental apparatus are included in this research

  20. Single Tube Rupture at Cold Side of Steam Generator Simulation Test Report Using the ATLAS

    International Nuclear Information System (INIS)

    Kang, Kyoung Ho; Park, Hyun Sik; Cho, Seok

    2010-12-01

    In this study, a postulated SGTR event of the APR1400 was experimentally investigated with the ATLAS. In order to simulate a double-ended rupture of a single U-tube in the APR1400, the SGTR-CL-01 test was performed with the ATLAS. The main objectives of this test were not only to provide a physical insight into the system response of the APR1400 during the SGTR but also to produce integral effect experimental data to validate the safety analysis code. In the present report, major thermal-hydraulic phenomena such as the system pressures, the collapsed water levels, and the break flow rate were presented and discussed. Following the reactor trip induced by high steam generator level (HSGL) signal, the primary system pressure decreased and the secondary system pressure increased until the MSSVs was opened. The MSSVs repeated on and off status depending on the secondary system pressure during the whole test period. Due to the break flow, the collapsed water level of the affected steam generator showed milder decrease than that of the intact steam generator. This integral effect test data will be used to evaluate the prediction capability of existing safety analysis codes of the MARS and the RELAP5 as well as the SPACE code. Furthermore, this data can be utilized to identify any code deficiency for a SGTR simulation, especially for DVI-adapted plants

  1. Use of generalized regression models for the analysis of stress-rupture data

    International Nuclear Information System (INIS)

    Booker, M.K.

    1978-01-01

    The design of components for operation in an elevated-temperature environment often requires a detailed consideration of the creep and creep-rupture properties of the construction materials involved. Techniques for the analysis and extrapolation of creep data have been widely discussed. The paper presents a generalized regression approach to the analysis of such data. This approach has been applied to multiple heat data sets for types 304 and 316 austenitic stainless steel, ferritic 2 1 / 4 Cr-1 Mo steel, and the high-nickel austenitic alloy 800H. Analyses of data for single heats of several materials are also presented. All results appear good. The techniques presented represent a simple yet flexible and powerful means for the analysis and extrapolation of creep and creep-rupture data

  2. Accuracy of physical diagnostic tests for assessing ruptures of the anterior curciate ligament: a meta-analysis.

    NARCIS (Netherlands)

    Scholten, R.J.P.M.; Opstelten, W.; Plas, C.G. van der; Bijl, D.; Devillé, W.L.J.M.; Bouter, L.M.

    2003-01-01

    OBJECTIVE: This systematic review summarizes the evidence on the accuracy of tests for assessing ACL ruptures of the knee. SEARCH STRATEGY: A computerized search of MEDLINE (1966-2003) and EMBASE (1980-2003) with additional reference tracking. SELECTION CRITERIA: Articles included were written in

  3. Methods to diagnose acute anterior cruciate ligament rupture: a meta-analysis of instrumented knee laxity tests

    NARCIS (Netherlands)

    van Eck, Carola F.; Loopik, Miette; van den Bekerom, Michel P.; Fu, Freddie H.; Kerkhoffs, Gino M. M. J.

    2013-01-01

    The aims of this meta-analysis were to determine the sensitivity and specificity of the KT 1000 Arthrometer, Stryker Knee Laxity Tester and Genucom Knee Analysis System for ACL rupture. It was hypothesized that the KT 1000 test is the most sensitive and specific. Secondly, it was hypothesized that

  4. Physical examination tests for the diagnosis of posterior cruciate ligament rupture: a systematic review.

    Science.gov (United States)

    Kopkow, Christian; Freiberg, Alice; Kirschner, Stephan; Seidler, Andreas; Schmitt, Jochen

    2013-11-01

    Systematic literature review. To summarize and evaluate research on the accuracy of physical examination tests for diagnosis of posterior cruciate ligament (PCL) tear. Rupture of the PCL is a severe knee injury that can lead to delayed rehabilitation, instability, or chronic knee pathologies. To our knowledge, there is currently no systematic review of studies on the diagnostic accuracy of clinical examination tests to evaluate the integrity of the PCL. A comprehensive systematic literature search was conducted in MEDLINE from 1946, Embase from 1974, and the Allied and Complementary Medicine Database from 1985 until April 30, 2012. Studies were considered eligible if they compared the results of physical examination tests performed in the context of a PCL physical examination to those of a reference standard (arthroscopy, arthrotomy, magnetic resonance imaging). Methodological quality assessment was performed by 2 independent reviewers using the revised version of the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. The search strategy revealed 1307 articles, of which 11 met the inclusion criteria for this review. In these studies, 11 different physical examination tests were identified. Due to differences in study types, different patient populations, and methodological quality, meta-analysis was not indicated. Presently, most physical examination tests have not been evaluated sufficiently enough to be confident in their ability to either confirm or rule out a PCL tear. The diagnostic accuracy of physical examination tests to assess the integrity of the PCL is largely unknown. There is a strong need for further research in this area. Level of Evidence Diagnosis, level 3a.

  5. Estimation of time to rupture in a fire using 6FIRE, a lumped parameter UF6 cylinder transient heat transfer/stress analysis model

    International Nuclear Information System (INIS)

    Williams, W.R.; Anderson, J.C.

    1995-01-01

    The transportation of UF 6 is subject to regulations requiring the evaluation of packaging under a sequence of hypothetical accident conditions including exposure to a 30-min 800 degree C (1475 degree F) fire [10 CFR 71.73(c)(3)]. An issue of continuing interest is whether bare cylinders can withstand such a fire without rupturing. To address this issue, a lumped parameter heat transfer/stress analysis model (6FIRE) has been developed to simulate heating to the point of rupture of a cylinder containing UF 6 when it is exposed to a fire. The model is described, then estimates of time to rupture are presented for various cylinder types, fire temperatures, and fill conditions. An assessment of the quantity of UF 6 released from containment after rupture is also presented. Further documentation of the model is referenced

  6. 77 FR 3166 - Annual Stress Test

    Science.gov (United States)

    2012-01-23

    ... FEDERAL DEPOSIT INSURANCE CORPORATION 12 CFR Part 325, Subpart C RIN 3064-AD91 Annual Stress Test... Reform and Consumer Protection Act (the ``Dodd-Frank Act'') regarding stress tests (``proposed rule... to conduct annual stress tests in accordance with the proposed rule, report the results of such...

  7. 77 FR 61238 - Annual Stress Test

    Science.gov (United States)

    2012-10-09

    ...-2011-0029] RIN 1557-AD58 Annual Stress Test AGENCY: Office of the Comptroller of the Currency (``OCC... conduct annual stress tests pursuant to regulations prescribed by their respective primary financial... annual stress test as prescribed by this rule. Under the final rule covered institutions are divided into...

  8. 77 FR 16484 - Annual Stress Test

    Science.gov (United States)

    2012-03-21

    ...-2011-0029] RIN 1557-AD58 Annual Stress Test AGENCY: Office of the Comptroller of the Currency, Treasury... billion to conduct an annual stress test and comply with certain reporting and disclosure requirements. To... conduct annual stress tests pursuant to regulations prescribed by their respective Federal primary...

  9. Creep-rupture-test on the stainless steel X6CRNI1811 (DIN 1.4948) in the frame of the ''Extrapolation-Program''. (Part III)

    International Nuclear Information System (INIS)

    Solano, R.; Las Rivas, M. de; Barroso, S.

    1982-01-01

    The austenitic stainless steel X6CrNi1811 (DIN 1.4948) used as a structure material for the German Fast Breeder Reactor SNR 300 was creep tested in a temperature range of 550-650 deg under base material condition as well as welded material condition. The main point of this program (''Extrapolation-Program'') lies in the knowledge of the creep-rupture-strength and creepbehaviour up to 3 x 10 4 hours at higher temperatures in order to extrapolate up to >=10 5 hours for operating temperatures. In order to study the stress dependency of the minimum creep rate additional tests were carried out of 550 deg - 750 deg C. The present report describes the state in the running program with test-times of 23.000 hours and results from tests up to 55.000 hours belonging to other parallel programs are taken into account. Besides the creep-rupture behaviour it is also made a study of ductility between 550 and 750 deg C. Extensive metallographic examinations have been made to study the fracture behaviour and changes in structure. (author)

  10. Creep-rupture-test on the stainless steel X6crni1811 (Din 1.494.8) in the frame of the Extrapolation-Program. (Part III)

    International Nuclear Information System (INIS)

    Solano, R.; Schirra, M.; Rivas, M. de la; Barroso, S.; Seith, B.

    1982-01-01

    The austenitic stainless steel X6crni1811 (Din 1.4948) used as a structure material for the German Fast Breeder Reactor SNR 300 was creep tested in a temperature range of 550-650 degree centigree material condition as well as welded material condition. The main point of this program (Extrapolation-Program) lies in the knowledge of the creep-rupture-strength and creep-behaviour up to 3 x 10 4 hours higher temperatures in order to extrapolated up to ≥10 5 hours for operating temperatures. In order to study the stress dependency of the minimum creep rate additional tests were carried out of 550 degree centigree - 750 degree centigree. The present report describes the state in the running program with test-times of 23.000 hours and results from tests up to 55.000 hours belonging to other parallel programs are taken into account. Besides the creep-rupture behaviour it is also made a study of ductility between 550 and 750 degree centigree. Extensive metallographic examinations have been made to study the fracture behaviour and changes in structure. (Author)

  11. Pipe rupture test results: 4-inch pipe whip tests under PWR LOCA conditions

    International Nuclear Information System (INIS)

    Miyazaki, Noriyuki; Ueda, Shuzo; Isozaki, Toshikuni; Kato, Rokuro; Kurihara, Ryoichi; Yano, Toshikazu; Miyazono, Shohachiro

    1982-09-01

    This report summarizes the results of 4-inch pipe whip tests (RUN No. 5506, 5507, 5508 and 5604) under the PWR LOCA conditions. The dynamic behaviors of the test pipe and restraints were studied in the tests. In the tests, the gap between the test pipe and the restraints was kept at the constant value of 8.85 mm and the overhang length was varied from 250 mm to 650 mm. The dynamic behaviors of the test pipe and the restraint were made clear by the outputs of strain gages and the measurements of residual deformations. The data of water hammer in subcooled water were also obtained by the pressure transducers mounted on the test pipe. The main conclusions obtained from the tests are as follows. (1) The whipping of pipe can be prevented more effectively as the overhang length becomes shorter. (2) The load acting on the restraint-support structure becomes larger as the overhang length becomes shorter. (3) The restraint farther from the break location does not limit the pipe movement except for the first impact when the overhang length is long. (4) The ultimate moment M sub(u) of the pipe at the restraint location can be used to predict the plastic collapse of the whipping pipe. (5) The restraints slide along the pipe axis and are subjected to bending moment, when the overhang length is long. (author)

  12. Probability of a surface rupture offset beneath a nuclear test reactor

    International Nuclear Information System (INIS)

    Reed, J.W.; Meehan, R.L.; Crellin, G.L.

    1981-01-01

    A probabilistic analysis was conducted to determine the likelihood of a surface rupture offset of any size beneath the 50 megawatt General Electric Test Reactor (GETR), which is located at the Vallecitos Nuclear Center near Pleasanton, California. Geologic faults have been observed at the GETR site. These faults may be due to surface folds, landslides, or deep tectonic movement. They are referred to in the paper as 'existing faults;' however, use of this term does not imply that they are tectonic in origin. The objective of the analysis was to evaluate whether a conservative estimate of the probability of occurrence of a future fault movement is sufficiently low so that movement beneath the reactor building need not be considered as a design basis event. The reactor building is located between two existing faults which are approximately 1320 feet apart. If a fault movement occurs in the future, it is conservatively assumed to occur either on the existing faults or between the faults, or on a fault(s) and between the two faults at the same time. The probabilistic model included the possibility of movements occurring due to unknown, undiscovered faults in the region. For this part, movements were assumed to occur according to a Poisson process. For the possibility of new faults occurring due to the two existing faults, a hazard function was used which increases with time since the last offset. (orig./RW)

  13. Creep-rupture-tests on thestainless steel X6 CrNi1811 (DIN 1.4948) in the frame of the ''Extrapolation-Program'' Pt. 2

    International Nuclear Information System (INIS)

    Solano, R.R.; Barroso, S.; Rivas, M. de las; Schirra, M.; Seith, B.

    1979-01-01

    The austenitic stainless steel X6 CrNi 1811 (DIN 1.4948) that is used as a structure material for the German Fast Breeder Reactor SNR 300 was creep tested in a temperature range of 550-650 deg under base material condition as well as welded material condition. The main point of this program (''Extrapolation-Program'') lies in the knowledge of the cree-rupture-strength and creep-behaviour up to 3X10 - 4 hours at higher temperatures in order to extrapolate up to (>=)10 5 hours for operating temperatures. In order to study the stress dependency of the minimum creep rate additional tests were carried out over temperature range 550 deg - 750 deg C. The present report describes the state in the running program with test-time up to 35.000 hours. Besides the cree-rupture behaviour it is possible to make a distinct quantitative statement for the creep-behaviour and ductility. Extensive metallographic examinations show the fracture behaviour and changes in structure. (author)

  14. Histological evidence of oxidative stress and premature senescence in preterm premature rupture of the human fetal membranes recapitulated in vitro.

    Science.gov (United States)

    Menon, Ramkumar; Boldogh, Istvan; Hawkins, Hal K; Woodson, Michael; Polettini, Jossimara; Syed, Tariq Ali; Fortunato, Stephen J; Saade, George R; Papaconstantinou, John; Taylor, Robert N

    2014-06-01

    Preterm prelabor rupture of the membranes (pPROM) may lead to preterm births (PTBs). We investigated premature senescence of fetal membranes in women with pPROM and spontaneous PTB with intact membranes (PTBs, and term births. Term fetal membranes were exposed to cigarette smoke extract to induce oxidative stress. Western blots documented p-p53 and p-p38 MAPK. Transmission electron microscopy assessed cellular morphologic features in clinical and cigarette smoke extract-treated membranes. A total of 80% of pPROM cells and >60% of term cells were positive for all three senescence phenotype markers, and concentrations were higher than in PTBs (P PTBs. Histologic and biochemical resemblance of pPROM and term membranes suggests premature senescence of the membranes is a mechanistic feature in pPROM, and this can be phenocopied in an in vitro model. Copyright © 2014 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

  15. Biaxial Stress Tests of Plain Concrete

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.K.; Cho, M.S.; Song, Y.C. [Korea Electric Power Research Institute, Taejon (Korea)

    2001-07-01

    Containment concrete specimens(4000, 5000psi) were tested under biaxial stress and presented basic physical properties and biaxial failure envelops for the concrete specimens. Failure behaviors of concrete under biaxial stress were assessed with stress-strain responses and failure modes. Here provided real test data to develop nonlinear finite element concrete models. (author). 15 refs., 46 figs., 4 tabs.

  16. Pipe rupture test results; 4 inch pipe whip tests under BWR operational condition-clearance parameter experiments

    International Nuclear Information System (INIS)

    Ueda, Syuzo; Isozaki, Toshikuni; Miyazaki, Noriyuki; Kurihara, Ryoichi; Kato, Rokuro; Saito, Kazuo; Miyazono, Shohachiro

    1981-05-01

    The purpose of pipe rupture studies in JAERI is to perform the model tests on pipe whip, restraint behavior, jet impingement and jet thrust force, and to establish the computational method for analyzing these phenomena. This report describes the experimental results of pipe whip on the pipe specimens of 4 inch in diameter under BWR condition on which the pressure is 6.77 MPa and the temperature is 285 0 C. The pipe specimens were 114.3 mm (4 inch) in diameter and 8.6 mm in thickness and 4500 mm in length. Four pipe whip restraints used in the tests were the U-bar type of 8 mm in diameter and fabricated from type 304 stainless steel. The experimental parameter was the clearance (30, 50 and 100 mm). The dynamic strain behavior of the pipe specimen and the restraints was investigated by strain gages and their residual deformation was obtained by measuring marking points provided on their surface. The Pressure-time history in the pipe specimens was also obtained by pressure gages. The maximum pipe strain is caused near the restraints and increases with increase of the clearance. The experimental results of pipe whip tests indicate the effectiveness of pipe whip restraints. The ratio of absorbed strain energy of the pipe specimen to that of the restraints is nearly constant for different clearances at the overhang length of 400 mm. (author)

  17. Test amnioinfusion to determine suitability for serial therapeutic amnioinfusion in midtrimester premature rupture of membranes.

    Science.gov (United States)

    Tan, L-K; Kumar, S; Jolly, M; Gleeson, C; Johnson, P; Fisk, N M

    2003-01-01

    To evaluate whether a test amnioinfusion procedure is useful in selecting cases of midtrimester preterm premature rupture of membranes (PPROM) which may benefit from serial amnioinfusions if the initial fluid is retained. The Centre for Fetal Care database between 1992 and 2000 was reviewed for women with PPROM amnioinfusion. Amniotic fluid index (AFI) was assessed before and after a test amnioinfusion procedure. Those who retained fluid > or =48 h underwent serial AFI assessment with a view to serial amnioinfusion when oligohydramnios recurred. Eighty-five amnioinfusion procedures were performed in 60 women with oligohydramnios. Nineteen of these women presented with confirmed PPROM at a median gestation of 19 (range 15-22) weeks and severe olighohydramnios (median AFI 1, range 0-3 cm), in whom 20 test amnioinfusions were carried out. Two amnioinfusions were abandoned during the procedure because of fetal bradycardia and both mothers opted for termination of pregnancy. Only 4 women retained fluid during the test amnioinfusion, 1 of whom miscarried at 19 weeks before serial amnioinfusion could be started. The remaining 3 underwent a median of 4 (range 1-6) serial amnioinfusion procedures; none had evidence of pulmonary hypoplasia. Thirteen (68%) leaked fluid within 48 h; within this group there was 1 subsequent miscarriage and 9 pregnancy terminations. The remaining 3 pregnancies resulted in livebirths 2 of which had pulmonary hypoplasia with 1 early neonatal death. Overall survival was poor (4/19), largely attributed to the high incidence of terminations in the presence of persistent severe oligohydramnios. In continuing pregnancies reaching viability survival was 67% (4 of 6). Three quarters of women with mid-trimester PPROM lose fluid at test amnioinfusion and therefore would not be suitable candidates for serial amnioinfusion. However, if infused fluid is retained, this allows subsequent serial amnioinfusion and prolongation of pregnancy in about 75%, with an

  18. The accuracy of placental alpha-microglobuline-1 test in diagnosis of premature rupture of the membranes

    Directory of Open Access Journals (Sweden)

    Maryam Khooshideh

    2015-06-01

    Full Text Available Background: Premature rupture of membranes (PROM is a common obstetric issue during pregnancy which might lead to serious fetal or maternal problems. Therefore, an appropriate diagnosis and management of PROM are of significant importance in patients. Objective: The aim of this study was to determine the accuracy of placental alpha microglobuline-1 (PAMG-1 test in PROM diagnosis and compare this diagnostic method with other standard tests in diagnosis of PROM. Materials and Methods: In this prospective diagnostic accuracy study, patients with symptoms of membrane rupture in 16-39 weeks of gestation were involved. Three tests including Fern, Nitrazine and PAMG-1 were performed at the same time. Results: PROM was confirmed in 86 patients out of 100. The sensitivity and specificity were respectively 81.3% and 100% for Fern test, 93% and 92.8% for Nitrazine test, 98.9% and 92.8% for PAMG-1 test. PAMG-1 test showed higher sensitivity (98.9% with p<0.001 and accuracy (98% compared with conventional tests. Although PAMG-1showed a lower positive predictive value (PPV compared to conventional tests such as Fern test (100%, it was shown to be more accurate. Conclusion: The accuracy of PAMG-1 test was superior to both Fern and Nitrazine test in PROM diagnosis.

  19. Technique for the residual life assessment of high temperature components based on creep-rupture testing on welded miniature specimens

    Energy Technology Data Exchange (ETDEWEB)

    Garzillo, A.; Guardamagna, C.; Moscotti, L.; Ranzani, L. [Ente Nazionale per l`Energia Elettrica, Milan (Italy)

    1995-06-01

    Following the present trend in the development of advanced methodologies for residual life assessment of high temperature components operating in power plants, particularly in non destructive methods, a testing technique has been set up at ENEL-CRAM based on creep-rupture testa in an argon on welded miniature specimens. Five experimental systems for creep-rupture tests in an argon atmosphere have been set up which include high accuracy systems, vacuum chambers and exrwnsometer devices. With the aim of establishing and validating the suitability of the experimental methodology, creep-rupture and interrupted creep testing programmes have been performed on miniature specimens (2 mm diameter and 10 mm gauge lenght). On the basis of experience gathered by various European research laboratories, a miniature specimen construction procedure has been developed using a laser welding technique for joining threaded heads to sample material. Low alloy ferritic steels, such as virgin 2.25CrlMo, 0.5Cr 0.5Mo 0.25V, and IN 738 superalloy miniature specimens have been investigated and the results, compared with those from standard specimens, show a regular trend in deformation vs time. Additional efforts to provide guidelines for material sampling from each plant component will be required in order to reduce uncertainties in residual life prediction.

  20. The effects of Ta on the stress rupture properties and microstructural stability of a novel Ni-base superalloy for land-based high temperature applications

    International Nuclear Information System (INIS)

    Zheng, Liang; Zhang, Guoqing; Lee, Tung L.; Gorley, Michael J.; Wang, Yue; Xiao, Chengbo; Li, Zhou

    2014-01-01

    Highlights: • An equiaxed superalloy has high rupture life equivalent to single crystal alloy DD3. • Low Cr and high W superalloys possess good microstructrual stability at 850–1100 °C. • Tantalum promotes, strengthens and stabilizes the eutectic γ′ and MC carbides. • Excessive Ta leads to form harmful abnormal primary α and plate-like M 6 C phases. • Proper Ta can improve the stress rupture life at intermediate and high temperatures. - Abstract: A novel polycrystalline Ni-base superalloy was developed for land-based high temperature applications, such as isothermal forging dies and industrial gas turbines. The alloy possessed surprisingly high stress rupture life of 52 h at 1100 °C/118 MPa which is comparable to the first generation single crystal (SC) superalloy and exhibited good microstructural stability. The effects of Ta addition on the phase change, stress rupture properties and microstructural stability of the alloy were investigated. The results indicated that Ta is a γ′-former and promotes the formation of eutectic γ′. The alloys with ∼7 vol.% eutectic γ′ possess higher stress rupture life at 1100 °C/118 MPa than the alloys with higher ∼20 vol.% eutectic. However, ∼20 vol.% excessive eutectic phases will enhance the stress rupture life at intermediate temperature of 760 °C for 686 MPa but weaken high temperature stress rupture properties. The (Al + Ta) content over 14.4 at.% led to the formation of large amounts of eutectic γ′ and exceeded the solubility of W and Mo in the residue liquid pool, which then promoted the precipitation of primary α-(W,Mo) and M 6 C phases. Tantalum was also found as a strong MC carbides forming element. The order of ability to form monocarbide decreased from NbC to TaC to TiC. 6Al–0Ta (wt.%) alloys possessed good microstructural stability with no harmful topologically close-packed (TCP) phases being observed after thermal exposure at 850 °C/3000 h, 900 °C/1000 h. Only trace amounts of

  1. Evaluation of stress histories of reactor coolant loop piping for pipe rupture prediction

    International Nuclear Information System (INIS)

    Lu, S.C.; Larder, R.A.; Ma, S.M.

    1981-01-01

    This paper describes the analyses used to evaluate stress histories in the primary coolant loop piping of a selected four-loop PNR power station. In order to make the simulation as realistic as possible, best estimates rather than conservative assumptions were considered throughout. The best estimate solution, however, was aided by a sensitivity study to assess the possible variation of outcomes resulted from uncertainties associated with these assumptions. Sources of stresses considered in the evaluation were pressure, dead weight, thermal expansion, thermal gradients through the pipe wall, residual welding, pump vibrations, and finally seismic excitations. The best estimates of pressure and thermal transient histories arising from plant operations were based on actual plant operation records supplemented by specified plant design conditions. Seismic motions were generated from response spectrum curves developed specifically for the region surrounding the plant site. Stresses due to dead weight and thermal expansion were computed from a three dimensional finite element model which used a combination of pipe, truss, and beam elements to represent the coolant loop piping, the pressure vessel, coolant pumps, steam generators, and the pressurizer. Stresses due to pressure and thermal gradients were obtained by closed form solutions. Seismic stress calculations considered the soil structure interaction, the coupling effect between the containment structure and the reactor coolant system. A time history method was employed for the seismic analysis. Calculations of residual stresses accounted for the actual heat impact, welding speed, weld preparation geometry, and pre- and post-heat treatments. Vibrational stresses due to pump operation were estimated by a dynamic analysis using existing measurements of pump vibrations. (orig./HP)

  2. Strength and rupture-life transitions caused by secondary carbide precipitation in HT-9 during high-temperature low-rate mechanical testing

    International Nuclear Information System (INIS)

    DiMelfi, R.J.; Gruber, E.E.; Kramer, J.M.; Hughes, T.H.

    1992-01-01

    The martensitic-ferritic alloy HT-9 is slated for long-term use as a fuel-cladding material in the Integral Fast Reactor. Analysis of published high-temperature mechanical property data suggests that secondary carbide precipitation would occur during service life causing substantial strengthening of the as-heat-treated material. Aspects of the kinetics of this precipitation process are extracted from calculations of the back stress necessary to produce the observed strengthening effect under various creep loading conditions. The resulting Arrhenius factor is shown to agree quantitatively with shifts to higher strength of crept material in reference to the intrinsic strength of HT-9. The results of very low constant strain-rate high-temperature tensile tests on as-heat-treated HT-9 that focus on the transition in strength with precipitation will be presented and related to rupture-life

  3. Stress Testing with Student's t Dependence

    NARCIS (Netherlands)

    H.J.W.G. Kole (Erik); C.G. Koedijk (Kees); M.J.C.M. Verbeek (Marno)

    2003-01-01

    textabstractIn this study we propose the use of the Student's t dependence function to model dependence between asset returns when conducting stress tests. To properly include stress testing in a risk management system, it is important to have accurate information about the (joint) probabilities of

  4. Diagnostic performance of placental alpha-microglobulin-1 test in women with prolonged pre-labour rupture of membranes.

    Science.gov (United States)

    Eleje, George Uchenna; Ezugwu, Euzebus Chinonye; Eke, Ahizechukwu Chigoziem; Eleje, Lydia Ijeoma; Ikechebelu, Joseph Ifeanyichukwu; Afiadigwe, Evaristus Anthony; Ezugwu, Frank O; Udigwe, Gerald Okanandu; Okafor, Charles I; Ezeama, Chukwuemeka Okwudili

    2016-01-01

    To determine diagnostic performance of placental alpha-microglobulin-1 (PAMG-1) test compared to conventional clinical assessment (CCA) in women with prolonged pre-labour rupture of membranes (PROM). A double-blind study of women with symptoms and signs of PROM in Nnamdi Azikiwe University Teaching Hospital, Nnewi and University of Nigeria Teaching Hospital, Enugu, in south-east Nigeria using CCA for PROM and PAMG-1 test was done. Women were included if their symptoms, signs or complaints suggestive of PROM was more than 24 h duration. PROM was diagnosed if two out of three methods from CCA (pooling, positive nitrazine test or ferning) were present. Confirmation of PROM was done after delivery using any two of these clinical criteria: delivery in 48 h to 7 days, evidence of chorioamnionitis, membranes obviously ruptured at delivery and adverse perinatal outcomes strongly correlated with prolonged PROM. Accuracy, specificity and sensitivity value for CCA were 72.5, 36.8 and 86.0% lower than for PAMG-1 test which were 95.7, 94.1 and 96.2%. In equivocal cases, PAMG-1 was significantly more accurate than CCA (92.3% versus 38.5%; p < 0.001). This study in women with prolonged PROM, confirms that PAMG-1 test has high diagnostic accuracy irrespective of the duration of PROM before clinical evaluation.

  5. Residual Stress Testing of Outer 3013 Containers

    International Nuclear Information System (INIS)

    Dunn, K.

    2004-01-01

    A Gas Tungsten Arc Welded (GTAW) outer 3013 container and a laser welded outer 3013 container have been tested for residual stresses according to the American Society for Testing Materials (ASTM) Standard G-36-94 [1]. This ASTM standard describes a procedure for conducting stress-corrosion cracking tests in boiling magnesium chloride (MgCl2) solution. Container sections in both the as-fabricated condition as well as the closure welded condition were evaluated. Significantly large residual stresses were observed in the bottom half of the as-fabricated container, a result of the base to can fabrication weld because through wall cracks were observed perpendicular to the weld. This observation indicates that regardless of the closure weld technique, sufficient residual stresses exist in the as-fabricated container to provide the stress necessary for stress corrosion cracking of the container, at the base fabrication weld. Additionally, sufficiently high residual stresses were observed in both the lid and the body of the GTAW as well as the laser closure welded containers. The stresses are oriented perpendicular to the closure weld in both the container lid and the container body. Although the boiling MgCl2 test is not a quantitative test, a comparison of the test results from the closure welds shows that there are noticeably more through wall cracks in the laser closure welded container than in the GTAW closure welded container

  6. Analysis of localized damage in creep rupture

    International Nuclear Information System (INIS)

    Wang Zhengdong; Wu Dongdi

    1992-01-01

    Continuum Damage Mechanics studies the effect of distributed defects, whereas the failure of engineering structures is usually caused by local damage. In this paper, an analysis of localized damage in creep rupture is carried out. The material tested is a 2 1/4Cr-1Mo pressure vessel steel and the material constants necessary for damage analysis are evaluated. Notched specimens are used to reflect localized damage in creep rupture and the amount of damage is measured using DCPD method. Through FEM computation, stress components and effective stress in the region of notch root are evaluated and it is found that the von Mises effective stress can represent the damage effective stress in the analysis of localized creep damage. It is possible to develop a method for the assessment of safety of pressure vessels under creep through localized creep damage analysis. (orig.)

  7. Microballoon Occlusion Test to Predict Colonic Ischemia After Transcatheter Embolization of a Ruptured Aneurysm of the Middle Colic Artery

    International Nuclear Information System (INIS)

    Tajima, Tsuyoshi; Yoshimitsu, Kengo; Inokuchi, Hiroyuki; Irie, Hiroyuki; Nishie, Akihiro; Hirakawa, Masakazu; Ishigami, Kousei; Ushijima, Yasuhiro; Okamoto, Daisuke; Honda, Hiroshi; Itoh, Hiroyuki; Morita, Masaru; Kakeji, Yoshihiro

    2008-01-01

    A 76-year-old woman presented with sudden massive melena, and superior mesenteric arteriography showed an aneurysm in the middle colic artery (MCA). Because she had a history of right hemicolectomy and ligation of the inferior mesenteric artery (IMA) during open abdominal aortic aneurysm repair, embolization of the MCA aneurysm was considered to pose a risk comparable to that of colonic ischemia. A microballoon occlusion test during occlusion of the MCA confirmed retrograde visualization of the IMA branches through the collateral arteries by way of the left internal iliac artery, and embolization was successfully performed using microcoils. No colonic ischemia or aneurysm rupture occurred after embolization.

  8. Cyclic creep-rupture behavior of three high-temperature alloys.

    Science.gov (United States)

    Halford, G. R.

    1972-01-01

    Study of some important characteristics of the cyclic creep-rupture curves for the titanium alloy 6Al-2Sn-4Zr-2Mo at 900 and 1100 F (755 and 865 K), the cobalt-base alloy L-605 at 1180 F (910 K), and for two hardness levels of 316 stainless steel at 1300 F (980 K). The cyclic creep-rupture curve relates tensile stress and tensile time-to-rupture for strain-limited cyclic loading and has been found to be independent of the total strain range and the level of compressive stress employed in the cyclic creep-rupture tests. The cyclic creep-rupture curve was always found to be above and to the right of the conventional (constant load) monotonic creep-rupture curve by factors ranging from 2 to 10 in time-to-rupture. This factor tends to be greatest when the creep ductility is large. Cyclic creep acceleration was observed in every cyclic creep-rupture test conducted. The phenomenon was most pronounced at the highest stress levels and when the tensile and compressive stresses were completely reversed. In general, creep rates were found to be lower in compression than in tension for equal true stresses. The differences, however, were strongly material-dependent.

  9. Stress testing - ettevaatliku investori abimees / Peeter Teder

    Index Scriptorium Estoniae

    Teder, Peeter

    2005-01-01

    Autor selgitab stress testingut kui investeerimisportfelli varade väärtuse hindamist ning tutvustab selle võimalusi ja ohtusid. Diagrammid: Portfelli testimis-stsenaariumiks sobivad hästi börsikrahhid. Vt. samas: Stress testing toimib ka mujal

  10. Rupture disc

    International Nuclear Information System (INIS)

    Newton, R.G.

    1977-01-01

    The intermediate heat transport system for a sodium-cooled fast breeder reactor includes a device for rapidly draining the sodium therefrom should a sodium-water reaction occur within the system. This device includes a rupturable member in a drain line in the system and means for cutting a large opening therein and for positively removing the sheared-out portion from the opening cut in the rupturable member. According to the preferred embodiment of the invention the rupturable member includes a solid head seated in the end of the drain line having a rim extending peripherally therearound, the rim being clamped against the end of the drain line by a clamp ring having an interior shearing edge, the bottom of the rupturable member being convex and extending into the drain line. Means are provided to draw the rupturable member away from the drain line against the shearing edge to clear the drain line for outflow of sodium therethrough

  11. Experimental evaluation of emergency operating procedures on multiple steam generator tube rupture in INER integral system test facility

    International Nuclear Information System (INIS)

    Liu, T.J.; Lin, Y.M.; Lee, C.H.; Chang, C.Y.; Hong, W.T.

    1997-01-01

    The multiple steam generator tube rupture (SGTR) scenario in Westinghouse type pressurized water reactor (PWR) has been investigated at the Institute of Nuclear Energy Research (INER) Integral System Test (IIST) facility. This reduced-height and reduced-pressure test facility was designed to simulate the main features of Maanshan nuclear power plant. The SGTR test scenario assumes the double-ended break of one-, two- and six- tubes without other failures. The major operator actions follow the related symptom-oriented Emergency Operating Procedure (EOP) on the reference plant. This study focuses on the investigation of thermal-hydraulics phenomena and the adequacy of associated EOP to limit primary-to-secondary leakage. Through this study, it is found that the adequacy of current EOP in minimizing the radioactivity release demands early substantial operator involvement, especially in the multi-tubes break events. Also, the detailed mechanism of the main thermal-hydraulic phenomena during the SGTR transient are explored. (author)

  12. Stress examination of flexor tendon pulley rupture in the crimp grip position: a 1.5-Tesla MRI cadaver study

    Energy Technology Data Exchange (ETDEWEB)

    Bayer, Thomas; Janka, Rolf [University of Erlangen-Nuremberg, Department of Radiology, Erlangen (Germany); Fries, Simon [Cantonal Hospital Lucerne, Orthopaedic Department, Wolhusen (Switzerland); Schweizer, Andreas [University of Zurich, Department of Orthopaedics, Balgrist, Zurich (Switzerland); Schoeffl, Isabelle [Klinikum Bamberg, Department of Pediatrics, Bamberg (Germany); Bongartz, Georg [University Basel, Department of Radiology, Basel (Switzerland)

    2015-01-15

    The objectives of this study were the evaluation of flexor tendon pulley rupture of the fingers in the crimp grip position using magnetic resonance imaging (MRI) and the comparison of the results with MRI in the neutral position in a cadaver study. MRI in the crimp grip position and in the neutral position was performed in 21 cadaver fingers with artificially created flexor tendon pulley tears (combined pulley rupture, n = 14; single pulley rupture, n = 7). Measurement of the distance between the tendon and bone was performed. Images were evaluated by two readers, first independently and in cases of discrepancy in consensus. Sensitivity and specificity for detecting combined pulley ruptures were calculated. Tendon bone distances were significantly higher in the crimp grip position than in the neutral position. Sensitivity and specificity for detecting combined pulley rupture were 92.86 % and 100 % respectively in the crimp grip position and 78.57 % and 85.71 % respectively in the neutral position. Kappa values for interobserver reliability were 0.87 in the crimp grip position and 0.59 in the neutral position. MRI examination in the crimp grip position results in higher tendon bone distances by subjecting the pulleys to a higher strain, which facilitates image evaluation with higher interobserver reliability, higher sensitivity, and higher specificity for combined pulley rupture compared with examination in the neutral position. (orig.)

  13. Viscoelastic characterization of carbon fiber-epoxy composites by creep and creep rupture tests; Caracterizacao viscoelastica por meio de ensaios de fluencia e ruptura por fluencia de compositos polimericos de matriz de matriz de resina epoxidica e fibra de carbono

    Energy Technology Data Exchange (ETDEWEB)

    Farina, Luis Claudio

    2009-07-01

    One of the main requirements for the use of fiber-reinforced polymer matrix composites in structural applications is the evaluation of their behavior during service life. The warranties of the integrity of these structural components demand a study of the time dependent behavior of these materials due to viscoelastic response of the polymeric matrix and of the countless possibilities of design configurations. In the present study, creep and creep rupture test in stress were performed in specimens of unidirectional carbon fiber-reinforced epoxy composites with fibers orientations of 60 degree and 90 degree, at temperatures of 25 and 70 degree C. The aim is the viscoelastic characterization of the material through the creep curves to some levels of constant tension during periods of 1000 h, the attainment of the creep rupture envelope by the creep rupture curves and the determination of the transition of the linear for non-linear behavior through isochronous curves. In addition, comparisons of creep compliance curves with a viscoelastic behavior prediction model based on Schapery equation were also performed. For the test, a modification was verified in the behavior of the material, regarding the resistance, stiffness and deformation, demonstrating that these properties were affected for the time and tension level, especially in work temperature above the ambient. The prediction model was capable to represent the creep behavior, however the determination of the equations terms should be considered, besides the variation of these with the applied tension and the elapsed time of test. (author)

  14. Accelerated stress testing of terrestrial solar cells

    Science.gov (United States)

    Lathrop, J. W.; Hawkins, D. C.; Prince, J. L.; Walker, H. A.

    1982-01-01

    The development of an accelerated test schedule for terrestrial solar cells is described. This schedule, based on anticipated failure modes deduced from a consideration of IC failure mechanisms, involves bias-temperature testing, humidity testing (including both 85-85 and pressure cooker stress), and thermal-cycle thermal-shock testing. Results are described for 12 different unencapsulated cell types. Both gradual electrical degradation and sudden catastrophic mechanical change were observed. These effects can be used to discriminate between cell types and technologies relative to their reliability attributes. Consideration is given to identifying laboratory failure modes which might lead to severe degradation in the field through second quadrant operation. Test results indicate that the ability of most cell types to withstand accelerated stress testing depends more on the manufacturer's design, processing, and worksmanship than on the particular metallization system. Preliminary tests comparing accelerated test results on encapsulated and unencapsulated cells are described.

  15. Globe Rupture

    Directory of Open Access Journals (Sweden)

    Reid Honda

    2017-07-01

    Full Text Available History of present illness: A 46-year-old male presented to the emergency department (ED with severe left eye pain and decreased vision after tripping and striking the left side of his head on the corner of his wooden nightstand. The patient arrived as an inter-facility transfer for a suspected globe rupture with a protective eye covering in place; thus, further physical examination of the eye was not performed by the emergency physician in order to avoid further leakage of aqueous humor. Significant findings: The patient’s computed tomography (CT head demonstrated a deformed left globe, concerning for ruptured globe. The patient had hyperdense material in the posterior segment (see green arrow, consistent with vitreous hemorrhage. CT findings that are consistent with globe rupture may include a collapsed globe, intraocular air, or foreign bodies. Discussion: A globe rupture is a full-thickness defect in the cornea, sclera, or both.1 It is an ophthalmologic emergency. Globe ruptures are almost always secondary to direct perforation via a penetrating mechanism; however, it can occur due to blunt injury if the force generated creates sufficient intraocular pressure to tear the sclera.2 Globes most commonly rupture at the insertions of the intraocular muscles or at the limbus. They are associated with a high rate of concomitant orbital floor fractures.2,3 Possible physical examination findings include a shallow anterior chamber on slit-lamp exam, hyphema, and an irregular “teardrop” pupil. Additionally, a positive Seidel sign, which is performed by instilling fluorescein in the eye and then examining for a dark stream of aqueous humor, is indicative of a globe rupture.4 CT is often used to assess for globe rupture; finds of a foreign body, intraocular air, abnormal contour or volume of the globe, or disruption of the sclera suggest globe rupture.2 The sensitivity of CT scan for diagnosis of globe rupture is only 75%; thus, high clinical

  16. Test design requirements for overcoring stress measurements

    International Nuclear Information System (INIS)

    Stickney, R.G.

    1985-12-01

    This document establishes the test design requirements for a series of overcoring stress measurements to be performed in the Exploratory Shaft Facility. The stress measurements will be made to determine the in situ state of stress within the candidate repository horizon and to determine the magnitude and distribution of the stresses induced by the mined openings of the facility. The overcoring technique involves the measurement of strain (or deformation) in a volume of rock as the stress acting on the rock volume is relieved. This document presents an overview of the measurements, including objectives and rationale for the measurements. A description of the measurements is included. The support requirements are identified as are constraints for the design of the measurements. Discussions on Quality Assurance and Safety are also included in the document. 13 refs

  17. Formation of carbides and their effects on stress rupture of a Ni-base single crystal superalloy

    International Nuclear Information System (INIS)

    Liu, L.R.; Jin, T.; Zhao, N.R.; Sun, X.F.; Guan, H.R.; Hu, Z.Q.

    2003-01-01

    Creep tests of a nickel-base single crystal superalloy with minor C addition and non-carbon were carried out at different temperatures and stresses. Correlations between microstructural change and testing temperature and stress were enabled through scanning electron microscopy (SEM) and transmission electron microscopy (TEM), detailing the rafting microstucture and carbides precipitation. The results showed that minor carbon addition prolonged the second stage of creep strain curves and improved creep properties. Some carbide was precipitated during creep tests in modified alloy. M 23 C 6 carbide precipitated at lower temperature (871-982 deg. C), while (M 6 C) 2 carbide precipitated at higher temperature (>1000 deg. C), all of which was considered to be beneficial to creep properties. A small amount of MC carbide formed during solidification and its decomposition product (M 6 C) 1 were detrimental to mechanical properties, which together with micropores provided the site of initiation of cracks and led to the final fracture

  18. Stress corrosion testing of irradiated cladding tubes

    International Nuclear Information System (INIS)

    Lunde, L.; Olshausen, K.D.

    1980-01-01

    Samples from two fuel rods with different cladding have been stress corrosion tested by closed-end argon-iodine pressurization at 320 0 C. The fuel rods with stress relieved and recrystallized Zircaloy-2 had received burnups of 10.000 and 20.000 MWd/ton UO 2 , respectively. It was found that the SCC failure stress was unchanged or slightly higher for the irradiated than for the unirradiated control tubes. The tubes failed consistently in the end with the lowest irradiation dose. The diameter increase of the irradiated cladding during the test was 1.1% for the stress-relieved samples and 0.24% for the recrystallized samples. SEM examination revealed no major differences between irradiated and unirradiated cladding. A ''semi-ductile'' fracture zone in recrystallized material is described in some detail. (author)

  19. Ruptured Spleen

    Science.gov (United States)

    ... be caused by various underlying problems, such as mononucleosis and other infections, liver disease, and blood cancers. ... cause a ruptured spleen. For instance, people with mononucleosis — a viral infection that can cause an enlarged ...

  20. Splenic rupture masquerading ruptured ectopic pregnancy | Kigbu ...

    African Journals Online (AJOL)

    The classical triad of presentation of delayed menses, irregular vaginal bleeding and abdominal pain may not be encountered at all! Overwhelming features of abdominal pain, amenorrhea, pallor, abdominal tenderness, shifting dullness with positive pregnancy test gave a clinical diagnosis of ruptured ectopic pregnancy.

  1. High Temperature Performance Evaluation of As-serviced 25Cr35Ni Type Heat-resistant Steel Based on Stress Relaxation Tests

    Directory of Open Access Journals (Sweden)

    XU Jun

    2017-08-01

    Full Text Available Based on an as-serviced 25Cr35Ni type steel, the high temperature property evaluation using stress relaxation test(SRT method and residual life prediction were studied. The results show that creep rupture property decreases because of the formation of network carbides along grain boundaries and coarsening of secondary carbides in the austenitic matrix. Based on the relationship of stress relaxation strain rate curves obtained at different temperatures, and the extrapolation equation of stress relaxation rate-rupture time, it is capable to perform residual life evaluation by combining SRT data and a small amount of creep rupture test(CRT. Good agreement is observed for predicting results performed by current method and traditional method.

  2. Panel manipulation in social stress testing: The Bath Experimental Stress Test for Children (BEST-C).

    Science.gov (United States)

    Cheetham, Tara J; Turner-Cobb, Julie M

    2016-01-01

    Whilst acute stress paradigms in adults make use of adult panel members, similar paradigms modified for child participants have not manipulated the panel. Most work has utilised an audience of adult confederates, regardless of the age of the population being tested. The aim of this study was to trial a social stress test for children that provided a meaningful environment using age-matched child peers as panel actors. Thirty-three participants (7-11 years) underwent the Bath Experimental Stress Test for Children (BEST-C). Based on the Trier Social Stress Test (TSST), it comprises a shortened six-minute public speaking task and four-minute maths challenge. It differs from previous stress tests by using age-matched children on the panel, pre-recorded and presented as a live feed, and includes an expanded manipulation check of subjective experience. Salivary cortisol was assessed at four time points, pre-post stress testing; life events, daily hassles and coping strategies were measured through questionnaires. A simple numerical coding scheme was applied to post-test interview data. The BEST-C generated a typical stress and adaptation response in salivary cortisol (p=.032). Age and gender differences were observed during recovery. Cortisol responses mapped directly onto three distinct subjective response patterns: (i) expected response and recovery; (ii) expected response, no recovery; (iii) no response. The BEST-C, utilising child confederates of participant target age is a meaningful social stress test for children. This is the first social stress test developed specifically for children that manipulates panel characteristics by using child confederates and a pre-recorded sham panel. Greater cortisol responses to the test were also found to match subjective verbal accounts of the experience. It offers a meaningful acute stress paradigm with potential applications to other child and adolescent age groups. Furthermore, it leads the way in the use of panel manipulation

  3. Pad stress tests with increasing load for the diagnosis of stress urinary incontinence.

    Science.gov (United States)

    Rimstad, Liv; Larsen, Elsa Skjønhaug; Schiøtz, Hjalmar A; Kulseng-Hanssen, Sigurd

    2014-09-01

    The aim of the study was to test the ability of pad stress tests with increasing load (supine, jumping on the floor, and jumping on a trampoline) to document stress incontinence in subjectively stress incontinent women. In this prospective study 147 subjectively stress and mixed incontinent women performed consecutively the three pad stress tests with a bladder volume of 300 ml. Nineteen women performed a second trampoline pad stress test to test repeatability of the test. Nine continent women performed a trampoline pad stress test in order to determine if subjectively continent women would leak during the test. Seventy-two women (49%) leaked during the supine, 136 (93%) leaked during the jumping, and 146 (99%) leaked during the trampoline pad stress test. The differences between pad stress tests were significant with P trampoline pad stress tests was high at 0.8. None of the nine continent women leaked during the trampoline pad stress test. The supine pad stress test has low sensitivity and is therefore often falsely negative. The jumping pad stress test is a simple test to perform and is satisfactory for everyday use. Subjectively stress incontinent women who do not leak during the jumping pad stress test may perform a trampoline pad stress test to document stress incontinence. The trampoline pad stress test is also simple to perform and detected leakage in 91% of the women who did not leak during the jumping pad stress test. © 2013 Wiley Periodicals, Inc.

  4. 77 FR 62417 - Annual Stress Test

    Science.gov (United States)

    2012-10-15

    ...;Prices of new books are listed in the first FEDERAL REGISTER issue of each #0;week. #0; #0; #0; #0;#0..., require a covered bank to report stress test results using a simpler format to be specified by the FDIC. G... Federal Register. Section 553(d)(3) of the Administrative Procedure Act (``APA'') provides that...

  5. Have you stress tested your assay?

    Directory of Open Access Journals (Sweden)

    Zheng Cao

    2016-08-01

    Full Text Available Objectives: When a clinical assay is stressed with extraordinarily high volume of specimens over a short period of time, extra caution may be needed to avoid systematic errors and biases. Here we report our experience with a HgbA1c assay used for high volume wellness screening purpose, to illustrate the importance of stress testing during assay validation. Design and Methods: Over 15,000 whole blood specimens were tested for HgbA1c in a period of 2 months. HgbA1c was tested by an immunoturbidimetric method on a high through-put automation line. The HgbA1c population distribution in our study was compared to that from the NHANES database. Daily distributions of HgbA1c values ≥6%, means and medians were plotted. Correlation studies were performed between the high through-put immunoturbidimetric assay and a medium through-put HPLC method. Results: We observed a shift of HgbA1c distribution to the higher values compared to the NHANES. A bias of 15–20% was noted from further stress testing where large number of samples were batched and tested using the immunoturbidimetric assay. A 5–7% higher bias remained after implementing a cuvette washing program after each HgbA1c sample. We hypothesized this bias was caused by build-up of blood cell fragments in the cuvettes when continuous whole blood samples are run through the system. Our experience suggests stress testing needs to be incorporated early in the test validation process for high volume batched screening applications. This seemingly extra validation step may save significant troubleshooting and retesting efforts down the road. Keywords: Hemoglobin A1c, Immunoturbidimetric assay, HPLC, Quality assurance, Systematic bias, High volume, Automation

  6. Mechanical testing of newly developed biomaterial designed for intra-articular reinforcement of partially ruptured cranial cruciate ligament: ex vivo pig model

    Directory of Open Access Journals (Sweden)

    Petra Fedorová

    2014-01-01

    Full Text Available The study deals with mechanical testing of newly developed material polyethylene terephtalate coated with polycaprolactone nanofibers in combination with biodagradable Hexalon ACL/PCL screws as a new possibility of intra-articular reinforcement of partially ruptured cranial cruciate ligament. Four groups of ex vivo models of pig stifle joints were prepared and tested: a model with intact CCL (group 1, a model with partial CCL rupture (group 2, a model with CCL rupture stabilized with 7 mm Mersilene® strip (group 3, and a model with CCL rupture stabilized with 5 mm PET/PCL biomaterial strip (group 4. The models were loaded in the standing angle of 100° and the maximum load (N and the shift (mm were monitored. The mean maximum peak power and the shift were 1266.0 ± 146.9 N and 13.7 ± 2.5 mm for group 1, and 1164.7 ± 228.2 N and 1 6.8 ± 3.3 mm for group 2, respectively. In all cases after reaching the maximum load, a tibial fracture occurred but never a CCL rupture. In groups 3 and 4, the initial fixation failure occurred in the mean values of 375.7 ± 81.5 and 360.4 ± 52.0 N, respectively, and with a bigger shift of 52.3 ± 11.9 mm and 39.4 ± 14.6 mm, respectively, compared to group 1. A critical point of failure was the anchoring in the bone. It can be concluded that the PET/PCL substitute in the ex vivo model has mechanically comparable properties with the clinically used Mersilene®, and based on its proven ability to carry stem cells it could be appropriate for partially ruptured CCL protection.

  7. New considerations on variability of creep rupture data and life prediction

    International Nuclear Information System (INIS)

    Kim, Seon Jin; Jeong, Won Taek; Kong, Yu Sik

    2009-01-01

    This paper deals with the variability analysis of short term creep rupture test data based on the previous creep rupture tests and the possibility of the creep life prediction. From creep tests performed by constant uniaxial stresses at 600, 650 and 700 .deg. C elevated temperature, in order to investigate the variability of short-term creep rupture data, the creep curves were analyzed for normalized creep strain divided by initial strain. There are some variability in thee creep rupture data. And, the difference between general creep curves and normalized creep curves were obtained. The effects of the creep rupture time and state steady creep rate on the Weibull distribution parameters were investigated. There were good relation between normal Weibull parameters and normalized Weibull parameters. Finally, the predicted creep life were compared with the Monkman-Grant model.

  8. New Considerations on Variability of Creep Rupture Data and Life Prediction

    International Nuclear Information System (INIS)

    Jung, Won Taek; Kong, Yu Sik; Kim, Seon Jin

    2009-01-01

    This paper deals with the variability analysis of short term creep rupture test data based on the previous creep rupture tests and the possibility of the creep life prediction. From creep tests performed by constant uniaxial stresses at 600, 650 and 700 .deg. C elevated temperature, in order to investigate the variability of short-term creep rupture data, the creep curves were analyzed for normalized creep strain divided by initial strain. There are some variability in the creep rupture data. And, the difference between general creep curves and normalized creep curves were obtained. The effects of the creep rupture time (RT) and steady state creep rate (SSCR) on the Weibull distribution parameters were investigated. There were good relation between normal Weibull parameters and normalized Weibull parameters. Finally, the predicted creep life were compared with the Monkman-Grant model

  9. Describing Soils: Calibration Tool for Teaching Soil Rupture Resistance

    Science.gov (United States)

    Seybold, C. A.; Harms, D. S.; Grossman, R. B.

    2009-01-01

    Rupture resistance is a measure of the strength of a soil to withstand an applied stress or resist deformation. In soil survey, during routine soil descriptions, rupture resistance is described for each horizon or layer in the soil profile. The lower portion of the rupture resistance classes are assigned based on rupture between thumb and…

  10. A support-operator method for 3-D rupture dynamics

    Science.gov (United States)

    Ely, Geoffrey P.; Day, Steven M.; Minster, Jean-Bernard

    2009-06-01

    We present a numerical method to simulate spontaneous shear crack propagation within a heterogeneous, 3-D, viscoelastic medium. Wave motions are computed on a logically rectangular hexahedral mesh, using the generalized finite-difference method of Support Operators (SOM). This approach enables modelling of non-planar surfaces and non-planar fault ruptures. Our implementation, the Support Operator Rupture Dynamics (SORD) code, is highly scalable, enabling large-scale, multiprocessors calculations. The fault surface is modelled by coupled double nodes, where rupture occurs as dictated by the local stress conditions and a frictional failure law. The method successfully performs test problems developed for the Southern California Earthquake Center (SCEC)/U.S. Geological Survey (USGS) dynamic earthquake rupture code validation exercise, showing good agreement with semi-analytical boundary integral method results. We undertake further dynamic rupture tests to quantify numerical errors introduced by shear deformations to the hexahedral mesh. We generate a family of meshes distorted by simple shearing, in the along-strike direction, up to a maximum of 73°. For SCEC/USGS validation problem number 3, grid-induced errors increase with mesh shear angle, with the logarithm of error approximately proportional to angle over the range tested. At 73°, rms misfits are about 10 per cent for peak slip rate, and 0.5 per cent for both rupture time and total slip, indicating that the method (which, up to now, we have applied mainly to near-vertical strike-slip faulting) is also capable of handling geometries appropriate to low-angle surface-rupturing thrust earthquakes. Additionally, we demonstrate non-planar rupture effects, by modifying the test geometry to include, respectively, cylindrical curvature and sharp kinks.

  11. Comparing slow and fast rupture in laboratory experiments

    Science.gov (United States)

    Aben, F. M.; Brantut, N.; David, E.; Mitchell, T. M.

    2017-12-01

    During the brittle failure of rock, elastically stored energy is converted into a localized fracture plane and surrounding fracture damage, seismic radiation, and thermal energy. However, the partitioning of energy might vary with the rate of elastic energy release during failure. Here, we present the results of controlled (slow) and dynamic (fast) rupture experiments on dry Lanhélin granite and Westerly granite samples, performed under triaxial stress conditions at confining pressures of 50 and 100 MPa. During the tests, we measured sample shortening, axial load and local strains (with 2 pairs of strain gauges glued directly onto the sample). In addition, acoustic emissions (AEs) and changes in seismic velocities were monitored. The AE rate was used as an indicator to manually control the axial load on the sample to stabilize rupture in the quasi-static failure experiments. For the dynamic rupture experiments a constant strain rate of 10-5 s-1 was applied until sample failure. A third experiment, labeled semi-controlled rupture, involved controlled rupture up to a point where the rupture became unstable and the remaining elastic energy was released dynamically. All experiments were concluded after a macroscopic fracture had developed across the whole sample and frictional sliding commenced. Post-mortem samples were epoxied, cut and polished to reveal the macroscopic fracture and the surrounding damage zone. The samples failed with average rupture velocities varying from 5x10-6 m/s up to >> 0.1 m/s. The analyses of AE locations on the slow ruptures reveal that within Westerly granite samples - with a smaller grain size - fracture planes are disbanded in favor of other planes when a geometrical irregularity is encountered. For the coarser grained Lanhélin granite a single fracture plane is always formed, although irregularities are recognized as well. The semi-controlled experiments show that for both rock types the rupture can become unstable in response to these

  12. Coincident steam generator tube rupture and stuck-open safety relief valve carryover tests: MB-2 steam generator transient response test program

    International Nuclear Information System (INIS)

    Garbett, K.; Mendler, O.J.; Gardner, G.C.; Garnsey, R.; Young, M.Y.

    1987-03-01

    In PWR steam generator tube rupture (SGTR) faults, a direct pathway for the release of radioactive fission products can exist if there is a coincident stuck-open safety relief valve (SORV) or if the safety relief valve is cycled. In addition to the release of fission products from the bulk steam generator water by moisture carryover, there exists the possibility that some primary coolant may be released without having first mixed with the bulk water - a process called primary coolant bypassing. The MB-2 Phase II test program was designed specifically to identify the processes for droplet carryover during SGTR faults and to provide data of sufficient accuracy for use in developing physical models and computer codes to describe activity release. The test program consisted of sixteen separate tests designed to cover a range of steady-state and transient fault conditions. These included a full SGTR/SORV transient simulation, two SGTR overfill tests, ten steady-state SGTR tests at water levels ranging from very low levels in the bundle up to those when the dryer was flooded, and three moisture carryover tests without SGTR. In these tests the influence of break location and the effect of bypassing the dryer were also studied. In a final test the behavior with respect to aerosol particles in a dry steam generator, appropriate to a severe accident fault, was investigated

  13. Rupture Complexity Promoted by Damaged Fault Zones in Earthquake Cycle Models

    Science.gov (United States)

    Idini, B.; Ampuero, J. P.

    2017-12-01

    Pulse-like ruptures tend to be more sensitive to stress heterogeneity than crack-like ones. For instance, a stress-barrier can more easily stop the propagation of a pulse than that of a crack. While crack-like ruptures tend to homogenize the stress field within their rupture area, pulse-like ruptures develop heterogeneous stress fields. This feature of pulse-like ruptures can potentially lead to complex seismicity with a wide range of magnitudes akin to the Gutenberg-Richter law. Previous models required a friction law with severe velocity-weakening to develop pulses and complex seismicity. Recent dynamic rupture simulations show that the presence of a damaged zone around a fault can induce pulse-like rupture, even under a simple slip-weakening friction law, although the mechanism depends strongly on initial stress conditions. Here we aim at testing if fault zone damage is a sufficient ingredient to generate complex seismicity. In particular, we investigate the effects of damaged fault zones on the emergence and sustainability of pulse-like ruptures throughout multiple earthquake cycles, regardless of initial conditions. We consider a fault bisecting a homogeneous low-rigidity layer (the damaged zone) embedded in an intact medium. We conduct a series of earthquake cycle simulations to investigate the effects of two fault zone properties: damage level D and thickness H. The simulations are based on classical rate-and-state friction, the quasi-dynamic approximation and the software QDYN (https://github.com/ydluo/qdyn). Selected fully-dynamic simulations are also performed with a spectral element method. Our numerical results show the development of complex rupture patterns in some damaged fault configurations, including events of different sizes, as well as pulse-like, multi-pulse and hybrid pulse-crack ruptures. We further apply elasto-static theory to assess how D and H affect ruptures with constant stress drop, in particular the flatness of their slip profile

  14. Creep/Stress Rupture Behavior and Failure Mechanisms of Full CVI and Full PIP SiC/SiC Composites at Elevated Temperatures in Air

    Science.gov (United States)

    Bhatt, R. T.; Kiser, J. D.

    2017-01-01

    SiC/SiC composites fabricated by melt infiltration are being considered as potential candidate materials for next generation turbine components. However these materials are limited to 2400 F application because of the presence of residual silicon in the SiC matrix. Currently there is an increasing interest in developing and using silicon free SiC/SiC composites for structural aerospace applications above 2400 F. Full PIP or full CVI or CVI + PIP hybrid SiC/SiC composites can be fabricated without excess silicon, but the upper temperature stress capabilities of these materials are not fully known. In this study, the on-axis creep and rupture properties of the state-of-the-art full CVI and full PIP SiC/SiC composites with Sylramic-iBN fibers were measured at temperatures to 2700 F in air and their failure modes examined. In this presentation creep rupture properties, failure mechanisms and upper temperature capabilities of these two systems will be discussed and compared with the literature data.

  15. In-reactor creep rupture behavior of the D9 alloys

    International Nuclear Information System (INIS)

    Puigh, R.J.; Hamilton, M.L.

    1986-06-01

    The uncertainties in the in-reactor stress rupture data have been significantly reduced with the acquisition of the Materials Open Test Assembly (MOTA) for testing of materials in the Fast Flux Test Facility (FFTF). The temperature uncertainty associated with irradiation in this vehicle is +- 5 0 C. Moreover, through the use of tag gases and an on-line cover gas monitoring system, on-line detection of specimen ruptures is possible during irradiation, thereby significantly reducing the uncertainty associated with the rupture times. Titanium additions, increases in nickel content and decreases in chromium content, which were made to improve the swelling response of 316 SS, resulted in an alloy class referred to as ''D9''. In-reactor stress rupture data from the MOTA experiment have been reported on two conditions of the D9-type alloys for exposure times corresponding to 2,400 hours at irradiation temperatures of 575, 605, 670, and 750 0 C. For these conditions the in-reactor rupture times were similar to those observed in thermal control tests. This report will describe both the in-reactor stress rupture behavior and the thermal control data for 20% cold work (CW) 316 SS and for 10 and 20% CW D9-type alloy over a similar temperature range for in-reactor exposure times corresponding to 13170 hr. and peak fast fluences corresponding to 17 x 10 22 n/cm 2 (E > 0.1 MeV)

  16. 40 CFR 90.329 - Catalyst thermal stress test.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Catalyst thermal stress test. 90.329... Equipment Provisions § 90.329 Catalyst thermal stress test. (a) Oven characteristics. The oven used for thermally stressing the test catalyst must be capable of maintaining a temperature of 500 ±5 °C and 1000 ±10...

  17. 40 CFR 91.329 - Catalyst thermal stress test.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Catalyst thermal stress test. 91.329....329 Catalyst thermal stress test. (a) Oven characteristics. The oven used for termally stressing the test catalyst must be capable of maintaining a temperature of 500 ±5 °C and 1000 ±10 °C. (b) Evaluation...

  18. 40-in. OMS Kevlar(Registered Trademark) COPV S/N 007 Stress Rupture Test NDE

    Science.gov (United States)

    Saulsberry, Regor; Greene, Nate; Forth, Scott; Leifeste, Mark; Gallus, Tim; Yoder, Tommy; Keddy, Chris; Mandaras, Eric; Wincheski, Buzz; Williams, Philip; hide

    2010-01-01

    The presentation examines pretest nondestructive evaluation (NDE), including external/internal visual inspection, raman spectroscopy, laser shearography, and laser profilometry; real-time NDE including eddy current, acoustic emission (AE), and real-time portable raman spectroscopy; and AE application to carbon/epoxy composite overwrapped pressure vessels.

  19. A study on stress analysis of small punch-creep test and its experimental correlations with uniaxial-creep test

    International Nuclear Information System (INIS)

    Lee, Song In; Baek, Seoung Se; Kwon, Il Hyun; Yu, Hyo Sun

    2002-01-01

    A basic research was performed to ensure the usefulness of Small Punch-creep(SP-creep) test for residual life evaluation of heat resistant components effectively. This paper presents analytical results of initial stress and strain distributions in SP specimen caused by constant loading for SP-creep test and its experimental correlations with uniaxial creep(Ten-creep) test on 9CrlMoVNb steel. It was shown that the initial maximum equivalent stress, σ eq · max from FE analysis was correlated with steady-state equivalent creep strain rate, ε qf-ss , rupture time, t r , activation energy, Q and Larson-Miller parameter, LMP during SP-creep deformation. The simple correlation laws, σ SP - σ TEN , P SP -σ TEN and Q SP -Q TEN adopted to established a quantitative correlation between SP-creep and Ten-creep test data. Especially, the activation energy obtained from SP-creep test is linearly related to that from Ten-creep test at 650 deg. C as follows : Q SP-P =1.37 Q TEN , Q SP-σ =1.53 Q TEN

  20. Rupture properties

    International Nuclear Information System (INIS)

    Marandet, B.; Sanz, G.

    1977-01-01

    Linear elastic fracture mechanics can be applied to medium strength steels when they are used in large thicknesses. In this case it is possible to put in evidence the existence of a parameter, Ksub(Ic), characteristic of the material, which depends only on the strain rate and the temperature, and which can be used to predict quantitatively the conditions for fracture of a structure containing a defect. The determination of Ksub(Ic) involves the use of large specimens, and thus of big testing machines. It is then clear that such tests can not be performed systematically on many steels, and certainly not at all in metallurgical quality control. The aim of this study was to check and develop further certain new theories which make it possible, according to their authors, to evaluate Ksub(Ic) with small specimens: correlations between Ksub(Ic) and Charpy V toughness, J-integral, equivalent energy concept. As these techniques lead to values of toughness in plane-strain conditions, we have also studied the significance of R-curves, a concept which has be proposed to characterize the toughness of a material in plane-stress conditions. This report has thus been divided into four parts which correspond to the four approaches just mentionned

  1. Stress analysis of shear/compression test

    International Nuclear Information System (INIS)

    Nishijima, S.; Okada, T.; Ueno, S.

    1997-01-01

    Stress analysis has been made on the glass fiber reinforced plastics (GFRP) subjected to the combined shear and compression stresses by means of finite element method. The two types of experimental set up were analyzed, that is parallel and series method where the specimen were compressed by tilted jigs which enable to apply the combined stresses, to the specimen. Modified Tsai-Hill criterion was employed to judge the failure under the combined stresses that is the shear strength under the compressive stress. The different failure envelopes were obtained between the two set ups. In the parallel system the shear strength once increased with compressive stress then decreased. On the contrary in the series system the shear strength decreased monotonicly with compressive stress. The difference is caused by the different stress distribution due to the different constraint conditions. The basic parameters which control the failure under the combined stresses will be discussed

  2. Hemodynamic stress testing using pacing tachycardia

    International Nuclear Information System (INIS)

    McKay, R.G.; Grossman, W.

    1986-01-01

    A trial pacing was first introduced in 1967 by Sowton and co-workers as a stress test which could be used in the cardiac catheterization laboratory to evaluate patients with schemic heart disease. Sowton noted that artificially increasing the heart rate by pacing the right atrium could usually induce angina in patients with symptomatic coronary artery disease. Since Sowton's original description, numerous investigators have described characteristic pacing-induced electrocardiographic changes, derangements of myocardial lactate metabolism, hemodynamic abnormalities, regional wall abnormalities, and defects in thallium scintigraphy. Although agreement on the overall usefulness of atrial pacing has not been uniform, it is clear that the technique can safely and reliably induce ischemia in most patients with coronary artery disease and that information obtained during the pacing-induced ischemic state can often be helpful in the diagnosis and treatment of the patient's underlying disease

  3. Stress analysis for CANDU reactor structure assembly following a postulated p/t, c/t rupture after flow blockage

    Energy Technology Data Exchange (ETDEWEB)

    Soliman, S A; Lee, T; Ibrahim, A M; Hodgson, S [Atomic Energy of Canada Ltd., Saskatoon, SK (Canada)

    1996-12-31

    This paper describes the collapse load calculations for the reactor structure assembly under the postulated fuel channel flow blockage Level D (faulted) loading condition. Under the flow blockage condition, the primary coolant flow path is obstructed between the inlet and outlet feeder connections to the headers. This, in turn, is postulated to cause the pressure tube and calandria tube to rupture and release hot molten fuel into the moderator, producing a hydrodynamic transient within the calandria shell. The most severe hydrodynamic loads occur within a fraction of a second (0.14 second). The peak pressure for the limiting case scenario for Level D condition is 120 psig, due to a single channel failure event. Under this accident condition, it is shown that the reactor structure assembly can withstand the pressure transient and the structural integrity of the core is assured. A finite element model is generated and used to calculate the minimum collapse load. The ANSYS code is used with element type Stif-43 for elastic/plastic, large deformation and small strain analysis. (author). 1 ref., 3 tabs., 9 figs.

  4. Stress analysis for CANDU reactor structure assembly following a postulated p/t, c/t rupture after flow blockage

    International Nuclear Information System (INIS)

    Soliman, S.A.; Lee, T.; Ibrahim, A.M.; Hodgson, S.

    1995-01-01

    This paper describes the collapse load calculations for the reactor structure assembly under the postulated fuel channel flow blockage Level D (faulted) loading condition. Under the flow blockage condition, the primary coolant flow path is obstructed between the inlet and outlet feeder connections to the headers. This, in turn, is postulated to cause the pressure tube and calandria tube to rupture and release hot molten fuel into the moderator, producing a hydrodynamic transient within the calandria shell. The most severe hydrodynamic loads occur within a fraction of a second (0.14 second). The peak pressure for the limiting case scenario for Level D condition is 120 psig, due to a single channel failure event. Under this accident condition, it is shown that the reactor structure assembly can withstand the pressure transient and the structural integrity of the core is assured. A finite element model is generated and used to calculate the minimum collapse load. The ANSYS code is used with element type Stif-43 for elastic/plastic, large deformation and small strain analysis. (author). 1 ref., 3 tabs., 9 figs

  5. Female False Positive Exercise Stress ECG Testing - Fact Verses Fiction.

    Science.gov (United States)

    Fitzgerald, Benjamin T; Scalia, William M; Scalia, Gregory M

    2018-03-07

    Exercise stress testing is a well validated cardiovascular investigation. Accuracy for treadmill stress electrocardiograph (ECG) testing has been documented at 60%. False positive stress ECGs (exercise ECG changes with non-obstructive disease on anatomical testing) are common, especially in women, limiting the effectiveness of the test. This study investigates the incidence and predictors of false positive stress ECG findings, referenced against stress echocardiography (SE) as a standard. Stress echocardiography was performed using the Bruce treadmill protocol. False positive stress ECG tests were defined as greater than 1mm of ST depression on ECG during exertion, without pain, with a normal SE. Potential causes for false positive tests were recorded before the test. Three thousand consecutive negative stress echocardiograms (1036 females, 34.5%) were analysed (age 59+/-14 years. False positive (F+) stress ECGs were documented in 565/3000 tests (18.8%). F+ stress ECGs were equally prevalent in females (194/1036, 18.7%) and males (371/1964, 18.9%, p=0.85 for the difference). Potential causes (hypertension, left ventricular hypertrophy, known coronary disease, arrhythmia, diabetes mellitus, valvular heart disease) were recorded in 36/194 (18.6%) of the female F+ ECG tests and 249/371 (68.2%) of the male F+ ECG tests (preinforce the value of stress imaging, particularly in women. Copyright © 2018 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). All rights reserved.

  6. Discrimination of DPRK M5.1 February 12th, 2013 Earthquake as Nuclear Test Using Analysis of Magnitude, Rupture Duration and Ratio of Seismic Energy and Moment

    Science.gov (United States)

    Salomo Sianipar, Dimas; Subakti, Hendri; Pribadi, Sugeng

    2015-04-01

    On February 12th, 2013 morning at 02:57 UTC, there had been an earthquake with its epicenter in the region of North Korea precisely around Sungjibaegam Mountains. Monitoring stations of the Preparatory Commission for the Comprehensive Nuclear Test-Ban Treaty Organization (CTBTO) and some other seismic network detected this shallow seismic event. Analyzing seismograms recorded after this event can discriminate between a natural earthquake or an explosion. Zhao et. al. (2014) have been successfully discriminate this seismic event of North Korea nuclear test 2013 from ordinary earthquakes based on network P/S spectral ratios using broadband regional seismic data recorded in China, South Korea and Japan. The P/S-type spectral ratios were powerful discriminants to separate explosions from earthquake (Zhao et. al., 2014). Pribadi et. al. (2014) have characterized 27 earthquake-generated tsunamis (tsunamigenic earthquake or tsunami earthquake) from 1991 to 2012 in Indonesia using W-phase inversion analysis, the ratio between the seismic energy (E) and the seismic moment (Mo), the moment magnitude (Mw), the rupture duration (To) and the distance of the hypocenter to the trench. Some of this method was also used by us to characterize the nuclear test earthquake. We discriminate this DPRK M5.1 February 12th, 2013 earthquake from a natural earthquake using analysis magnitude mb, ms and mw, ratio of seismic energy and moment and rupture duration. We used the waveform data of the seismicity on the scope region in radius 5 degrees from the DPRK M5.1 February 12th, 2013 epicenter 41.29, 129.07 (Zhang and Wen, 2013) from 2006 to 2014 with magnitude M ≥ 4.0. We conclude that this earthquake was a shallow seismic event with explosion characteristics and can be discriminate from a natural or tectonic earthquake. Keywords: North Korean nuclear test, magnitude mb, ms, mw, ratio between seismic energy and moment, ruptures duration

  7. High temperature aqueous stress corrosion testing device

    International Nuclear Information System (INIS)

    Bornstein, A.N.; Indig, M.E.

    1975-01-01

    A description is given of a device for stressing tensile samples contained within a high temperature, high pressure aqueous environment, thereby permitting determination of stress corrosion susceptibility of materials in a simple way. The stressing device couples an external piston to an internal tensile sample via a pull rod, with stresses being applied to the sample by pressurizing the piston. The device contains a fitting/seal arrangement including Teflon and weld seals which allow sealing of the internal system pressure and the external piston pressure. The fitting/seal arrangement allows free movement of the pull rod and the piston

  8. Ultrasonic test of highly stressed gear shafts

    Energy Technology Data Exchange (ETDEWEB)

    Schreiner, T. [Siemens AG, Power Generation, KWU, Muelheim (Germany); Heinrich, W. [Siemens AG, Power Generation, KWU, Berlin (Germany); Achtzehn, J. [Siemens AG, Power Generation, ICVW, Erlangen (Germany); Hensley, H. [Siemens Power Generation (Germany)

    1998-12-31

    In the power plant industry, gears are used for increasingly higher turbine capacities. Efficiency enhancements, particularly for the combined gas and steam turbine process, lead to an increase in stresses, even for high-performance gears. Consequently, the requirements for non-destructive material testing are on the increase as well. At Siemens KWU, high-performance gears are used so far only for gas turbines with lower rating (65 MW) to adapt the gas turbine speed (5413 rpm) to the generator speed (3000 rpm/ 50 Hz or 3600 rpm/60 Hz). The gear train consists of a forged and case-hardened wheel shaft and pinion shaft made of material 17 CrNiMo 6, where the wheel shaft can be either a solid or a hollow shaft. Dimensions are typically 2.3 m length and 1 m diameter. As a rule, pinion shafts are solid. The gear design, calling for an additional torsion shaft turning inside the hollow wheel shaft, can absorb more torsional load surges and is more tolerant of deviations during gear train alignment. This design requires two additional forgings (torsion shaft and hub) and an additional bearing 2 refs.

  9. Ultrasonic test of highly stressed gear shafts

    Energy Technology Data Exchange (ETDEWEB)

    Schreiner, T [Siemens AG, Power Generation, KWU, Muelheim (Germany); Heinrich, W [Siemens AG, Power Generation, KWU, Berlin (Germany); Achtzehn, J [Siemens AG, Power Generation, ICVW, Erlangen (Germany); Hensley, H [Siemens Power Generation (Germany)

    1999-12-31

    In the power plant industry, gears are used for increasingly higher turbine capacities. Efficiency enhancements, particularly for the combined gas and steam turbine process, lead to an increase in stresses, even for high-performance gears. Consequently, the requirements for non-destructive material testing are on the increase as well. At Siemens KWU, high-performance gears are used so far only for gas turbines with lower rating (65 MW) to adapt the gas turbine speed (5413 rpm) to the generator speed (3000 rpm/ 50 Hz or 3600 rpm/60 Hz). The gear train consists of a forged and case-hardened wheel shaft and pinion shaft made of material 17 CrNiMo 6, where the wheel shaft can be either a solid or a hollow shaft. Dimensions are typically 2.3 m length and 1 m diameter. As a rule, pinion shafts are solid. The gear design, calling for an additional torsion shaft turning inside the hollow wheel shaft, can absorb more torsional load surges and is more tolerant of deviations during gear train alignment. This design requires two additional forgings (torsion shaft and hub) and an additional bearing 2 refs.

  10. Accuracy and cost-analysis of placental alpha-microglobulin-1 test in the diagnosis of premature rupture of fetal membranes in resource-limited community settings.

    Science.gov (United States)

    Eleje, George Uchenna; Ezugwu, Euzebus Chinonye; Ogunyemi, Dotun; Eleje, Lydia Ijeoma; Ikechebelu, Joseph Ifeanyichukwu; Igwegbe, Anthony Osita; Okonkwo, John E; Ikpeze, Okechukwu Christian; Udigwe, Gerald Okanandu; Onah, Hyacinth Eze; Nwosu, Betrand Obi; Ezeama, Chukwuemeka Okwudili; Ezenkwele, Eziamaka Pauline

    2015-01-01

    To determine accuracy and costs of placental α-microglobulin-1 (PAMG-1) test compared to standard clinical assessment (SCA) for diagnosing rupture of membranes (ROM). A multicenter double-blind study of consecutive women with symptoms and signs of ROM in Nnamdi Azikiwe University Teaching Hospital, Nnewi and University of Nigeria Teaching Hospital, Enugu, both in south-east Nigeria using SCA for ROM and the PAMG-1 test was done. ROM was diagnosed if two out of three methods from SCA (pooling, positive nitrazine test or ferning) were present and confirmed post-delivery based on presence of any two of these clinical criteria: delivery in 48 h to 7 days, evidence of chorioamnionitis, membranes overtly ruptured at delivery and adverse perinatal outcomes strongly correlated with prolonged PROM. A cost-analysis was also done. The outcome measures included sensitivity, specificity, accuracy and costs for the two tests. Accuracy, sensitivity and specificity for the PAMG-1 test were 97.2%, 97.4% and 96.7%, higher than for SCA which were 83.7%, 87.9% and 70.5%, respectively (P < 0.001). Accuracy of SCA was higher at less than 34 weeks than 34 weeks or more (88.3% vs 81.4%) while the PAMG-1 test performed equally at both gestational age categories (96.1% vs 97.7%). In women without pooling, accuracy of the PAMG-1 test was 96.7%, while it was 40.0% with SCA. Analysis showed that the overall cost of SCA was 45% higher than the PAMG-1 test. This study confirms that the PAMG-1 test has a consistently high diagnostic accuracy at all gestational ages and with equivocal cases of ROM. The PAMG-1 test appears less costly than SCA. © 2014 The Authors. Journal of Obstetrics and Gynaecology Research © 2014 Japan Society of Obstetrics and Gynecology.

  11. Test plan for in situ stress measurement system development

    International Nuclear Information System (INIS)

    Kim, K.

    1981-09-01

    The tests are to be performed to provide information regarding the state of stress of the basalt rock beneath the Hanford Site. This test series is designed to obtain information necessary to determine if hydrofracturing stress measurement is feasible in a fractured basalt medium. During the course of these field tests, it will be attempted to adapt the conventional hydrofracturing test method and analysis techniques to the basalt medium. If the test is shown to be feasible, more holes will be identified for testing. A comprehensive in situ stress determination program will be initiated. 2 figs

  12. Validation of statistical models for creep rupture by parametric analysis

    Energy Technology Data Exchange (ETDEWEB)

    Bolton, J., E-mail: john.bolton@uwclub.net [65, Fisher Ave., Rugby, Warks CV22 5HW (United Kingdom)

    2012-01-15

    Statistical analysis is an efficient method for the optimisation of any candidate mathematical model of creep rupture data, and for the comparative ranking of competing models. However, when a series of candidate models has been examined and the best of the series has been identified, there is no statistical criterion to determine whether a yet more accurate model might be devised. Hence there remains some uncertainty that the best of any series examined is sufficiently accurate to be considered reliable as a basis for extrapolation. This paper proposes that models should be validated primarily by parametric graphical comparison to rupture data and rupture gradient data. It proposes that no mathematical model should be considered reliable for extrapolation unless the visible divergence between model and data is so small as to leave no apparent scope for further reduction. This study is based on the data for a 12% Cr alloy steel used in BS PD6605:1998 to exemplify its recommended statistical analysis procedure. The models considered in this paper include a) a relatively simple model, b) the PD6605 recommended model and c) a more accurate model of somewhat greater complexity. - Highlights: Black-Right-Pointing-Pointer The paper discusses the validation of creep rupture models derived from statistical analysis. Black-Right-Pointing-Pointer It demonstrates that models can be satisfactorily validated by a visual-graphic comparison of models to data. Black-Right-Pointing-Pointer The method proposed utilises test data both as conventional rupture stress and as rupture stress gradient. Black-Right-Pointing-Pointer The approach is shown to be more reliable than a well-established and widely used method (BS PD6605).

  13. Critical wall shear stress for the EHEDG test method

    DEFF Research Database (Denmark)

    Jensen, Bo Boye Busk; Friis, Alan

    2004-01-01

    In order to simulate the results of practical cleaning tests on closed processing equipment, based on wall shear stress predicted by computational fluid dynamics, a critical wall shear stress is required for that particular cleaning method. This work presents investigations that provide a critical...... wall shear stress of 3 Pa for the standardised EHEDG cleaning test method. The cleaning tests were performed on a test disc placed in a radial flowcell assay. Turbulent flow conditions were generated and the corresponding wall shear stresses were predicted from CFD simulations. Combining wall shear...... stress predictions from a simulation using the low Re k-epsilon and one using the two-layer model of Norris and Reynolds were found to produce reliable predictions compared to empirical solutions for the ideal flow case. The comparison of wall shear stress curves predicted for the real RFC...

  14. Stress Optical Coefficient, Test Methodology, and Glass Standard Evaluation

    Science.gov (United States)

    2016-05-01

    ARL-TN-0756 ● MAY 2016 US Army Research Laboratory Stress Optical Coefficient, Test Methodology , and Glass Standard Evaluation...Stress Optical Coefficient, Test Methodology , and Glass Standard Evaluation by Clayton M Weiss Oak Ridge Institute for Science and Education...ORISE), Belcamp, MD Parimal J Patel Weapons and Materials Research Directorate, ARL Approved for public release; distribution is

  15. Stress Testing as a Tool of Bank Risk Management

    Directory of Open Access Journals (Sweden)

    Antonyuk Oksana I.

    2013-12-01

    Full Text Available The goal of the article is development of theoretical, methodological and practical recommendations on the use of stress testing by Ukrainian commercial banks. Stress testing is defined as a part of bank risk management on the basis of scientific studies of domestic and foreign scientists. The article marks the essence of the bank stress testing and identifies its role in the structure of banks’ risk management in Ukraine. It considers goals of conducting stress testing in banking institutions. It identifies main aspects and specific features of conducting stress testing of bank risks. It characterises main advantages and shortcomings of use of stress testing in the modern bank risk management. It generalises the world and European approaches to the methods of conducting stress testing in commercial banks in comparison with the Ukrainian methodical recommendations. It shows that results of stress testing have practical value, since they help to preliminary assess influence of potentially negative events upon the state of the loan portfolio of the bank and make relevant managerial decisions.

  16. Thermal stresses in the space shuttle orbiter: Analysis versus test

    International Nuclear Information System (INIS)

    Grooms, H.R.; Gibson, W.F. Jr.; Benson, P.L.

    1984-01-01

    Significant temperature differences occur between the internal structure and the outer skin of the Space Shuttle Orbiter as it returns from space. These temperature differences cause important thermal stresses. A finite element model containing thousands of degrees of freedom is used to predict these stresses. A ground test was performed to verify the prediction method. The analysis and test results compare favorably. (orig.)

  17. 77 FR 60948 - Stress Testing of Regulated Entities

    Science.gov (United States)

    2012-10-05

    ... regulated by a primary federal financial regulatory agency, to conduct annual stress tests to determine... the regulated entities under the Federal Housing Enterprises Financial Safety and Soundness Act of... regulated by a primary Federal financial regulatory agency shall conduct annual stress tests * * * (emphasis...

  18. Relationships between adolescents' test anxiety, stress and sleep

    NARCIS (Netherlands)

    Dewald, J.F.; Meijer, A.M.; Oort, F.J.; Bögels, S.M.

    2012-01-01

    Objective. This study aims to investigate the relationship between adolescents' test anxiety, stress and different aspects of sleep. Method. 175 adolescents (70.8% girls, mean age 15.14 years) participated in the study. Test anxiety, stress and chronic sleep reduction were assessed at baseline using

  19. Vortex dynamics in ruptured and unruptured intracranial aneurysms

    Science.gov (United States)

    Trylesinski, Gabriel

    Intracranial aneurysms (IAs) are a potentially devastating pathological dilation of brain arteries that affect 1.5-5 % of the population. Causing around 500 000 deaths per year worldwide, their detection and treatment to prevent rupture is critical. Multiple recent studies have tried to find a hemodynamics predictor of aneurysm rupture, but concluded with distinct opposite trends using Wall Shear Stress (WSS) based parameters in different clinical datasets. Nevertheless, several research groups tend to converge for now on the fact that the flow patterns and flow dynamics of the ruptured aneurysms are complex and unstable. Following this idea, we investigated the vortex properties of both unruptured and ruptured cerebral aneurysms. A brief comparison of two Eulerian vortex visualization methods (Q-criterion and lambda 2 method) showed that these approaches gave similar results in our complex aneurysm geometries. We were then able to apply either one of them to a large dataset of 74 patient specific cases of intracranial aneurysms. Those real cases were obtained by 3D angiography, numerical reconstruction of the geometry, and then pulsatile CFD simulation before post-processing with the mentioned vortex visualization tools. First we tested the two Eulerian methods on a few cases to verify their implementation we made as well as compare them with each other. After that, the Q-criterion was selected as method of choice for its more obvious physical meaning (it shows the balance between two characteristics of the flow, its swirling and deformation). Using iso-surfaces of Q, we started by categorizing the patient-specific aneurysms based on the gross topology of the aneurysmal vortices. This approach being unfruitful, we found a new vortex-based characteristic property of ruptured aneurysms to stratify the rupture risk of IAs that we called the Wall-Kissing Vortices, or WKV. We observed that most ruptured aneurysms had a large amount of WKV, which appears to agree with

  20. Variability in creep and rupture test results in a single heat of type 304 stainless steel. R and D report LR:75:4213-01:3

    International Nuclear Information System (INIS)

    Leyda, W.E.; Schultz, C.C.

    1975-09-01

    Results of uniaxial creep and rupture tests, from a single heat of type 304 stainless steel, are examined to determine the reasons for their greater-than-expected variability. The test results were obtained as part of a program to develop and verify high temperature structural design methods for liquid metal fast breeder reactor system components. A single heat of material (heat 9T2796) is being used throughout the program, by all investigators and in several product forms, to minimize the problem of heat-to-heat variations in elevated temperature behavior. The same laboratory reanneal was specified for each product form to reduce differences in behavior among the several being used. The data discussed was obtained from the 5/8-inch diameter, hot-rolled bar product form. The laboratory reanneal was performed after finish machining to minimize specimen-to-specimen differences. In spite of these efforts to reduce data variability, significant scatter was observed in both short-time and long-time deformation response, and also in time-to-rupture results

  1. Current trends and future development in pharmacologic stress testing

    International Nuclear Information System (INIS)

    Bae, Jin Ho; Lee, Jae Tae

    2005-01-01

    Pharmacologic stress testing for myocardial perfusion imaging is a widely used noninvasive method for the evaluation of known or suspected coronary artery disease. The use of exercise for cardiac stress has been practiced for over 60 years and clinicians are familiar with its using. However, there are inevitable situations in which exercise stress is inappropriate. A large number of patients with cardiac problems are unable to exercise to their full potential due to comorbidity such as osteoarthritis, vascular disease and pulmonary disease and a standard exercise stress test for myocardial perfusion imaging is suboptimal means for assessment of coronary artery disease. This problem has led to the development of the pharmacologic stress test and to a great increase in its popularity. All of the currently used pharmacologic agents have well-documented diagnostic value. This review deals the physiological actions, clinical protocols, safety, nuclear imaging applications of currently available stress agents and future development of new vasodilating agents

  2. Material Parameters for Creep Rupture of Austenitic Stainless Steel Foils

    Science.gov (United States)

    Osman, H.; Borhana, A.; Tamin, M. N.

    2014-08-01

    Creep rupture properties of austenitic stainless steel foil, 347SS, used in compact recuperators have been evaluated at 700 °C in the stress range of 54-221 MPa to establish the baseline behavior for its extended use. Creep curves of the foil show that the primary creep stage is brief and creep life is dominated by tertiary creep deformation with rupture lives in the range of 10-2000 h. Results are compared with properties of bulk specimens tested at 98 and 162 MPa. Thin foil 347SS specimens were found to have higher creep rates and higher rupture ductility than their bulk specimen counterparts. Power law relationship was obtained between the minimum creep rate and the applied stress with stress exponent value, n = 5.7. The value of the stress exponent is indicative of the rate-controlling deformation mechanism associated with dislocation creep. Nucleation of voids mainly occurred at second-phase particles (chromium-rich M23C6 carbides) that are present in the metal matrix by decohesion of the particle-matrix interface. The improvement in strength is attributed to the precipitation of fine niobium carbides in the matrix that act as obstacles to the movement of dislocations.

  3. Life time forecasting method upon occurrence of stress corrosion cracking of structure and test device therefor

    International Nuclear Information System (INIS)

    Anzai, Hideya; Kida, Toshitaka; Urayama, Yoshinao; Kikuchi, Eiji; Shimanuki, Sei; Kuniya, Jiro; Nakata, Kiyotomo; Izumitani, Masakiyo; Hattori, Shigeo.

    1993-01-01

    A load stress is applied to a metal piece made of a material identical with the constituent material of a structure and having the sensitivity enhanced to a predetermined level, and plurality of such pieces are immersed in a corrosive circumstance in this state. Then, the time from the immersion till the rupture thereof and the number of ruptured pieces of the metal pieces are detected while observing them. The relation with the probability of rupture is plotted on a paper to determine the life time for the occurrence of minimum stress corrosion creacks (SSC) of the metal pieces. Based on the relationship between the previously determined stress and the life time for the occurrence of minimum SSC, the ratio between the life time for the occurrence of minimum SSC relative to estimated stress applied to the structure and the life time for the occurrence of minimum SSC relative to the stress applied to the metal pieces is determined as a first SSC acceleration rate. The ratio between the time of occurrence for minimum SSC and the sensitivity is determined as a second SSC acceleration rate. The first and the second SSC acceleration rates are multiplied to estimate the time for the occurrence of SSC of the structure. Then, the life time for the occurrence of SSC for the equipments and structures can be recognized quantitatively, to prevent ruptures of actual equipments and extend the life time. (N.H.)

  4. Exertional headache and coronary ischemia despite normal electrocardiographic stress testing.

    Science.gov (United States)

    Cutrer, F Michael; Huerter, Karina

    2006-01-01

    Exertional headaches may under certain conditions reflect coronary ischemia. We report the case of a patient seen in a neurology referral practice whose exertional headaches, even in the face of two normal electrocardiographic stress tests and in the absence of underlying chest pain were the sole symptoms of coronary ischemia as detected by Tc-99m Sestamibi testing SPECT stress testing. Stent placement resulted in complete resolution of headaches. Exertional headache in the absence of chest pain may reflect underlying symptomatic coronary artery disease (CAD) even when conventional electrocardiographic stress testing does not indicate ischemia.

  5. Shared and Distinct Rupture Discriminants of Small and Large Intracranial Aneurysms.

    Science.gov (United States)

    Varble, Nicole; Tutino, Vincent M; Yu, Jihnhee; Sonig, Ashish; Siddiqui, Adnan H; Davies, Jason M; Meng, Hui

    2018-04-01

    Many ruptured intracranial aneurysms (IAs) are small. Clinical presentations suggest that small and large IAs could have different phenotypes. It is unknown if small and large IAs have different characteristics that discriminate rupture. We analyzed morphological, hemodynamic, and clinical parameters of 413 retrospectively collected IAs (training cohort; 102 ruptured IAs). Hierarchal cluster analysis was performed to determine a size cutoff to dichotomize the IA population into small and large IAs. We applied multivariate logistic regression to build rupture discrimination models for small IAs, large IAs, and an aggregation of all IAs. We validated the ability of these 3 models to predict rupture status in a second, independently collected cohort of 129 IAs (testing cohort; 14 ruptured IAs). Hierarchal cluster analysis in the training cohort confirmed that small and large IAs are best separated at 5 mm based on morphological and hemodynamic features (area under the curve=0.81). For small IAs (IAs (area under the curve=0.84; 95% confidence interval, 0.78-0.88), whereas for large IAs (≥5 mm), the model included undulation index, low wall shear stress, previous subarachnoid hemorrhage, and IA location (area under the curve=0.87; 95% confidence interval, 0.82-0.93). The model for the aggregated training cohort retained all the parameters in the size-dichotomized models. Results in the testing cohort showed that the size-dichotomized rupture discrimination model had higher sensitivity (64% versus 29%) and accuracy (77% versus 74%), marginally higher area under the curve (0.75; 95% confidence interval, 0.61-0.88 versus 0.67; 95% confidence interval, 0.52-0.82), and similar specificity (78% versus 80%) compared with the aggregate-based model. Small (IAs have different hemodynamic and clinical, but not morphological, rupture discriminants. Size-dichotomized rupture discrimination models performed better than the aggregate model. © 2018 American Heart Association, Inc.

  6. Creep-rupture behavior of candidate Stirling engine iron supperalloys in high-pressure hydrogen. Volume 2: Hydrogen creep-rupture behavior

    Science.gov (United States)

    Bhattacharyya, S.; Peterman, W.; Hales, C.

    1984-01-01

    The creep rupture behavior of nine iron base and one cobalt base candidate Stirling engine alloys is evaluated. Rupture life, minimum creep rate, and time to 1% strain data are analyzed. The 3500 h rupture life stress and stress to obtain 1% strain in 3500 h are also estimated.

  7. Effects of cobalt on creep rupture properties and dislocation structures in nickel base superalloys

    International Nuclear Information System (INIS)

    Wang, W.Z.; Jin, T.; Jia, J.H.; Liu, J.L.; Hu, Z.Q.

    2015-01-01

    The influences of cobalt (Co) on creep rupture lives and dislocation structures in nickel base superalloys with and without rhenium (Re) are investigated. The creep rupture test conditions were high temperature low stress (1100 °C/150 MPa), intermediate temperature and stress (982 °C, 1010 °C) and low temperature high stress (850 °C/586 MPa). The results show that increasing Co content could enhance the creep rupture lives at low and intermediate temperature, and does not degrade the creep rupture lives of alloys at high temperature. In Re-containing alloys, at high temperature low stress (1100 °C/150 MPa), the effects of Co on the dislocation structures are negligible, while at low temperature high stress (850 °C/586 MPa), stacking faults are generated in alloy with 12% Co, and in alloy with 3% Co and free of Co, gamma prime particles are sheared by dislocation pairs. In Re-free alloys, at intermediate temperature and stress (1010 °C/248 MPa), large quantities of stacking faults appear in alloy without Co, while in alloy having 12% Co, gamma prime particles are sheared by dislocation pairs coupled by anti-phase boundary (APB). The gamma prime sheared by stacking faults or by dislocation pairs coupled by APB depends on the competition of stacking faults energy and APB energy which is affected by temperature and the interaction of Re and Co

  8. Sex and stress: Men and women show different cortisol responses to psychological stress induced by the Trier social stress test and the Iowa singing social stress test.

    Science.gov (United States)

    Reschke-Hernández, Alaine E; Okerstrom, Katrina L; Bowles Edwards, Angela; Tranel, Daniel

    2017-01-02

    Acute psychological stress affects each of us in our daily lives and is increasingly a topic of discussion for its role in mental illness, aging, cognition, and overall health. A better understanding of how such stress affects the body and mind could contribute to the development of more effective clinical interventions and prevention practices. Over the past 3 decades, the Trier Social Stress Test (TSST) has been widely used to induce acute stress in a laboratory setting based on the principles of social evaluative threat, namely, a judged speech-making task. A comparable alternative task may expand options for examining acute stress in a controlled laboratory setting. This study uses a within-subjects design to examine healthy adult participants' (n = 20 men, n = 20 women) subjective stress and salivary cortisol responses to the standard TSST (involving public speaking and math) and the newly created Iowa Singing Social Stress Test (I-SSST). The I-SSST is similar to the TSST but with a new twist: public singing. Results indicated that men and women reported similarly high levels of subjective stress in response to both tasks. However, men and women demonstrated different cortisol responses; men showed a robust response to both tasks, and women displayed a lesser response. These findings are in line with previous literature and further underscore the importance of examining possible sex differences throughout various phases of research, including design, analysis, and interpretation of results. Furthermore, this nascent examination of the I-SSST suggests a possible alternative for inducing stress in the laboratory. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  9. The SCEC/USGS dynamic earthquake rupture code verification exercise

    Science.gov (United States)

    Harris, R.A.; Barall, M.; Archuleta, R.; Dunham, E.; Aagaard, Brad T.; Ampuero, J.-P.; Bhat, H.; Cruz-Atienza, Victor M.; Dalguer, L.; Dawson, P.; Day, S.; Duan, B.; Ely, G.; Kaneko, Y.; Kase, Y.; Lapusta, N.; Liu, Yajing; Ma, S.; Oglesby, D.; Olsen, K.; Pitarka, A.; Song, S.; Templeton, E.

    2009-01-01

    rupture (hereafter called “spontaneous rupture”) solutions. For these types of numerical simulations, rather than prescribing the slip function at each location on the fault(s), just the friction constitutive properties and initial stress conditions are prescribed. The subsequent stresses and fault slip spontaneously evolve over time as part of the elasto-dynamic solution. Therefore, spontaneous rupture computer simulations of earthquakes allow us to include everything that we know, or think that we know, about earthquake dynamics and to test these ideas against earthquake observations.

  10. Stress Tests for Chest Pain: When You Need an Imaging Test -- and When You Don't

    Science.gov (United States)

    ... Resources Adult , Geriatric Stress Tests for Chest Pain Stress Tests for Chest Pain When you need an ... pain isn’t from heart disease. A cardiac stress test makes the heart work hard so your ...

  11. California's Drought - Stress test for the future

    Science.gov (United States)

    Lund, J. R.

    2014-12-01

    The current California drought is in its third dry years, with this year being the third driest years in a 106-year record. This drought occurs at a time when urban, agricultural, and environmental water demands have never been greater. This drought has revealed the importance of more quantitative evaluation and methods for water assessment and management. All areas of water and environmental management are likely to become increasingly stressed, and have essentially drought-like conditions, in the future, as California's urban, agricultural, and environmental demands continue to expand and as the climate changes. In the historical past, droughts have pre-viewed stresses developing in the future and helped focus policy-makers, the public, and stakeholders on preparing for these developing future conditions. Multi-decade water management strategies are often galvinized by drought. Irrigation was galvanized by California droughts in the 1800s, reservoir systems by the 1928-32 drought, urban water conservation by the 1976-77 drought, and water markets by the 1988-92 drought. With each drought, demands for tighter accounting, rights, and management have increased. This talk reviews the prospects and challenges for increased development and use of water data and systems analysis in the service of human and environmental water demands in California's highly decentralized water management system, and the prospects if these challenges are not more successfully addressed.

  12. Rupture prediction for induction bends under opening mode bending with emphasis on strain localization

    International Nuclear Information System (INIS)

    Mitsuya, Masaki; Sakanoue, Takashi

    2015-01-01

    This study focuses on the opening mode of induction bends; this mode represents the deformation outside a bend. Bending experiments on induction bends are shown and the manner of failure of these bends was investigated. Ruptures occur at the intrados of the bends, which undergo tensile stress, and accompany the local reduction of wall thickness, i.e., necking that indicates strain localization. By implementing finite element analysis (FEA), it was shown that the rupture is dominated not by the fracture criterion of material but by the initiation of strain localization that is a deformation characteristic of the material. These ruptures are due to the rapid increase of local strain after the initiation of strain localization and suddenly reach the fracture criterion. For the evaluation of the deformability of the bends, a method based on FEA that can predict the displacement at the rupture is proposed. We show that the yield surface shape and the true stress–strain relationship after uniform elongation have to be defined on the basis of the actual properties of the bend material. The von Mises yield criterion, which is commonly used in cases of elastic–plastic FEA, could not predict the rupture and overestimated the deformability. In contrast, a yield surface obtained by performing tensile tests on a biaxial specimen could predict the rupture. The prediction of the rupture was accomplished by an inverse calibration method that determined the true stress-strain relationship after uniform elongation. As an alternative to the inverse calibration, a simple extrapolation method of the true stress-strain relationship after uniform elongation which can predict the rupture is proposed. - Highlights: • A method based on FEA that can predict the displacement at the rupture is proposed. • The yield surface shape and the true stress–strain have to be defined precisely. • The von Mises yield criterion overestimated the deformability. • The ruptures are due to the

  13. Metrics for comparing dynamic earthquake rupture simulations

    Science.gov (United States)

    Barall, Michael; Harris, Ruth A.

    2014-01-01

    Earthquakes are complex events that involve a myriad of interactions among multiple geologic features and processes. One of the tools that is available to assist with their study is computer simulation, particularly dynamic rupture simulation. A dynamic rupture simulation is a numerical model of the physical processes that occur during an earthquake. Starting with the fault geometry, friction constitutive law, initial stress conditions, and assumptions about the condition and response of the near‐fault rocks, a dynamic earthquake rupture simulation calculates the evolution of fault slip and stress over time as part of the elastodynamic numerical solution (Ⓔ see the simulation description in the electronic supplement to this article). The complexity of the computations in a dynamic rupture simulation make it challenging to verify that the computer code is operating as intended, because there are no exact analytic solutions against which these codes’ results can be directly compared. One approach for checking if dynamic rupture computer codes are working satisfactorily is to compare each code’s results with the results of other dynamic rupture codes running the same earthquake simulation benchmark. To perform such a comparison consistently, it is necessary to have quantitative metrics. In this paper, we present a new method for quantitatively comparing the results of dynamic earthquake rupture computer simulation codes.

  14. Creep-rupture correlations for type 304 stainless steel heat 9T2796

    International Nuclear Information System (INIS)

    Swindeman, R.W.

    1975-01-01

    Creep-rupture data are presented for a reference heat of type 304 stainless steel tested at temperatures between 482 and 816 0 C (900-1500 0 F) and for times to 10,000 hr. The ability of several popular time-temperature parameters to correlate the rupture data is examined, and it shows that the Orr-Sherby-Dorn parameter provides a slightly better fit to the data than the Larson-Miller, Manson-Haferd, and Manson-Succop parameters. An alternative model is developed, based on the Barrett-Ardell-Sherby parameter, which makes use of modulus-compensated true stresses. These stresses are approximated on the basis of the strain about halfway through the test. Although the parameter does not fit the data quite as well as the Orr-Sherby-Dorn parameter, the activation energy associated with the parameter approaches the value expected for solute element diffusion in stainless steel. In the very high-stress region the master curve generated by the parameter is used to examine the interface between the results of tensile tests, described in terms of the Voce equation, and the creep-rupture tests. The tensile data can be correlated with the Barrett-Ardel-Sherby parameter when the tensile testing conditions are such that rupture is initiated by grain boundary failures

  15. Stress Testing of Transactional Database Systems

    OpenAIRE

    Meira , Jorge Augusto; Cunha De Almeida , Eduardo; Sunyé , Gerson; Le Traon , Yves; Valduriez , Patrick

    2013-01-01

    International audience; Transactional database management systems (DBMS) have been successful at supporting traditional transaction processing workloads. However, web-based applications that tend to generate huge numbers of concurrent business operations are pushing DBMS performance over their limits, thus threatening overall system availability. Then, a crucial question is how to test DBMS performance under heavy workload conditions. Answering this question requires a testing methodology to ...

  16. [Stress-corrosion test of TIG welded CP-Ti].

    Science.gov (United States)

    Li, H; Wang, Y; Zhou, Z; Meng, X; Liang, Q; Zhang, X; Zhao, Y

    2000-12-01

    In this study TIG (Tungsten Inert Gas) welded CP-Ti were subjected to stress-corrosion test under 261 MPa in artificial saliva of 37 degrees C for 3 months. No significant difference was noted on mechanical test (P > 0.05). No color-changed and no micro-crack on the sample's surface yet. These results indicate that TIG welded CP-Ti offers excellent resistance to stress corrosion.

  17. Creep rupture strength of activated-TIG welded 316L(N) stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Sakthivel, T., E-mail: tsakthivel@igcar.gov.in [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Vasudevan, M.; Laha, K.; Parameswaran, P.; Chandravathi, K.S.; Mathew, M.D.; Bhaduri, A.K. [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India)

    2011-06-01

    316L(N) stainless steel plates were joined using activated-tungsten inert gas (A-TIG) welding and conventional TIG welding process. Creep rupture behavior of 316L(N) base metal, and weld joints made by A-TIG and conventional TIG welding process were investigated at 923 K over a stress range of 160-280 MPa. Creep test results showed that the enhancement in creep rupture strength of weld joint fabricated by A-TIG welding process over conventional TIG welding process. Both the weld joints fractured in the weld metal. Microstructural observation showed lower {delta}-ferrite content, alignment of columnar grain with {delta}-ferrite along applied stress direction and less strength disparity between columnar and equiaxed grains of weld metal in A-TIG joint than in MP-TIG joint. These had been attributed to initiate less creep cavitation in weld metal of A-TIG joint leading to improvement in creep rupture strength.

  18. Creep rupture strength of activated-TIG welded 316L(N) stainless steel

    International Nuclear Information System (INIS)

    Sakthivel, T.; Vasudevan, M.; Laha, K.; Parameswaran, P.; Chandravathi, K.S.; Mathew, M.D.; Bhaduri, A.K.

    2011-01-01

    316L(N) stainless steel plates were joined using activated-tungsten inert gas (A-TIG) welding and conventional TIG welding process. Creep rupture behavior of 316L(N) base metal, and weld joints made by A-TIG and conventional TIG welding process were investigated at 923 K over a stress range of 160-280 MPa. Creep test results showed that the enhancement in creep rupture strength of weld joint fabricated by A-TIG welding process over conventional TIG welding process. Both the weld joints fractured in the weld metal. Microstructural observation showed lower δ-ferrite content, alignment of columnar grain with δ-ferrite along applied stress direction and less strength disparity between columnar and equiaxed grains of weld metal in A-TIG joint than in MP-TIG joint. These had been attributed to initiate less creep cavitation in weld metal of A-TIG joint leading to improvement in creep rupture strength.

  19. Creep rupture strength of activated-TIG welded 316L(N) stainless steel

    Science.gov (United States)

    Sakthivel, T.; Vasudevan, M.; Laha, K.; Parameswaran, P.; Chandravathi, K. S.; Mathew, M. D.; Bhaduri, A. K.

    2011-06-01

    316L(N) stainless steel plates were joined using activated-tungsten inert gas (A-TIG) welding and conventional TIG welding process. Creep rupture behavior of 316L(N) base metal, and weld joints made by A-TIG and conventional TIG welding process were investigated at 923 K over a stress range of 160-280 MPa. Creep test results showed that the enhancement in creep rupture strength of weld joint fabricated by A-TIG welding process over conventional TIG welding process. Both the weld joints fractured in the weld metal. Microstructural observation showed lower δ-ferrite content, alignment of columnar grain with δ-ferrite along applied stress direction and less strength disparity between columnar and equiaxed grains of weld metal in A-TIG joint than in MP-TIG joint. These had been attributed to initiate less creep cavitation in weld metal of A-TIG joint leading to improvement in creep rupture strength.

  20. Long-time rupture strength and creep behaviour of welded joints on heat-resistant CrMoV steels with 1 and 12% chrome

    International Nuclear Information System (INIS)

    Maier, G.; Maile, K.; Theofel, H.

    1985-01-01

    Power plant components in the creep range are damaged frequently in the weld joint zones. The investigation concentrated therefore on the reliability of the information supplied by tests on small- and large-size samples. Creep rupture tests of dissimilar welded joints (1% with 12% chrome) with variations of heat input and weld metal have been conducted. At creep rupture times of about 10 4 h all joints failed in the outside heat affected zone of the weaker base metal. Large-size samples, proved in comparison at same stresses, showed distinctly longer times to rupture. (orig.) [de

  1. Time, stress, and temperature-dependent deformation in nanostructured copper: Stress relaxation tests and simulations

    International Nuclear Information System (INIS)

    Yang, Xu-Sheng; Wang, Yun-Jiang; Wang, Guo-Yong; Zhai, Hui-Ru; Dai, L.H.; Zhang, Tong-Yi

    2016-01-01

    In the present work, stress relaxation tests, high-resolution transmission electron microscopy (HRTEM), and molecular dynamics (MD) simulations were conducted on coarse-grained (cg), nanograined (ng), and nanotwinned (nt) copper at temperatures of 22 °C (RT), 30 °C, 40 °C, 50 °C, and 75 °C. The comprehensive investigations provide sufficient information for the building-up of a formula to describe the time, stress, and temperature-dependent deformation and clarify the relationship among the strain rate sensitivity parameter, stress exponent, and activation volume. The typically experimental curves of logarithmic plastic strain rate versus stress exhibited a three staged relaxation process from a linear high stress relaxation region to a subsequent nonlinear stress relaxation region and finally to a linear low stress relaxation region, which only showed-up at the test temperatures higher than 22 °C, 22 °C, and 30 °C, respectively, in the tested cg-, ng-, and nt-Cu specimens. The values of stress exponent, stress-independent activation energy, and activation volume were determined from the experimental data in the two linear regions. The determined activation parameters, HRTEM images, and MD simulations consistently suggest that dislocation-mediated plastic deformation is predominant in all tested cg-, ng-, and nt-Cu specimens in the initial linear high stress relaxation region at the five relaxation temperatures, whereas in the linear low stress relaxation region, the grain boundary (GB) diffusion-associated deformation is dominant in the ng- and cg-Cu specimens, while twin boundary (TB) migration, i.e., twinning and detwinning with parallel partial dislocations, governs the time, stress, and temperature-dependent deformation in the nt-Cu specimens.

  2. Rupture of primigravid uterus and recurrent rupture

    Directory of Open Access Journals (Sweden)

    Nahreen Akhtar

    2016-08-01

    Full Text Available Uterine rupture is a deadly obstetrical emergency endangering the life of both mother and fetus. In Bangladesh, majority of deliveries arc attended by unskilled traditional birth attendant and maternal mortality is still quite high. It is rare Ln developed country but unfortunately it is common in a developing country like Bangladesh. We report a case history of a patient age 32yrs from Daudkandi, Comilla admitted with H/0 previous two rupture uterus and repair with no living issue. We did caesarean section at her 31+ weeks of pregnancy when she developed Jabour pain. A baby of 1.4 kg was delivered. During cesarean section, focal rupture was noted in previous scar of rupture. Unfortunately the baby expired in neonatal ICU after 36 hours.

  3. Dynamics of the rupture precursors for heterogeneous materials: application to vitreous polymers foams

    International Nuclear Information System (INIS)

    Deschanel, St.

    2005-12-01

    New physical approaches concerning the damage mechanisms consist to consider the rupture phenomenon as the critical point of a phase transition. Rupture can then result for some materials by a percolation of microcracks. This multi-crack implies the choice of heterogeneous materials. Mechanical tests on solid polymer foams have been carried out until rupture and have been coupled to the follow-up of the acoustic activity. The energies distributions reveal power laws independently of the material density, of the load mode or of the behaviour laws. On the other hand, the agreement with a power law of time periods seems to require a quasi constant stress on the most part of the test. The trend of the cumulated energy in the case of creep experiments seems to present a power law on a narrow period of time. On the other hand, for tensile tests, no power law has been observed. (O.M.)

  4. Triaxial Wetting Test on Rockfill Materials under Stress Combination Conditions of Spherical Stress p and Deviatoric Stress q

    Directory of Open Access Journals (Sweden)

    Yan-yi Zhang

    2018-01-01

    Full Text Available A GCTS medium-sized triaxial apparatus is used to conduct a single-line method wetting test on three kinds of rockfill materials of different mother rocks such as mixture of sandstone and slate, and dolomite and granite, and the test stress conditions is the combination of spherical stress p and deviatoric stress q. The test results show that (1 for wetting shear strain, the effects of spherical stress p and deviatoric stress q are equivalent, and wetting shear strain and deviatoric stress q show the power function relationship preferably. (2 For wetting volumetric strain, the effect of deviatoric stress q can be neglected because it is extremely insignificant, and spherical stress p is the main influencing factor and shows the power function relationship preferably. (3 The wetting strains decrease significantly with the increase in initial water content and sample density generally, but the excessively high dry density will increase the wetting deformation. Also, the wetting strains will decrease with the increase in the saturated uniaxial compressive strength and average softening coefficient of the mother rock. Based on the test results, a wetting strain model is proposed for rockfill materials. The verification results indicate that the model satisfactorily reflects the development law of wetting deformation.

  5. Influence of flowing sodium on creep deformation and rupture behaviour of 316L(N) austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Ravi, S., E-mail: sravi@igcar.gov.in [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Laha, K.; Mathew, M.D. [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Vijayaraghavan, S.; Shanmugavel, M.; Rajan, K.K. [Fast Reactor Technology Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Jayakumar, T. [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India)

    2012-08-15

    The influence of flowing sodium on creep deformation and rupture behaviour of AISI 316L(N) austenitic stainless steel has been investigated at 873 K over a stress range of 235-305 MPa. The results were compared with those obtained from testing in air environment. The steady state creep rates of the material were not influenced appreciably by the testing environments. The time to onset of tertiary stage of creep deformation was delayed in sodium environment. The creep-rupture lives of the material increased in sodium environment, which became more pronounced at lower applied stresses. The increase in rupture life of the material in flowing sodium was accompanied by an increase in rupture ductility. The creep damage on specimen surface as well as inside the specimen was less in specimen tested in sodium. SEM fractographic investigation revealed predominantly transgranular dimple failure for the specimen tested in sodium, whereas predominantly intergranular creep failure was observed in the air tested specimens. Almost no oxidation was observed in the specimens creep tested in the sodium environment. Absence of oxidation and less creep damage cavitation extended the secondary state in liquid sodium tests and lead to increase in creep rupture life and ductility of the material as compared to in air.

  6. Dipyridamole cerebral flow stress test evaluating ischemic cerebrovascular diseases

    International Nuclear Information System (INIS)

    Xiu, Y.; Chen, S.; Sun, X.; Liu, S.; Li, W.; Fan, W.; Wang, X.

    2000-01-01

    To detect the clinical value of dipyridamole cerebral blood flow stress test in cerebrovascular diseases (CVD). Nineteen patients (9 male, 10 female, mean age=65) who were diagnosed as CVD were included. One suffered from infarct, two suffered from thrombosis, one feel dizziness. All 4 performed rest and stress test. The other 15 were VBI, 9 of them performed stress test. Rest and stress test were done two-day method using Elscint Apex SP-6 SPECT equipped with low energy all purpose collimator. Rest perfusion imaging was started 30 min after injecting 1.11 GBq 99m Tc-ECD. Dipyridamole stress test was done within one week. 0.56 mg/Kg dipyridamole was injected intravenously during 4 min the same dose of ECD was injected 2 min later. The acquisition started 30 min later with the same parameter. Heart rate, ECG and the patient's complaint were monitored 2 min before and after dipyridamole. After correction for attenuation, transverse, coronal and sagittal slices were reconstructed. Eighteen ROIs were drawn symmetrically on cingulate, frontal, temporal-parietal, temporal, occipital, vision cortex, basal ganglia, superior frontal and parietal on the 3 rd , 6 th , 9 th transverse slices, selecting the contralateral as the reference region. The counts per pixel in each ROI were divided by the counts of the mirror region to obtain the relative uptake ratio. We think it abnormality when the ratio is above 1,1 or below 0.9. The sensitivity for rest and stress rCBF test was compared. rCBF was decreased at 10 of 19 patients (sensitivity 52.6%). 14 had low rCBF after dipyridamole (sensitivity 72.3%), Among the patients who studied stress test, 6 had normal rCBF at rest and low rCBF after stress. The abnormal area was enlarged after dipyridamole for 1 patients, 2 improved and 2 unchanged. 8 of 15 VBI had normal rCBF at rest (sensitivity 53.3%). 9 of 15 VBI performed stress test. rCBF was normal at rest for 5 patients, rCBF was decreased after stress, it was improved for one

  7. Pilot Testing of the NURSE Stress Management Intervention.

    Science.gov (United States)

    Delaney, Colleen; Barrere, Cynthia; Robertson, Sue; Zahourek, Rothlyn; Diaz, Desiree; Lachapelle, Leeanne

    2016-12-01

    Student nurses experience significant stress during their education, which may contribute to illness and alterations in health, poor academic performance, and program attrition. The aim of this pilot study was to evaluate the feasibility and potential efficacy of an innovative stress management program in two baccalaureate nursing programs in Connecticut, named NURSE (Nurture nurse, Use resources, foster Resilience, Stress and Environment management), that assists nursing students to develop stress management plans. An explanatory sequential mixed-methods design was used to evaluate the effects of the intervention with 40 junior nursing students. Results from this study provide evidence that the NURSE intervention is highly feasible, and support further testing to examine the effect of the intervention in improving stress management in nursing students. © The Author(s) 2015.

  8. Evaluation of creep rupture property of high strength ferritic/martensitic steel (PNC-FMS)

    International Nuclear Information System (INIS)

    Uehira, Akihiro; Mizuno, Tomoyasu; Ukai, Shigeharu; Yoshida, Eiichi

    1999-04-01

    High Strength Ferritic/Martensitic Steel (PNC-FMS : 11Cr-0.5Mo-2W,Nb,V), developed by JNC, is one of the candidate materials for the long-life core of large-scale fast breeder reactor. The material design base standard (tentative) of PNC-FMS was established and the creep rupture strength reduction factor in the standard was determined in 1992. This factor was based on only evaluation of decarburization effect on tensile strength after sodium exposure. In this study, creep rupture properties of PNC-FMS under out of pile sodium exposure and in pile were evaluated, using recent test results as well as previous ones. The evaluation results are summarized as follows : a. Decarburization rate constant of pressurized tubes under sodium exposure is identical with stress free specimens. b. In case of the same decarburization content under out of pile sodium exposure, creep strength tends to decrease more significantly than tensile strength. c. Creep strength under out of pile sodium exposure showed significant decrease in high temperature and long exposure time, but in pile (MOTA) creep strength showed little decrease. A new creep rupture strength reduction factor, which is the ratio of creep rupture strength under sodium exposure or in pile to in air, was made by correlating the creep rupture strength. This new method directly using the ratio of creep rupture strength was evaluated and discussed from the viewpoint of design applicability, compared with the conventional method based on decarburization effect on tensile strength. (author)

  9. An improved stress corrosion test medium for aluminum alloys

    Science.gov (United States)

    Humphries, T. S.; Coston, J. E.

    1981-01-01

    A laboratory test method that is only mildly corrosive to aluminum and discriminating for use in classifying the stress corrosion cracking resistance of aluminum alloys is presented along with the method used in evaluating the media selected for testing. The proposed medium is easier to prepare and less expensive than substitute ocean water.

  10. Predictive Accuracy of Exercise Stress Testing the Healthy Adult.

    Science.gov (United States)

    Lamont, Linda S.

    1981-01-01

    Exercise stress testing provides information on the aerobic capacity, heart rate, and blood pressure responses to graded exercises of a healthy adult. The reliability of exercise tests as a diagnostic procedure is discussed in relation to sensitivity and specificity and predictive accuracy. (JN)

  11. Market risk stress testing for internationally active financial institutions

    Directory of Open Access Journals (Sweden)

    Marković Petar

    2011-01-01

    Full Text Available The paper develops a comprehensive framework for market risk stress testing in internationally active financial institutions. We begin by defining the scope and type of the stress test and explaining how to select risk factors and the stress time horizon. We then address challenges related to data gathering, followed by in-depth discussion of techniques for developing realistic shock scenarios. Next the process of shock application to a particular portfolio is described, followed by determination of portfolio profit and loss. We conclude by briefly discussing the issue of assigning probability to stress scenarios. We illustrate the framework by considering the development of a ‘worst case’ scenario using global financial market data from Thomson Reuters Datastream.

  12. Dynamic Models of Earthquake Rupture along branch faults of the Eastern San Gorgonio Pass Region in CA using Complex Fault Structure

    Science.gov (United States)

    Douilly, R.; Oglesby, D. D.; Cooke, M. L.; Beyer, J. L.

    2017-12-01

    Compilation of geomorphic and paleoseismic data have illustrated that the right-lateral Coachella segment of the southern San Andreas Fault is past its average recurrence time period. On its western edge, this fault segment is split into two branches: the Mission Creek strand, and the Banning fault strand, of the San Andreas. Depending on how rupture propagates through this region, there is the possibility of a through-going rupture that could lead to the channeling of damaging seismic energy into the Los Angeles Basin. The fault structures and rupture scenarios on these two strands are potentially very different, so it is important to determine which strand is a more likely rupture path, and under which circumstances rupture will take either one. In this study, we focus on the effect of different assumptions about fault geometry and stress pattern on the rupture process to test those scenarios and thus investigate the most likely path of a rupture that starts on the Coachella segment. We consider two types of fault geometry based on the SCEC Community Fault Model and create a 3D finite element mesh. These two meshes are then incorporated into the finite element method code FaultMod to compute a physical model for the rupture dynamics. We use the slip-weakening friction law, and we consider different assumptions of background stress such as constant tractions, regional stress regimes of different orientations, heterogeneous off-fault stresses and the results of long-term stressing rates from quasi-static crustal deformation models that consider time since last event on each fault segment. Both the constant and regional stress distribution show that it is more likely for the rupture to branch from the Coachella segment to the Mission Creek compared to the Banning fault segment. For the regional stress distribution, we encounter cases of super-shear rupture for one type of fault geometry and sub-shear rupture for the other one. The fault connectivity at this branch

  13. Safety of a rapid diagnostic protocol with accelerated stress testing.

    Science.gov (United States)

    Soremekun, Olan A; Hamedani, Azita; Shofer, Frances S; O'Conor, Katie J; Svenson, James; Hollander, Judd E

    2014-02-01

    Most patients at low to intermediate risk for an acute coronary syndrome (ACS) receive a 12- to 24-hour "rule out." Recently, trials have found that a coronary computed tomographic angiography-based strategy is more efficient. If stress testing were performed within the same time frame as coronary computed tomographic angiography, the 2 strategies would be more similar. We tested the hypothesis that stress testing can safely be performed within several hours of presentation. We performed a retrospective cohort study of patients presenting to a university hospital from January 1, 2009, to December 31, 2011, with potential ACS. Patients placed in a clinical pathway that performed stress testing after 2 negative troponin values 2 hours apart were included. We excluded patients with ST-elevation myocardial infarction or with an elevated initial troponin. The main outcome was safety of immediate stress testing defined as the absence of death or acute myocardial infarction (defined as elevated troponin within 24 hours after the test). A total of 856 patients who presented with potential ACS were enrolled in the clinical pathway and included in this study. Patients had a median age of 55.0 (interquartile range, 48-62) years. Chest pain was the chief concern in 86%, and pain was present on arrival in 73% of the patients. There were no complications observed during the stress test. There were 0 deaths (95% confidence interval, 0%-0.46%) and 4 acute myocardial infarctions within 24 hours (0.5%; 95% confidence interval, 0.14%-1.27%). The peak troponins were small (0.06, 0.07, 0.07, and 0.19 ng/mL). Patients who present to the ED with potential ACS can safely undergo a rapid diagnostic protocol with stress testing. © 2013.

  14. Hepatic rupture in preeclampsia

    International Nuclear Information System (INIS)

    Winer-Muram, H.T.; Muram, D.; Salazar, J.; Massie, J.D.

    1985-01-01

    The diagnosis of hepatic rupture in patients with pregnancy-induced hypertension (preeclampsia and eclampsia) is rarely made preoperatively. Diagnostic imaging can be utilized in some patients to confirm the preoperative diagnosis. Since hematoma formation precedes hepatic rupture, then, when diagnostic modalities such as sonography and computed tomography identify patients with hematomas, these patients are at risk of rupture, and should be hospitalized until the hematomas resolve

  15. The Reasons of Steam Pipeline Elbow Rupture

    Directory of Open Access Journals (Sweden)

    Mesjasz A.

    2016-09-01

    Full Text Available In the paper the reasons for steam pipeline’s elbow material rupture, made of steel 13CrMo4-5 (15HM that is being used in the energetics. Based on the mechanical properties in the ambient temperature (Rm, Rp0,2 and elongation A5 and in the increased temperature (Rp0,2t it was found, that the pipeline elbow’s material sampled from the ruptured area has lower Rp0,2 i Rp0,2t by around 2% than it is a requirement for 13CrMo4-5 steel in it’s base state. The damage appeared as a result of complex stress state, that substantially exceeded the admissible tensions, what was the consequence of considerable structure degradation level. As a result of the microstructure tests on HITACHI S4200 microscope, the considerable development of the creeping process associates were found. Also the advances progress of the microstructure degradation was observed, which is substantial decomposition of bainite and multiple, with varied secretion size, and in most cases forming the micro cracks chains. With the use of lateral micro sections the creeping voids were observed, that creates at some places the shrinkage porosities clusters and micro pores.

  16. A suite of exercises for verifying dynamic earthquake rupture codes

    Science.gov (United States)

    Harris, Ruth A.; Barall, Michael; Aagaard, Brad T.; Ma, Shuo; Roten, Daniel; Olsen, Kim B.; Duan, Benchun; Liu, Dunyu; Luo, Bin; Bai, Kangchen; Ampuero, Jean-Paul; Kaneko, Yoshihiro; Gabriel, Alice-Agnes; Duru, Kenneth; Ulrich, Thomas; Wollherr, Stephanie; Shi, Zheqiang; Dunham, Eric; Bydlon, Sam; Zhang, Zhenguo; Chen, Xiaofei; Somala, Surendra N.; Pelties, Christian; Tago, Josue; Cruz-Atienza, Victor Manuel; Kozdon, Jeremy; Daub, Eric; Aslam, Khurram; Kase, Yuko; Withers, Kyle; Dalguer, Luis

    2018-01-01

    We describe a set of benchmark exercises that are designed to test if computer codes that simulate dynamic earthquake rupture are working as intended. These types of computer codes are often used to understand how earthquakes operate, and they produce simulation results that include earthquake size, amounts of fault slip, and the patterns of ground shaking and crustal deformation. The benchmark exercises examine a range of features that scientists incorporate in their dynamic earthquake rupture simulations. These include implementations of simple or complex fault geometry, off‐fault rock response to an earthquake, stress conditions, and a variety of formulations for fault friction. Many of the benchmarks were designed to investigate scientific problems at the forefronts of earthquake physics and strong ground motions research. The exercises are freely available on our website for use by the scientific community.

  17. Creep rupture behavior of candidate materials for nuclear process heat applications

    International Nuclear Information System (INIS)

    Schubert, F.; te Heesen, E.; Bruch, U.; Cook, R.; Diehl, H.; Ennis, P.J.; Jakobeit, W.; Penkalla, H.J.; Ullrich, G.

    1984-01-01

    Creep and stress rupture properties are determined for the candidate materials to be used in hightemperature gas-cooled reactor (HTGR) components. The materials and test methods are briefly described based on experimental results of test durations of about20000 h. The medium creep strengths of the alloys Inconel-617, Hastelloy-X, Nimonic-86, Hastelloy-S, Manaurite-36X, IN-519, and Incoloy-800H are compared showing that Inconel-617 has the best creep rupture properties in the temperature range above 800 0 C. The rupture time of welded joints is in the lower range of the scatterband of the parent metal. The properties determined in different simulated HTGR atmospheres are within the scatterband of the properties obtained in air. Extrapolation methods are discussed and a modified minimum commitment method is favored

  18. The reliability of physical examination tests for the diagnosis of anterior cruciate ligament rupture--A systematic review.

    Science.gov (United States)

    Lange, Toni; Freiberg, Alice; Dröge, Patrik; Lützner, Jörg; Schmitt, Jochen; Kopkow, Christian

    2015-06-01

    Systematic literature review. Despite their frequent application in routine care, a systematic review on the reliability of clinical examination tests to evaluate the integrity of the ACL is missing. To summarize and evaluate intra- and interrater reliability research on physical examination tests used for the diagnosis of ACL tears. A comprehensive systematic literature search was conducted in MEDLINE, EMBASE and AMED until May 30th 2013. Studies were included if they assessed the intra- and/or interrater reliability of physical examination tests for the integrity of the ACL. Methodological quality was evaluated with the Quality Appraisal of Reliability Studies (QAREL) tool by two independent reviewers. 110 hits were achieved of which seven articles finally met the inclusion criteria. These studies examined the reliability of four physical examination tests. Intrarater reliability was assessed in three studies and ranged from fair to almost perfect (Cohen's k = 0.22-1.00). Interrater reliability was assessed in all included studies and ranged from slight to almost perfect (Cohen's k = 0.02-0.81). The Lachman test is the physical tests with the highest intrarater reliability (Cohen's k = 1.00), the Lachman test performed in prone position the test with the highest interrater reliability (Cohen's k = 0.81). Included studies were partly of low methodological quality. A meta-analysis could not be performed due to the heterogeneity in study populations, reliability measures and methodological quality of included studies. Systematic investigations on the reliability of physical examination tests to assess the integrity of the ACL are scarce and of varying methodological quality. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Alternate immersion stress corrosion testing of 5083 aluminum

    International Nuclear Information System (INIS)

    Briggs, J.L.; Dringman, M.R.; Hausburg, D.E.; Jackson, R.J.

    1978-01-01

    The stress corrosion susceptibility of Type 5083 aluminum--magnesium alloy in plate form and press-formed shapes was determined in the short transverse direction. C-ring type specimens were exposed to alternate immersion in a sodium chloride solution. The test equipment and procedure, with several innovative features, are described in detail. Statistical test results are listed for seven thermomechanical conditions. A certain processing scheme was shown to yield a work-strengthened part that is not sensitized with respect to stress corrosion cracking

  20. Stress relaxation in tempered glass caused by heat soak testing

    DEFF Research Database (Denmark)

    Schneider, Jens; Hilcken, Jonas; Aronen, Antti

    2016-01-01

    Heat soak testing of tempered glass is a thermal process required after the tempering process itself to bring glasses of commercial soda-lime-silica-glass to failure that are contaminated with nickel sulphide inclusions, diameter 50 mm to 500 mm typically. Thus, the tests avoid a so-called "spont...... of commercial soda-lime-silica glass, it causes stress relaxation in tempered glass and the fracture pattern of the glass changes accordingly, especially thin glasses are affected. Based on the Tool-Narayanaswamy-Model, this paper comprises the theoretical background of the stress...

  1. Dynamic Rupture Benchmarking of the ADER-DG Method

    Science.gov (United States)

    Gabriel, Alice; Pelties, Christian

    2013-04-01

    We will verify the arbitrary high-order derivative Discontinuous Galerkin (ADER-DG) method in various test cases of the 'SCEC/USGS Dynamic Earthquake Rupture Code Verification Exercise' benchmark suite (Harris et al. 2009). The ADER-DG scheme is able to solve the spontaneous rupture problem with high-order accuracy in space and time on three-dimensional unstructured tetrahedral meshes. Strong mesh coarsening or refinement at areas of interest can be applied to keep the computational costs feasible. Moreover, the method does not generate spurious high-frequency contributions in the slip rate spectra and therefore does not require any artificial damping as demonstrated in previous presentations and publications (Pelties et al. 2010 and 2012). We will show that the mentioned features hold also for more advanced setups as e.g. a branching fault system, heterogeneous background stresses and bimaterial faults. The advanced geometrical flexibility combined with an enhanced accuracy will make the ADER-DG method a useful tool to study earthquake dynamics on complex fault systems in realistic rheologies. References: Harris, R.A., M. Barall, R. Archuleta, B. Aagaard, J.-P. Ampuero, H. Bhat, V. Cruz-Atienza, L. Dalguer, P. Dawson, S. Day, B. Duan, E. Dunham, G. Ely, Y. Kaneko, Y. Kase, N. Lapusta, Y. Liu, S. Ma, D. Oglesby, K. Olsen, A. Pitarka, S. Song, and E. Templeton, The SCEC/USGS Dynamic Earthquake Rupture Code Verification Exercise, Seismological Research Letters, vol. 80, no. 1, pages 119-126, 2009 Pelties, C., J. de la Puente, and M. Kaeser, Dynamic Rupture Modeling in Three Dimensions on Unstructured Meshes Using a Discontinuous Galerkin Method, AGU 2010 Fall Meeting, abstract #S21C-2068 Pelties, C., J. de la Puente, J.-P. Ampuero, G. Brietzke, and M. Kaeser, Three-Dimensional Dynamic Rupture Simulation with a High-order Discontinuous Galerkin Method on Unstructured Tetrahedral Meshes, JGR. - Solid Earth, VOL. 117, B02309, 2012

  2. Negative Exercise Stress Test: Does it Mean Anything? Case study

    Directory of Open Access Journals (Sweden)

    Hassan A. Mohamed

    2007-01-01

    Full Text Available Despite its low sensitivity and specificity (67% and 72%, respectively, exercise testing has remained one of the most widely used noninvasive tests to determine the prognosis in patients with suspected or established coronary disease.As a screening test for coronary artery disease, the exercise stress test is useful in that it is relatively simple and inexpensive. It has been considered particularly helpful in patients with chest pain syndromes who have moderate probability for coronary artery disease, and in whom the resting electrocardiogram (ECG is normal. The following case presentation and discussion will question the predictive value of a negative stress testing in patients with moderate probability for coronary artery disease.

  3. NUMERICAL SIMULATION OF AN AGRICULTURAL SOIL SHEAR STRESS TEST

    Directory of Open Access Journals (Sweden)

    Andrea Formato

    2007-03-01

    Full Text Available In this work a numerical simulation of agricultural soil shear stress tests was performed through soil shear strength data detected by a soil shearometer. We used a soil shearometer available on the market to measure soil shear stress and constructed special equipment that enabled automated detection of soil shear stress. It was connected to an acquisition data system that displayed and recorded soil shear stress during the full field tests. A soil shearometer unit was used to the in situ measurements of soil shear stress in full field conditions for different types of soils located on the right side of the Sele river, at a distance of about 1 km from each other, along the perpendicular to the Sele river in the direction of the sea. Full field tests using the shearometer unit were performed alongside considered soil characteristic parameter data collection. These parameter values derived from hydrostatic compression and triaxial tests performed on considered soil samples and repeated 4 times and we noticed that the difference between the maximum and minimum values detected for every set of performed tests never exceeded 4%. Full field shear tests were simulated by the Abaqus program code considering three different material models of soils normally used in the literature, the Mohr-Coulomb, Drucker-Prager and Cam-Clay models. We then compared all data outcomes obtained by numerical simulations with those from the experimental tests. We also discussed any further simulation data results obtained with different material models and selected the best material model for each considered soil to be used in tyre/soil contact simulation or in soil compaction studies.

  4. Creep-rupture-test on the stainless steel X6crni1811 (Din 1.494.8) in the frame of the Extrapolation-Program. (Part III); Ensayos de fluencia lenta en el acero inoxidable X6 Cr Ni 1811 (1.4948) en el marco del Programa Extrapolacion

    Energy Technology Data Exchange (ETDEWEB)

    Solano, R; Schirra, M; Rivas, M de la; Barroso, S; Seith, B

    1982-07-01

    The austenitic stainless steel X6crni1811 (Din 1.4948) used as a structure material for the German Fast Breeder Reactor SNR 300 was creep tested in a temperature range of 550-650 degree centigree material condition as well as welded material condition. The main point of this program (Extrapolation-Program) lies in the knowledge of the creep-rupture-strength and creep-behaviour up to 3 x 10{sup 4} hours higher temperatures in order to extrapolated up to {>=}10{sup 5} hours for operating temperatures. In order to study the stress dependency of the minimum creep rate additional tests were carried out of 550 degree centigree - 750 degree centigree. The present report describes the state in the running program with test-times of 23.000 hours and results from tests up to 55.000 hours belonging to other parallel programs are taken into account. Besides the creep-rupture behaviour it is also made a study of ductility between 550 and 750 degree centigree. Extensive metallographic examinations have been made to study the fracture behaviour and changes in structure. (Author)

  5. Panel manipulation in social stress testing:The Bath experimental stress test for children (BEST-C)

    OpenAIRE

    Cheetham, Tara J.; Turner-Cobb, Julie M.

    2016-01-01

    BackgroundWhilst acute stress paradigms in adults make use of adult panel members, similar paradigms modified for child participants have not manipulated the panel. Most work has utilised an audience of adult confederates, regardless of the age of the population being tested. The aim of this study was to trial a social stress test for children that provided a meaningful environment using age-matched child peers as panel actors.MethodsThirty-three participants (7-11 years) underwent the Bath E...

  6. An acceleration test for stress corrosion cracking using humped specimen

    International Nuclear Information System (INIS)

    Kamaya, Masayuki; Fukumura, Takuya; Totsuka, Nobuo

    2003-01-01

    By using the humped specimen, which is processed by the humped die, in the slow strain rate technique (SSRT) test, fracture facet due to stress corrosion cracking (SCC) can be observed in relatively short duration. Although the cold work and concentrated stress and strain caused by the characteristic shape of the specimen accelerate the SCC, to date these acceleration effects have not been examined quantitatively. In the present study, the acceleration effects of the humped specimen were examined through experiments and finite element analyses (FEA). The experiments investigated the SCC of alloy 600 in the primary water environment of a pressurized water reactor. SSRT tests were conducted using two kinds of humped specimen: one was annealed after hump processing in order to eliminate the cold work, and the other was hump processed after the annealing treatment. The work ratio caused by the hump processing and stress/strain conditions during SSRT test were evaluated by FEA. It was found that maximum work ratio of 30% is introduced by the hump processing and that the distribution of the work ratio is not uniform. Furthermore, the work ratio is influenced by the friction between the specimen and dies as well as by the shape of dies. It was revealed that not only the cold work but also the concentrated stress and strain during SSRT test accelerate the crack initiation and growth of the SCC. (author)

  7. Stress test, what is the reality and significance of it?

    International Nuclear Information System (INIS)

    Sawada, Tetsuo

    2012-01-01

    Stress test was introduced in July 2011 by 'political judgment' to demonstrate the ability of nuclear power plants to withstand severe earthquake and tsunami. Stress test consisted of two stages and the first stage using computerized simulation required to obtain 'cliff edge' for earthquake, tsunami, their superposition, loss of all alternating current power and loss of final heat sink, and effectiveness of severe accident management after emergency safety measures. Clearing the first stage of the test was a prerequisite for restarting reactors that had been suspended for regular inspections. NISA had received such test results for 14 nuclear reactors as of January 18, 2012. After passing IAEA's evaluation of stress test review process, NISA's endorsement of test results, NSC's confirmation of NISA's screening results and approval of local government, Prime Minister and relevant ministers concerned would decide whether reactors could be restarted as 'political judgment'. Using ranking list and referring to respective experiences of 14 reactors hit by earthquake and tsunami at the Great East Japan earthquake might better perform comprehensive judgment. (T. Tanaka)

  8. Quantification of Applied Stresses of C-Ring Specimens for Stress Corrosion Cracking Tests

    International Nuclear Information System (INIS)

    Kim, Woo Gon; Kim, Sun Jae; Rhee, Chang Kyu; Kuk, Il Hiun; Choi, Jong Ho

    1997-01-01

    For comparing their resistances for stress-corrosion cracking(SCC) in the K600-MA, K690-MA, and K600-TT tubes, C-ring specimens were fabricated with the various thermal-treatments to control the distributions of the precipitates like Cr-carbides. The bending stresses were analyzed to determine the amounts to make the stress quantitatively to all the C-ring samples, and then the stresses were calculated with the relation to the outer diameter(O.D) deflection(δ) of the C-rings. To measure accurately the bending strains of the C-ring specimens, the strain gauges were used and the compression test was also carried out. In the elastic region, the stresses in both the transverse and the circumferential directions were different with the locations of the strain gauges as attached at α= 30 .deg., 45 .deg., and 90 .deg. to the principal stress direction, but those in the longitudinal direction were independent of their attached locations. Calculated stresses from the strains obtained using the strain gauges were well agreed with the theoretical. In the plastic region over δ=1.0mm, the stresses for the TT tubes showed lower values of about 400MPa than those for the MA tubes. However, the stresses among the TT tubes showed almost the similar values in this region. Therefore, the states of the stresses applied to the C-ring specimens would be different with the material conditions, i.e, the chemical compositions, the thermal treatments such as MA and TT

  9. Predictive value of vaginal IL-6 and TNFα bedside tests repeated until delivery for the prediction of maternal-fetal infection in cases of premature rupture of membranes.

    Science.gov (United States)

    Kayem, Gilles; Batteux, Frederic; Girard, Noémie; Schmitz, Thomas; Willaime, Marion; Maillard, Francoise; Jarreau, Pierre Henri; Goffinet, Francois

    2017-04-01

    Examine the predictive value for maternal-fetal infection of routine bedside tests detecting the proinflammatory cytokines, TNFα and IL-6, in the vaginal secretions of women with premature rupture of the membranes (PROM). This prospective two-center cohort study included all women hospitalized for PROM over a 2-year period. A bedside test assessed IL-6 and TNFα in vaginal secretions. Both centers routinely tested CRP and leukocytes, assaying both in maternal serum, and analyzed vaginal bacterial flora; all samples were repeated twice weekly until delivery. The study included 689 women. In cases of preterm PROM (PPROM) before 37 weeks (n=184), a vaginal sample positive for one or more bacteria was the only marker associated with early neonatal infection (OR 5.6, 95%CI; 2.0-15.7). Its sensitivity was 82% (95%CI; 62-94) and its specificity 56% (95%CI; 47-65). All positive markers of infection were associated with the occurrence of chorioamnionitis. In cases of PROM from 37 weeks onward (n=505), only CRP >5mg/dL was associated with early neonatal infection (OR=8.3, 95%CI; 1.1-65.4) or clinical chorioamnionitis (OR=6.8, 95%CI; 1.5-30.0). The sensitivity of CRP >5mg/dL was 91% (95%CI; 59-100) and its specificity 45% (95%CI; 40-51) for predicting early neonatal infection, and 89% (95%CI; 65-99) and 46% (95%CI; 41-51), respectively, for predicting clinical chorioamnionitis. The association of vaginal cytokines with maternal-fetal infection is weak and thus prevents their use as a good predictor of maternal-fetal infection. CRP and vaginal samples may be useful for identifying a group of women at low risk of infection. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Testing the Predictive Power of Coulomb Stress on Aftershock Sequences

    Science.gov (United States)

    Woessner, J.; Lombardi, A.; Werner, M. J.; Marzocchi, W.

    2009-12-01

    Empirical and statistical models of clustered seismicity are usually strongly stochastic and perceived to be uninformative in their forecasts, since only marginal distributions are used, such as the Omori-Utsu and Gutenberg-Richter laws. In contrast, so-called physics-based aftershock models, based on seismic rate changes calculated from Coulomb stress changes and rate-and-state friction, make more specific predictions: anisotropic stress shadows and multiplicative rate changes. We test the predictive power of models based on Coulomb stress changes against statistical models, including the popular Short Term Earthquake Probabilities and Epidemic-Type Aftershock Sequences models: We score and compare retrospective forecasts on the aftershock sequences of the 1992 Landers, USA, the 1997 Colfiorito, Italy, and the 2008 Selfoss, Iceland, earthquakes. To quantify predictability, we use likelihood-based metrics that test the consistency of the forecasts with the data, including modified and existing tests used in prospective forecast experiments within the Collaboratory for the Study of Earthquake Predictability (CSEP). Our results indicate that a statistical model performs best. Moreover, two Coulomb model classes seem unable to compete: Models based on deterministic Coulomb stress changes calculated from a given fault-slip model, and those based on fixed receiver faults. One model of Coulomb stress changes does perform well and sometimes outperforms the statistical models, but its predictive information is diluted, because of uncertainties included in the fault-slip model. Our results suggest that models based on Coulomb stress changes need to incorporate stochastic features that represent model and data uncertainty.

  11. System for stress corrosion conditions tests on PWR reactors

    International Nuclear Information System (INIS)

    Castro, Andre Cesar de Jesus

    2007-01-01

    The study of environmentally assisted cracking (EAC) involves the consideration and evaluation of the inherent compatibility between a material and the environment under conditions of either applied or residual stress. EAC is a critical problem because equipment, components and structure are subject to the influence of mechanical stress, water environment of different composition, temperature and different material history. Testing for resistance to EAC is one of the most effective ways to determine the interrelationships among this variables on the process of EAC. Up to now, several experimental techniques have been developed worldwide, which address different aspects of environmental caused damage. Constant loading of CT specimens test is a typical example of test, which is used for the estimation of parameters of stress corrosion cracking. To assess the initiation stages and kinetics of crack growth, the testing facility should allow active loading of specimens in the environment that is close to the actual operation conditions of assessed component. This paper presents a testing facility for stress corrosion cracking to be installed at CDTN, which was designed and developed at CDTN. The facility is used to carry out constant load tests under simulated PWR environment, where temperature, water pressure and chemistry are controlled, which are considered the most important factors in SCC. Also, the equipment operational conditions, its applications, and restrictions are presented. The system was developed to operate at temperature until 380 degree C and pressure until 180 bar. It consists in a autoclave stuck at a mechanical system, responsible of producing load , a water treatment station, and a data acquisition system. This testing facility allows the evaluation of cracking progress, especially at PWR reactor. (author) operational conditions. (author)

  12. Development of rupture discs for the FBTR

    International Nuclear Information System (INIS)

    Chetal, S.C.; Raju, C.; Anandkumar, V.; Seetharaman, V.; Rajan, K.K.

    1984-01-01

    Rupture discs are required as a safety device for protecting the secondary sodium circuit and its components against high pressure surges due to accidental water steam leaks in sodium heated steam generator and the consequent sodium water reaction. For identical reasons, rupture discs are also required on the vessels used for decontamination of sodium components. Reverse buckling knife blade concept with austenitic stainless steel disc has been developed for the rupture disc assemblies required for Fast Breeder Test Reactor (FBTR). Hydroforming process without any die has been used for disc fabrication. One rupture disc assembly required for steam generator is undergoing sodium endurance test and has accumulated 4,500 hours. The present status of development work as demonstrated by room temperature experimental results as well as the scope for future work are discussed. (author)

  13. Color Shift Modeling of Light-Emitting Diode Lamps in Step-Loaded Stress Testing

    NARCIS (Netherlands)

    Cai, Miao; Yang, Daoguo; Huang, J.; Zhang, Maofen; Chen, Xianping; Liang, Caihang; Koh, S.W.; Zhang, G.Q.

    2017-01-01

    The color coordinate shift of light-emitting diode (LED) lamps is investigated by running three stress-loaded testing methods, namely step-up stress accelerated degradation testing, step-down stress accelerated degradation testing, and constant stress accelerated degradation testing. A power

  14. Yield stress determination from miniaturized disk bend test data

    International Nuclear Information System (INIS)

    Sohn, D.S.; Kohse, G.; Harling, O.K.

    1985-04-01

    Methodology for testing 3.0 mm diameter by 0.25 mm thick disks by bending in a punch and die has been described previously. This paper describes the analysis of load/deflection data from such miniaturized disk bend tests (MDBT) using a finite element simulation. Good simulation has been achieved up to a point just beyond the predominantly elastic response, linear initial region. The load at which deviation from linearity begins has been found to correlate with yield stress, and yield stress has been successfully extracted from disk bend tests of a number of known materials. Although finite element codes capable of dealing with large strains and large rotations have been used, simulation of the entire load/deflection curve up to fracture of the specimen has not yet been achieved

  15. A prognostic scoring system for arm exercise stress testing.

    Science.gov (United States)

    Xie, Yan; Xian, Hong; Chandiramani, Pooja; Bainter, Emily; Wan, Leping; Martin, Wade H

    2016-01-01

    Arm exercise stress testing may be an equivalent or better predictor of mortality outcome than pharmacological stress imaging for the ≥50% for patients unable to perform leg exercise. Thus, our objective was to develop an arm exercise ECG stress test scoring system, analogous to the Duke Treadmill Score, for predicting outcome in these individuals. In this retrospective observational cohort study, arm exercise ECG stress tests were performed in 443 consecutive veterans aged 64.1 (11.1) years. (mean (SD)) between 1997 and 2002. From multivariate Cox models, arm exercise scores were developed for prediction of 5-year and 12-year all-cause and cardiovascular mortality and 5-year cardiovascular mortality or myocardial infarction (MI). Arm exercise capacity in resting metabolic equivalents (METs), 1 min heart rate recovery (HRR) and ST segment depression ≥1 mm were the stress test variables independently associated with all-cause and cardiovascular mortality by step-wise Cox analysis (all pstatistic of 0.81 before and 0.88 after adjustment for significant demographic and clinical covariates. Arm exercise scores for the other outcome end points yielded C-statistic values of 0.77-0.79 before and 0.82-0.86 after adjustment for significant covariates versus 0.64-0.72 for best fit pharmacological myocardial perfusion imaging models in a cohort of 1730 veterans who were evaluated over the same time period. Arm exercise scores, analogous to the Duke Treadmill Score, have good power for prediction of mortality or MI in patients who cannot perform leg exercise.

  16. RESEARCH ON REDUCING PREMATURITY RUPTURE OF MEMBRANE

    Directory of Open Access Journals (Sweden)

    Maria URSACHI (BOLOTA

    2016-12-01

    -term (3 days and distance (2 years interventional methods applied; clinical investigation of complications arising post intervention; studying behavior synthetic amnion. Conclusions: The cause of PRAS is multifactorial. Traditionally, fetal membrane rupture has been attributed to increased physical stress, which weakens the membranes. At the molecular level PRAS is the result of reducing collagen synthesis, alteration of the structure of collagen to accelerate degradation. In addition, these biochemical changes can be amplified and biophysical stress today. The priorities of this research include elucidation of the normal biological process of fetal membranes, including extracellular matrix remodeling, apoptosis.

  17. Stress Testing of Organic Light- Emitting Diode Panels and Luminaires

    Energy Technology Data Exchange (ETDEWEB)

    Lynn Davis, Kelley Rountree, Karmann Mills

    2018-01-31

    This report builds on previous DOE efforts with OLED technology by updating information on a previously benchmarked OLED product (the Chalina luminaire from Acuity Brands) and provides new benchmarks on the performance of Brite 2 and Brite Amber OLED panels from OLEDWorks. During the tests described here, samples of these devices were subjected to continuous operation in stress tests at elevated ambient temperature environments of 35°C or 45°C. In addition, samples were also operated continuously at room temperature in a room temperature operational life test (RTOL). One goal of this study was to investigate whether these test conditions can accelerate failure of OLED panels, either through panel shorting or an open circuit in the panel. These stress tests are shown to provide meaningful acceleration of OLED failure modes, and an acceleration factor of 2.6 was calculated at 45°C for some test conditions. In addition, changes in the photometric properties of the emitted light (e.g., luminous flux and chromaticity maintenance) was also evaluated for insights into the long-term stability of these products compared to earlier generations. Because OLEDs are a lighting system, electrical testing was also performed on the panel-driver pairs to provide insights into the impact of the driver on long-term panel performance.

  18. Impulsivity and Stress Response in Pathological Gamblers During the Trier Social Stress Test

    NARCIS (Netherlands)

    Maniaci, G.; Goudriaan, A. E.; Cannizzaro, C.; van Holst, R. J.

    2017-01-01

    Gambling has been associated with increased sympathetic nervous system output and stimulation of the hypothalamic-pituitary-adrenal axis. However it is unclear how these systems are affected in pathological gambling. This study aimed to investigate the effect of the Trier Social Stress Test (TSST)

  19. Premature rupture of membranes

    Science.gov (United States)

    ... gov/ency/patientinstructions/000512.htm Premature rupture of membranes To use the sharing features on this page, ... water that surrounds your baby in the womb. Membranes or layers of tissue hold in this fluid. ...

  20. Ruptured submitral aneurysm

    Directory of Open Access Journals (Sweden)

    V. Shukla

    2016-09-01

    Full Text Available Submitral aneurysm is a rare entity, with around few hundred cases reported till date. Presentation can be varied. We describe here a case of submitral aneurysm in a young male with rupture into the left atrium cavity.

  1. Achilles Tendon Rupture

    Science.gov (United States)

    ... is a strong fibrous cord that connects the muscles in the back of your calf to your heel bone. If you overstretch your Achilles tendon, it can tear (rupture) completely or just partially. If your Achilles ...

  2. Biological and psychological markers of stress in humans: focus on the Trier Social Stress Test.

    Science.gov (United States)

    Allen, Andrew P; Kennedy, Paul J; Cryan, John F; Dinan, Timothy G; Clarke, Gerard

    2014-01-01

    Validated biological and psychological markers of acute stress in humans are an important tool in translational research. The Trier Social Stress Test (TSST), involving public interview and mental arithmetic performance, is among the most popular methods of inducing acute stress in experimental settings, and reliably increases hypothalamic-pituitary-adrenal axis activation. However, although much research has focused on HPA axis activity, the TSST also affects the sympathetic-adrenal-medullary system, the immune system, cardiovascular outputs, gastric function and cognition. We critically assess the utility of different biological and psychological markers, with guidance for future research, and discuss factors which can moderate TSST effects. We outline the effects of the TSST in stress-related disorders, and if these responses can be abrogated by pharmacological and psychological treatments. Modified TSST protocols are discussed, and the TSST is compared to alternative methods of inducing acute stress. Our analysis suggests that multiple readouts are necessary to derive maximum information; this strategy will enhance our understanding of the psychobiology of stress and provide the means to assess novel therapeutic agents. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Major outcomes of the stress tests. Learning from each other

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2013-11-15

    Performed by the EU's 'nuclear' member states plus Switzerland and Ukraine, the European stress tests were carried out with some differences, notably in the scope considered. The action plans derived from the conclusions of the national reports peer-reviewed by TSO experts also differ in terms of scope, priorities and scheduling. Similar safety reassessments were performed in other countries such as Japan or Russia. The country-specific focuses described below provide an overview of the similarities and dissimilarities between twelve countries which are represented at EUROSAFE. One common denominator among them might be the fact that the conclusions from the stress tests did not reveal any major deficiency calling for immediate steps to be taken. (orig.)

  4. Fault geometry, rupture dynamics and ground motion from potential earthquakes on the North Anatolian Fault under the Sea of Marmara

    KAUST Repository

    Oglesby, David D.

    2012-03-01

    Using the 3-D finite-element method, we develop dynamic spontaneous rupture models of earthquakes on the North Anatolian Fault system in the Sea of Marmara, Turkey, considering the geometrical complexity of the fault system in this region. We find that the earthquake size, rupture propagation pattern and ground motion all strongly depend on the interplay between the initial (static) regional pre-stress field and the dynamic stress field radiated by the propagating rupture. By testing several nucleation locations, we observe that those far from an oblique normal fault stepover segment (near Istanbul) lead to large through-going rupture on the entire fault system, whereas nucleation locations closer to the stepover segment tend to produce ruptures that die out in the stepover. However, this pattern can change drastically with only a 10° rotation of the regional stress field. Our simulations also reveal that while dynamic unclamping near fault bends can produce a new mode of supershear rupture propagation, this unclamping has a much smaller effect on the speed of the peak in slip velocity along the fault. Finally, we find that the complex fault geometry leads to a very complex and asymmetric pattern of near-fault ground motion, including greatly amplified ground motion on the insides of fault bends. The ground-motion pattern can change significantly with different hypocentres, even beyond the typical effects of directivity. The results of this study may have implications for seismic hazard in this region, for the dynamics and ground motion of geometrically complex faults, and for the interpretation of kinematic inverse rupture models.

  5. Fault geometry, rupture dynamics and ground motion from potential earthquakes on the North Anatolian Fault under the Sea of Marmara

    KAUST Repository

    Oglesby, David D.; Mai, Paul Martin

    2012-01-01

    Using the 3-D finite-element method, we develop dynamic spontaneous rupture models of earthquakes on the North Anatolian Fault system in the Sea of Marmara, Turkey, considering the geometrical complexity of the fault system in this region. We find that the earthquake size, rupture propagation pattern and ground motion all strongly depend on the interplay between the initial (static) regional pre-stress field and the dynamic stress field radiated by the propagating rupture. By testing several nucleation locations, we observe that those far from an oblique normal fault stepover segment (near Istanbul) lead to large through-going rupture on the entire fault system, whereas nucleation locations closer to the stepover segment tend to produce ruptures that die out in the stepover. However, this pattern can change drastically with only a 10° rotation of the regional stress field. Our simulations also reveal that while dynamic unclamping near fault bends can produce a new mode of supershear rupture propagation, this unclamping has a much smaller effect on the speed of the peak in slip velocity along the fault. Finally, we find that the complex fault geometry leads to a very complex and asymmetric pattern of near-fault ground motion, including greatly amplified ground motion on the insides of fault bends. The ground-motion pattern can change significantly with different hypocentres, even beyond the typical effects of directivity. The results of this study may have implications for seismic hazard in this region, for the dynamics and ground motion of geometrically complex faults, and for the interpretation of kinematic inverse rupture models.

  6. Ruptured cornual pregnancy

    International Nuclear Information System (INIS)

    Hussain, M.; Yasmeen, H.; Noorani, K.

    2003-01-01

    A case of ruptured cornual pregnancy is presented here. The patient presented with history of 30 weeks gestational amenorrhoea and pain in the lower abdomen and epigastrium for the last seven days. Ultrasound revealed a 29 weeks abdominal pregnancy with blood in the pelvic cavity. On laparotomy; there was a ruptured right cornual pregnancy, treated cornual resection and uterine repair. An alive male baby of one kg weight was delivered from the resected cornua of the uterus. (author)

  7. INTERFACE DEVICE FOR NONDESTRUCTIVE TESTING OF RESIDUAL SURFACE STRESSES

    Directory of Open Access Journals (Sweden)

    Gennady A. Perepelkin

    2016-01-01

    Full Text Available The paper considers the organization of connection of a personal computer with a device for nondestructive testing of residual surface stresses. The device works is based on the phenomenon of diffraction of ionizing radiation from the crystal lattice near the surface of the crystallites. Proposed software interface to the organization for each type of user: the device developers, administrators, users. Some aspects of the organization of communication microcontroller to a PC via USB-port

  8. A Simple Stress Test on Indonesian Islamic Banking Industry

    Directory of Open Access Journals (Sweden)

    Dece Kurniadi

    2018-02-01

    Full Text Available The purpose of this study is to conduct a stress test on Indonesian Islamic Banking industry in order toassess the capability of the industry to absorb the extreme risks that may happen in the future. Using data from April 2008 to September 2014, the study employs balance sheet approach in performing the stress test on profitability and capital position and the value at risk technique for liquidity stress test. The results of this study show that in term of profitability, Islamic banks in Indonesia are immune from losses if the default rate (Non-Performing Loan is less than 8.5 %. If the industry can improve the profit margin, the resistance will be higher.In term of capital position, by assuming loss given default (LGD is constant at 40%, the industry will not go bankrupt if probability of default (PD is less than 9%. If the PD is more than 9%, total expected loss is more than available capital. Using the value at risk (VaR at 99% confidence, the study finds that possible deposit flight will not exceed IDR 26 trillion and the liquid asset available is IDR 28 trillion. The study concludes that there is no liquidity threat for Islamic banks in Indonesia. The findingsalso uncover the risky condition that even though the capital adequacy ratio (CAR is on average 14%, real capital measured by Equity to total asset (ETA is only 5.4%

  9. Creep Rupture Life Prediction Based on Analysis of Large Creep Deformation

    Directory of Open Access Journals (Sweden)

    YE Wenming

    2016-08-01

    Full Text Available A creep rupture life prediction method for high temperature component was proposed. The method was based on a true stress-strain elastoplastic creep constitutive model and the large deformation finite element analysis method. This method firstly used the high-temperature tensile stress-strain curve expressed by true stress and strain and the creep curve to build materials' elastoplastic and creep constitutive model respectively, then used the large deformation finite element method to calculate the deformation response of high temperature component under a given load curve, finally the creep rupture life was determined according to the change trend of the responsive curve.The method was verified by durable test of TC11 titanium alloy notched specimens under 500 ℃, and was compared with the three creep rupture life prediction methods based on the small deformation analysis. Results show that the proposed method can accurately predict the high temperature creep response and long-term life of TC11 notched specimens, and the accuracy is better than that of the methods based on the average effective stress of notch ligament, the bone point stress and the fracture strain of the key point, which are all based on small deformation finite element analysis.

  10. SFC/SFBMN guidelines update for nuclear cardiology procedures: stress testing in adults and children

    International Nuclear Information System (INIS)

    Manrique, A.; Marie, P.Y.; Maunoury, Ch.; Acar, Ph.; Agostini, D.

    2002-01-01

    The guidelines update for nuclear cardiology procedures are studied in this article. We find the minimum technique conditions for the stress testing practice, the recommendations for the different ischemia activation tests, the choice of the stress test. (N.C.)

  11. Rapid microbiological testing: monitoring the development of bacterial stress.

    Directory of Open Access Journals (Sweden)

    Boris Zavizion

    2010-10-01

    Full Text Available The ability to respond to adverse environments effectively along with the ability to reproduce are sine qua non conditions for all sustainable cellular forms of life. Given the availability of an appropriate sensing modality, the ubiquity and immediacy of the stress response could form the basis for a new approach for rapid biological testing. We have found that measuring the dielectric permittivity of a cellular suspension, an easily measurable electronic property, is an effective way to monitor the response of bacterial cells to adverse conditions continuously. The dielectric permittivity of susceptible and resistant strains of Escherichia coli and Staphylococcus aureus, treated with gentamicin and vancomycin, were measured directly using differential impedance sensing methods and expressed as the Normalized Impedance Response (NIR. These same strains were also heat-shocked and chemically stressed with Triton X-100 or H(2O(2. The NIR profiles obtained for antibiotic-treated susceptible organisms showed a strong and continuous decrease in value. In addition, the intensity of the NIR value decrease for susceptible cells varied in proportion to the amount of antibiotic added. Qualitatively similar profiles were found for the chemically treated and heat-shocked bacteria. In contrast, antibiotic-resistant cells showed no change in the NIR values in the presence of the drug to which it is resistant. The data presented here show that changes in the dielectric permittivity of a cell suspension are directly correlated with the development of a stress response as well as bacterial recovery from stressful conditions. The availability of a practical sensing modality capable of monitoring changes in the dielectric properties of stressed cells could have wide applications in areas ranging from the detection of bacterial infections in clinical specimens to antibiotic susceptibility testing and drug discovery.

  12. Pressure tube rupture in a closed tank

    International Nuclear Information System (INIS)

    Khater, H.A.; Hadaller, G.I.; Stern, F.

    1985-06-01

    A study has been prepared on the feasibility of conducting pressure tube/calandria tube rupture tests in a closed tank, simulating a scaled-down calandria vessel. The study includes: i) a review of previous work, ii) an analytical investigation of the scaling problem of the calandria vessel and relevant in-core structures, iii) selection of a method for initiating pressure tube/calandria tube rupture, iv) a set of specifications for the test assembly, v) general arrangement drawings, vi) a proposal for a test matrix, vii) a survey and evaluation of existing facilities which could provide the required high pressure, temperature and fluid inventory, and viii) a cost estimate for the detailed design and construction, instrumentation, data acquisition and reduction, testing and reporting. The study concludes that it is both technically and practically feasible to conduct pressure tube rupture tests in a closed tank

  13. Accelerated stress testing of amorphous silicon solar cells

    Science.gov (United States)

    Stoddard, W. G.; Davis, C. W.; Lathrop, J. W.

    1985-01-01

    A technique for performing accelerated stress tests of large-area thin a-Si solar cells is presented. A computer-controlled short-interval test system employing low-cost ac-powered ELH illumination and a simulated a-Si reference cell (seven individually bandpass-filtered zero-biased crystalline PIN photodiodes) calibrated to the response of an a-Si control cell is described and illustrated with flow diagrams, drawings, and graphs. Preliminary results indicate that while most tests of a program developed for c-Si cells are applicable to a-Si cells, spurious degradation may appear in a-Si cells tested at temperatures above 130 C.

  14. Pt-Rh alloys. Investigation of creep rate and rupture time at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Trumic, Biserka; Gomidzelovic, Lidija; Marjanovic, Sasa; Ivanovic, Aleksandra; Dimitrijevic, Silvana [Belgrade Univ., Bor (Serbia). Inst. of Mining and Metallurgy; Krstic, Vesna

    2013-02-01

    The results of experimental investigation of creep rate and rupture time of the alloys of Pt-Rh system are presented in this paper. Selected alloys with 7-40 wt.-% Rh content were examined using a universal device for tensile testing of materials at high temperatures, and monitoring structure changes of the samples by electron microscopy. Investigations were performed in the temperature range between 1200 C and 1700 C at a stress between 2 MPa and 15 MPa. (orig.)

  15. STRESS TESTS FOR VIDEOSTREAMING SERVICES BASED ON RTSP PROTOCOL

    Directory of Open Access Journals (Sweden)

    Gabriel Elías Chanchí Golondrino

    2015-11-01

    Full Text Available Video-streaming is a technology with major implications these days in such diverse contexts as education, health and the business sector; all of this regarding the ease it provides for remote access to live or recorded media content, allowing communication regardless of geographic location. One standard protocol that enables implementation of this technology is real time streaming protocol, or RTSP. However, since most application servers and Internet services are supported on HTTP requests, very little research has been done on generating tools for carrying out stress tests on streaming servers. This paper presents a stress measuring tool called Hermes, developed in Python, which allows calculation of response times for establishing RTSP connections to streaming servers, as well as obtaining RAM memory consumption and CPU usage rate data from these servers. Hermes was deployed in a video-streaming environment where stress testing was carried out on the LIVE555 server, using calls in the background to VLC and OpenRTSP open source clients. 

  16. Creep rupture behavior of unidirectional advanced composites

    Science.gov (United States)

    Yeow, Y. T.

    1980-01-01

    A 'material modeling' methodology for predicting the creep rupture behavior of unidirectional advanced composites is proposed. In this approach the parameters (obtained from short-term tests) required to make the predictions are the three principal creep compliance master curves and their corresponding quasi-static strengths tested at room temperature (22 C). Using these parameters in conjunction with a failure criterion, creep rupture envelopes can be generated for any combination of in-plane loading conditions and ambient temperature. The analysis was validated experimentally for one composite system, the T300/934 graphite-epoxy system. This was done by performing short-term creep tests (to generate the principal creep compliance master curves with the time-temperature superposition principle) and relatively long-term creep rupture tensile tests of off-axis specimens at 180 C. Good to reasonable agreement between experimental and analytical results is observed.

  17. Fault Branching and Long-Term Earthquake Rupture Scenario for Strike-Slip Earthquake

    Science.gov (United States)

    Klinger, Y.; CHOI, J. H.; Vallage, A.

    2017-12-01

    Careful examination of surface rupture for large continental strike-slip earthquakes reveals that for the majority of earthquakes, at least one major branch is involved in the rupture pattern. Often, branching might be either related to the location of the epicenter or located toward the end of the rupture, and possibly related to the stopping of the rupture. In this work, we examine large continental earthquakes that show significant branches at different scales and for which ground surface rupture has been mapped in great details. In each case, rupture conditions are described, including dynamic parameters, past earthquakes history, and regional stress orientation, to see if the dynamic stress field would a priori favor branching. In one case we show that rupture propagation and branching are directly impacted by preexisting geological structures. These structures serve as pathways for the rupture attempting to propagate out of its shear plane. At larger scale, we show that in some cases, rupturing a branch might be systematic, hampering possibilities for the development of a larger seismic rupture. Long-term geomorphology hints at the existence of a strong asperity in the zone where the rupture branched off the main fault. There, no evidence of throughgoing rupture could be seen along the main fault, while the branch is well connected to the main fault. This set of observations suggests that for specific configurations, some rupture scenarios involving systematic branching are more likely than others.

  18. A Randomized Comparative Study Evaluating Various Cough Stress Tests and 24-Hour Pad Test with Urodynamics in the Diagnosis of Stress Urinary Incontinence.

    Science.gov (United States)

    Henderson, Joseph W; Kane, Sarah M; Mangel, Jeffrey M; Kikano, Elias G; Garibay, Jorge A; Pollard, Robert R; Mahajan, Sangeeta T; Debanne, Sara M; Hijaz, Adonis K

    2018-06-01

    The cough stress test is a common and accepted tool to evaluate stress urinary incontinence but there is no agreement on how the test should be performed. We assessed the diagnostic ability of different cough stress tests performed when varying patient position and bladder volume using urodynamic stress urinary incontinence as the gold standard. The 24-hour pad test was also evaluated. We recruited women who presented to specialty outpatient clinics with the complaint of urinary incontinence and who were recommended to undergo urodynamic testing. A total of 140 patients were randomized to 4 cough stress test groups, including group 1-a comfortably full bladder, group 2-an empty bladder, group 3- a bladder infused with 200 cc saline and group 4-a bladder filled to half functional capacity. The sequence of standing and sitting was randomly assigned. The groups were compared by 1-way ANOVA or the generalized Fisher exact test. The κ statistic was used to evaluate agreement between the sitting and standing positions. The 95% CIs of sensitivity and specificity were calculated using the Wilson method. ROC analysis was done to evaluate the performance of the 24-hour pad test. The cough stress test performed with a bladder filled to half functional capacity was the best performing test with 83% sensitivity and 90% specificity. There was no statistically significant evidence that the sensitivity or specificity of 1 cough stress test differed from that of the others. The pad test had no significant predictive ability to diagnose urodynamic stress urinary incontinence (AUC 0.60, p = 0.08). Cough stress tests were accurate to diagnose urodynamic stress urinary incontinence. The 24-hour pad test was not predictive of urodynamic stress urinary incontinence and not helpful when used in conjunction with the cough stress test. Copyright © 2018 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

  19. Accelerated stress testing of thin film solar cells: Development of test methods and preliminary results

    Science.gov (United States)

    Lathrop, J. W.

    1985-01-01

    If thin film cells are to be considered a viable option for terrestrial power generation their reliability attributes will need to be explored and confidence in their stability obtained through accelerated testing. Development of a thin film accelerated test program will be more difficult than was the case for crystalline cells because of the monolithic construction nature of the cells. Specially constructed test samples will need to be fabricated, requiring committment to the concept of accelerated testing by the manufacturers. A new test schedule appropriate to thin film cells will need to be developed which will be different from that used in connection with crystalline cells. Preliminary work has been started to seek thin film schedule variations to two of the simplest tests: unbiased temperature and unbiased temperature humidity. Still to be examined are tests which involve the passage of current during temperature and/or humidity stress, either by biasing in the forward (or reverse) directions or by the application of light during stress. Investigation of these current (voltage) accelerated tests will involve development of methods of reliably contacting the thin conductive films during stress.

  20. Stress Reactivity to an Electronic Version of the Trier Social Stress Test: A Pilot Study

    Directory of Open Access Journals (Sweden)

    Sage E Hawn

    2015-05-01

    Full Text Available Social stressors that rely on the inclusion of confederates (i.e., Trier Social Stress Test; TSST are often used in clinical laboratory research paradigms to elicit a measurable stress response in participants. Although effective, the TSST is labor intensive and may introduce error variance as a function of confederate race, gender, and/or response characteristics. The present study aimed to develop and validate an electronic version of the TSST (e-TSST. The primary aim was to compare the e-TSST to an e-neutral control condition; the exploratory aim was to compare the magnitude of stress response elicited by the e-TSST to that elicited by the traditional TSST. Forty-three healthy adults were randomized to the e-TSST or e-neutral condition. Subjective (participant-rated distress and objective (cortisol, heart rate and blood pressure indices of stress were collected prior to, and multiple times following, the stressor. Using archival data collected from 19 healthy participants exposed to the traditional TSST in a prior study, stress reactivity was compared between the electronic and traditional versions of the TSST. The e-TSST elicited significant increases in all measures of stress reactivity compared to the e-neutral condition, with the exception of heart rate (HR. Results showed that the magnitude of subjective distress, BP, and HR responses elicited by the e-TSST did not differ significantly from that elicited by the traditional TSST. The traditional TSST elicited significantly higher cortisol than the e-TSST. Although these findings provide initial support for the development of electronic versions of the TSST, further refinement of the e-TSST is warranted prior to broad adoption of this technology. A refined, reliable e-TSST could allow for increased utilization of the TSST by enhancing convenience, reducing labor costs, and limiting potential error variance introduced by human confederates.

  1. Comparison of exercise stress testing with dobutamine stress echocardiography and radionuclide ventriculography for diagnosis of coronary artery disease

    International Nuclear Information System (INIS)

    Ozdemir, K.; Kisacik, H.L.; Oguzhan, A.

    1999-01-01

    Dobutamine stress echocardiography, Tc-99m radionuclide ventriculography (RNVG), and exercise stress testing were performed prospectively in 63 patients with suspected coronary artery disease to compare the values of exercise testing, dobutamine stress echocardiography and RNVG in the non-invasive diagnosis of coronary artery disease. The sensitivities of dobutamine stress echocardiography and RNVG were found to be higher than that of exercise testing (93-62%, p 0.05). There were no differences between the sensitivities of the three techniques in multiple vessel disease (p>0.05). The specificities of dobutamine stress echocardiography and RNVG were higher than that of exercise testing (for both of the tests 86-62%, p 0.05). The results of dobutamine stress echocardiography RNVG were concordant with each other in 46 patients (76%, kappa=65%) in sectional analysis. Dobutamine stress echocardiography and RNVG tests were comparable with each other in 85% of the 189 segments (kappa=64%). The expected 5% decrease at peak doses of dobutamine was not detected in stress echocardiography in 25 patients and in RNVG in 26 of the patients. Dobutamine stress echocardiography and RNVG are superior to exercise testing in the diagnosis of single vessel disease and there is no significant difference between the two techniques. When the ejection fraction is considered in dobutamine stress echocardiography and RNVG, it does not make an additional contribution to the diagnosis of coronary artery disease. (author)

  2. Investigation of creep rupture properties in air and He environments of alloy 617 at 800 °C

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Woo-Gon, E-mail: wgkim@kaeri.re.k [Korea Atomic Energy Research Institute, 989-111 Daedeok-daero, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Ekaputra, I.M.W.; Park, Jae-Young [Pukyong National University, Busan 608-739 (Korea, Republic of); Kim, Min-Hwan; Kim, Yong-Wan [Korea Atomic Energy Research Institute, 989-111 Daedeok-daero, Yuseong-gu, Daejeon 305-353 (Korea, Republic of)

    2016-09-15

    Creep rupture properties for Alloy 617 were investigated by a series of creep tests under different applied stresses in air and He environments at 800 °C. The creep rupture time in air and He environments exhibited almost similar life in a short rupture time. However, when the creep rupture time reaches above 3000 h, the creep life in the He environment reduced compared with those of the air environment. The creep strain rate in the He environment was a little faster than that in the air environment above 3000 h. The reduction of creep life in the He environment was due to the difference of various microstructure features such as the carbide depleted zone, oxidation structures, surface cracking, voids below the surface, and voids in the matrix in air and He environments. Alloy 617 followed Norton’s power law and the Monkman–Grant relationship well. As the stress decreased, the creep ductility decreased slightly. The thickness of the outer and internal oxide layers presented the trend of a parabolic increase with an increase in creep rupture time in both the air and He environments. The thickness in the He environment was found to be thicker than in the air environment, although pure helium gas of 99.999% was used in the present investigation. The differences in the oxide-layer thickness caused detrimental effects on the creep resistance, even in a low oxygen-containing He agent.

  3. Investigation of creep rupture properties in air and He environments of alloy 617 at 800 °C

    International Nuclear Information System (INIS)

    Kim, Woo-Gon; Ekaputra, I.M.W.; Park, Jae-Young; Kim, Min-Hwan; Kim, Yong-Wan

    2016-01-01

    Creep rupture properties for Alloy 617 were investigated by a series of creep tests under different applied stresses in air and He environments at 800 °C. The creep rupture time in air and He environments exhibited almost similar life in a short rupture time. However, when the creep rupture time reaches above 3000 h, the creep life in the He environment reduced compared with those of the air environment. The creep strain rate in the He environment was a little faster than that in the air environment above 3000 h. The reduction of creep life in the He environment was due to the difference of various microstructure features such as the carbide depleted zone, oxidation structures, surface cracking, voids below the surface, and voids in the matrix in air and He environments. Alloy 617 followed Norton’s power law and the Monkman–Grant relationship well. As the stress decreased, the creep ductility decreased slightly. The thickness of the outer and internal oxide layers presented the trend of a parabolic increase with an increase in creep rupture time in both the air and He environments. The thickness in the He environment was found to be thicker than in the air environment, although pure helium gas of 99.999% was used in the present investigation. The differences in the oxide-layer thickness caused detrimental effects on the creep resistance, even in a low oxygen-containing He agent.

  4. Stress test of the nuclear power plants performed in Taiwan

    Energy Technology Data Exchange (ETDEWEB)

    Wu, C.H.; Teng, W.C.; Chang, S.; Chen, Y.B. [Atomic Energy Council, Taipei, Taiwan (China)

    2014-07-01

    In the wake of Japan's Fukushima Daiichi Nuclear Power Plants event, the Atomic Energy Council (AEC) has asked Taiwan's Nuclear Power Plant operator (TPC) to re-examine and re-evaluate the vulnerabilities of its nuclear units, and furthermore, take possible countermeasures against extreme natural disasters, including earthquake, tsunami and rock-and-mud slide. The evaluation process should be based on both within and beyond Design Basis Accidents, by reference to the actions recommended by the world nuclear authorities and groups, namely, IAEA, USNRC, NEI, ENSREG and WANO. Taiwan is a very densely populated region of the world. Furthermore, like Japan, due to its geophysical position, Taiwan is prone to large scale earthquakes, and although historically rare, Taiwan also faces the potential risk of tsunamis. AEC also asked TPC to perform the stress test following the specification given by WENRA (later ENSREG) and conducted in all the EU's nuclear reactors. After completion of the stress test for all the nuclear power plants, AEC was trying to have the reports peer reviewed by international organizations, as EU did. The OECD/NEA accepted AEC's request and formed a review team specific to the review of Taiwan's National Report for the Stress Test. There were 18 follow-up items after the NEA's review. Based on these items, AEC developed five orders to require TPC further enhancing their capabilities to cope with extreme natural hazards. The ENSREG also formed a nine-expert review team for Taiwan's Stress Test in response to AEC's request almost at the same time as the OECD/NEA. The ENSREG review team began their works in June 2013 by desktop review, and ended in early October 2013 by country visit to Taiwan. While the assessment of post-Fukushima evaluation reveals neither immediate nuclear safety concerns nor threats to the public health and safety, AEC requested that TPC focus on strengthening its re-evaluation on design

  5. Stress test of the nuclear power plants performed in Taiwan

    International Nuclear Information System (INIS)

    Wu, C.H.; Teng, W.C.; Chang, S.; Chen, Y.B.

    2014-01-01

    In the wake of Japan's Fukushima Daiichi Nuclear Power Plants event, the Atomic Energy Council (AEC) has asked Taiwan's Nuclear Power Plant operator (TPC) to re-examine and re-evaluate the vulnerabilities of its nuclear units, and furthermore, take possible countermeasures against extreme natural disasters, including earthquake, tsunami and rock-and-mud slide. The evaluation process should be based on both within and beyond Design Basis Accidents, by reference to the actions recommended by the world nuclear authorities and groups, namely, IAEA, USNRC, NEI, ENSREG and WANO. Taiwan is a very densely populated region of the world. Furthermore, like Japan, due to its geophysical position, Taiwan is prone to large scale earthquakes, and although historically rare, Taiwan also faces the potential risk of tsunamis. AEC also asked TPC to perform the stress test following the specification given by WENRA (later ENSREG) and conducted in all the EU's nuclear reactors. After completion of the stress test for all the nuclear power plants, AEC was trying to have the reports peer reviewed by international organizations, as EU did. The OECD/NEA accepted AEC's request and formed a review team specific to the review of Taiwan's National Report for the Stress Test. There were 18 follow-up items after the NEA's review. Based on these items, AEC developed five orders to require TPC further enhancing their capabilities to cope with extreme natural hazards. The ENSREG also formed a nine-expert review team for Taiwan's Stress Test in response to AEC's request almost at the same time as the OECD/NEA. The ENSREG review team began their works in June 2013 by desktop review, and ended in early October 2013 by country visit to Taiwan. While the assessment of post-Fukushima evaluation reveals neither immediate nuclear safety concerns nor threats to the public health and safety, AEC requested that TPC focus on strengthening its re-evaluation on design

  6. Accelerated Testing Methodology in Constant Stress-Rate Testing for Advanced Structural Ceramics: A Preloading Technique

    Science.gov (United States)

    Choi, Sung R.; Gyekenyesi, John P.; Huebert, Dean; Bartlett, Allen; Choi, Han-Ho

    2001-01-01

    Preloading technique was used as a means of an accelerated testing methodology in constant stress-rate (dynamic fatigue) testing for two different brittle materials. The theory developed previously for fatigue strength as a function of preload was further verified through extensive constant stress-rate testing for glass-ceramic and CRT glass in room temperature distilled water. The preloading technique was also used in this study to identify the prevailing failure mechanisms at elevated temperatures, particularly at lower test rates in which a series of mechanisms would be associated simultaneously with material failure, resulting in significant strength increase or decrease. Two different advanced ceramics including SiC whisker-reinforced composite silicon nitride and 96 wt% alumina were used at elevated temperatures. It was found that the preloading technique can be used as an additional tool to pinpoint the dominant failure mechanism that is associated with such a phenomenon of considerable strength increase or decrease.

  7. HammerCloud: A Stress Testing System for Distributed Analysis

    International Nuclear Information System (INIS)

    Ster, Daniel C van der; García, Mario Úbeda; Paladin, Massimo; Elmsheuser, Johannes

    2011-01-01

    Distributed analysis of LHC data is an I/O-intensive activity which places large demands on the internal network, storage, and local disks at remote computing facilities. Commissioning and maintaining a site to provide an efficient distributed analysis service is therefore a challenge which can be aided by tools to help evaluate a variety of infrastructure designs and configurations. HammerCloud is one such tool; it is a stress testing service which is used by central operations teams, regional coordinators, and local site admins to (a) submit arbitrary number of analysis jobs to a number of sites, (b) maintain at a steady-state a predefined number of jobs running at the sites under test, (c) produce web-based reports summarizing the efficiency and performance of the sites under test, and (d) present a web-interface for historical test results to both evaluate progress and compare sites. HammerCloud was built around the distributed analysis framework Ganga, exploiting its API for grid job management. HammerCloud has been employed by the ATLAS experiment for continuous testing of many sites worldwide, and also during large scale computing challenges such as STEP'09 and UAT'09, where the scale of the tests exceeded 10,000 concurrently running and 1,000,000 total jobs over multi-day periods. In addition, HammerCloud is being adopted by the CMS experiment; the plugin structure of HammerCloud allows the execution of CMS jobs using their official tool (CRAB).

  8. Ruptured Ectopic Pregnancy

    Directory of Open Access Journals (Sweden)

    Valentina Park

    2016-09-01

    Full Text Available History of present illness: A 21-year-old female presented with sudden onset suprapubic abdominal pain associated with dysuria. The patient also experienced near syncope during bowel movements three times three days ago without falling or losing consciousness. She denied fever, nausea, and vomiting. She stated that she was five weeks pregnant by last menstrual period. She had an ultrasound a few weeks before that showed no intrauterine pregnancy, but she had not followed up for additional testing. Significant findings: The patient’s serum beta-hCG was 5,637 mIU/mL. The transvaginal ultrasound showed an empty uterus with free fluid posteriorly in the pelvis and Pouch of Douglas (00:00. A 4.5 cm heterogeneous mass was visible in the left adnexa concerning for an ectopic pregnancy (00:10. Discussion: Ectopic pregnancies are a leading cause of maternal morbidity and mortality, as well as decreased fertility.1,2 Differentiating between an ectopic pregnancy and a normal early pregnancy may be difficult, since ultrasound and quantitative beta-hCG may show inconclusive results.3,4 Patients who have used fertility treatment may further complicate the picture because they are at risk for heterotypic pregnancies.5 Ectopic pregnancies most commonly implant in the fallopian tube, but may alternatively implant in the ovary, cervix, abdomen, or uterine cornua.4 Ultrasonography may show an empty uterus, adnexal mass, pelvic free fluid, or an extra-uterine gestational sac, yolk sac, and/or embryo.6 Treatment options for ectopic pregnancy include surgery or methotrexate.2,4 Some patients may be candidates for close outpatient surveillance if the diagnosis is unclear or in very limited cases for early, non-ruptured ectopic pregnancies.2,4

  9. Color Shift Modeling of Light-Emitting Diode Lamps in Step-Loaded Stress Testing

    OpenAIRE

    Cai, Miao; Yang, Daoguo; Huang, J.; Zhang, Maofen; Chen, Xianping; Liang, Caihang; Koh, S.W.; Zhang, G.Q.

    2017-01-01

    The color coordinate shift of light-emitting diode (LED) lamps is investigated by running three stress-loaded testing methods, namely step-up stress accelerated degradation testing, step-down stress accelerated degradation testing, and constant stress accelerated degradation testing. A power model is proposed as the statistical model of the color shift (CS) process of LED products. Consequently, a CS mechanism constant is obtained for detecting the consistency of CS mechanisms among various s...

  10. Testing the tenets of minority stress theory in workplace contexts.

    Science.gov (United States)

    Velez, Brandon L; Moradi, Bonnie; Brewster, Melanie E

    2013-10-01

    The links of minority stressors (workplace discrimination, expectations of stigma, internalized heterosexism, and identity management strategies) with psychological distress and job satisfaction were examined in a sample of 326 sexual minority employees. Drawing from minority stress theory and the literature on the vocational experiences of sexual minority people, patterns of mediation and moderation were tested. Minority stressors were associated with greater distress and lower job satisfaction. A mediation model was supported in which the links of discrimination and internalized heterosexism with psychological distress were mediated by a concealment-focused identity management strategy (i.e., avoiding), and the links of discrimination, expectations of stigma, and internalized heterosexism with job satisfaction were mediated by a disclosure-focused identity management strategy (i.e., integrating). Tests of moderation indicated that for sexual minority women (but not men), the positive association of discrimination with distress was stronger at higher levels of internalized heterosexism than at lower levels. In addition, lower levels of internalized heterosexism and concealment strategies (i.e., counterfeiting and avoiding) and higher levels of a disclosure strategy (i.e., integrating) were associated with higher job satisfaction in the context of low discrimination, but this buffering effect disappeared as level of discrimination increased. The implications of these findings for minority stress research are discussed, and clinical recommendations are made.

  11. DECOVALEX I - Test Case 1: Coupled stress-flow model

    International Nuclear Information System (INIS)

    Rosengren, L.; Christianson, M.

    1995-12-01

    This report presents the results of the coupled stress-flow model, test case 1 of Decovalex. The model simulates the fourth loading cycle of a coupled stress-flow test and subsequent shearing up to and beyond peak shear resistance. The first loading sequence (A) consists of seven normal loading steps: 0, 5, 15, 25, 15, 5, 0 MPa. The second loading sequence (B) consists of the following eight steps: unstressed state, normal boundary loading of 25 MPa (no shearing), and then shearing of 0.5, 0.8, 2, 4, 2, 0 mm. Two different options regarding the rock joint behaviour were modeled in accordance with the problem definition. In option 1 a linear elastic joint model with Coulomb slip criterion was used. In option 2 a non-linear empirical (i.e. Barton-Bandis) joint model was used. The hydraulic condition during both load sequence A and B was a constant head of 5 m at the inlet point and 0 m at the outlet point. All model runs presented in this report were performed using the two-dimensional distinct element computer code UDEC, version 1.8. 30 refs, 36 figs

  12. Rupture model based on non-associated plasticity

    Science.gov (United States)

    Pradeau, Adrien; Yoon, Jeong Whan; Thuillier, Sandrine; Lou, Yanshan; Zhang, Shunying

    2018-05-01

    This research work is about modeling the mechanical behavior of metallic sheets of AA6016 up to rupture using non-associated flow rule. Experiments were performed at room temperature in uniaxial tension and simple shear in different directions according to the rolling direction and an additional hydraulic bulge test. The anisotropy of the material is described by a Yld2000-2d yield surface [1], calibrated by stress ratios, and a plastic potential represented by Hill1948 [2], calibrated using Lankford coefficients. That way, the former is able to reproduce the yield stresses in different directions and the latter is able to reproduce the deformations in different directions as well [3], [4]. Indeed, the non-associated flow rule allows for the direction of the plastic flow not to be necessarily normal to the yield surface. Concerning the rupture, the macroscopic ductile fracture criterion DF2014 was used [5]. It indirectly uses the three invariants of the stress tensor by using the three following parameters: the stress triaxiality η, the Lode parameter L and the equivalent plastic strain to fracture ∈f-p . In order to be consistent with the plastic model and to add more flexibility to the p criterion, the equivalent stress σ ¯ and the equivalent strain to fracture ∈f-p have been substituted respectively as Yld2000-2d and Hill1948 in the DF2014 fracture criterion. The parameters for the fracture criterion were obtained by optimization and the fracture locus can be plotted in the (η ,L ,∈-p) space. The damage indicator D is then numerically predicted with respect of average strain values. A good correlation with the experimental results is obtained.

  13. Study on tube rupture strength evaluation method for rapid overheating

    International Nuclear Information System (INIS)

    Komine, Ryuji; Wada, Yusaku

    1998-08-01

    A sodium-water reaction derived from the single tube break in steam generator might overheat neighbor tubes rapidly under internal pressure loadings. If the temperature of tube wall becomes too high, it has to be evaluated that the stress of tube does not exceed the material strength limit to prevent the propagation of tube rupture. In the present study this phenomenon was recognized as the fracture of cylindrical tube with the large deformation due to overheating, and the evaluation method was investigated based on both of experimental and analytical approaches. The results obtained are as follows. (1) As for the nominal stress estimation, it was clarified through the experimental data and the detailed FEM elasto-plastic large deformation analysis that the formula used in conventional designs can be applied. (2) Within the overheating temperature limits of tubes, the creep effect is dominant, even if the loading time is too short. So the strain rate on the basis of JIS elevated temperature tensile test method for steels and heat-resisting alloys is too late and almost of total strain is composed by creep one. As a result the time dependent effect cannot be evaluated under JIS strain rate condition. (3) Creep tests in shorter time condition than a few minutes and tensile tests in higher strain rate condition than 10%/min of JIS are carried out for 2 1/4Cr-1Mo(NT) steel, and the standard values for tube rupture strength evaluation are formulated. (4) The above evaluation method based on both of the stress estimation and the strength standard values application is justified by using the tube burst test data under internal pressure. (5) The strength standard values on Type 321 ss is formulated in accordance with the procedure applied for 2 1/4Cr-1Mo(NT) steel. (author)

  14. Microstructure-based assessment of creep rupture behaviour of cast-forged P91 steel

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, Chandan, E-mail: chandanpy.1989@gmail.com [Department of Mechanical and Industrial Engineering, Indian Institute of Technology Roorkee, Uttrakhand 247667 (India); Mahapatra, M.M. [School of Mechanical Sciences, Indian Institute of Technology Bhubaneswar, Odisha 751013 (India); Kumar, Pradeep; Vidyrathy, R.S. [Department of Mechanical and Industrial Engineering, Indian Institute of Technology Roorkee, Uttrakhand 247667 (India); Srivastava, A. [Senior Engineer, HEEP Section, BHEL Haridwar (India)

    2017-05-17

    The work presented in this study was performed with the intent to characterize the microstructure evolution for short term creep exposure of cast-forged P91 steel. The short-term creep test was performed at temperature range of 620–650 °C and stresses ranging from 120 to 200 MPa. To characterize the sample after creep exposure, field emission scanning electron microscopy (FESEM) with energy dispersive X-ray spectroscopy (EDS), optical microscope and micro-hardness testing were utilized. Creep tests were performed on round creep specimens. For low temperature service condition, longer creep life was obtained. The fracture surface of creep ruptured specimen were characterized by using the FESEM. The transgranular fracture mode was noticed in all the tests condition. The creep rupture life was found to be decreased with increase in applied stress. The maximum rupture life was measured about to be 3329.28 h for the sample exposed at 620 °C for 120 MPa. A negligible microstructural change was measured in gripping area compared to the gauge area (necking area) of crept sample. The laves phase formation was also noticed along the grain boundaries for creep exposure life of 3329.28 h.

  15. Microstructure-based assessment of creep rupture behaviour of cast-forged P91 steel

    International Nuclear Information System (INIS)

    Pandey, Chandan; Mahapatra, M.M.; Kumar, Pradeep; Vidyrathy, R.S.; Srivastava, A.

    2017-01-01

    The work presented in this study was performed with the intent to characterize the microstructure evolution for short term creep exposure of cast-forged P91 steel. The short-term creep test was performed at temperature range of 620–650 °C and stresses ranging from 120 to 200 MPa. To characterize the sample after creep exposure, field emission scanning electron microscopy (FESEM) with energy dispersive X-ray spectroscopy (EDS), optical microscope and micro-hardness testing were utilized. Creep tests were performed on round creep specimens. For low temperature service condition, longer creep life was obtained. The fracture surface of creep ruptured specimen were characterized by using the FESEM. The transgranular fracture mode was noticed in all the tests condition. The creep rupture life was found to be decreased with increase in applied stress. The maximum rupture life was measured about to be 3329.28 h for the sample exposed at 620 °C for 120 MPa. A negligible microstructural change was measured in gripping area compared to the gauge area (necking area) of crept sample. The laves phase formation was also noticed along the grain boundaries for creep exposure life of 3329.28 h.

  16. 77 FR 62396 - Annual Company-Run Stress Test Requirements for Banking Organizations With Total Consolidated...

    Science.gov (United States)

    2012-10-12

    ... minimum risk-based capital requirements.\\3\\ Stress testing is one tool that helps both bank supervisors... the FDIC and the OCC to help to ensure that the company-run stress testing regulations are consistent... purposes of the annual company-run stress tests so that the same set of scenarios can be used to conduct...

  17. Stress criteria for nuclear vessel concrete

    International Nuclear Information System (INIS)

    Costes, D.

    1975-01-01

    Concrete nuclear vessels are submitted to prestressing forces which limit tensile stresses in concrete when the vessel is under pressure with thermal gradients. Hence, the most severe conditions for concrete appear when the vessel is prestressed and not submitted to internal pressure. The triaxial states of stress in the concrete may be computed postulating elastic or other behavior and compared with safe limits obtained from rupture tests and fatigue tests. The first part of the paper, recalls experimental rupture results and the acceptability procedures currently used. Criteria founded on the lemniscoid surfaces are proposed, parameters for which are obtained by various tests and safety considerations. In the second part, rupture tests are reported on small, thick, cylindrical vessels submitted to external hydraulic pressure simulating prestressing forces. Materials used are plain concrete, microconcrete, marble and graphite. The strengths obtained are much higher than those which could be elastically computed, triaxial rupture states being provided by previous experiments. Such results may be due to a plastic stress redistribution before fracture and to stabilizing effects of stress gradients around the more stressed areas. Fatigue tests by external hydraulic loading are reported [fr

  18. Microscopic creep models and the interpretation of stress-dip tests during creep

    International Nuclear Information System (INIS)

    Poirier, J.P.

    1976-09-01

    A critical analysis is made of the principal divergent view points concerning stress-dip tests. The raw data are examined and interpreted in the light of various creep models. The following problems are discussed: is the reverse strain anelastic or plastic; is the zero creep rate periodic due to recovery or is it spurious; can the existence or inexistence of an internal stress be deduced from stress-dip tests; can stress-dip tests allow to determine whether glide is jerky or viscous; can the internal stress be measured by stress-dip tests

  19. Rupture, waves and earthquakes.

    Science.gov (United States)

    Uenishi, Koji

    2017-01-01

    Normally, an earthquake is considered as a phenomenon of wave energy radiation by rupture (fracture) of solid Earth. However, the physics of dynamic process around seismic sources, which may play a crucial role in the occurrence of earthquakes and generation of strong waves, has not been fully understood yet. Instead, much of former investigation in seismology evaluated earthquake characteristics in terms of kinematics that does not directly treat such dynamic aspects and usually excludes the influence of high-frequency wave components over 1 Hz. There are countless valuable research outcomes obtained through this kinematics-based approach, but "extraordinary" phenomena that are difficult to be explained by this conventional description have been found, for instance, on the occasion of the 1995 Hyogo-ken Nanbu, Japan, earthquake, and more detailed study on rupture and wave dynamics, namely, possible mechanical characteristics of (1) rupture development around seismic sources, (2) earthquake-induced structural failures and (3) wave interaction that connects rupture (1) and failures (2), would be indispensable.

  20. Simulating Earthquake Rupture and Off-Fault Fracture Response: Application to the Safety Assessment of the Swedish Nuclear Waste Repository

    KAUST Repository

    Falth, B.

    2014-12-09

    To assess the long-term safety of a deep repository of spent nuclear fuel, upper bound estimates of seismically induced secondary fracture shear displacements are needed. For this purpose, we analyze a model including an earthquake fault, which is surrounded by a number of smaller discontinuities representing fractures on which secondary displacements may be induced. Initial stresses are applied and a rupture is initiated at a predefined hypocenter and propagated at a specified rupture speed. During rupture we monitor shear displacements taking place on the nearby fracture planes in response to static as well as dynamic effects. As a numerical tool, we use the 3Dimensional Distinct Element Code (3DEC) because it has the capability to handle numerous discontinuities with different orientations and at different locations simultaneously. In tests performed to benchmark the capability of our method to generate and propagate seismic waves, 3DEC generates results in good agreement with results from both Stokes solution and the Compsyn code package. In a preliminary application of our method to the nuclear waste repository site at Forsmark, southern Sweden, we assume end-glacial stress conditions and rupture on a shallow, gently dipping, highly prestressed fault with low residual strength. The rupture generates nearly complete stress drop and an M-w 5.6 event on the 12 km(2) rupture area. Of the 1584 secondary fractures (150 m radius), with a wide range of orientations and locations relative to the fault, a majority move less than 5 mm. The maximum shear displacement is some tens of millimeters at 200 m fault-fracture distance.

  1. Improved Accelerated Stress Tests Based on Fuel Cell Vehicle Data

    Energy Technology Data Exchange (ETDEWEB)

    Patterson, Timothy [Research Engineer; Motupally, Sathya [Research Engineer

    2012-06-01

    UTC will led a top-tier team of industry and national laboratory participants to update and improve DOE’s Accelerated Stress Tests (AST’s) for hydrogen fuel cells. This in-depth investigation will focused on critical fuel cell components (e.g. membrane electrode assemblies - MEA) whose durability represented barriers for widespread commercialization of hydrogen fuel cell technology. UTC had access to MEA materials that had accrued significant load time under real-world conditions in PureMotion® 120 power plant used in transit buses. These materials are referred to as end-of-life (EOL) components in the rest of this document. Advanced characterization techniques were used to evaluate degradation mode progress using these critical cell components extracted from both bus power plants and corresponding materials tested using the DOE AST’s. These techniques were applied to samples at beginning-of-life (BOL) to serve as a baseline. These comparisons advised the progress of the various failure modes that these critical components were subjected to, such as membrane degradation, catalyst support corrosion, platinum group metal dissolution, and others. Gaps in the existing ASTs predicted the degradation observed in the field in terms of these modes were outlined. Using the gaps, new AST’s were recommended and tested to better reflect the degradation modes seen in field operation. Also, BOL components were degraded in a test vehicle at UTC designed to accelerate the bus field operation.

  2. HammerCloud: A Stress Testing System for Distributed Analysis

    CERN Document Server

    van der Ster, Daniel C; Ubeda Garcia, Mario; Paladin, Massimo

    2011-01-01

    Distributed analysis of LHC data is an I/O-intensive activity which places large demands on the internal network, storage, and local disks at remote computing facilities. Commissioning and maintaining a site to provide an efficient distributed analysis service is therefore a challenge which can be aided by tools to help evaluate a variety of infrastructure designs and configurations. HammerCloud (HC) is one such tool; it is a stress testing service which is used by central operations teams, regional coordinators, and local site admins to (a) submit arbitrary number of analysis jobs to a number of sites, (b) maintain at a steady-state a predefined number of jobs running at the sites under test, (c) produce web-based reports summarizing the efficiency and performance of the sites under test, and (d) present a web-interface for historical test results to both evaluate progress and compare sites. HC was built around the distributed analysis framework Ganga, exploiting its API for grid job management. HC has been ...

  3. Failure analysis on a ruptured petrochemical pipe

    Energy Technology Data Exchange (ETDEWEB)

    Harun, Mohd [Industrial Technology Division, Malaysian Nuclear Agency, Ministry of Science, Technology and Innovation Malaysia, Bangi, Kajang, Selangor (Malaysia); Shamsudin, Shaiful Rizam; Kamardin, A. [Univ. Malaysia Perlis, Jejawi, Arau (Malaysia). School of Materials Engineering

    2010-08-15

    The failure took place on a welded elbow pipe which exhibited a catastrophic transverse rupture. The failure was located on the welding HAZ region, parallel to the welding path. Branching cracks were detected at the edge of the rupture area. Deposits of corrosion products were also spotted. The optical microscope analysis showed the presence of transgranular failures which were related to the stress corrosion cracking (SCC) and were predominantly caused by the welding residual stress. The significant difference in hardness between the welded area and the pipe confirmed the findings. Moreover, the failure was also caused by the low Mo content in the stainless steel pipe which was detected by means of spark emission spectrometer. (orig.)

  4. Multi-Fault Rupture Scenarios in the Brawley Seismic Zone

    Science.gov (United States)

    Kyriakopoulos, C.; Oglesby, D. D.; Rockwell, T. K.; Meltzner, A. J.; Barall, M.

    2017-12-01

    Dynamic rupture complexity is strongly affected by both the geometric configuration of a network of faults and pre-stress conditions. Between those two, the geometric configuration is more likely to be anticipated prior to an event. An important factor in the unpredictability of the final rupture pattern of a group of faults is the time-dependent interaction between them. Dynamic rupture models provide a means to investigate this otherwise inscrutable processes. The Brawley Seismic Zone in Southern California is an area in which this approach might be important for inferring potential earthquake sizes and rupture patterns. Dynamic modeling can illuminate how the main faults in this area, the Southern San Andreas (SSAF) and Imperial faults, might interact with the intersecting cross faults, and how the cross faults may modulate rupture on the main faults. We perform 3D finite element modeling of potential earthquakes in this zone assuming an extended array of faults (Figure). Our results include a wide range of ruptures and fault behaviors depending on assumptions about nucleation location, geometric setup, pre-stress conditions, and locking depth. For example, in the majority of our models the cross faults do not strongly participate in the rupture process, giving the impression that they are not typically an aid or an obstacle to the rupture propagation. However, in some cases, particularly when rupture proceeds slowly on the main faults, the cross faults indeed can participate with significant slip, and can even cause rupture termination on one of the main faults. Furthermore, in a complex network of faults we should not preclude the possibility of a large event nucleating on a smaller fault (e.g. a cross fault) and eventually promoting rupture on the main structure. Recent examples include the 2010 Mw 7.1 Darfield (New Zealand) and Mw 7.2 El Mayor-Cucapah (Mexico) earthquakes, where rupture started on a smaller adjacent segment and later cascaded into a larger

  5. Effect of some thermomechanical variables on plastic flow and creep-rupture of type 304 stainless steel at 5930C

    International Nuclear Information System (INIS)

    Swindeman, R.W.

    1977-01-01

    As part of an effort to examine sources of variability in the creep-rupture behavior of type 304 stainless steel, specimens subjected to a variety of prior thermomechanical treatments were tested. Included were different reannealing temperatures, cooling rates, types of prior straining, and a 24-hr age at 816 0 C. Two product forms of a single heat (heat 9T2796) were involved, and most testing was at 593 0 C. For material with coarse grain size, reannealing temperature had no pronounced influence. However, slow cooling rates and the 816 0 C aging significantly extended the rupture life. On the other hand, cold working by an equivalent of 4% tensile strain had very little influence on rupture life. Slow cooling or aging increased rupture life as a result of greatly improved creep ductility. This finding is consistent with similar observations in the literature for this and other stainless steels, and is believed to be due to the development of coarse, beneficial carbides on grain boundaries before stressing. The creep response in the primary and secondary stages was influenced by nearly all the thermomechanical treatments, but the variability in the response at relatively high stresses was scarcely greater than the variability observed in multiple tests on specimens having a common thermomechanical history. 10 figures, 1 table

  6. Welded rupture disc assemblies for use in Tritium Research Laboratory

    International Nuclear Information System (INIS)

    Faltings, R.E.

    1976-01-01

    Welded rupture disc assemblies were investigated and developed in various ranges for probable use by experimenters in their activities in the Tritium Research Laboratory at Sandia Laboratories, Livermore. This study indicates that currently welded rupture disc assemblies with appropriate testing and installation by certified pressure installers may be used in pressure systems in the Tritium Research Laboratory and other areas at SLL

  7. The Danish anal sphincter rupture questionnaire: Validity and reliability

    DEFF Research Database (Denmark)

    Due, Ulla; Ottesen, Marianne

    2008-01-01

    Objective. To revise, validate and test for reliability an anal sphincter rupture questionnaire in relation to construct, content and face validity. Setting and background. Since 1996 women with anal sphincter rupture (ASR) at one of the public university hospitals in Copenhagen, Denmark have bee...

  8. Crystal plastic earthquakes in dolostones: from slow to fast ruptures.

    Science.gov (United States)

    Passelegue, F. X.; Aubry, J.; Nicolas, A.; Fondriest, M.; Schubnel, A.; Di Toro, G.

    2017-12-01

    Dolostone is the most dominant lithology of the seismogenic upper crust around the Mediterranean Sea. Understanding the internal mechanisms controlling fault friction is crucial for understanding seismicity along active faults. Displacement in such fault zones is frequently highlighted by highly reflective (mirror-like) slip surfaces, created by thin films of nanogranular fault rock. Using saw-cut dolostone samples coming from natural fault zones, we conducted stick-slip experiments under triaxial loading conditions at 30, 60 and 90 MPa confining pressure and temperature ranging from 30 to 100 degrees C. At 30 and 65 degrees C, only slow rupture was observed and the experimental fault exhibits frictional behaviour, i.e. a dependence of normal stress on peak shear stress. At 65 degrees C, a strengthening behaviour is observed after the main rupture, leading to a succession of slow rupture. At 100 degrees C, the macroscopic behaviour of the fault becomes ductile, and no dependence of pressure on the peak shear stress is observed. In addition, the increase of the confining pressure up to 60 and 90 MPa allow the transition from slow to fast rupture, highlighted by the records of acoustic activity and by dynamic stress drop occurring in a few tens of microseconds. Using strain gages located along the fault surface and acoustic transducers, we were able to measure the rupture velocities during slow and fast rupture. Slow ruptures propagated around 0.1 m/s, in agreement with natural observations. Fast ruptures propagated up to supershear velocities, i.e. faster than the shear wave speed (>3500 m/s). A complete study of the microstructures was realized before and after ruptures. Slow ruptures lead to the production of mirror-like surface driven by the production of nanograins due to dislocation processes. Fast ruptures induce the production of amorphous material along the fault surface, which may come from decarbonation and melting processes. We demonstrate that the

  9. Creep rupture behavior of welded Grade 91 steel

    Energy Technology Data Exchange (ETDEWEB)

    Shrestha, Triratna [Department of Chemical and Materials Engineering, University of Idaho, Moscow, ID 83844 (United States); Basirat, Mehdi [Department of Mechanical Engineering, University of Idaho, Moscow, ID 83844 (United States); Alsagabi, Sultan; Sittiho, Anumat [Department of Chemical and Materials Engineering, University of Idaho, Moscow, ID 83844 (United States); Charit, Indrajit, E-mail: icharit@uidaho.edu [Department of Chemical and Materials Engineering, University of Idaho, Moscow, ID 83844 (United States); Potirniche, Gabriel P. [Department of Mechanical Engineering, University of Idaho, Moscow, ID 83844 (United States)

    2016-07-04

    Creep rupture behavior of fusion welded Grade 91 steel was studied in the temperature range of 600 – 700 °C and at stresses of 50–200 MPa. The creep data were analyzed in terms of the Monkman-Grant relation and Larson-Miller parameter. The creep damage tolerance factor was used to identify the origin of creep damage. The creep damage was identified as the void growth in combination with microstructural degradation. The fracture surface morphology of the ruptured specimens was studied by scanning electron microscopy and deformed microstructure examined by transmission electron microscopy, to further elucidate the rupture mechanisms.

  10. Principal modes of rupture encountered in expertise of advanced components

    International Nuclear Information System (INIS)

    Tavassoli, A.A.; Bougault, A.

    1986-10-01

    Failure of many metallic components investigated can be classified into two categories: intergranular or transgranular according to their principal mode of rupture. Intergranular ruptures are often provoked by segregation of impurities at the grain boundaries. Three examples are cited where this phenomenon occured, one of them is a steel (A 508 cl 3) used for PWR vessel. Intergranular failures are in general induced by fatigue in the advanced components operating under thermal or load transients. One example concerning a sodium mixer which was subjected to thermal loadings is presented. Examples of stress corrosion and intergranular sensitization failures are cited. These examples show the importance of fractography for the determination of rupture causes [fr

  11. Stress Tests Worldwide - IAEA Nuclear Safety Action Plan

    International Nuclear Information System (INIS)

    Lyons, J.E.

    2012-01-01

    The IAEA nuclear safety action plan relies on 11 important issues. 1) Safety assessments in light of the Fukushima accident: the IAEA secretariat will develop a methodology for stress tests against specific extreme natural hazards and will provide assistance for their implementation; 2) Strengthen existing IAEA peer reviews; 3) Emergency preparedness and response; 4) National Regulatory bodies in terms of independence and adequacy of human and financial resources; 5) The development of safety culture and scientific and technical capacity in Operating Organizations; 6) The upgrading of IAEA safety standards in a more efficient way; 7) A better implementation of relevant conventions concerning nuclear safety and nuclear accidents; 8) To provide a broad assistance on safety standard for countries embarking on a nuclear power program; 9) To facilitate the use of available information, expertise and techniques concerning radiation protection; 10) To enhance the transparency of nuclear industry; and 11) To promote the cooperation between member states in nuclear safety. (A.C.)

  12. The transition of dynamic rupture styles in elastic media under velocity-weakening friction

    KAUST Repository

    Gabriel, A.-A.; Ampuero, J.-P.; Dalguer, L. A.; Mai, Paul Martin

    2012-01-01

    Although kinematic earthquake source inversions show dominantly pulse-like subshear rupture behavior, seismological observations, laboratory experiments and theoretical models indicate that earthquakes can operate with different rupture styles: either as pulses or cracks, that propagate at subshear or supershear speeds. The determination of rupture style and speed has important implications for ground motions and may inform about the state of stress and strength of active fault zones. We conduct 2D in-plane dynamic rupture simulations with a spectral element method to investigate the diversity of rupture styles on faults governed by velocity-and-state-dependent friction with dramatic velocity-weakening at high slip rate. Our rupture models are governed by uniform initial stresses, and are artificially initiated. We identify the conditions that lead to different rupture styles by investigating the transitions between decaying, steady state and growing pulses, cracks, sub-shear and super-shear ruptures as a function of background stress, nucleation size and characteristic velocity at the onset of severe weakening. Our models show that small changes of background stress or nucleation size may lead to dramatic changes of rupture style. We characterize the asymptotic properties of steady state and self-similar pulses as a function of background stress. We show that an earthquake may not be restricted to a single rupture style, but that complex rupture patterns may emerge that consist of multiple rupture fronts, possibly involving different styles and back-propagating fronts. We also demonstrate the possibility of a super-shear transition for pulse-like ruptures. Finally, we draw connections between our findings and recent seismological observations.

  13. The transition of dynamic rupture styles in elastic media under velocity-weakening friction

    KAUST Repository

    Gabriel, A.-A.

    2012-09-01

    Although kinematic earthquake source inversions show dominantly pulse-like subshear rupture behavior, seismological observations, laboratory experiments and theoretical models indicate that earthquakes can operate with different rupture styles: either as pulses or cracks, that propagate at subshear or supershear speeds. The determination of rupture style and speed has important implications for ground motions and may inform about the state of stress and strength of active fault zones. We conduct 2D in-plane dynamic rupture simulations with a spectral element method to investigate the diversity of rupture styles on faults governed by velocity-and-state-dependent friction with dramatic velocity-weakening at high slip rate. Our rupture models are governed by uniform initial stresses, and are artificially initiated. We identify the conditions that lead to different rupture styles by investigating the transitions between decaying, steady state and growing pulses, cracks, sub-shear and super-shear ruptures as a function of background stress, nucleation size and characteristic velocity at the onset of severe weakening. Our models show that small changes of background stress or nucleation size may lead to dramatic changes of rupture style. We characterize the asymptotic properties of steady state and self-similar pulses as a function of background stress. We show that an earthquake may not be restricted to a single rupture style, but that complex rupture patterns may emerge that consist of multiple rupture fronts, possibly involving different styles and back-propagating fronts. We also demonstrate the possibility of a super-shear transition for pulse-like ruptures. Finally, we draw connections between our findings and recent seismological observations.

  14. Experimental and numerical studies of the effect of plasticity mechanisms on the brittle rupture by cleavage in low alloy steels; Etudes experimentale et numerique de l'effet des mecanismes de plasticite sur la rupture fragile par clivage dans les aciers faiblement allies

    Energy Technology Data Exchange (ETDEWEB)

    Libert, M

    2007-09-15

    It is indispensable to guarantee the integrity of PWR reactor vessels during an accidental running: in this context, the understanding and the modelling of the mechanisms of brittle rupture of steels are decisive elements of the complicated estimation of the service life of reactor vessels. The models of local approach of rupture by cleavage are one of the main tools of anticipation of the tensile strength of low alloy steels. In this work, the effect of the stresses heterogeneities in a local criteria of initiation of cleavage has been taken into account. The results of the microstructure calculations are used for proposing a statistical description of the local stresses distribution evolution. This statistical approach allows to propose a local approach model of the rupture depending both of the mechanical heterogeneities and of the sizes distributions of the defects. The behaviour of the material and its evolution are characterized at the microscopic and macroscopic scales in the temperature range [25 C, -196 C]. Simple tensile tests, velocity and temperature rises tests and toughness tests have been carried out. A micro-mechanical behaviour model describing the plastic behaviour below the transition temperature T{sub a} has been proposed. The behaviour law is based on the deformation mechanisms described in bibliography and identified by an inverse method from mechanical tests. The TEM observations and the characterization of the behaviour thermally activated allow to determine several parameters of the model. Simulations are carried out in order to model the main stress distributions {sigma}{sub 1} in two bainite microstructures corresponding to the elementary volume of the local approach of the rupture. The temperature and the triaxiality effects on the evolutions of the heterogeneities is characterized. A distribution function describing the distribution of the local values of {sigma}{sub 1} in terms of the main and equivalent mean stresses {sigma}{sub 1

  15. Experimental and numerical studies of the effect of plasticity mechanisms on the brittle rupture by cleavage in low alloy steels; Etudes experimentale et numerique de l'effet des mecanismes de plasticite sur la rupture fragile par clivage dans les aciers faiblement allies

    Energy Technology Data Exchange (ETDEWEB)

    Libert, M

    2007-09-15

    It is indispensable to guarantee the integrity of PWR reactor vessels during an accidental running: in this context, the understanding and the modelling of the mechanisms of brittle rupture of steels are decisive elements of the complicated estimation of the service life of reactor vessels. The models of local approach of rupture by cleavage are one of the main tools of anticipation of the tensile strength of low alloy steels. In this work, the effect of the stresses heterogeneities in a local criteria of initiation of cleavage has been taken into account. The results of the microstructure calculations are used for proposing a statistical description of the local stresses distribution evolution. This statistical approach allows to propose a local approach model of the rupture depending both of the mechanical heterogeneities and of the sizes distributions of the defects. The behaviour of the material and its evolution are characterized at the microscopic and macroscopic scales in the temperature range [25 C, -196 C]. Simple tensile tests, velocity and temperature rises tests and toughness tests have been carried out. A micro-mechanical behaviour model describing the plastic behaviour below the transition temperature T{sub a} has been proposed. The behaviour law is based on the deformation mechanisms described in bibliography and identified by an inverse method from mechanical tests. The TEM observations and the characterization of the behaviour thermally activated allow to determine several parameters of the model. Simulations are carried out in order to model the main stress distributions {sigma}{sub 1} in two bainite microstructures corresponding to the elementary volume of the local approach of the rupture. The temperature and the triaxiality effects on the evolutions of the heterogeneities is characterized. A distribution function describing the distribution of the local values of {sigma}{sub 1} in terms of the main and equivalent mean stresses {sigma}{sub 1

  16. Double rupture disc experience

    International Nuclear Information System (INIS)

    1979-01-01

    Result of these observations, comparisons and evaluations can be summarized in the following list of concerns regarding the use of double rupture discs coupled to the liquid space of a steam generator that is subjected to a large leak sodium water reaction event. Single rupture disc show delayed collapse characteristics in LLTR Series I and double disc assemblies are presumed to be more complex with additional delay before opening to give pressure relief. Delayed failure increases pressures in the IHTS and must be adequately covered by design requirements. With CRBR design, the first disc may fail only partially reducing the loading on the second disc with the result that relief performance may not meet requirements

  17. Diagnosis of foetal membrane ruptures: Placental alpha ...

    African Journals Online (AJOL)

    Context: Pre‑labour rupture of membranes (PROM) is a common obstetric complication which presents a diagnostic challenge, especially in equivocal ... problematic with the need to balance the risk of prematurity with that of prolonged ... array of rapid, minimally invasive tests based on biochemical markers in amniotic fluid ...

  18. Methods and Models of Market Risk Stress-Testing of the Portfolio of Financial Instruments

    Directory of Open Access Journals (Sweden)

    Alexander M. Karminsky

    2015-01-01

    Full Text Available Amid instability of financial markets and macroeconomic situation the necessity of improving bank risk-management instrument arises. New economic reality defines the need for searching for more advanced approaches of estimating banks vulnerability to exceptional, but plausible events. Stress-testing belongs to such instruments. The paper reviews and compares the models of market risk stress-testing of the portfolio of different financial instruments. These days the topic of the paper is highly acute due to the fact that now stress-testing is becoming an integral part of anticrisis risk-management amid macroeconomic instability and appearance of new risks together with close interest to the problem of risk-aggregation. The paper outlines the notion of stress-testing and gives coverage of goals, functions of stress-tests and main criteria for market risk stress-testing classification. The paper also stresses special aspects of scenario analysis. Novelty of the research is explained by elaborating the programme of aggregated complex multifactor stress-testing of the portfolio risk based on scenario analysis. The paper highlights modern Russian and foreign models of stress-testing both on solo-basis and complex. The paper lays emphasis on the results of stress-testing and revaluations of positions for all three complex models: methodology of the Central Bank of stress-testing portfolio risk, model relying on correlations analysis and copula model. The models of stress-testing on solo-basis are different for each financial instrument. Parametric StressVaR model is applicable to shares and options stress-testing;model based on "Grek" indicators is used for options; for euroobligation regional factor model is used. Finally some theoretical recommendations about managing market risk of the portfolio are given.

  19. Impulsivity and Stress Response in Pathological Gamblers During the Trier Social Stress Test.

    Science.gov (United States)

    Maniaci, G; Goudriaan, A E; Cannizzaro, C; van Holst, R J

    2018-03-01

    Gambling has been associated with increased sympathetic nervous system output and stimulation of the hypothalamic-pituitary-adrenal axis. However it is unclear how these systems are affected in pathological gambling. This study aimed to investigate the effect of the Trier Social Stress Test (TSST) on cortisol and on cardiac interbeat intervals in relation to impulsivity, in a sample of male pathological gamblers compared to healthy controls. In addition, we investigated the correlation between the TSST, duration of the disorder and impulsivity. A total of 35 pathological gamblers and 30 healthy controls, ranging from 19 to 58 years old and all male, participated in this study. Stress response was measured during and after the TSST by salivary cortisol and cardiac interbeat intervals; impulsivity was assessed with the Barratt Impulsiveness Scale (BIS-11). Exposure to the TSST produced a significant increase in salivary cortisol and interbeat intervals in both groups, without differences between groups. We found a negative correlation between baseline cortisol and duration of pathological gambling indicating that the longer the duration of the disorder the lower the baseline cortisol levels. Additionally, we found a main effect of impulsivity across groups on interbeat interval during the TSST, indicating an association between impulsivity and the intensity of the neurovegetative stress response during the TSST. Involvement of the hypothalamic-pituitary-adrenal axis in pathological gambling was confirmed together with evidence of a correlation between length of the disorder and diminished baseline cortisol levels. Impulsivity emerged as a personality trait expressed by pathological gamblers; however the neurovegetative response to the TSST, although associated with impulsivity, appeared to be independent of the presence of pathological gambling.

  20. Rupture directivity and slip distribution of the M 4.3 foreshock to the 1992 Joshua Tree earthquake, Southern California

    Science.gov (United States)

    Mori, J.

    1996-01-01

    Details of the M 4.3 foreshock to the Joshua Tree earthquake were studied using P waves recorded on the Southern California Seismic Network and the Anza network. Deconvolution, using an M 2.4 event as an empirical Green's function, corrected for complicated path and site effects in the seismograms and produced simple far-field displacement pulses that were inverted for a slip distribution. Both possible fault planes, north-south and east-west, for the focal mechanism were tested by a least-squares inversion procedure with a range of rupture velocities. The results showed that the foreshock ruptured the north-south plane, similar to the mainshock. The foreshock initiated a few hundred meters south of the mainshock and ruptured to the north, toward the mainshock hypocenter. The mainshock (M 6.1) initiated near the northern edge of the foreshock rupture 2 hr later. The foreshock had a high stress drop (320 to 800 bars) and broke a small portion of the fault adjacent to the mainshock but was not able to immediately initiate the mainshock rupture.

  1. Investigation programme and procedure for creep and long-term rupture strength in materials with accounting for stress deviator and loading history

    International Nuclear Information System (INIS)

    Mozharovskaya, T.N.

    1984-01-01

    A programme and procedure are given to study 08Kh18N9 steel at 600 deg C and 15Kh2MFA steel at 550 deg C for creep and long-term strength at different parameters of proportional loading as well as at different parameters under loading in two-link irregular trajectories. This makes it possible to estimate the effect of the kind of a stress deviator, history and prehistory of loading on plastic deformation in creep and on failure under long-term loading

  2. Investigation programme and procedure for creep and long-term rupture strength in materials with accounting for stress deviator and loading history

    Energy Technology Data Exchange (ETDEWEB)

    Mozharovskaya, T N [AN Ukrainskoj SSR, Kiev. Inst. Problem Prochnosti

    1984-11-01

    A programme and procedure are given to study 08Kh18N9 steel at 600 deg C and 15Kh2MFA steel at 550 deg C for creep and long-term strength at different parameters of proportional loading as well as at different parameters under loading in two-link irregular trajectories. This makes it possible to estimate the effect of the kind of a stress deviator, history and prehistory of loading on plastic deformation in creep and on failure under long-term loading.

  3. Creep-Fatigue Life Design with Various Stress and Temperature Conditions on the Basis of Lethargy Coefficient

    International Nuclear Information System (INIS)

    Park, Jung Eun; Yang, Sung Mo; Han, Jae Hee; Yu, Hyo Sun

    2011-01-01

    High temperature and stress are encounted in power plants and vehicle engines. Therefore, determination of the creep-fatigue life of a material is necessary prior to fabricating equipment. In this study, life design was determined on the basis of the lethargy coefficient for different temperatures, stress and rupture times. SP-Creep test data was compared with computed data. The SP-Creep test was performed to obtain the rupture time for X20CrMoV121 steel. The integration life equation was considered for three cases with various load, temperature and load-temperature. First, the lethargy coefficient was calculated by using the obtained rupture stress and the rupture time that were determined by carrying out the SP-Creep test. Next, life was predicted on the basis of the temperature condition. Finally, it was observed that life decreases considerably due to the coupling effect that results when fatigue and creep occur simultaneously

  4. Mathematical modeling and numerical simulation of unilateral dynamic rupture propagation along very-long reverse faults

    Science.gov (United States)

    Hirano, S.

    2017-12-01

    For some great earthquakes, dynamic rupture propagates unilaterally along a horizontal direction of very-long reverse faults (e.g., the Mw9.1 Sumatra earthquake in 2004, the Mw8.0 Wenchuan earthquake in 2008, and the Mw8.8 Maule earthquake in 2010, etc.). It seems that barriers or creeping sections may not lay along the opposite region of the co-seismically ruptured direction. In fact, in the case of Sumatra, the Mw8.6 earthquake occurred in the opposite region only three months after the mainshock. Mechanism of unilateral mode-II rupture along a material interface has been investigated theoretically and numerically. For mode-II rupture propagating along a material interface, an analytical solution implies that co-seismic stress perturbation depends on the rupture direction (Weertman, 1980 JGR; Hirano & Yamashita, 2016 BSSA), and numerical modeling of plastic yielding contributes to simulating the unilateral rupture (DeDonteny et al., 2011 JGR). However, mode-III rupture may dominate for the very-long reverse faults, and it can be shown that stress perturbation due to mode-III rupture does not depend on the rupture direction. Hence, an effect of the material interface is insufficient to understand the mechanism of unilateral rupture along the very-long reverse faults. In this study, I consider a two-dimensional bimaterial system with interfacial dynamic mode-III rupture under an obliquely pre-stressed configuration (i.e., the maximum shear direction of the background stress is inclined from the interfacial fault). First, I derived an analytical solution of regularized elastic stress field around a steady-state interfacial slip pulse using the method of Rice et al. (2005 BSSA). Then I found that the total stress, which is the sum of the background stress and co-seismic stress perturbation, depends on the rupture direction even in the mode-III case. Second, I executed a finite difference numerical simulation with a plastic yielding model of Andrews (1978 JGR; 2005

  5. Using the 2011 Mw9.0 Tohoku earthquake to test the Coulomb stress triggering hypothesis and to calculate faults brought closer to failure

    Science.gov (United States)

    Toda, Shinji; Lin, Jian; Stein, Ross S.

    2011-01-01

    The 11 March 2011 Tohoku Earthquake provides an unprecedented test of the extent to which Coulomb stress transfer governs the triggering of aftershocks. During 11-31 March, there were 177 aftershocks with focal mechanisms, and so the Coulomb stress change imparted by the rupture can be resolved on the aftershock nodal planes to learn whether they were brought closer to failure. Numerous source models for the mainshock have been inverted from seismic, geodetic, and tsunami observations. Here, we show that, among six tested source models, there is a mean 47% gain in positively-stressed aftershock mechanisms over that for the background (1997-10 March 2011) earthquakes, which serve as the control group. An aftershock fault friction of 0.4 is found to fit the data better than 0.0 or 0.8, and among all the tested models, Wei and Sladen (2011) produced the largest gain, 63%. We also calculate that at least 5 of the seven large, exotic, or remote aftershocks were brought ≥0.3 bars closer to failure. With these tests as confirmation, we calculate that large sections of the Japan trench megathrust, the outer trench slope normal faults, the Kanto fragment beneath Tokyo, and the Itoigawa-Shizuoka Tectonic Line, were also brought ≥0.3 bars closer to failure.

  6. Rupture Dynamics and Ground Motion from Earthquakes in Heterogeneous Media

    Science.gov (United States)

    Bydlon, S.; Dunham, E. M.; Kozdon, J. E.

    2012-12-01

    Heterogeneities in the material properties of Earth's crust scatter propagating seismic waves. The effects of scattered waves are reflected in the seismic coda and depend on the relative strength of the heterogeneities, spatial arrangement, and distance from source to receiver. In the vicinity of the fault, scattered waves influence the rupture process by introducing fluctuations in the stresses driving propagating ruptures. Further variability in the rupture process is introduced by naturally occurring geometric complexity of fault surfaces, and the stress changes that accompany slip on rough surfaces. We have begun a modeling effort to better understand the origin of complexity in the earthquake source process, and to quantify the relative importance of source complexity and scattering along the propagation path in causing incoherence of high frequency ground motion. To do this we extended our two-dimensional high order finite difference rupture dynamics code to accommodate material heterogeneities. We generate synthetic heterogeneous media using Von Karman correlation functions and their associated power spectral density functions. We then nucleate ruptures on either flat or rough faults, which obey strongly rate-weakening friction laws. Preliminary results for flat faults with uniform frictional properties and initial stresses indicate that off-fault material heterogeneity alone can lead to a complex rupture process. Our simulations reveal the excitation of high frequency bursts of waves, which radiate energy away from the propagating rupture. The average rupture velocity is thus reduced relative to its value in simulations employing homogeneous material properties. In the coming months, we aim to more fully explore parameter space by varying the correlation length, Hurst exponent, and amplitude of medium heterogeneities, as well as the statistical properties characterizing fault roughness.

  7. Influence of mechanical stress level in preliminary stress-corrosion testing on fatigue strength of a low-carbon steel

    International Nuclear Information System (INIS)

    Aleskerova, S.A.; Pakharyan, V.A.

    1978-01-01

    Effect of corrosion and mechanical factors of preliminary stress corrosion of a metal in its fatigue strength, has been investigated. Smooth cylindrical samples of 20 steel have been tested. Preliminary corrosion under stress has been carried out under natural sea conditions. It is shown that mechanical stresses in the case of preliminary corrosion affect fatigue strength of low-carbon steels, decreasing the range of limited durability and fatigue limit. This effect increases with the increase of stress level and agressivity of corrosive medium

  8. Validation of the German version of the Ford Insomnia Response to Stress Test.

    Science.gov (United States)

    Dieck, Arne; Helbig, Susanne; Drake, Christopher L; Backhaus, Jutta

    2018-06-01

    The purpose of this study was to assess the psychometric properties of a German version of the Ford Insomnia Response to Stress Test with groups with and without sleep problems. Three studies were analysed. Data set 1 was based on an initial screening for a sleep training program (n = 393), data set 2 was based on a study to test the test-retest reliability of the Ford Insomnia Response to Stress Test (n = 284) and data set 3 was based on a study to examine the influence of competitive sport on sleep (n = 37). Data sets 1 and 2 were used to test internal consistency, factor structure, convergent validity, discriminant validity and test-retest reliability of the Ford Insomnia Response to Stress Test. Content validity was tested using data set 3. Cronbach's alpha of the Ford Insomnia Response to Stress Test was good (α = 0.80) and test-retest reliability was satisfactory (r = 0.72). Overall, the one-factor model showed the best fit. Furthermore, significant positive correlations between the Ford Insomnia Response to Stress Test and impaired sleep quality, depression and stress reactivity were in line with the expectations regarding the convergent validity. Subjects with sleep problems had significantly higher scores in the Ford Insomnia Response to Stress Test than subjects without sleep problems (P Stress Test had significantly lower sleep quality (P = 0.01), demonstrating that vulnerability for stress-induced sleep disturbances accompanies poorer sleep quality in stressful episodes. The findings show that the German version of the Ford Insomnia Response to Stress Test is a reliable and valid questionnaire to assess the vulnerability to stress-induced sleep disturbances. © 2017 European Sleep Research Society.

  9. A novel method for estimating soil precompression stress from uniaxial confined compression tests

    DEFF Research Database (Denmark)

    Lamandé, Mathieu; Schjønning, Per; Labouriau, Rodrigo

    2017-01-01

    . Stress-strain curves were obtained by performing uniaxial, confined compression tests on undisturbed soil cores for three soil types at three soil water potentials. The new method performed better than the Gompertz fitting method in estimating precompression stress. The values of precompression stress...... obtained from the new method were linearly related to the maximum stress experienced by the soil samples prior to the uniaxial, confined compression test at each soil condition with a slope close to 1. Precompression stress determined with the new method was not related to soil type or dry bulk density......The concept of precompression stress is used for estimating soil strength of relevance to fieldtraffic. It represents the maximum stress experienced by the soil. The most recently developed fitting method to estimate precompression stress (Gompertz) is based on the assumption of an S-shape stress...

  10. Type A behavior and the thallium stress test

    International Nuclear Information System (INIS)

    Kahn, J.P.; Kornfeld, D.S.; Blood, D.K.; Lynn, R.B.; Heller, S.S.; Frank, K.A.

    1982-01-01

    Several recent studies have examined the association between Type A personality and coronary artery disease (CAD) by coronary angiography. Most of these studies have reported a significant association. The present study is an attempt at further confirmation, using a new non-invasive technique for measuring CAD. Subjects were 53 patients undergoing routine exercise stress tests with concomitant thallium-201 myocardial perfusion studies. Five aspects of Type A behavior were assessed by the use of the Rosenman-Friedman Semistructured Interview, and each was rated on a three-point scale. Severity of CAD was independently estimated on a four-point scale. Pearson correlation coefficients were separately computed for patients with and without reported history of myocardial infarction (MI). For 37 patients without reported MI, CAD severity was significantly correlated with Overall Type A (r . -0.53), Vocal Characteristics (r . -0.53), Job Involvement (r . -0.36) and Aggressiveness (r . -0.48), but not Time Urgency (r . -0.25). For 16 patients with reported MI, CAD severity was significantly correlated with Job Involvement only (r . +0.49). The data are consistent with the association of Type A personality and coronary atherogenesis, but may also reflect Type A psychological and physiological characteristics. Future studies may be able to examine these and other aspects of Type A behavior using this noninvasive technique in more diverse patient populations

  11. Results of stress tests of European nuclear power plants after the Fukushima-Daiichi accident

    International Nuclear Information System (INIS)

    Kovacs, Zoltan; Novakova, Helena

    2012-01-01

    In response to the Fukushima-Daiichi accident, the European Council laid down the requirement that a transparent and comprehensive risk assessment exercise ('stress tests') be carried out at each European nuclear power plant. The stress tests concentrated on the nuclear power plants' safety margins in the light of the lessons learned from the accident. The reviews focused on natural external events including earthquake, tsunami and extreme weather, loss of safety functions, and severe accident management. The stress test procedure comprised 3 steps: (i) The nuclear facility operators performed the stress tests and prepared proposals for safety improvements. (ii) The national regulators performed independent reviews of the stress tests and prepared national reports. (iii) The reports submitted by the national regulators were subjected to review at a European level. The article describes the scope of the stress tests and their results, verified at the European level. (orig.)

  12. An introduction to the 'Psycho-Physiological-Stress-Test' (PPST-A standardized instrument for evaluating stress reactions.

    Directory of Open Access Journals (Sweden)

    Elisabeth Neureiter

    Full Text Available Using a standardized instrument to evaluate patients' stress reactions has become more important in daily clinical routines. Different signs or symptoms of stress are often unilaterally explored: the physiological, psychological or social aspects of stress disorders are each viewed on a single dimension. However, all dimensions afflict patients who have persistent health problems due to chronic stress. Therefore, it is important to use a multidimensional approach to acquire data. The 'Psycho-Physiological-Stress-Test' (PPST was established to achieve a comprehensive understanding of stress and was further developed at the Charité-Universitätsmedizin Berlin in collaboration with the Psychological Department of Freie Universität Berlin. The PPST includes a series of varying stress phases, embedded in two periods of rest. Physiological and psychological parameters are simultaneously measured throughout the test session. Specifically, the PPST activates the sympathetic stress axis, which is measured by heart rate, blood pressure, respiration depth and rate, electro dermal activation and muscle tension (frontalis, masseter, trapezius. Psychological data are simultaneously collected, and include performance, motivation, emotion and behavior. After conducting this diagnostic test, it is possible to identify individual stress patterns that can be discussed with the individual patient to develop and recommend (outpatient treatment strategies. This paper introduces the PPST as a standardized way to evaluate stress reactions by presenting the results from a sample of psychosomatic inpatients (n = 139 who were treated in Charité-Universitätsmedizin Berlin, Germany. We observed that the varying testing conditions provoked adjusted changes in the different physiological parameters and psychological levels.

  13. [Achilles tendon rupture].

    Science.gov (United States)

    Thermann, H; Hüfner, T; Tscherne, H

    2000-03-01

    The treatment of acute of Achilles tendon rupture experienced a dynamic development in the last ten years. Decisive for this development was the application of MRI and above all the ultrasonography in the diagnostics of the pathological changes and injuries of tendons. The question of rupture morphology as well as different courses of healing could be now evaluated objectively. These advances led consequently to new modalities in treatment concepts and rehabilitation protocols. The decisive input for improvements of the outcome results and particularly the shortening of the rehabilitation period came with introduction of the early functional treatment in contrast to immobilizing plaster treatment. In a prospective randomized study (1987-1989) at the Trauma Dept. of the Hannover Medical School could show no statistical differences comparing functional non-operative with functional operative therapy with a special therapy boot (Variostabil/Adidas). The crucial criteria for therapy selection results from the sonographically measured position of the tendon stumps in plantar flexion (20 degrees). With complete adaptation of the tendons' ends surgical treatment does not achieve better results than non-operative functional treatment in term of tendon healing and functional outcome. Regarding the current therapeutic standards each method has is advantages and disadvantages. Both, the operative and non-operative functional treatment enable a stable tendon healing with a low risk of re-rupture (1-2%). Meanwhile there is consensus for early functional after-treatment of the operated Achilles' tendons. There seems to be a trend towards non-operative functional treatment in cases of adequate sonographical findings, or to minimal invasive surgical techniques.

  14. Slow rupture of frictional interfaces

    OpenAIRE

    Sinai, Yohai Bar; Brener, Efim A.; Bouchbinder, Eran

    2011-01-01

    The failure of frictional interfaces and the spatiotemporal structures that accompany it are central to a wide range of geophysical, physical and engineering systems. Recent geophysical and laboratory observations indicated that interfacial failure can be mediated by slow slip rupture phenomena which are distinct from ordinary, earthquake-like, fast rupture. These discoveries have influenced the way we think about frictional motion, yet the nature and properties of slow rupture are not comple...

  15. Creep strength and rupture ductility of creep strength enhanced ferritic steels

    Energy Technology Data Exchange (ETDEWEB)

    Kushima, Hideaki; Sawada, Kota; Kimura, Kazuhiro [National Inst. for Materials Science, Tsukuba, Ibaraki (Japan)

    2010-07-01

    Creep strength and rupture ductility of Creep Strength Enhanced Ferritic (CSEF) steels were investigated from a viewpoint of stress dependence in comparison with conventional low alloy ferritic creep resistant steels. Inflection of stress vs. time to rupture curve was observed at 50% of 0.2% offset yield stress for both CSEF and conventional ferritic steels. Creep rupture ductility tends to decrease with increase in creep exposure time, however, those of conventional low alloy steels indicate increase in the long-term. Creep rupture ductility of the ASME Grades 92 and 122 steels indicates drastic decrease with decrease in stress at 50% of 0.2% offset yield stress. Stress dependence of creep rupture ductility of the ASME Grades 92 and 122 steels is well described by stress ratio to 0.2% offset yield stress, regardless of temperature. Drop of creep rupture ductility is caused by inhomogeneous recovery at the vicinity of prior austenite grain boundary, and remarkable drop of creep rupture ductility of CSEF steels should be derived from those stabilized microstructure. (orig.)

  16. Stress test performed on gas transport pipelines as a method for quality assurance

    International Nuclear Information System (INIS)

    Kuelzer, J.; Baessler, R.

    1991-01-01

    Modern pipeline construction increasingly uses the stress test as an integral component test while aiming at enhanced safety and availability. The application described by the article highlights the particular fact that expanded and non-expanded pipes of identical material quality will reveal a different behaviour in the stress test. (orig.) [de

  17. Wolff-Parkinson-White syndrome: a single exercise stress test might be misleading.

    Science.gov (United States)

    Salavitabar, Arash; Silver, Eric S; Liberman, Leonardo

    2017-05-01

    Risk stratification of patients with Wolff-Parkinson-White syndrome for sudden death is a complex process, particularly in understanding the utility of the repeat exercise stress test. We report a case of an 18-year-old patient who was found to have a high-risk pathway by both invasive and exercise stress testing after an initial exercise stress test showing beat-to-beat loss of pre-excitation.

  18. The impact of training process on the stress tests results of women cross country skiing representation.

    OpenAIRE

    Fusková, Dana

    2015-01-01

    Title: The impact of training process on the stress tests results of women cross country skiing representation. Aim: The aim of this thesis is the comparison of the results of stress tests carried out preparatory period before and after the preparation period and whether the results were influenced by the applied training process. Methods: In this thesis was used background research of professional publications, content analyzes of documents and comparison of the results of stress tests and c...

  19. Single Event Gate Rupture in 130-nm CMOS Transistor Arrays Subjected to X-Ray Irradiation

    CERN Document Server

    Silvestri, M; Gerardin, Simone; Faccio, Federico; Paccagnella, Alessandro

    2010-01-01

    We present new experimental results on heavy ion-induced gate rupture on deep submicron CMOS transistor arrays. Through the use of dedicated test structures, composed by a large number of 130-nm MOSFETs connected in parallel, we show the response to heavy ion irradiation under high stress voltages of devices previously irradiated with X-rays. We found only a slight impact on gate rupture critical voltage at a LET of 32 MeV cm(2) mg(-1) for devices previously irradiated up to 3 Mrad(SiO2), and practically no change for 100 Mrad(SiO2) irradiation, dose of interest for the future super large hadron collider (SLHC).

  20. Slow rupture of frictional interfaces

    Science.gov (United States)

    Bar Sinai, Yohai; Brener, Efim A.; Bouchbinder, Eran

    2012-02-01

    The failure of frictional interfaces and the spatiotemporal structures that accompany it are central to a wide range of geophysical, physical and engineering systems. Recent geophysical and laboratory observations indicated that interfacial failure can be mediated by slow slip rupture phenomena which are distinct from ordinary, earthquake-like, fast rupture. These discoveries have influenced the way we think about frictional motion, yet the nature and properties of slow rupture are not completely understood. We show that slow rupture is an intrinsic and robust property of simple non-monotonic rate-and-state friction laws. It is associated with a new velocity scale cmin, determined by the friction law, below which steady state rupture cannot propagate. We further show that rupture can occur in a continuum of states, spanning a wide range of velocities from cmin to elastic wave-speeds, and predict different properties for slow rupture and ordinary fast rupture. Our results are qualitatively consistent with recent high-resolution laboratory experiments and may provide a theoretical framework for understanding slow rupture phenomena along frictional interfaces.

  1. Traumatic rupture of the aorta

    International Nuclear Information System (INIS)

    Dorfman, G.S.; Paolella, L.P.; Haas, R.A.; Lambiase, R.E.; Cronan, J.J.

    1988-01-01

    To evaluate the acceptability of digital subtraction angiography (DSA) in the evaluation of traumatic rupture of the aorta (TRA), the authors obtained 56 thoracic aortograms in 55 consecutive trauma patients, using both DSA and cut-film angiography (CFA). Both studies were ranked blindly and assigned scores for quality and diagnosis. Interobserver variance for DSA and CFA quality rankings was insignificant. CFA achieved significantly higher ranking for quality. In the 56 examinations, CFA demonstrated seven abnormalities that demanded intervention for follow-up angiography. DSA demonstrated only five of these and found no additional abnormalities. While this evaluation applies only to the particular digital system that the authors tested, they found that DSA, as compared with CFA, failed to demonstrate significant aortic injury. The confidence of diagnosis was significantly greater with CFA. Similar double-blind evaluation is mandatory at any trauma center prior to converting from CFA to DSA in the diagnosis of this life-threatening condition

  2. Retrieving rupture history using waveform inversions in time sequence

    Science.gov (United States)

    Yi, L.; Xu, C.; Zhang, X.

    2017-12-01

    The rupture history of large earthquakes is generally regenerated using the waveform inversion through utilizing seismological waveform records. In the waveform inversion, based on the superposition principle, the rupture process is linearly parameterized. After discretizing the fault plane into sub-faults, the local source time function of each sub-fault is usually parameterized using the multi-time window method, e.g., mutual overlapped triangular functions. Then the forward waveform of each sub-fault is synthesized through convoluting the source time function with its Green function. According to the superposition principle, these forward waveforms generated from the fault plane are summarized in the recorded waveforms after aligning the arrival times. Then the slip history is retrieved using the waveform inversion method after the superposing of all forward waveforms for each correspond seismological waveform records. Apart from the isolation of these forward waveforms generated from each sub-fault, we also realize that these waveforms are gradually and sequentially superimposed in the recorded waveforms. Thus we proposed a idea that the rupture model is possibly detachable in sequent rupture times. According to the constrained waveform length method emphasized in our previous work, the length of inverted waveforms used in the waveform inversion is objectively constrained by the rupture velocity and rise time. And one essential prior condition is the predetermined fault plane that limits the duration of rupture time, which means the waveform inversion is restricted in a pre-set rupture duration time. Therefore, we proposed a strategy to inverse the rupture process sequentially using the progressively shift rupture times as the rupture front expanding in the fault plane. And we have designed a simulation inversion to test the feasibility of the method. Our test result shows the prospect of this idea that requiring furthermore investigation.

  3. Help-Seeking Decisions of Battered Women: A Test of Learned Helplessness and Two Stress Theories.

    Science.gov (United States)

    Wauchope, Barbara A.

    This study tested the learned helplessness theory, stress theory, and a modified stress theory to determine the best model for predicting the probability that a woman would seek help when she experienced severe violence from a male partner. The probability was hypothesized to increase as the stress of the violence experienced increased. Data were…

  4. Using Uncertainty Analysis to Guide the Development of Accelerated Stress Tests (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Kempe, M.

    2014-03-01

    Extrapolation of accelerated testing to the long-term results expected in the field has uncertainty associated with the acceleration factors and the range of possible stresses in the field. When multiple stresses (such as temperature and humidity) can be used to increase the acceleration, the uncertainty may be reduced according to which stress factors are used to accelerate the degradation.

  5. A comparative study of creep rupture behaviour of modified 316L(N) base metal and 316L(N)/16-8-2 weldment in air and liquid sodium environments

    International Nuclear Information System (INIS)

    Mishra, M.P.; Mathew, M.D.; Mannan, S.L.; Rodriguez, P.; Borgstedt, H.U.

    1997-01-01

    Creep rupture behaviour of modified type 316L(N) stainless steel base metal and weldments prepared with 16-8-2 filler wire has been investigated in air and flowing sodium environments at 823 K. No adverse environmental effects have been noticed due to sodium on the creep rupture behaviour of these weldments for tests up to 10 000 h. Rupture lives of the weldment were higher in the sodium environment than those in air. Rupture lives of the weldments were found to be lower than those of the base metal by a factor of two to five in both air and sodium environments. Minimum creep rates were essentially the same for the weldment as well as for the base metal in both the environments, whereas rupture strain was usually lower for the weldment than that of the base metal. The reduction in area of the weldment specimens increased with increase in stress. Failures in the specimens of weldments were in the weld metal region. Microstructural studies carried out on failed weldment specimens after the creep rupture tests revealed extensive cavitation in the weld metal region in air tested specimens predominantly at the austerite/δ-ferrite interphase. However, no cavitation was observed in specimens tested in sodium. (author)

  6. Assessment of an improved multiaxial strength theory based on creep-rupture data for Inconel 600

    International Nuclear Information System (INIS)

    Huddleston, R.L.

    1993-01-01

    A new multiaxial strength theory incorporating three independent stress parameters was developed and reported by the author in 1984. It was formally incorporated into ASME Code Case N47-29 in 1990. The new theory provided significantly more accurate stress-rupture life predictions than obtained using the classical theories of von Mises, Tresca, and Rankins (maximum principal stress), for Types 304 and 316 stainless steel tested at 593 and 600 degrees C respectively under different biaxial stress states. Additional results for Inconel 600 specimens tested at 816 degrees C under tension-tension and tension-compression stress states are presented in this paper and show a factor of approximately 2.4 reduction in the scatter of predicted versus observed lives as compared to the classical theories of von Mises and Tresca and a factor of about 5 as compared to the Rankins theory. A key feature of the theory, which incorporates the maximum deviatoric stress, the first invariant of the stress tensor, and the second invariant of the deviatoric stress tensor, is its ability to distinguish between life under tensile versus compressive stress states

  7. When we test, do we stress? Impact of the testing environment on cortisol secretion and memory performance in older adults.

    Science.gov (United States)

    Sindi, Shireen; Fiocco, Alexandra J; Juster, Robert-Paul; Pruessner, Jens; Lupien, Sonia J

    2013-08-01

    The majority of studies find that older adults have worse memory performance than young adults. However, contextual features in the testing environment may be perceived as stressful by older adults, increasing their stress hormone levels. Given the evidence that older adults are highly sensitive to the effects of stress hormones (cortisol) on memory performance, it is postulated that a stressful testing environment in older adults can lead to an acute stress response and to memory impairments. The current study compared salivary cortisol levels and memory performance in young and older adults tested in environments manipulated to be stressful (unfavourable condition) or not stressful (favourable condition) for each age group. 28 young adults and 32 older adults were tested in two testing conditions: (1) a condition favouring young adults (constructed to be less stressful for young adults), and (2) a condition favouring older adults (constructed to be less stressful for older adults). The main outcome measure was salivary cortisol levels. Additionally, immediate and delayed memory performances were assessed during each condition. In older adults only, we found significantly high cortisol levels and low memory performance in the condition favouring young adults. In contrast, cortisol levels were lower and memory performance was better when older adults were tested in conditions favouring them. There was no effect of testing condition in young adults. The results demonstrate that older adults' memory performance is highly sensitive to the testing environment. These findings have important implications for both research and clinical settings in which older adults are tested for memory performance. Copyright © 2012 Elsevier Ltd. All rights reserved.

  8. The effect of vacuum environment on creep rupture properties of Inconel 617 at 1000 deg C

    International Nuclear Information System (INIS)

    Ohnami, Masateru; Imamura, Riuzo

    1981-01-01

    The creep rupture strength of nickel-base superalloy in weakly acidic gas at high temperature above 1000 deg C lowers remarkably as compared with that in the atmosphere, and this problem is one of the important subjects in connection with the research and development of high temperature heat exchangers for multi-purpose high temperature gas-cooled reactor system being developed in Japan. In the case of Inconel 617, abnormal decarbonization phenomenon occurs in weakly acidic gas, and this is regarded as the cause of lowering the creep strength. In this study, the effects of the decarbonization in weak vacuum at 1000 deg C and the oxidation of Inconel 617 on its crack occurrence and propagation were clarified experimentally with notched plate test pieces. The material used was Inconel 617 nickel-base superalloy made by Huntington Alloys Inc. in the U.S. The creep rupture experiment was carried out with a simple tension creep tester. At the nominal stress of 3.5 kg/mm 2 , the creep rupture time in 0.3 Torr was the shortest when the grain size was 78 μm, and the creep rupture time increased as the grain size became larger. The creep rupture time in 0.3 Torr decreased to a half of that in the atmosphere. In 0.3 Torr, cracks occurred early, and propagated fast as compared with in the atmosphere. This is because the local creep velocity at the bottom of notches and in front of creep cracks is fast owing to the lack of protective oxide film. (Kako, I.)

  9. Estimation of the Blood Pressure Response With Exercise Stress Testing.

    Science.gov (United States)

    Fitzgerald, Benjamin T; Ballard, Emma L; Scalia, Gregory M

    2018-04-20

    The blood pressure response to exercise has been described as a significant increase in systolic BP (sBP) with a smaller change in diastolic BP (dBP). This has been documented in small numbers, in healthy young men or in ethnic populations. This study examines these changes in low to intermediate risk of myocardial ischaemia in men and women over a wide age range. Consecutive patients having stress echocardiography were analysed. Ischaemic tests were excluded. Manual BP was estimated before and during standard Bruce protocol treadmill testing. Patient age, sex, body mass index (BMI), and resting and peak exercise BP were recorded. 3200 patients (mean age 58±12years) were included with 1123 (35%) females, and 2077 males, age range 18 to 93 years. Systolic BP increased from 125±17mmHg to 176±23mmHg. The change in sBP (ΔsBP) was 51mmHg (95% CI 51,52). The ΔdBP was 1mmHg (95% CI 1, 1), from 77 to 78mmHg, p<0.001). The upper limit of normal peak exercise sBP (determined by the 90th percentile) was 210mmHg in males and 200mmHg in females. The upper limit of normal ΔsBP was 80mmHg in males and 70mmHg in females. The lower limit of normal ΔsBP was 30mmHg in males and 20mmHg in females. In this large cohort, sBP increased significantly with exercise. Males had on average higher values than females. Similar changes were seen with the ΔsBP. The upper limit of normal for peak exercise sBP and ΔsBP are reported by age and gender. Copyright © 2018 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). All rights reserved.

  10. Creep Rupture Properties for Base and Weld Metals of Alloy 617

    International Nuclear Information System (INIS)

    Kim, Woo-Gon; Kim, Min-Hwan; Park, Jae-Young; Ekaputra, I. M. W.

    2015-01-01

    The allowable deformation in the welds is also restricted to half the deformation permitted for the base metal, since the ductility of the welds at elevated temperatures is generally low. For a design use, the data of the tensile and creep properties for Alloy 617 WM should be sufficiently provided, and in particular, to develop a design code of Alloy 617 WM. However, the data for the WM are very rare and limited until now, although the data for the BM are available in the ASME draft code case, which was suspended at the end of the 1980s owing to a lack of support and interes. In this report, the creep data for Alloy 617 WM, which was fabricated by a gas tungsten arc welding (GTAW) procedure, were obtained by a series of creep tests at 800 .deg. C, and the creep properties of the WM were compared with those of the BM. The high-temperature creep properties for Alloy 617 WM, fabricated by a gas tungsten arc welding (GTAW) procedure, were investigated by a series of creep tests with different stress levels at 800 .deg. C, and the creep test data for the WM were compared with those of the BM. From the results, it was found that the WM had a slightly longer creep rupture life and lower creep rate than the BM, and a particularly lower rupture elongation. The lower creep rate in the WM was due to the lower rupture elongation than the BM

  11. Surgical management of spontaneous ruptured hepatocellular adenoma

    Directory of Open Access Journals (Sweden)

    Marcelo Augusto Fontenelle Ribeiro Junior

    2009-01-01

    Full Text Available AIMS: Spontaneous ruptured hepatocellular adenoma (SRHA is a rare life-threatening condition that may require surgical treatment to control hemorrhaging and also stabilize the patient. We report a series of emergency surgeries performed at our institution for this condition. METHODS: We reviewed medical records and radiology files of 28 patients (from 1989 to 2006 with a proven diagnosis of hepatocellular adenoma (HA. Three (10.7% of 28 patients had spontaneous ruptured hepatocellular adenoma, two of which were associated with intrahepatic hemorrhage while one had intraperitoneal bleeding. Two patients were female and one was male. Both female patients had a background history of oral contraceptive use. Sudden abdominal pain associated with hemodynamic instability occurred in all patients who suffered from spontaneous ruptured hepatocellular adenoma. The mean age was 41.6 years old. The preoperative assessment included liver function tests, ultrasonography and computed tomography. RESULTS: The surgical approaches were as follows: right hemihepatectomy for controlling intraperitoneal bleeding, and right extended hepatectomy and non-anatomic resection of the liver for intrahepatic hemorrhage. There were no deaths, and the postoperative complications were bile leakage and wound infection (re-operation, as well as intraperitoneal abscess (re-operation and pleural effusion. CONCLUSION: Spontaneous ruptured hepatocellular adenoma may be treated by surgery for controlling hemorrhages and stabilizing the patient, and the decision to operate depends upon both the patient's condition and the expertise of the surgical team.

  12. Creep deformation and rupture behavior of CLAM steel at 823 K and 873 K

    Science.gov (United States)

    Zhong, Boyu; Huang, Bo; Li, Chunjing; Liu, Shaojun; Xu, Gang; Zhao, Yanyun; Huang, Qunying

    2014-12-01

    China Low Activation Martensitic (CLAM) steel is selected as the candidate structural material in Fusion Design Study (FDS) series fusion reactor conceptual designs. The creep property of CLAM steel has been studied in this paper. Creep tests have been carried out at 823 K and 873 K over a stress range of 150-230 MPa. The creep curves showed three creep regimes, primary creep, steady-state creep and tertiary creep. The relationship between minimum creep rate (ε˙min) and the applied stress (σ) could be described by Norton power law, and the stress exponent n was decreased with the increase of the creep temperature. The creep mechanism was analyzed with the fractographes of the rupture specimens which were examined by scanning electron microscopy (SEM). The coarsening of precipitates observed with transmission electron microscope (TEM) indicated the microstructural degradation after creep test.

  13. Creep deformation and rupture behavior of CLAM steel at 823 K and 873 K

    International Nuclear Information System (INIS)

    Zhong, Boyu; Huang, Bo; Li, Chunjing; Liu, Shaojun; Xu, Gang; Zhao, Yanyun; Huang, Qunying

    2014-01-01

    China Low Activation Martensitic (CLAM) steel is selected as the candidate structural material in Fusion Design Study (FDS) series fusion reactor conceptual designs. The creep property of CLAM steel has been studied in this paper. Creep tests have been carried out at 823 K and 873 K over a stress range of 150–230 MPa. The creep curves showed three creep regimes, primary creep, steady-state creep and tertiary creep. The relationship between minimum creep rate (ε-dot min ) and the applied stress (σ) could be described by Norton power law, and the stress exponent n was decreased with the increase of the creep temperature. The creep mechanism was analyzed with the fractographes of the rupture specimens which were examined by scanning electron microscopy (SEM). The coarsening of precipitates observed with transmission electron microscope (TEM) indicated the microstructural degradation after creep test

  14. Stress analysis of the tokamak engineering test breeder blanket

    International Nuclear Information System (INIS)

    Huang Zhongqi

    1992-01-01

    The design features of the hybrid reactor blanket and main parameters are presented. The stress analysis is performed by using computer codes SAP5p and SAP6 with the three kinds of blanket module loadings, i.e, the pressure of coolant, the blanket weight and the thermal loading. Numerical calculation results indicate that the stresses of the blanket are smaller than the allowable ones of the material, the blanket design is therefore reasonable

  15. The Influence of Test-Based Accountability Policies on Early Elementary Teachers: School Climate, Environmental Stress, and Teacher Stress

    Science.gov (United States)

    Saeki, Elina; Segool, Natasha; Pendergast, Laura; von der Embse, Nathaniel

    2018-01-01

    This study examined the potential influence of test-based accountability policies on school environment and teacher stress among early elementary teachers. Structural equation modeling of data from 541 kindergarten through second grade teachers across three states found that use of student performance on high-stakes tests to evaluate teachers…

  16. Standard practice for preparation and use of Bent-Beam stress-corrosion test specimens

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    1.1 This practice covers procedures for designing, preparing, and using bent-beam stress-corrosion specimens. 1.2 Different specimen configurations are given for use with different product forms, such as sheet or plate. This practice applicable to specimens of any metal that are stressed to levels less than the elastic limit of the material, and therefore, the applied stress can be accurately calculated or measured (see Note 1). Stress calculations by this practice are not applicable to plastically stressed specimens. Note 1—It is the nature of these practices that only the applied stress can be calculated. Since stress-corrosion cracking is a function of the total stress, for critical applications and proper interpretation of results, the residual stress (before applying external stress) or the total elastic stress (after applying external stress) should be determined by appropriate nondestructive methods, such as X-ray diffraction (1). 1.3 Test procedures are given for stress-corrosion testing by ex...

  17. Cornea stress test--evaluation of corneal endothelial function in vivo by contact lens induced stress

    Directory of Open Access Journals (Sweden)

    Saini Jagjit

    1997-01-01

    Full Text Available Reliable and valid assessment of corneal endothelial function is a critical input for diagnosing, prognosticating and monitoring progression of disorders affecting corneal endothelium. In 123 eyes, corneal endothelial function was assessed employing data from the corneal hydration recovery dynamics. Serial pachometric readings were recorded on Haag-Striet pachometer with Mishima-Hedbys modification before and after two hours of thick soft contact lens wear. Percentage Recovery Per Hour (PRPH was derived from raw data as an index of endothelial function. Assessed PRPH in pseudophakic corneal oedema and Fuchs′ endothelial dystrophy eyes (35.9 +/- 9.8% was significantly lower than normal controls (61.9 +/- 10.5%. On employing receiver operation characteristics curve analysis the tested results demonstrated high sensitivity (87% and specificity (92% for detection of low endothelial function at PRPH cut off of 47.5%. Using this PRPH cut off, 80% of Fuchs′ endothelial dystrophy and 93.3% of pseudophakic corneal oedema eyes could be demonstrated to have low endothelial function. A total of 66.7% of diabetic eyes also demonstrated PRPH of lower than 47.5%. Clear corneal grafts demonstrated PRPH values of 24.6% to 73.0%. Of 6 corneal grafts that demonstrated initial PRPH of lower than 47.5%, 4 failed within 4 to 6 months. Our data demonstrated high sensitivity and specificity of this corneal stress test. PRPH index was useful in quantifying endothelial function in clinical disorders including diabetes mellitus. The index PRPH was demonstrated to be useful in monitoring and prognosticating outcome of corneal grafts.

  18. Untreated silicone breast implant rupture

    DEFF Research Database (Denmark)

    Hölmich, Lisbet R; Vejborg, Ilse M; Conrad, Carsten

    2004-01-01

    Implant rupture is a well-known complication of breast implant surgery that can pass unnoticed by both patient and physician. To date, no prospective study has addressed the possible health implications of silicone breast implant rupture. The aim of the present study was to evaluate whether untre...

  19. Stress corrosion evaluation of powder metallurgy aluminum alloy 7091 with the breaking load test method

    Science.gov (United States)

    Domack, Marcia S.

    1987-01-01

    The stress corrosion behavior of the P/M aluminum alloy 7091 is evaluated in two overaged heat treatment conditions, T7E69 and T7E70, using an accelerated test technique known as the breaking load test method. The breaking load data obtained in this study indicate that P/M 7091 alloy is highly resistant to stress corrosion in both longitudinal and transverse orientations at stress levels up to 90 percent of the material yield strength. The reduction in mean breaking stress as a result of corrosive attack is smallest for the more overaged T7E70 condition. Details of the test procedure are included.

  20. The rupture strength of dissimilar joints in high temperature

    International Nuclear Information System (INIS)

    Groenwall, B.

    1992-05-01

    In dissimilar joints between austenitic stainless steels and ferritic steels the heat affected zone in the ferritic steel always is the weakest link. Two different joints where the ferritic steel has been 10CrMo910 (2.25Cr1Mo) and X20CrMoV121 respectively (162Cr1Mo0.3V) has been investigated through thermal cycling and isothermal creep testing. In this case the purpose has been to investigate the weakest link and therefore both 10CrMo910 and X20CrMoV121 have been welded to themselves using the TIG-method with Inconel 82 (70Cr20Cr3Mn2). 5Nb as filler wire. Crossweld specimens have been taken from the joints. To accelerate the testing the tip temperature at thermal cycling and the temperature at isothermal creep testing has been in the region 600-650 degrees C. Low ductile fracture, which is typical for failures in practice, has been obtained by using a moderate tensile stress, 63 N/mm 2 . In the high temperature range, 650 degrees C, the thermal cycling compared to the isothermal testing had no influence but in lower temperatures the cycling caused decreased time to rupture. The time to rupture in thermal cycling as well as in isothermal testing as a function of testing temperature can be fitted to exponential curve of type t = a x e bT (where t and T are time and temperature respectively). Through extrapolation of the measured data it has been found that 10CrMo910 in hard conditions that is thermal cycling has a life time at 500 degrees C of about 100 000 h. If the operational temperature is constant the life time will be about four times longer. The X20CrMoV121 on the other hand has a life time at thermal cycling at 500 degrees C and moderate tensile stress of about 3 000 000 h. This means that the tensile stress can be increased considerably. The cracks appear in 10CrMo910 closely to the fusion line but in the X20CrMoV121 steel cracking and fracture arise in the heat affected zone some millimeters from the fusion line. (au)

  1. Studies on laws of stress-magnetization based on magnetic memory testing technique

    Science.gov (United States)

    Ren, Shangkun; Ren, Xianzhi

    2018-03-01

    Metal magnetic memory (MMM) testing technique is a novel testing method which can early test stress concentration status of ferromagnetic components. Under the different maximum tensile stress, the relationship between the leakage magnetic field of at certain point of cold rolled steel specimen and the tensile stress was measured during the process of loading and unloading by repeated. It shows that when the maximum tensile stress is less than 610 MPa, the relationship between the magnetic induction intensity and the stress is linear; When the maximum tensile stress increase from 610 MPa to 653 MPa of yield point, the relationship between the magnetic induction intensity and the tensile becomes bending line. The location of the extreme point of the bending line will move rapidly from the position of smaller stress to the larger stress position, and the variation of magnetic induction intensity increases rapidly. When the maximum tensile stress is greater than the 653 MPa of yield point, the variation of the magnetic induction intensity remains large, and the position of the extreme point moves very little. In theoretical aspects, tensile stress is to be divided into ordered stress and disordered stress. In the stage of elastic stress, a microscopic model of the order stress magnetization is established, and the conclusions are in good agreement with the experimental data. In the plastic deformation stage, a microscopic model of disordered stress magnetization is established, and the conclusions are in good agreement with the experimental data, too. The research results can provide reference for the accurate quantitative detection and evaluation of metal magnetic memory testing technology.

  2. 12 CFR 652.100 - Audit of the risk-based capital stress test.

    Science.gov (United States)

    2010-01-01

    ... 12 Banks and Banking 6 2010-01-01 2010-01-01 false Audit of the risk-based capital stress test... AGRICULTURAL MORTGAGE CORPORATION FUNDING AND FISCAL AFFAIRS Risk-Based Capital Requirements § 652.100 Audit of the risk-based capital stress test. You must have a qualified, independent external auditor review...

  3. Bending fatigue tests on SiC-Al tapes under alternating stress at room temperature

    Science.gov (United States)

    Herzog, J. A.

    1981-01-01

    The development of a testing method for fatigue tests on SiC-Al tapes containing a small amount of SiC filaments under alternating stress is reported. The fatigue strength curves resulting for this composite are discussed. They permit an estimate of its behavior under continuous stress and in combination with various other matrices, especially metal matrices.

  4. Blunt traumatic diaphragmatic rupture

    Directory of Open Access Journals (Sweden)

    Antonio Carlos Nogueira

    2011-09-01

    Full Text Available Traumatic injury of the diaphragm ranges from 0.6 to 1.2% and rise up to 5%among patients who were victims of blunt trauma and underwent laparotomy.Clinical suspicion associated with radiological assessment contributes to earlydiagnosis. Isolated diaphragmatic injury has a good prognosis. Generallyworse outcomes are associated with other trauma injuries. Bilateral andright diaphragmatic lesions have worse prognosis. Multi detector computed tomography (MDCT scan of the chest and abdomen provides better diagnosticaccuracy using the possibility of image multiplanar reconstruction. Surgicalrepair via laparotomy and/ or thoracotomy in the acute phase of the injury hasa better outcome and avoids chronic complications of diaphragmatic hernia.The authors present the case of a young male patient, victim of blunt abdominaltrauma due to motor vehicle accident with rupture of the diaphragm, spleenand kidney injuries. The diagnosis was made by computed tomography of thethorax and abdomen and was confirmed during laparotomy.

  5. Summary report - development of laboratory tests and the stress- strain behaviour of Olkiluoto mica gneiss

    Energy Technology Data Exchange (ETDEWEB)

    Hakala, M.; Heikkilae, E. [Helsinki Univ. of Technology, Espoo (Finland). Lab. of Rock Engineering

    1997-05-01

    This work summarizes the project aimed at developing and qualifying a suitable combination of laboratory tests to establish a statistically reliable stress-strain behaviour of the main rock types at Posiva Oy`s detailed investigation sites for disposal of spent nuclear fuel. The work includes literature study of stress-strain behaviour of brittle rock, development and qualification of laboratory tests, suggested test procedures and interpretation methods and finally testing of Olkiluoto mica gneiss. The Olkiluoto study includes over 130 loading tests. Besides the commonly used laboratory tests, direct tensile tests, damage controlled tests and acoustic emission measurements were also carried out. (orig.) (54 refs.).

  6. Summary report - development of laboratory tests and the stress- strain behaviour of Olkiluoto mica gneiss

    International Nuclear Information System (INIS)

    Hakala, M.; Heikkilae, E.

    1997-05-01

    This work summarizes the project aimed at developing and qualifying a suitable combination of laboratory tests to establish a statistically reliable stress-strain behaviour of the main rock types at Posiva Oy's detailed investigation sites for disposal of spent nuclear fuel. The work includes literature study of stress-strain behaviour of brittle rock, development and qualification of laboratory tests, suggested test procedures and interpretation methods and finally testing of Olkiluoto mica gneiss. The Olkiluoto study includes over 130 loading tests. Besides the commonly used laboratory tests, direct tensile tests, damage controlled tests and acoustic emission measurements were also carried out. (orig.) (54 refs.)

  7. Progress and Challenges of Ultrasonic Testing for Stress in Remanufacturing Laser Cladding Coating

    Directory of Open Access Journals (Sweden)

    Xiao-Ling Yan

    2018-02-01

    Full Text Available Stress in laser cladding coating is an important factor affecting the safe operation of remanufacturing components. Ultrasonic testing has become a popular approach in the nondestructive evaluation of stress, because it has the advantages of safety, nondestructiveness, and online detection. This paper provides a review of ultrasonic testing for stress in remanufacturing laser cladding coating. It summarizes the recent research outcomes on ultrasonic testing for stress, and analyzes the mechanism of ultrasonic testing for stress. Remanufacturing laser cladding coating shows typical anisotropic behaviors. The ultrasonic testing signal in laser cladding coating is influenced by many complex factors, such as microstructure, defect, temperature, and surface roughness, among others. At present, ultrasonic testing for stress in laser cladding coating can only be done roughly. This paper discusses the active mechanism of micro/macro factors in the reliability of stress measurement, as well as the impact of stress measurement on the quality and safety of remanufacturing components. Based on the discussion, this paper proposes strategies to nondestructively, rapidly, and accurately measure stress in remanufacturing laser cladding coating.

  8. Testing of a single-polarity piezoresistive three-dimensional stress-sensing chip

    International Nuclear Information System (INIS)

    Gharib, H H; Moussa, W A

    2013-01-01

    A new piezoresistive stress-sensing rosette is developed to extract the components of the three-dimensional (3D) stress tensor using single-polarity (n-type) piezoresistors. This paper presents the testing of a micro-fabricated sensing chip utilizing the developed single-polarity rosette. The testing is conducted using a four-point bending of a chip-on-beam to induce five controlled stress components, which are analyzed both numerically and experimentally. Numerical analysis using finite element analysis is conducted to study the levels of the induced stress components at three rosette-sites and the levels of the stress field non-uniformities, and to simulate the extracted stress components from the sensing rosette. The experimental analysis applied tensile and compressive loads over three rosette-sites at different load increments. The experimentally extracted stress components show good linearity with the applied load and values close to the numerical model. (paper)

  9. [Unpredictable chronic mild stress effects on antidepressants activities in forced swim test].

    Science.gov (United States)

    Kudryashov, N V; Kalinina, T S; Voronina, T A

    2015-02-01

    The experiments has been designed to study unpredictable chronic mild stress effect on anti-depressive activities of amitriptyline (10 mg/kg) and fluoxetine (20 mg/kg) in forced swim test in male outbred mice. It is shown that acute treatment with fluoxetine does not produce any antidepressant effects in mice following stress of 14 days while the sub-chronic injections of fluoxetine result in more deep depressive-like behavior. In 28 daily stressed mice, antidepressant effect of fluoxetine is observed independently of the injection rates. Amitriptyline demonstrates the antidepressant activity regardless of the duration of stress or administration scheduling, but at the same time the severity of anti-immobilization effect of amitriptyline in stressed mice is weaker in compare to non-stressed trails. Thus, the injection rates and duration of unpredictable mild chronic stress are the parameters that determine the efficiency of antidepressants in the mouse forced swimming test.

  10. Rupture of Al matrix in U-Mo/Al dispersion fuel by fission induced creep

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Gwan Yoon; Sohn, Dong Seong [UNIST, Daejeon (Korea, Republic of); Kim, Yeon Soo [Argonne National Laboratory, Argonnge (United States); Lee, Kyu Hong [KAERI, Daejeon (Korea, Republic of)

    2016-05-15

    This phenomenon was found specifically in the dispersion fuel plate with Si addition in the Al matrix to suppress interaction layer (IL) formation between UMo and Al. It is known that the stresses induced by fission induced swelling in U-Mo fuel particles are relieved by creep deformation of the IL, surrounding the fuel particles, that has a much higher creep rate than the Al matrix. Thus, when IL growth is suppressed, the stress is instead exerted on the Al matrix. The observed rupture in the Al matrix is believed to be caused when the stress exceeded the rupture strength of the Al matrix. In this study, the possibility of creep rupture of the Al matrix between the neighboring U-Mo fuel particles was examined using the ABAQUS finite element analysis (FEA) tool. The predicted rupture time for a plate was much shorter than its irradiation life indicating a rupture during the irradiation. The higher stress leads Al matrix to early creep rupture in this plate for which the Al matrix with lower creep strain rate does not effectively relieve the stress caused by the swelling of the U-Mo fuel particles. For the other plate, no rupture was predicted for the given irradiation condition. The effect of creeping of the continuous phase on the state of stress is significant.

  11. Source properties of dynamic rupture pulses with off-fault plasticity

    KAUST Repository

    Gabriel, A.-A.

    2013-08-01

    Large dynamic stresses near earthquake rupture fronts may induce an inelastic response of the surrounding materials, leading to increased energy absorption that may affect dynamic rupture. We systematically investigate the effects of off-fault plastic energy dissipation in 2-D in-plane dynamic rupture simulations under velocity-and-state-dependent friction with severe weakening at high slip velocity. We find that plasticity does not alter the nature of the transitions between different rupture styles (decaying versus growing, pulse-like versus crack-like, and subshear versus supershear ruptures) but increases their required background stress and nucleation size. We systematically quantify the effect of amplitude and orientation of background shear stresses on the asymptotic properties of self-similar pulse-like ruptures: peak slip rate, rupture speed, healing front speed, slip gradient, and the relative contribution of plastic strain to seismic moment. Peak slip velocity and rupture speed remain bounded. From fracture mechanics arguments, we derive a nonlinear relation between their limiting values, appropriate also for crack-like and supershear ruptures. At low background stress, plasticity turns self-similar pulses into steady state pulses, for which plastic strain contributes significantly to the seismic moment. We find that the closeness to failure of the background stress state is an adequate predictor of rupture speed for relatively slow events. Our proposed relations between state of stress and earthquake source properties in the presence of off-fault plasticity may contribute to the improved interpretation of earthquake observations and to pseudodynamic source modeling for ground motion prediction.

  12. The Influence of Cardiac Risk Factor Burden on Cardiac Stress Test Outcomes.

    Science.gov (United States)

    Schrock, Jon W; Li, Morgan; Orazulike, Chidubem; Emerman, Charles L

    2011-06-01

    Chest pain is the most common admission diagnosis for observation unit patients. These patients often undergo cardiac stress testing to further risk stratify for coronary artery disease (CAD). The decision of whom to stress is currently based on clinical judgment. We sought to determine the influence of cardiac risk factor burden on cardiac stress test outcome for patients tested from an observation unit, inpatient or outpatient setting. We performed a retrospective observational cohort study for all patients undergoing stress testing in our institution from June 2006 through July 2007. Cardiac risk factors were collected at the time of stress testing. Risk factors were evaluated in a summative fashion using multivariate regression adjusting for age and known coronary artery disease. The model was tested for goodness of fit and collinearity and the c statistic was calculated using the receiver operating curve. A total of 4026 subjects were included for analysis of which 22% had known CAD. The rates of positive outcome were 89 (12.0%), 95 (12.6%), and 343 (16.9%) for the OU, outpatients, and hospitalized patients respectively. While the odds of a positive test outcome increased for additional cardiac risk factors, ROC curve analysis indicates that simply adding the number of risk factors does not add significant diagnostic value. Hospitalized patients were more likely to have a positive stress test, OR 1.41 (1.10 - 1.81). Our study does not support basing the decision to perform a stress test on the number of cardiac risk factors.

  13. Effect of chemistry variations on the short-term rupture life and tensile properties of 20% cold-worked type 316 stainless steel

    International Nuclear Information System (INIS)

    Duncan, D.R.; Paxton, M.M.

    1977-01-01

    The effects of compositional variations on the rupture life of 20% cold-worked Type 316 stainless steel were investigated at 19-ksi (131-MPa) uniaxial tensile stress and at 1400 0 F (1033 K). Forty-nine different alloys were studied, with compositional variations from nominal in carbon, nitrogen, phosphorus, sulfur, boron, manganese, copper, silicon, molybdenum, cobalt, chromium and nickel. This alloy and cold-work level represents the duct and fuel cladding material choice for the first four core loadings of the Fast Flux Test Facility, a key element in the Liquid-Metal Fast Breeder Reactor Program. Tensile properties of four of the alloys were studied at temperatures from room temperature to 1600 0 F (1144 K). Boron, nitrogen, and molybdenum plus silicon additions significantly increased rupture life, while chromium and carbon additions decreased rupture life. Molybdenum plus silicon additions increased yield and ultimate strength and ductility at 1200 0 F (922 K) and below

  14. A fluid-structure interaction study using patient-specific ruptured and unruptured aneurysm: the effect of aneurysm morphology, hypertension and elasticity.

    Science.gov (United States)

    Lee, C J; Zhang, Y; Takao, H; Murayama, Y; Qian, Y

    2013-09-27

    Fluid-structure interaction (FSI) simulations using five patient-specific aneurysm geometries are carried out to investigate the difference between ruptured and unruptured aneurysms. Two different blood pressure conditions (normal and hypertension, for all cases), and two different values of elastic modulus (1 and 2MPa, for two cases) are tested. Ruptured aneurysms (RA) generally displayed larger displacement at the dome, lower area-average WSS and higher von Mises stress than unruptured aneurysms (URA) regardless of elasticity or blood pressure condition. RAs had a longitudinal expansion whereas URAs had a radial expansion, which was the key difference between the two types. The difference in expansion pattern may be one of the keys to explaining aneurysm rupture, and further analysis is required in the future to confirm this theory. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. 78 FR 59219 - Stress Testing of Regulated Entities

    Science.gov (United States)

    2013-09-26

    ... institutions. C. Methodologies The Banks requested that Sec. 1238.4 of the rule expressly state that the stress... the scenarios provided by FHFA. FHFA will clarify questions about materiality and about which... its regulated financial institutions. Methodologies and Practices--Sec. 1238.4 Section 1238.4 provides...

  16. Facial temperature data Sing-a-Song StressTest

    NARCIS (Netherlands)

    Brouwer, A.M.

    2013-01-01

    We here introduce a new experimental paradigm to induce mental stress in a quick and easy way while adhering to ethical standards and controlling for potential confounds resulting from sensory input, body movements and behavior of people involved in conducting the experiment. In our Sing-a-Song

  17. Consistent creep and rupture properties for creep-fatigue evaluation

    International Nuclear Information System (INIS)

    Schultz, C.C.

    1978-01-01

    The currently accepted practice of using inconsistent representations of creep and rupture behaviors in the prediction of creep-fatigue life is shown to introduce a factor of safety beyond that specified in current ASME Code design rules for 304 stainless steel Class 1 nuclear components. Accurate predictions of creep-fatigue life for uniaxial tests on a given heat of material are obtained by using creep and rupture properties for that same heat of material. The use of a consistent representation of creep and rupture properties for a mininum strength heat is also shown to provide adequate predictions. The viability of using consistent properties (either actual or those of a minimum heat) to predict creep-fatigue life thus identifies significant design uses for the results of characterization tests and improved creep and rupture correlations

  18. Consistent creep and rupture properties for creep-fatigue evaluation

    International Nuclear Information System (INIS)

    Schultz, C.C.

    1979-01-01

    The currently accepted practice of using inconsistent representations of creep and rupture behaviors in the prediction of creep-fatigue life is shown to introduce a factor of safety beyond that specified in current ASME Code design rules for 304 stainless steel Class 1 nuclear components. Accurate predictions of creep-fatigue life for uniaxial tests on a given heat of material are obtained by using creep and rupture properties for that same heat of material. The use of a consistent representation of creep and rupture properties for a minimum strength heat is also shown to provide reasonable predictions. The viability of using consistent properties (either actual or those of a minimum strength heat) to predict creep-fatigue life thus identifies significant design uses for the results of characterization tests and improved creep and rupture correlations. 12 refs

  19. Depressive symptoms and perceived chronic stress predict test anxiety in nursing students

    Directory of Open Access Journals (Sweden)

    Christoph Augner

    2015-09-01

    Full Text Available Aim: The aim of this study is to identify predictors of test anxiety in nursing students. Design: Cross sectional pilot study. Methods: A questionnaire was administered to 112 students of an Austrian nursing school (mean age = 21.42, SD = 5.21. Test anxiety (measured by the standardized PAF Test Anxiety Questionnaire, perceived chronic stress, depressive symptoms, pathological eating and further psychological and health parameters were measured. Results: We found highly significant correlations between test anxiety and working hours (0.25, depression score (0.52, emotional stability (-0.31, and perceived chronic stress (0.65 (p < 0.01, for all. Regression analysis revealed chronic stress and emotional instability as best predictors for test anxiety. Furthermore, path analysis revealed that past negative academic performance outcomes contribute to test anxiety via depressive symptoms and perceived chronic stress. Conclusion: Depressive symptoms and perceived chronic stress are strongly related to test anxiety. Therefore therapy and training methods that address depressive symptoms and perceived chronic stress, and thereby aim to modify appraisal of potential stressful situations, may be successful in addressing test anxiety.

  20. Facility-level association of preoperative stress testing and postoperative adverse cardiac events.

    Science.gov (United States)

    Valle, Javier A; Graham, Laura; Thiruvoipati, Thejasvi; Grunwald, Gary; Armstrong, Ehrin J; Maddox, Thomas M; Hawn, Mary T; Bradley, Steven M

    2018-06-22

    Despite limited indications, preoperative stress testing is often used prior to non-cardiac surgery. Patient-level analyses of stress testing and outcomes are limited by case mix and selection bias. Therefore, we sought to describe facility-level rates of preoperative stress testing for non-cardiac surgery, and to determine the association between facility-level preoperative stress testing and postoperative major adverse cardiac events (MACE). We identified patients undergoing non-cardiac surgery within 2 years of percutaneous coronary intervention in the Veterans Affairs (VA) Health Care System, from 2004 to 2011, facility-level rates of preoperative stress testing and postoperative MACE (death, myocardial infarction (MI) or revascularisation within 30 days). We determined risk-standardised facility-level rates of stress testing and postoperative MACE, and the relationship between facility-level preoperative stress testing and postoperative MACE. Among 29 937 patients undergoing non-cardiac surgery at 131 VA facilities, the median facility rate of preoperative stress testing was 13.2% (IQR 9.7%-15.9%; range 6.0%-21.5%), and 30-day postoperative MACE was 4.0% (IQR 2.4%-5.4%). After risk standardisation, the median facility-level rate of stress testing was 12.7% (IQR 8.4%-17.4%) and postoperative MACE was 3.8% (IQR 2.3%-5.6%). There was no correlation between risk-standardised stress testing and composite MACE at the facility level (r=0.022, p=0.81), or with individual outcomes of death, MI or revascularisation. In a national cohort of veterans undergoing non-cardiac surgery, we observed substantial variation in facility-level rates of preoperative stress testing. Facilities with higher rates of preoperative stress testing were not associated with better postoperative outcomes. These findings suggest an opportunity to reduce variation in preoperative stress testing without sacrificing patient outcomes. © Article author(s) (or their employer(s) unless otherwise

  1. Creep Rupture Analysis and Life Estimation of 1.25Cr-0.5Mo, 2.25Cr-1Mo and Modified 9Cr-1Mo Steel: A Comparative Study

    Science.gov (United States)

    Roy, Prabir Kumar

    2018-04-01

    This paper highlights a comparative assessment of creep life of 1.25Cr-0.5Mo, 2.25Cr-1Mo and modified 9Cr-1Mo steels based on accelerated creep rupture tests. Creep rupture test data have been analysed and creep life of the above mentioned materials have been assessed using Larson Miller parameter at the stress levels of 60 and 42 MPa for different temperatures. Limiting steam temperatures for minimum design life of 105 h at 42 and 60 MPa for the above mentioned steels have also been calculated. Microstructural studies for the three above mentioned steels are also done.

  2. Reliability analysis for the creep rupture mode of failure

    International Nuclear Information System (INIS)

    Vaidyanathan, S.

    1975-01-01

    An analytical study has been carried out to relate the factors of safety employed in the design of a component to the probability of failure in the thermal creep rupture mode. The analysis considers the statistical variations in the operating temperature, stress and rupture time, and applies the life fraction damage criterion as the indicator of failure. Typical results for solution annealed type 304-stainless steel material for the temperature and stress variations expected in an LMFBR environment have been obtained. The analytical problem was solved by considering the joint distribution of the independent variables and deriving the distribution for the function associated with the probability of failure by integrating over proper regions as dictated by the deterministic design rule. This leads to a triple integral for the final probability of failure where the coefficients of variation associated with the temperature, stress and rupture time distributions can be specified by the user. The derivation is general, and can be used for time varying stress histories and the case of irradiated material where the rupture time varies with accumulated fluence. Example calculations applied to solution annealed type 304 stainless steel material have been carried out for an assumed coefficient of variation of 2% for temperature and 6% for stress. The results show that the probability of failure associated with dependent stress intensity limits specified in the ASME Boiler and Pressure Vessel Section III Code Case 1592 is less than 5x10 -8 . Rupture under thermal creep conditions is a highly complicated phenomenon. It is believed that the present study will help in quantizing the reliability to be expected with deterministic design factors of safety

  3. Standard test method for determining residual stresses by the hole-drilling strain-gage method

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 Residual Stress Determination: 1.1.1 This test method specifies a hole-drilling procedure for determining residual stress profiles near the surface of an isotropic linearly elastic material. The test method is applicable to residual stress profile determinations where in-plane stress gradients are small. The stresses may remain approximately constant with depth (“uniform” stresses) or they may vary significantly with depth (“non-uniform” stresses). The measured workpiece may be “thin” with thickness much less than the diameter of the drilled hole or “thick” with thickness much greater than the diameter of the drilled hole. Only uniform stress measurements are specified for thin workpieces, while both uniform and non-uniform stress measurements are specified for thick workpieces. 1.2 Stress Measurement Range: 1.2.1 The hole-drilling method can identify in-plane residual stresses near the measured surface of the workpiece material. The method gives localized measurements that indicate the...

  4. Representative stresses for creep deformation and failure of pressurised tubes and pipes

    International Nuclear Information System (INIS)

    Cane, B.J.; Browne, R.J.

    1982-01-01

    Results of a series of tube and uniaxial tests on two casts of 1/2CrMoV pipe steel are examined to determine the representative stress which must be applied to uniaxial data in order to predict the strain rates and lives of pressurised tubes and pipes. The stress criterion for deformation is shown to correlate with the analytically derived reference stress (σsub(R)) at low pressure while at high pressures a modified reference stress (> σsub(R)) must be used. The rupture life exhibits a similar correlation such that the representative stress for rupture is given by σsub(R) at low stresses yet, at high stresses, it is greater than σsub(R) and attains a value comparable with the mean diameter hoop stress. The latter thus describes the rupture life at high pressures but significantly underestimates the life at low pressures approaching those in service. Consideration is given to the multiaxial stress rupture criterion and the effect of geometry in constant load tests. (author)

  5. Optimal design of constant-stress accelerated degradation tests using the M-optimality criterion

    International Nuclear Information System (INIS)

    Wang, Han; Zhao, Yu; Ma, Xiaobing; Wang, Hongyu

    2017-01-01

    In this paper, we propose the M-optimality criterion for designing constant-stress accelerated degradation tests (ADTs). The newly proposed criterion concentrates on the degradation mechanism equivalence rather than evaluation precision or prediction accuracy which is usually considered in traditional optimization criteria. Subject to the constraints of total sample number, test termination time as well as the stress region, an optimum constant-stress ADT plan is derived by determining the combination of stress levels and the number of samples allocated to each stress level, when the degradation path comes from inverse Gaussian (IG) process model with covariates and random effects. A numerical example is presented to verify the robustness of our proposed optimum plan and compare its efficiency with other test plans. Results show that, with a slightly relaxed requirement of evaluation precision and prediction accuracy, our proposed optimum plan reduces the dispersion of the estimated acceleration factor between the usage stress level and a higher accelerated stress level, which makes an important contribution to reliability demonstration and assessment tests. - Highlights: • We establish the necessary conditions for degradation mechanism equivalence of ADTs. • We propose the M-optimality criterion for designing constant-stress ADT plans. • The M-optimality plan reduces the dispersion of the estimated accelerated factors. • An electrical connector with its stress relaxation data is used for illustration.

  6. Stress transfer in microdroplet tensile test: PVC-coated and uncoated Kevlar-29 single fiber

    Science.gov (United States)

    Zhenkun, Lei; Quan, Wang; Yilan, Kang; Wei, Qiu; Xuemin, Pan

    2010-11-01

    The single fiber/microdroplet tensile test is applied for evaluating the interfacial mechanics between a fiber and a resin substrate. It is used to investigate the influence of a polymer coating on a Kevlar-29 fiber surface, specifically the stress transfer between the fiber and epoxy resin in a microdroplet. Unlike usual tests, this new test ensures a symmetrical axial stress on the embedded fiber and reduces the stress singularity that appears at the embedded fiber entry. Using a homemade loading device, symmetrical tensile tests are performed on a Kevlar-29 fiber with or without polyvinylchloride (PVC) coating, the surface of which is in contact with two epoxy resin microdroplets during curing. Raman spectra on the embedded fiber are recorded by micro-Raman Spectroscopy under different strain levels. Then they are transformed to the distributions of fiber axis stress based on the relationship between stress and Raman shift. The Raman results reveal that the fiber axial stresses increase with the applied loads, and the antisymmetric interfacial shear stresses, obtained by a straightforward balance of shear-to-axial forces argument, lead to the appearance of shear stress concentrations at a distance to the embedded fiber entry. The load is transferred from the outer fiber to the embedded fiber in the epoxy microdroplet. As is observed by scanning electronic microscopy (SEM), the existence of a flexible polymer coating on the fiber surface reduces the stress transfer efficiency.

  7. Republic of Poland; Technical Note on Stress Testing the Banking Sector

    OpenAIRE

    International Monetary Fund

    2013-01-01

    This Technical Note discusses results of stress testing of the banking sector in Poland. The Polish banking system is well capitalized and liquid, as confirmed by stress tests results. Polish banks are, in aggregate, resilient even under severe adverse scenarios. Some small banks could fail to meet minimum regulatory capital and liquidity requirements in these scenarios, but with little impact on the overall banking system. Tests showed that only small banks, together representing up to 30 pe...

  8. Nigeria; Publication of Financial Sector Assessment Program Documentation––Technical Note on Stress Testing

    OpenAIRE

    International Monetary Fund

    2013-01-01

    To assess the financial stability in Nigeria, various stress tests and analytic processes were undertaken jointly by the Nigerian authorities and the Financial Sector Assessment Program (FSAP) team. The exercise included macroeconomic scenario analysis and its transmission into a range of single- and multifactor shocks. The tests covered the entire Nigerian banking system and looked at the short-term horizon, in part because of data constraints. Sensitivity stress tests estimated the impact o...

  9. Presence of Bacteria in Spontaneous Achilles Tendon Ruptures.

    Science.gov (United States)

    Rolf, Christer G; Fu, Sai-Chuen; Hopkins, Chelsea; Luan, Ju; Ip, Margaret; Yung, Shu-Hang; Friman, Göran; Qin, Ling; Chan, Kai-Ming

    2017-07-01

    The structural pathology of Achilles tendon (AT) ruptures resembles tendinopathy, but the causes remain unknown. Recently, a number of diseases were found to be attributed to bacterial infections, resulting in low-grade inflammation and progressive matrix disturbance. The authors speculate that spontaneous AT ruptures may also be influenced by the presence of bacteria. Bacteria are present in ruptured ATs but not in healthy tendons. Cross-sectional study; Level of evidence, 3. Patients with spontaneous AT ruptures and patients undergoing anterior cruciate ligament (ACL) reconstruction were recruited for this study. During AT surgical repair, excised tendinopathic tissue was collected, and healthy tendon samples were obtained as controls from hamstring tendon grafts used in ACL reconstruction. Half of every sample was reserved for DNA extraction and the other half for histology. Polymerase chain reaction (PCR) was conducted using 16S rRNA gene universal primers, and the PCR products were sequenced for the identification of bacterial species. A histological examination was performed to compare tendinopathic changes in the case and control samples. Five of 20 AT rupture samples were positive for the presence of bacterial DNA, while none of the 23 hamstring tendon samples were positive. Sterile operating and experimental conditions and tests on samples, controlling for harvesting and processing procedures, ruled out the chance of postoperative bacterial contamination. The species identified predominantly belonged to the Staphylococcus genus. AT rupture samples exhibited histopathological features characteristic of tendinopathy, and most healthy hamstring tendon samples displayed normal tendon features. There were no apparent differences in histopathology between the bacterial DNA-positive and bacterial DNA-negative AT rupture samples. The authors have demonstrated the presence of bacterial DNA in ruptured AT samples. It may suggest the potential involvement of bacteria

  10. Rupture Dynamics and Scaling Behavior of Hydraulically Stimulated Micro-Earthquakes in a Shale Reservoir

    Science.gov (United States)

    Viegas, G. F.; Urbancic, T.; Baig, A. M.

    2014-12-01

    In hydraulic fracturing completion programs fluids are injected under pressure into fractured rock formations to open escape pathways for trapped hydrocarbons along pre-existing and newly generated fractures. To characterize the failure process, we estimate static and dynamic source and rupture parameters, such as dynamic and static stress drop, radiated energy, seismic efficiency, failure modes, failure plane orientations and dimensions, and rupture velocity to investigate the rupture dynamics and scaling relations of micro-earthquakes induced during a hydraulic fracturing shale completion program in NE British Columbia, Canada. The relationships between the different parameters combined with the in-situ stress field and rock properties provide valuable information on the rupture process giving insights into the generation and development of the fracture network. Approximately 30,000 micro-earthquakes were recorded using three multi-sensor arrays of high frequency geophones temporarily placed close to the treatment area at reservoir depth (~2km). On average the events have low radiated energy, low dynamic stress and low seismic efficiency, consistent with the obtained slow rupture velocities. Events fail in overshoot mode (slip weakening failure model), with fluids lubricating faults and decreasing friction resistance. Events occurring in deeper formations tend to have faster rupture velocities and are more efficient in radiating energy. Variations in rupture velocity tend to correlate with variation in depth, fault azimuth and elapsed time, reflecting a dominance of the local stress field over other factors. Several regions with different characteristic failure modes are identifiable based on coherent stress drop, seismic efficiency, rupture velocities and fracture orientations. Variations of source parameters with rock rheology and hydro-fracture fluids are also observed. Our results suggest that the spatial and temporal distribution of events with similar

  11. The Application of Normal Stress Reduction Function in Tilt Tests for Different Block Shapes

    Science.gov (United States)

    Kim, Dong Hyun; Gratchev, Ivan; Hein, Maw; Balasubramaniam, Arumugam

    2016-08-01

    This paper focuses on the influence of the shapes of rock cores, which control the sliding or toppling behaviours in tilt tests for the estimation of rock joint roughness coefficients (JRC). When the JRC values are estimated by performing tilt tests, the values are directly proportional to the basic friction of the rock material and the applied normal stress on the sliding planes. Normal stress obviously varies with the shape of the sliding block, and the basic friction angle is also affected by the sample shapes in tilt tests. In this study, the shapes of core blocks are classified into three representative shapes and those are created using plaster. Using the various shaped artificial cores, a set of tilt tests is carried out to identify the shape influences on the normal stress and the basic friction angle in tilt tests. The test results propose a normal stress reduction function to estimate the normal stress for tilt tests according to the sample shapes based on Barton's empirical equation. The proposed normal stress reduction functions are verified by tilt tests using artificial plaster joints and real rock joint sets. The plaster joint sets are well matched and cast in detailed printed moulds using a 3D printing technique. With the application of the functions, the obtained JRC values from the tilt tests using the plaster samples and the natural rock samples are distributed within a reasonable JRC range when compared with the measured values.

  12. Creep rupture behavior of Stirling engine materials

    Science.gov (United States)

    Titran, R. H.; Scheuerman, C. M.; Stephens, J. R.

    1985-01-01

    The automotive Stirling engine, being investigated jointly by the Department of Energy and NASA Lewis as an alternate to the internal combustion engine, uses high-pressure hydrogen as the working fluid. The long-term effects of hydrogen on the high temperature strength properties of materials is relatively unknown. This is especially true for the newly developed low-cost iron base alloy NASAUT 4G-A1. This iron-base alloy when tested in air has creep-rupture strengths in the directionally solidified condition comparable to the cobalt base alloy HS-31. The equiaxed (investment cast) NASAUT 4G-A1 has superior creep-rupture to the equiaxed iron-base alloy XF-818 both in air and 15 MPa hydrogen.

  13. Fatigue and rupture codified rules comparison

    International Nuclear Information System (INIS)

    Faidy, C.

    2004-01-01

    The European Directive on Pressure Equipment requests risk studies and in particular to assure no risk of fatigue and rupture in operation. The answers to these questions are different in the different existing design codes (EN Standards, ASME III and VIII or RCC-M or CODAP-CODETI codes) and corresponding in operation codes (ASME or RSE-M). Design safety factors, material properties, fabrication, refinement in the analysis methods, monitoring in operation, hydro-proof test level... Around these Codes, different rules are under development. A16 in France, R6 in UK or FITNET at the EC level. This paper is concerned by a comparison between 2 different Codes to analyze the risk of fatigue or rupture of pressure equipments and mainly a comparison between RCC-M Code and EN 13445 standard for pressure vessel. Recommendations for future work will be proposed. (authors)

  14. Cardiac stress testing for the diagnosis and management of coronary artery disease: a reference for the primary care physician.

    Science.gov (United States)

    Gajulapalli, Rama Dilip; Aneja, Ashish; Rovner, Aleksandr

    2012-02-01

    Choosing the appropriate stress test is important in the workup of patients with possible myocardial ischemia. This choice often is challenging and sometimes confusing because of the plethora of tests and guidelines available. We present a broad overview of commonly available stress tests and indications to help physicians select the most appropriate stress test for their patients.

  15. Influence of steam generator tube ruptures during semiscale loss-of-coolant experiments

    International Nuclear Information System (INIS)

    Cozzuol, J.M.; Larson, T.K.

    1978-01-01

    Tests which simulated rupture of steam generator tubes during loss-of-coolant experiments in a PWR type system have been conducted in the Semiscale Mod-1 system. Analysis of test data indicates that high rod cladding temperatures occured only for a band of tube ruptures (between 12 and 20 tubes) and that the peak cladding temperatures attained within this band were strongly dependent on the magnitude of the tube rupture flow rates. Maximum cladding temperature of about 1255 K was observed for tests which simulated tube ruptures within this narrow band. (author)

  16. Simultaneous bilateral patellar tendon rupture ?

    OpenAIRE

    Moura, Diogo Lino; Marques, Jos? Pedro; Lucas, Francisco Manuel; Fonseca, Fernando Pereira

    2016-01-01

    Bilateral patellar tendon rupture is a rare entity, often associated with systemic diseases and patellar tendinopathy. The authors report a rare case of a 34-year-old man with simultaneous bilateral rupture of the patellar tendon caused by minor trauma. The patient is a retired basketball player with no past complaints of chronic knee pain and a history of steroid use. Surgical management consisted in primary end-to-end tendon repair protected temporarily with cerclage wiring, followed by a s...

  17. Source properties of dynamic rupture pulses with off-fault plasticity

    KAUST Repository

    Gabriel, A.-A.; Ampuero, J.-P.; Dalguer, L. A.; Mai, Paul Martin

    2013-01-01

    styles (decaying versus growing, pulse-like versus crack-like, and subshear versus supershear ruptures) but increases their required background stress and nucleation size. We systematically quantify the effect of amplitude and orientation of background

  18. Indigenous development of rupture discs for FBTR (Paper No. 028)

    International Nuclear Information System (INIS)

    Chetal, S.C.; Raju, Chander; Anandkumar, V.; Seetharaman, V.

    1987-02-01

    Rupture discs are required as a safety device for protecting the secondary sodium circuit and its components against high pressure surges due to accidental water-steam leaks in sodium heated steam generator and the consequent sodium water reaction. For identical reasons, rupture discs are also required on the vessels used for decontamination of sodium components. As an import substitution of the costly items for the FBTR Project, development of the rupture disc assemblies has been in progress at Indira Gandhi Centre for Atomic Research, Kalpakkam. Reverse buckling knife blade concept with stainless steel disc has been taken up for development. Hydroforming process without any die has been selected for disc fabrication. One rupture disc assembly required for steam generator has been tested in sodium satisfactorily. (author). 4 tables, 5 figs

  19. The diagnosis of breast implant rupture

    DEFF Research Database (Denmark)

    Hölmich, Lisbet R; Vejborg, Ilse; Conrad, Carsten

    2005-01-01

    participated in either one or two study MRI examinations, aiming at determining the prevalence and incidence of silent implant rupture, respectively, and who subsequently underwent explantation. Implant rupture status was determined by four independent readers and a consensus diagnosis of either rupture...... were in fact ruptured at surgery. Thirty-four of the 43 intact implants were described as intact at surgery. When categorising possible ruptures as ruptures, there were one false positive and nine false negative rupture diagnoses at MRI yielding an accuracy of 92%, a sensitivity of 89...

  20. Uncertainty analysis for probabilistic steam generators tube rupture in LBB applications

    Energy Technology Data Exchange (ETDEWEB)

    Durbec, V.; Pitner, P.; Pages, D. [Electricite de France, 78 - Chatou (France). Research and Development Div.; Riffard, T. [Electricite de France, 69 - Villeurbanne (France). Engineering and Construction Div.; Flesch, B. [Electricite de France, 92 - Paris la Defense (France). Generation and Transmission Div.

    1997-10-01

    Steam Generators (SG) of Pressurized Water Reactors have experienced world wide various types of tube degradations, mainly from stress corrosion cracking; because of this damage, primary-secondary leakage or tube rupture can occur. Safety against the risk of tube rupture is achieved through a combination of periodic in-service inspections (eddy current testing), surveillance of leaks during operation (leak before break concept) and tube plugging. In order to optimize the tube bundle SG maintenance, Electricite de France has developed a specific software named COMPROMIS. The model, based on probabilistic fracture mechanics makes it possible to quantify the influence of in service inspections and maintenance work on the risk of a SG Tube Rupture (SGTR), taking all significant parameters into account as random variables (initial defect size distribution, reliability of non-destructive examinations, crack initiation and propagation, critical sizes, leak before risk of break, etc...). This paper focuses on the leak rate calculation module and presents a sensitivity study of the influence of the leak before break on the conditional failure probability. (author) 8 refs.

  1. Uncertainty analysis for probabilistic steam generators tube rupture in LBB applications

    International Nuclear Information System (INIS)

    Durbec, V.; Pitner, P.; Pages, D.; Riffard, T.; Flesch, B.

    1997-10-01

    Steam Generators (SG) of Pressurized Water Reactors have experienced world wide various types of tube degradations, mainly from stress corrosion cracking; because of this damage, primary-secondary leakage or tube rupture can occur. Safety against the risk of tube rupture is achieved through a combination of periodic in-service inspections (eddy current testing), surveillance of leaks during operation (leak before break concept) and tube plugging. In order to optimize the tube bundle SG maintenance, Electricite de France has developed a specific software named COMPROMIS. The model, based on probabilistic fracture mechanics makes it possible to quantify the influence of in service inspections and maintenance work on the risk of a SG Tube Rupture (SGTR), taking all significant parameters into account as random variables (initial defect size distribution, reliability of non-destructive examinations, crack initiation and propagation, critical sizes, leak before risk of break, etc...). This paper focuses on the leak rate calculation module and presents a sensitivity study of the influence of the leak before break on the conditional failure probability. (author)

  2. Development of in-situ rock shear test under low compressive to tensile normal stress

    International Nuclear Information System (INIS)

    Nozaki, Takashi; Shin, Koichi

    2003-01-01

    The purpose of this study is to develop an in-situ rock shear testing method to evaluate the shear strength under low normal stress condition including tensile stress, which is usually ignored in the assessment of safety factor of the foundations for nuclear power plants against sliding. The results are as follows. (1) A new in-situ rock shear testing method is devised, in which tensile normal stress can be applied on the shear plane of a specimen by directly pulling up a steel box bonded to the specimen. By applying the counter shear load to cancel the moment induced by the main shear load, it can obtain shear strength under low normal stress. (2) Some model tests on Oya tuff and diatomaceous mudstone have been performed using the developed test method. The shear strength changed smoothly from low values at tensile normal stresses to higher values at compressive normal stresses. The failure criterion has been found to be bi-linear on the shear stress vs normal stress plane. (author)

  3. [Stress-ECG is adequate to detect myocardial ischemia: when are additional diagnostic tests needed?].

    Science.gov (United States)

    Baer, F M

    2007-09-01

    The stress-ECG is the most often adopted and most cost effective initial diagnostic test for the assessment of myocardial ischemia in patients with suspected coronary artery disease (CAD). Prerequisites for the diagnostic usefullness of stress-ECG are a clearly interpretable ST-segment, ability to reach the predicted work load, an intermediate pretest probability for CAD ranging between 10% and 90% and the absence of any contraindications for dynamic exercise. Because of the limited diagnostic sensitivity of about 70%, and a high percentage of patients, who are unable to exercise, a negative stress ECG can definitely not exclude hemodynamically significant CAD. Therefore, stress imaging techniques like myocardial scintigraphy, stress-echocardiography and stress magnetic resonance imaging play a major role in the stepwise diagnostic work-up of patients with suspected CAD. These stress imaging techniques are basically interchangeable since no method is definitely superior to one of the others. However, each method has its specific pros and cons and inherent contraindications. Therefore the choice of the stress imaging method and the form of stress applied should be based on the individual patients characteristics to gain optimal image quality and diagnostic accuracy. Moreover, the decision for one method should take the local availability and institutional expertise of diagnostic centers into account. Although partly substituted by stress imaging techniques the stress-ECG still remains the workhorse for a stepwise diagnostic work-up of patients with suspected CAD.

  4. FlowPing - The New Tool for Throughput and Stress Testing

    Directory of Open Access Journals (Sweden)

    Ondrej Vondrous

    2015-01-01

    Full Text Available This article presents a new tool for network throughput and stress testing. The FlowPing tool is easy to use, and its basic output is very similar to standard Linux ping application. The FlowPing tool is not limited to reach-ability or round trip time testing but is capable of complex UDP based throughput stress testing with rich reporting capabilities on client and server sides. Our new tool implements features, which allow the user to perform tests with variable packet size and traffic rate. All these features can be used in one single test run. This allows the user to use and develop new methodologies for network throughput and stress testing. With the FlowPing tool, it is easy to perform the test with the slowly increasing the amount of network traffic and monitor the behavior of network when the congestion occurs.

  5. Testing the responses of four wheat crop models to heat stress at anthesis and grain filling.

    Science.gov (United States)

    Liu, Bing; Asseng, Senthold; Liu, Leilei; Tang, Liang; Cao, Weixing; Zhu, Yan

    2016-05-01

    Higher temperatures caused by future climate change will bring more frequent heat stress events and pose an increasing risk to global wheat production. Crop models have been widely used to simulate future crop productivity but are rarely tested with observed heat stress experimental datasets. Four wheat models (DSSAT-CERES-Wheat, DSSAT-Nwheat, APSIM-Wheat, and WheatGrow) were evaluated with 4 years of environment-controlled phytotron experimental datasets with two wheat cultivars under heat stress at anthesis and grain filling stages. Heat stress at anthesis reduced observed grain numbers per unit area and individual grain size, while heat stress during grain filling mainly decreased the size of the individual grains. The observed impact of heat stress on grain filling duration, total aboveground biomass, grain yield, and grain protein concentration (GPC) varied depending on cultivar and accumulated heat stress. For every unit increase of heat degree days (HDD, degree days over 30 °C), grain filling duration was reduced by 0.30-0.60%, total aboveground biomass was reduced by 0.37-0.43%, and grain yield was reduced by 1.0-1.6%, but GPC was increased by 0.50% for cv Yangmai16 and 0.80% for cv Xumai30. The tested crop simulation models could reproduce some of the observed reductions in grain filling duration, final total aboveground biomass, and grain yield, as well as the observed increase in GPC due to heat stress. Most of the crop models tended to reproduce heat stress impacts better during grain filling than at anthesis. Some of the tested models require improvements in the response to heat stress during grain filling, but all models need improvements in simulating heat stress effects on grain set during anthesis. The observed significant genetic variability in the response of wheat to heat stress needs to be considered through cultivar parameters in future simulation studies. © 2016 John Wiley & Sons Ltd.

  6. Present-day stress magnitude at depth from leak-off tests in Italy

    Science.gov (United States)

    Mariucci, M. T.; Montone, P.; Pierdominici, S.

    2012-04-01

    We present new results from the analysis of leak-off tests, performed in deep oil wells in Italy, to characterize the present-day stress magnitude and regime in the crust. In the last years we have collected a large number of data (more than 500) from different stress indicators, mainly borehole breakouts, earthquake focal mechanisms and fault data, which provided information on the present-day stress orientations. In some areas the tectonic regime has been inferred either from fault plane solutions of M≥4 earthquakes or from stress inversions of smaller earthquakes. Where seismicity lacks, the regime is not well constrained and little or no information on the magnitude of the crustal stresses is available. In order to improve our knowledge in stress regime and its magnitude in Italy, in this work we use the leak-off test technique. Each test is performed at the bottom of an open hole by sealing off a section and then slowly pressurizing with a fluid until hydraulic tensile fractures develop. The minimum horizontal stress is inferred by leak-off pressure record, the vertical stress is computed by rock density data and the maximum horizontal stress is estimated applying a specific formula from the literature. Thanks to ENI S.p.A. (Italian oil company), that kindly provided new well data, we have been able to perform a critical review of our preliminary calculations and to enhance our previous results concerning stress magnitudes. Totally, we have analyzed 192 leak-off tests at depth between 200 and 5400m (average 1800m). In particular, wells are located along the Italian peninsula and in Sicily: most of them are in the Po Plain and along the Apenninic foredeep; few are in southern Apenninic belt and a few tens are in Sicily. After an accurate selection of the most robust results, we better characterize the Italian stress regime at depth.

  7. Cardiac Stress Test Trends Among US Patients Younger Than 65 Years, 2005-2012.

    Science.gov (United States)

    Kini, Vinay; McCarthy, Fenton H; Dayoub, Elias; Bradley, Steven M; Masoudi, Frederick A; Ho, P Michael; Groeneveld, Peter W

    2016-12-01

    After a period of rapid growth, use of cardiac stress testing has recently decreased among Medicare beneficiaries and in a large integrated health system. However, it is not known whether declines in cardiac stress testing are universal or are confined to certain populations. To determine trends in rates of cardiac stress testing among a large and diverse cohort of commercially insured patients. A serial cross-sectional study with time trends was conducted using administrative claims from all members aged 25 to 64 years belonging to a large, national managed care company from January 1, 2005, to December 31, 2012. Linear trends in rates were determined using negative binomial regression models with procedure count as the dependent variable, calendar quarter as the key independent variable, and the size of the population as a logged offset term. Data analysis was performed from January 1, 2005, to December 31, 2012. Age- and sex-adjusted rates of cardiac stress tests per calendar quarter (reported as number of tests per 100 000 person-years). A total of 2 085 591 cardiac stress tests were performed among 32 921 838 persons (mean [SD] age, 43.2 [10.9] years; 16 625 528 women [50.5%] and 16 296 310 [49.5%] men; 7 604 945 nonwhite [23.1%]). There was a 3.0% increase in rates of cardiac stress testing from 2005 (3486 tests; 95% CI, 3458-3514) to 2012 (3589 tests; 95% CI, 3559-3619; P = .01 for linear trend). Use of nuclear single-photon emission computed tomography decreased by 14.9% from 2005 (1907 tests; 95% CI, 1888-1926) to 2012 (1623 tests; 95% CI, 1603-1643; P = .03). Use of stress echocardiography increased by 27.8% from 2005 (709 tests; 95% CI, 697-721) to 2012 (906 tests; 95% CI, 894 to 920; P < .001). Use of exercise electrocardiography increased by 12.5% from 2005 (861 tests; 95% CI, 847-873) to 2012 (969 tests; 95% CI, 953-985; P < .001). Use of other stress testing modalities increased 65.5% from 2006 (55 tests; 95% CI

  8. Bayesian Approach for Constant-Stress Accelerated Life Testing for Kumaraswamy Weibull Distribution with Censoring

    Directory of Open Access Journals (Sweden)

    Abeer Abd-Alla EL-Helbawy

    2016-09-01

    Full Text Available The accelerated life tests provide quick information on the life time distributions by testing materials or products at higher than basic conditional levels of stress such as pressure, high temperature, vibration, voltage or load to induce failures. In this paper, the acceleration model assumed is log linear model. Constant stress tests are discussed based on Type I and Type II censoring. The Kumaraswmay Weibull distribution is used. The estimators of the parameters, reliability, hazard rate functions and p-th percentile at normal condition, low stress, and high stress are obtained. In addition, credible intervals for parameters of the models are constructed. Optimum test plan are designed. Some numerical studies are used to solve the complicated integrals such as Laplace and Markov Chain Monte Carlo methods.

  9. Bayesian Approach for Constant-Stress Accelerated Life Testing for Kumaraswamy Weibull Distribution with Censoring

    Directory of Open Access Journals (Sweden)

    Abeer Abd-Alla EL-Helbawy

    2016-12-01

    Full Text Available The accelerated life tests provide quick information on the life time distributions by testing materials or products at higher than basic conditional levels of stress such as pressure, high temperature, vibration, voltage or load to induce failures. In this paper, the acceleration model assumed is log linear model. Constant stress tests are discussed based on Type I and Type II censoring. The Kumaraswmay Weibull distribution is used. The estimators of the parameters, reliability, hazard rate functions and p-th percentile at normal condition, low stress, and high stress are obtained. In addition, credible intervals for parameters of the models are constructed. Optimum test plan are designed. Some numerical studies are used to solve the complicated integrals such as Laplace and Markov Chain Monte Carlo methods.

  10. Validity of multiple stress creep recovery test for LADOTD asphalt binder specification.

    Science.gov (United States)

    2010-09-01

    The objectives of this research are to characterize the elastic response of various binders used by LADOTD to determine the feasibility of the Multiple Stress Creep Recovery (MSCR) test to be included in the LADOTD asphalt binder specification and to...

  11. Dynamic rupture analysis of reinforced concrete shells

    International Nuclear Information System (INIS)

    Rebora, B.; Zimmermann, Th.; Wolf, J.P.

    1976-01-01

    Extreme dynamic loading conditions often require the rupture analysis of reinforced and prestressed-concrete structures. The study presented in this paper extends a method of analysis of dynamic loading conditions which has proven efficient for short-time loads. Another aim is to adapt the method to thin-walled structures. It is not sufficient to work only with plastic rupture and yield surfaces locally which are compared to the elastic distribution of the stress resultants; it is essential to account for the redistribution of the latter. The method proposed consists of discretizing the structure into isoparametric three-dimensional elements with 20 nodes for the concrete and one-dimensional bar elements with three nodes for the steel. The latter can also be handled with a 'smeared' two-dimensional membrane element. In compression a three-dimensional non-linear elastic constitutive law is introduced for the concrete, and a triaxial failure surface expressed in the stress invariants is used, determining cracking and crushing. Two- and three-dimensional cracking surfaces in which no components of stress are transmitted are accounted for. The possibility exists that, during the history of loading, cracks can close up again. For steel, a yield criterion is selected. The non-linear analysis is based on the concept of initial stress. Residual loads are calculated using information in Gauss integration points. The ultimate load is reached when the algorithm does not converge. The corresponding failure modes can be interpreted as those for which a state of equilibrium is no longer possible. The equations of motion are discretized in time, using an extension of the linear acceleration method. (Auth.)

  12. Stress

    Science.gov (United States)

    ... can be life-saving. But chronic stress can cause both physical and mental harm. There are at least three different types of stress: Routine stress related to the pressures of work, family, and other daily responsibilities Stress brought about ...

  13. Study on the Correlation between PSR and Korean Stress Test for Continued Operation of Aging NPP

    International Nuclear Information System (INIS)

    Chung, June Ho; Kim, Tae Ryong

    2013-01-01

    Nuclear Safety and Security Commission (NSSC), Korean nuclear regulatory authority established the stress test guideline based on the EU stress test, and KHNP prepared the execution plan in response to the guideline for the CO of Kori Unit 1 and Wolsong Unit 1. PSR is a comprehensive safety review program for long term operation of NPP, which was developed by IAEA. Korea adopted PSR in 1999 as the regulatory requirement for CO of NPP. The IAEA standard guideline for PSR program was updated in 2003. However, the Korean PSR has not been revised yet to apply the new IAEA guidelines. Additionally, national legal systems and guidelines associated with the adoption of stress tests are urgently required as well. These revisions are imperative in order to ensure the reliability of NPPs, and to promote public acceptance and understanding. This study presents the technical basis and proposals for review actions necessary to address the issues and controversies surrounding the continued operation and decommissioning of aging NPPs in Korea. As discussed earlier in characteristics of Korean Stress Test, it is more comprehensive than the EU Stress Test in terms of its multilateral evaluation which includes equipment durability, plant operation, human factors, and safety margins, hence substantially raising the significance and value of the evaluation process. Thus, the addition of Korean Stress Test to the existing Korean Evaluation of CO is expected to greatly increase the quality of safety assessment of aging NPPs in Korea due to its stricter safety policies, hence providing a more meaningful evaluation process. However, a one-time application of the Korean Stress Test to only Kori Unit 1 and Wolsong Unit 1 would be a waste of the great effort that has been done thus far to improve the Korean Evaluation of CO and develop the Korean Stress Test. By extending the Korean Stress Test to all NPPs in Korea would maintain and ensure the reliability of NPPs as well as public

  14. Stress analysis of HLW containers advanced test work Compas project

    International Nuclear Information System (INIS)

    Ove Arup and Partners

    1990-01-01

    The Compas project is concerned with the structural performance of metal overpacks which may be used to encapsulate vitrified high-level waste forms before disposal in deep geological repositories. This document describes the activities performed between June and August 1989 forming the advanced test work phase of this project. This is the culmination of two years' analysis and test work to demonstrate whether the analytical ability exists to model containers subjected to realistic loads. Three mild steel containers were designed and manufactured to be one-third scale models of a realistic HLW container, modified to represent the effect of anisotropic loading and to facilitate testing. The containers were tested under a uniform external pressure and all failed by buckling in the mid-body region. The outer surface of each container was comprehensively strain-gauged to provide strain history data at all positions of interest. In parallel with the test work, Compas project partners, from five different European countries, independently modelled the behaviour of each of the containers using their computer codes to predict the failure pressure and produce strain history data at a number of specified locations. The first axisymmetric container was well modelled but predictions for the remaining two non-axisymmetric containers were much more varied, with differences of up to 50% occurring between failure predictions and test data

  15. Stress transfer of a Kevlar 49 fiber pullout test studied by micro-Raman spectroscopy.

    Science.gov (United States)

    Lei, Zhenkun; Wang, Quan; Qiu, Wei

    2013-06-01

    The interfacial stress transfer behavior of a Kevlar 49 aramid fiber-epoxy matrix was studied with fiber pullout tests, the fibers of which were stretched by a homemade microloading device. Raman spectra on the embedded fiber were recorded by micro-Raman spectroscopy, under different strain levels. Then, the fiber axial stress was obtained by the relationship between the stress and Raman shift of the aramid fiber. Experimental results revealed that the fiber axial stress increased significantly with the load. The shear stress concentration occurred at the fiber entry to the epoxy resin. Thus, interfacial friction stages exist in the debonded fiber segment, and the interfacial friction shear stress is constant within one stage. The experimental results are consistent with the theoretical model predictions.

  16. A Framework for Macroprudential Bank Solvency Stress Testing; Application to S-25 and Other G-20 Country FSAPs

    OpenAIRE

    Andreas A. Jobst; Li L Ong; Christian Schmieder

    2013-01-01

    The global financial crisis has placed the spotlight squarely on bank stress tests. Stress tests conducted in the lead-up to the crisis, including those by IMF staff, were not always able to identify the right risks and vulnerabilities. Since then, IMF staff has developed more robust stress testing methods and models and adopted a more coherent and consistent approach. This paper articulates the solvency stress testing framework that is being applied in the IMF’s surveillance of member countr...

  17. Evaluation of micro fatigue crack growth under equi-biaxial stress by membranous pressure fatigue test

    International Nuclear Information System (INIS)

    Iida, Satoshi; Abe, Shigeki; Nakamura, Takao; Kamaya, Masayuki

    2014-01-01

    For preventing nuclear power plant (NPP) accidents, NPPs are required to ensure system safety in long term safe operation under aging degradation. Now, fatigue accumulation is one of major ageing phenomena and are evaluated to ensure safety by design fatigue curve that are based on the results of uniaxial fatigue tests. On the other hand, thermal stress that occurs in piping of actual components is not uniaxial but equi-biaxial. For accurate evaluation, it is required to conform real circumstance. In this study, membranous pressure fatigue test was conducted to simulated equi-biaxial stress. Crack initiation and crack growth were examined by replica investigation. Calculation result of equivalent stress intensity factor shows crack growth under equi-biaxial stress is faster than under uniaxial stress. It is concluded that equi-biaxial fatigue behavior should be considered in the evaluation of fatigue crack initiation and crack growth. (author)

  18. Application of discrete scale invariance method on pipe rupture

    International Nuclear Information System (INIS)

    Rajkovic, M.; Mihailovic, Z.; Riznic, J.

    2007-01-01

    'Full text:' A process of material failure of a mechanical system in the form of cracks and microcracks, a catastrophic phenomenon of considerable technological and scientific importance, may be forecasted according to the recent advances in the theory of critical phenomena in statistical physics. Critical rupture scenario states that, in many concrete and composite heterogeneous materials under compression and materials with large distributed residual stresses, rupture is a genuine critical point, i.e., the culmination of a self-organization of damage and cracking characterized by power law signatures. The concept of discrete scale invariance leads to a complex critical exponent (or dimension) and may occur spontaneously in systems and materials developing rupture. It establishes, theoretically, the power law dependence of a measurable observable, such as the rate of acoustic emissions radiated during loading or rate of heat released during the process, upon the time to failure. However, the problem is the power law can be distinguished from other parametric functional forms such as an exponential only close to the critical time. In this paper we modify the functional renormalization method to include the noise elimination procedure and dimension reduction. The aim is to obtain the prediction of the critical rupture time only from the knowledge of the power law parameters at early times prior to rupture, and based on the assumption that the dynamics close to rupture is governed by the power law dependence of the temperature measured along the perimeter of the tube upon the time-to-failure. Such an analysis would not only enhance the precision of prediction related to the rupture mechanism but also significantly help in determining and predicting the leak rates. The prediction will be compared to experimental data on Zr-2.5%Nb made tubes. Note: The views expressed in the paper are those of the authors and do not necessary represents those of the commission. (author)

  19. Advanced LMFBR fuel cladding susceptability to stress corrosion due to reprocessing impurities

    International Nuclear Information System (INIS)

    Henslee, S.P.

    1987-03-01

    The potential degradation of LMFBR fuel cladding alloys by chlorides, when used in metallic fuel systems, was evaluated. The alloys tested were D-9 and HT-9 stainless steels, austenitic and ferritic alloys respectively. These two alloys were tested in parallel with and their performance compared to the austenitic stainless steel Type 316. All alloys were tested for 7400 hours in a stress rupture environment with chloride exposure at either 550/degree/C 650/degree/C. None of the alloys tested were found to exhibit any degradation in time-to-rupture by the presence of chlorides under the conditions imposed during testing. 8 refs., 4 figs., 2 tabs

  20. Rupture Dynamics along Thrust Dipping Fault: Inertia Effects due to Free Surface Wave Interactions

    Science.gov (United States)

    Vilotte, J. P.; Scala, A.; Festa, G.

    2017-12-01

    We numerically investigate the dynamic interaction between free surface and up-dip, in-plane rupture propagation along thrust faults, under linear slip-weakening friction. With reference to shallow along-dip rupture propagation during large subduction earthquakes, we consider here low dip-angle fault configurations with fixed strength excess and depth-increasing initial stress. In this configuration, the rupture undergoes a break of symmetry with slip-induced normal stress perturbations triggered by the interaction with reflected waves from the free surface. We found that both body-waves - behind the crack front - and surface waves - at the crack front - can trigger inertial effects. When waves interact with the rupture before this latter reaches its asymptotic speed, the rupture can accelerate toward the asymptotic speed faster than in the unbounded symmetric case, as a result of these inertial effects. Moreover, wave interaction at the crack front also affects the slip rate generating large ground motion on the hanging wall. Imposing the same initial normal stress, frictional strength and stress drop while varying the static friction coefficient we found that the break of symmetry makes the rupture dynamics dependent on the absolute value of friction. The higher the friction the stronger the inertial effect both in terms of rupture acceleration and slip amount. When the contact condition allows the fault interface to open close to the free surface, the length of the opening zone is shown to depend on the propagation length, the initial normal stress and the static friction coefficient. These new results are shown to agree with analytical results of rupture propagation in bounded media, and open new perspectives for understanding the shallow rupture of large subduction earthquakes and tsunami sources.

  1. Irradiation creep and creep rupture of titanium-modified austenitic stainless steels and their dependence on cold work level

    International Nuclear Information System (INIS)

    Garner, F.A.; Hamilton, M.L.; Eiholzer, C.R.; Toloczko, M.B.; Kumar, A.S.

    1991-11-01

    A titanium-modified austenitic type stainless steel was tested at three cold work levels to determine its creep and creep rupture properties under both thermal aging and neutron irradiation conditions. Both the thermal and irradiation creep behavior exhibit a complex non-monotonic relationship with cold work level that reflects the competition between a number of stress-sensitive and temperature-dependent microstructural processes. Increasing the degree of cold work to 30% from the conventional 20% level was detrimental to its performance, especially for applications above 550 degrees c. The 20% cold work level is preferable to the 10% level, in terms of both in-reactor creep rupture response and initial strength

  2. Morphological and Hemodynamic Discriminators for Rupture Status in Posterior Communicating Artery Aneurysms.

    Directory of Open Access Journals (Sweden)

    Nan Lv

    Full Text Available The conflicting findings of previous morphological and hemodynamic studies on intracranial aneurysm rupture may be caused by the relatively small sample sizes and the variation in location of the patient-specific aneurysm models. We aimed to determine the discriminators for aneurysm rupture status by focusing on only posterior communicating artery (PCoA aneurysms.In 129 PCoA aneurysms (85 ruptured, 44 unruptured, clinical, morphological and hemodynamic characteristics were compared between the ruptured and unruptured cases. Multivariate logistic regression analysis was performed to determine the discriminators for rupture status of PCoA aneurysms.While univariate analyses showed that the size of aneurysm dome, aspect ratio (AR, size ratio (SR, dome-to-neck ratio (DN, inflow angle (IA, normalized wall shear stress (NWSS and percentage of low wall shear stress area (LSA were significantly associated with PCoA aneurysm rupture status. With multivariate analyses, significance was only retained for higher IA (OR = 1.539, p < 0.001 and LSA (OR = 1.393, p = 0.041.Hemodynamics and morphology were related to rupture status of intracranial aneurysms. Higher IA and LSA were identified as discriminators for rupture status of PCoA aneurysms.

  3. Steam generator tube rupture simulation using extended finite element method

    Energy Technology Data Exchange (ETDEWEB)

    Mohanty, Subhasish, E-mail: smohanty@anl.gov; Majumdar, Saurin; Natesan, Ken

    2016-08-15

    Highlights: • Extended finite element method used for modeling the steam generator tube rupture. • Crack propagation is modeled in an arbitrary solution dependent path. • The FE model is used for estimating the rupture pressure of steam generator tubes. • Crack coalescence modeling is also demonstrated. • The method can be used for crack modeling of tubes under severe accident condition. - Abstract: A steam generator (SG) is an important component of any pressurized water reactor. Steam generator tubes represent a primary pressure boundary whose integrity is vital to the safe operation of the reactor. SG tubes may rupture due to propagation of a crack created by mechanisms such as stress corrosion cracking, fatigue, etc. It is thus important to estimate the rupture pressures of cracked tubes for structural integrity evaluation of SGs. The objective of the present paper is to demonstrate the use of extended finite element method capability of commercially available ABAQUS software, to model SG tubes with preexisting flaws and to estimate their rupture pressures. For the purpose, elastic–plastic finite element models were developed for different SG tubes made from Alloy 600 material. The simulation results were compared with experimental results available from the steam generator tube integrity program (SGTIP) sponsored by the United States Nuclear Regulatory Commission (NRC) and conducted at Argonne National Laboratory (ANL). A reasonable correlation was found between extended finite element model results and experimental results.

  4. Steam generator tube rupture simulation using extended finite element method

    International Nuclear Information System (INIS)

    Mohanty, Subhasish; Majumdar, Saurin; Natesan, Ken

    2016-01-01

    Highlights: • Extended finite element method used for modeling the steam generator tube rupture. • Crack propagation is modeled in an arbitrary solution dependent path. • The FE model is used for estimating the rupture pressure of steam generator tubes. • Crack coalescence modeling is also demonstrated. • The method can be used for crack modeling of tubes under severe accident condition. - Abstract: A steam generator (SG) is an important component of any pressurized water reactor. Steam generator tubes represent a primary pressure boundary whose integrity is vital to the safe operation of the reactor. SG tubes may rupture due to propagation of a crack created by mechanisms such as stress corrosion cracking, fatigue, etc. It is thus important to estimate the rupture pressures of cracked tubes for structural integrity evaluation of SGs. The objective of the present paper is to demonstrate the use of extended finite element method capability of commercially available ABAQUS software, to model SG tubes with preexisting flaws and to estimate their rupture pressures. For the purpose, elastic–plastic finite element models were developed for different SG tubes made from Alloy 600 material. The simulation results were compared with experimental results available from the steam generator tube integrity program (SGTIP) sponsored by the United States Nuclear Regulatory Commission (NRC) and conducted at Argonne National Laboratory (ANL). A reasonable correlation was found between extended finite element model results and experimental results.

  5. Performa Inhibitory Control dengan Induksi Sing-a-Song Stress Test pada Dewasa Awal

    Directory of Open Access Journals (Sweden)

    Akhmad Kurniawan

    2018-04-01

    Full Text Available Inhibitory control is able to control attention by inhibiting internal tendencies and external influences. Inhibitory control is controlled by dorsolateral prefrontal cortex and anterior cingulate cortex, that can be affected by stress variable. Sing-a-Song Stress Test (SSST is a current method to induce stress that has never been practiced in study of inhibitory control. This study aimed to determine the effect of SSST against inhibitory control in early adult. Between subjects design was applied in this study. A number of 35 participants with age range from 17 to 21 years old were randomly assigned into experimental group (n = 17 and control group (n = 18. Inhibitory control was measured using Computerized Stroop Color-Word Test (CSCWT. Positive Affect and Negative Affect Schedule (PANAS was used to conduct a manipulation check. Independent-Samples T Test explained no significant effect of stress on inhibitory control (t = -0,117; p > 0,05.

  6. Hysteresis analysis of graphene transistor under repeated test and gate voltage stress

    International Nuclear Information System (INIS)

    Yang Jie; Jia Kunpeng; Su Yajuan; Zhao Chao; Chen Yang

    2014-01-01

    The current transport characteristic is studied systematically based on a back-gate graphene field effect transistor, under repeated test and gate voltage stress. The interface trapped charges caused by the gate voltage sweep process screens the gate electric field, and results in the neutral point voltage shift between the forth and back sweep direction. In the repeated test process, the neutral point voltage keeps increasing with test times in both forth and back sweeps, which indicates the existence of interface trapped electrons residual and accumulation. In gate voltage stress experiment, the relative neutral point voltage significantly decreases with the reducing of stress voltage, especially in −40 V, which illustrates the driven-out phenomenon of trapped electrons under negative voltage stress. (semiconductor devices)

  7. Creep-rupture-strength and creep-behaviour of stainless steel X6CrNi 1811 (DIN 1.4948)

    International Nuclear Information System (INIS)

    Solano, R.R.; Rivas, M. de las; Seith, B.; Schirra, M.

    1977-01-01

    The steel X6CrNi 1811 (DIN 1.4948) that will be used as a structure material for the german fast breder reactor SNR 300, was creep-tested in a temperature range of 550-650 deg C under base material condition as well as welded material condition. Tests are foreseen up to 30.000 hours with a continous measuring of the elongation. The test results up to about 4.000 hours is described. Taking into account the results of other programs carried out with the same material between 550 and 600 deg C at similar rupture time, were defined the stresses for the longterm test. The main point of this program (''Extrapolation Program'') lies in the knowledge of the creep-rupture-strength and creep behaviour of the structure materials up to 3.10 4 h at high temperature in order to extrapolate up to 10 5 h for reactor operating temperatures. (author) [es

  8. Physics of Earthquake Rupture Propagation

    Science.gov (United States)

    Xu, Shiqing; Fukuyama, Eiichi; Sagy, Amir; Doan, Mai-Linh

    2018-05-01

    A comprehensive understanding of earthquake rupture propagation requires the study of not only the sudden release of elastic strain energy during co-seismic slip, but also of other processes that operate at a variety of spatiotemporal scales. For example, the accumulation of the elastic strain energy usually takes decades to hundreds of years, and rupture propagation and termination modify the bulk properties of the surrounding medium that can influence the behavior of future earthquakes. To share recent findings in the multiscale investigation of earthquake rupture propagation, we held a session entitled "Physics of Earthquake Rupture Propagation" during the 2016 American Geophysical Union (AGU) Fall Meeting in San Francisco. The session included 46 poster and 32 oral presentations, reporting observations of natural earthquakes, numerical and experimental simulations of earthquake ruptures, and studies of earthquake fault friction. These presentations and discussions during and after the session suggested a need to document more formally the research findings, particularly new observations and views different from conventional ones, complexities in fault zone properties and loading conditions, the diversity of fault slip modes and their interactions, the evaluation of observational and model uncertainties, and comparison between empirical and physics-based models. Therefore, we organize this Special Issue (SI) of Tectonophysics under the same title as our AGU session, hoping to inspire future investigations. Eighteen articles (marked with "this issue") are included in this SI and grouped into the following six categories.

  9. The "moving valgus stress test" for medial collateral ligament tears of the elbow.

    Science.gov (United States)

    O'Driscoll, Shawn W M; Lawton, Richard L; Smith, Adam M

    2005-02-01

    The diagnosis of a painful partial tear of the medial collateral ligament in overhead-throwing athletes is challenging, even for experienced elbow surgeons and despite the use of sophisticated imaging techniques. The "moving valgus stress test" is an accurate physical examination technique for diagnosis of medial collateral ligament attenuation in the elbow. Cohort study (diagnosis); Level of evidence, 2. Twenty-one patients underwent surgical intervention for medial elbow pain due to medial collateral ligament insufficiency or other abnormality of chronic valgus overload, and they were assessed preoperatively with an examination called the moving valgus stress test. To perform the moving valgus stress test, the examiner applies and maintains a constant moderate valgus torque to the fully flexed elbow and then quickly extends the elbow. The test is positive if the medial elbow pain is reproduced at the medial collateral ligament and is at maximum between 120 degrees and 70 degrees. The moving valgus stress test was highly sensitive (100%, 17 of 17 patients) and specific (75%, 3 of 4 patients) when compared to assessment of the medial collateral ligament by surgical exploration or arthroscopic valgus stress testing. The mean shear range (ie, the arc within which pain was produced with the moving valgus stress test) was 120 degrees to 70 degrees. The mean angle at which pain was at a maximum was 90 degrees of elbow flexion. The moving valgus stress test is an accurate physical examination technique that, when performed and interpreted correctly, is highly sensitive for medial elbow pain arising from the medial collateral ligament.

  10. Stress-Dilatancy of Cambria Sand for Triaxial Tests at High Pressures

    Science.gov (United States)

    Szypcio, Zenon

    2017-12-01

    In this paper, the stress-dilatancy relationship of Cambria sand for drained triaxial compression and extension tests at high stress level is investigated. The stress dilatancy relationship is obtained by use of frictional state theory and experimental tests data published in literature. It is shown that stress-dilatancy relationship is bilinear, described by three parameters of frictional state theory: critical frictional angle and two other parameters. It is accepted that critical friction angle is independent of confining pressure. The two additional parameters are strongly dependent on confining pressure and different for initial and advanced stages. The point at which the values of these parameters change is termed as Transformation Shear Point. This point is not simply visible either in stress ratio-strain or the volume strain-shear strain relationship which are traditionally shown in soil mechanics papers. Transformation Shear Point is very characteristic in stress ratio-plastic dilatancy plane. Thus, stress ratio- plastic dilatancy is very important for describing stress-strain behaviour of soils. The relationship shown in the paper can be used in soil modelling in the future.

  11. Unconscious fearful priming followed by a psychosocial stress test results in higher cortisol levels.

    Science.gov (United States)

    Hänsel, Alexander; von Känel, Roland

    2013-10-01

    Human perception of stress includes an automatic pathway that processes subliminal presented stimuli below the threshold of conscious awareness. Subliminal stimuli can therefore activate the physiologic stress system. Unconscious emotional signals were shown to significantly moderate reactions and responses to subsequent stimuli, an effect called 'priming'. We hypothesized that subliminal presentation of a fearful signal during the Stroop task compared with an emotionally neutral one will prime stress reactivity in a subsequently applied psychosocial stress task, thereby yielding a significant increase in salivary cortisol. Half of 36 participants were repeatedly presented either a fearful face or a neutral one. After this, all underwent a psychosocial stress task. The fearful group showed a significant increase in cortisol levels (p = 0.022). This change was not affected by sex, age and body mass index, and it also did not change when taking resting cortisol levels into account. Post-hoc analyses showed that the increase in cortisol in the fearful group started immediately after the psychosocial stress test. Hence, subliminal exposure to a fearful signal in combination with the Stroop and followed by a psychosocial stress test leads to an increase in stress reactivity. Copyright © 2012 John Wiley & Sons, Ltd.

  12. MDMA does not alter responses to the Trier Social Stress Test in humans.

    Science.gov (United States)

    Bershad, Anya K; Miller, Melissa A; de Wit, Harriet

    2017-07-01

    ±3,4-Methylenedioxymethamphetamine (MDMA, "ecstasy") is a stimulant-psychedelic drug with unique social effects. It may dampen reactivity to negative social stimuli such as social threat and rejection. Perhaps because of these effects, MDMA has shown promise as a treatment for post-traumatic stress disorder (PTSD). However, the effect of single doses of MDMA on responses to an acute psychosocial stressor has not been tested. In this study, we sought to test the effects of MDMA on responses to stress in healthy adults using a public speaking task. We hypothesized that the drug would reduce responses to the stressful task. Volunteers (N = 39) were randomly assigned to receive placebo (N = 13), 0.5 mg/kg MDMA (N = 13), or 1.0 mg/kg MDMA (N = 13) during a stress and a no-stress session. Dependent measures included subjective reports of drug effects and emotional responses to the task, as well as salivary cortisol, heart rate, and blood pressure. The stress task produced its expected increase in physiological responses (cortisol, heart rate) and subjective ratings of stress in all three groups, and MDMA produced its expected subjective and physiological effects. MDMA alone increased ratings of subjective stress, heart rate, and saliva cortisol concentrations, but contrary to our hypothesis, it did not moderate responses to the Trier Social Stress Test. Despite its efficacy in PTSD and anxiety, MDMA did not reduce either the subjective or objective responses to stress in this controlled study. The conditions under which MDMA relieves responses to negative events or memories remain to be determined.

  13. 3-D Spontaneous Rupture Simulations of the 2016 Kumamoto, Japan, Earthquake

    Science.gov (United States)

    Urata, Yumi; Yoshida, Keisuke; Fukuyama, Eiichi

    2017-04-01

    We investigated the M7.3 Kumamoto, Japan, earthquake to illuminate why and how the rupture of the main shock propagated successfully by 3-D dynamic rupture simulations, assuming a complicated fault geometry estimated based on the distributions of aftershocks. The M7.3 main shock occurred along the Futagawa and Hinagu faults. A few days before, three M6-class foreshocks occurred. Their hypocenters were located along by the Hinagu and Futagawa faults and their focal mechanisms were similar to those of the main shock; therefore, an extensive stress shadow can have been generated on the fault plane of the main shock. First, we estimated the geometry of the fault planes of the three foreshocks as well as that of the main shock based on the temporal evolution of relocated aftershock hypocenters. Then, we evaluated static stress changes on the main shock fault plane due to the occurrence of the three foreshocks assuming elliptical cracks with constant stress drops on the estimated fault planes. The obtained static stress change distribution indicated that the hypocenter of the main shock is located on the region with positive Coulomb failure stress change (ΔCFS) while ΔCFS in the shallow region above the hypocenter was negative. Therefore, these foreshocks could encourage the initiation of the main shock rupture and could hinder the rupture propagating toward the shallow region. Finally, we conducted 3-D dynamic rupture simulations of the main shock using the initial stress distribution, which was the sum of the static stress changes by these foreshocks and the regional stress field. Assuming a slip-weakening law with uniform friction parameters, we conducted 3-D dynamic rupture simulations by varying the friction parameters and the values of the principal stresses. We obtained feasible parameter ranges to reproduce the rupture propagation of the main shock consistent with those revealed by seismic waveform analyses. We also demonstrated that the free surface encouraged

  14. [Effects of psychological stress on performances in open-field test of rats and tyrosine's modulation].

    Science.gov (United States)

    Chen, Wei-Qiang; Cheng, Yi-Yong; Li, Shu-Tian; Hong, Yan; Wang, Dong-Lan; Hou, Yue

    2009-02-01

    To explore the effects of different doses of tyrosine modulation on behavioral performances in open field test of psychological stress rats. The animal model of psychological stress was developed by restraint stress for 21 days. Wistar rats were randomly assigned to five groups (n = 10) as follows: control group (CT), stress control group (SCT), low, medium and high-doses of tyrosine modulation stress groups (SLT, SMT and SIT). The changes of behavioral performances were examined by open-field test. Serum levels of cortisol, norepinephrine and dopamine were also detected. The levels of serum cortisol were all increased obviously in the four stress groups, and their bodyweight gainings were diminished. The behavioral performances of SCT rats in open-field test were changed significantly in contrast to that of CT rats. However, The behavioral performances of SMT and SHT rats were not different from that of CT rats. In addition, the serum levels of norepinephrine and dopamine were downregulated obviously in SCT and SLT groups, and no differences were observed in other groups. Psychological stress can impair body behavioral performances, and moderate tyrosine modulation may improve these abnormal changes. The related mechanisms may be involved with the changes of norepinephrine and dopamine.

  15. Stress transmission through Ti-Ni alloy, titanium and stainless steel in impact compression test.

    Science.gov (United States)

    Yoneyama, T; Doi, H; Kobayashi, E; Hamanaka, H; Tanabe, Y; Bonfield, W

    2000-06-01

    Impact stress transmission of Ti-Ni alloy was evaluated for biomedical stress shielding. Transformation temperatures of the alloy were investigated by means of DSC. An impact compression test was carried out with use of split-Hopkinson pressure-bar technique with cylindrical specimens of Ti-Ni alloy, titanium and stainless steel. As a result, the transmitted pulse through Ti-Ni alloy was considerably depressed as compared with those through titanium and stainless steel. The initial stress reduction was large through Ti-Ni alloy and titanium, but the stress reduction through Ti-Ni alloy was more continuous than titanium. The maximum value in the stress difference between incident and transmitted pulses through Ti-Ni alloy or titanium was higher than that through stainless steel, while the stress reduction in the maximum stress through Ti-Ni alloy was statistically larger than that through titanium or stainless steel. Ti-Ni alloy transmitted less impact stress than titanium or stainless steel, which suggested that the loading stress to adjacent tissues could be decreased with use of Ti-Ni alloy as a component material in an implant system. Copyright 2000 Kluwer Academic Publishers

  16. Results of fatigue tests and prediction of fatigue life under superposed stress wave and combined superposed stress wave

    International Nuclear Information System (INIS)

    Takasugi, Shunji; Horikawa, Takeshi; Tsunenari, Toshiyasu; Nakamura, Hiroshi

    1983-01-01

    In order to examine fatigue life prediction methods at high temperatures where creep damage need not be taken into account, fatigue tests were carried out on plane bending specimens of alloy steels (SCM 435, 2 1/4Cr-1Mo) under superposed and combined superposed stress waves at room temperature and 500 0 C. The experimental data were compared with the fatigue lives predicted by using the cycle counting methods (range pair, range pair mean and zero-cross range pair mean methods), the modified Goodman's equation and the modified Miner's rule. The main results were as follows. (1) The fatigue life prediction method which is being used for the data at room temperature is also applicable to predict the life at high temperatures. The range pair mean method is especially better than other cycle counting methods. The zero-cross range pair mean method gives the estimated lives on the safe side of the experimental lives. (2) The scatter bands of N-bar/N-barsub(es) (experimental life/estimated life) becomes narrower when the following equation is used instead of the modified Goodman's equation for predicting the effect of mean stress on fatigue life. σ sub(t) = σ sub(a) / (1 - Sigma-s sub(m) / kσ sub(B)) σ sub(t); stress amplitude at zero mean stress (kg/mm 2 ) σ sub(B); tensile strength (kg/mm 2 ) σ sub(m); mean stress (kg/mm 2 ) σ sub(a); stress amplitude (kg/mm 2 ) k; modified coefficient of σ sub(B) (author)

  17. Critical Review of EU Nuclear Stress Tests in Bulgaria, Hungary, Romania and Ukraine

    International Nuclear Information System (INIS)

    Becker, O.; Lorenz, P.; Wallner, A.

    2012-01-01

    In March 2011, the core melt accidents at the Fukushima Daiichi 1 nuclear power plant (NPP) showed the world that the nuclear industry cannot prevent severe accidents from happening. The accidents in Japan proved that highly unlikely accidents cannot be excluded. The Fukushima accident confirmed the mistrust towards nuclear power among the Japanese but also European citizens. In reaction to the devastating nuclear disaster in Japan the European Council concluded in March 2011, that the safety of all EU nuclear plants should be reviewed on the basis of a comprehensive and transparent risk and safety assessment ('stress tests'). The EU Nuclear Safety Regulators Group – ENSREG took over the task to provide a “targeted reassessment of the safety margins of nuclear power plants”, thus examining whether the safety margins which were used in the licensing of NPPs are sufficient to cover unexpected events. It is important to understand that the stress tests could not take into account all key safety issues such as the capability to prevent accidents - the scope of the stress tests defined by ENSREG didn´t promise to deliver a comprehensive risk and safety assessment. According to some observers the stress tests were mainly set up to improve the confidence in the safety of European NPPs. Nevertheless, the stress tests provided some interesting findings concerning safety: This study assesses the safety of the nuclear power plants in Bulgaria, Hungary, Romania and the Ukraine. The introduction contains an overview of the content and procedure of the stress tests. This “Critical Review of the Stress Tests” is based on the national stress tests reports written by the national nuclear safety authorities and on the Peer review country reports attached to the Peer review report - Stress tests performed on European nuclear power plants written by the Peer review Teams, the Peer Review Board respectively, and endorsed by ENSREG [ENSREG 2012a, ENSREG 2012c]. It

  18. Critical Review of EU Nuclear Stress Tests in Bulgaria, Hungary, Romania and Ukraine

    Energy Technology Data Exchange (ETDEWEB)

    Becker, O.; Lorenz, P.; Wallner, A.

    2012-07-01

    In March 2011, the core melt accidents at the Fukushima Daiichi 1 nuclear power plant (NPP) showed the world that the nuclear industry cannot prevent severe accidents from happening. The accidents in Japan proved that highly unlikely accidents cannot be excluded. The Fukushima accident confirmed the mistrust towards nuclear power among the Japanese but also European citizens. In reaction to the devastating nuclear disaster in Japan the European Council concluded in March 2011, that the safety of all EU nuclear plants should be reviewed on the basis of a comprehensive and transparent risk and safety assessment ('stress tests'). The EU Nuclear Safety Regulators Group – ENSREG took over the task to provide a “targeted reassessment of the safety margins of nuclear power plants”, thus examining whether the safety margins which were used in the licensing of NPPs are sufficient to cover unexpected events. It is important to understand that the stress tests could not take into account all key safety issues such as the capability to prevent accidents - the scope of the stress tests defined by ENSREG didn´t promise to deliver a comprehensive risk and safety assessment. According to some observers the stress tests were mainly set up to improve the confidence in the safety of European NPPs. Nevertheless, the stress tests provided some interesting findings concerning safety: This study assesses the safety of the nuclear power plants in Bulgaria, Hungary, Romania and the Ukraine. The introduction contains an overview of the content and procedure of the stress tests. This “Critical Review of the Stress Tests” is based on the national stress tests reports written by the national nuclear safety authorities and on the Peer review country reports attached to the Peer review report - Stress tests performed on European nuclear power plants written by the Peer review Teams, the Peer Review Board respectively, and endorsed by ENSREG [ENSREG 2012a, ENSREG 2012c]. It continues

  19. Laser-accelerated particle beams for stress testing of materials.

    Science.gov (United States)

    Barberio, M; Scisciò, M; Vallières, S; Cardelli, F; Chen, S N; Famulari, G; Gangolf, T; Revet, G; Schiavi, A; Senzacqua, M; Antici, P

    2018-01-25

    Laser-driven particle acceleration, obtained by irradiation of a solid target using an ultra-intense (I > 10 18  W/cm 2 ) short-pulse (duration testing materials and are particularly suited for identifying materials to be used in harsh conditions. We show that these laser-generated protons can produce, in a very short time scale, a strong mechanical and thermal damage, that, given the short irradiation time, does not allow for recovery of the material. We confirm this by analyzing changes in the mechanical, optical, electrical, and morphological properties of five materials of interest to be used in harsh conditions.

  20. Voltage stress effects on microcircuit accelerated life test failure rates

    Science.gov (United States)

    Johnson, G. M.

    1976-01-01

    The applicability of Arrhenius and Eyring reaction rate models for describing microcircuit aging characteristics as a function of junction temperature and applied voltage was evaluated. The results of a matrix of accelerated life tests with a single metal oxide semiconductor microcircuit operated at six different combinations of temperature and voltage were used to evaluate the models. A total of 450 devices from two different lots were tested at ambient temperatures between 200 C and 250 C and applied voltages between 5 Vdc and 15 Vdc. A statistical analysis of the surface related failure data resulted in bimodal failure distributions comprising two lognormal distributions; a 'freak' distribution observed early in time, and a 'main' distribution observed later in time. The Arrhenius model was shown to provide a good description of device aging as a function of temperature at a fixed voltage. The Eyring model also appeared to provide a reasonable description of main distribution device aging as a function of temperature and voltage. Circuit diagrams are shown.

  1. Strain rate effect on fault slip and rupture evolution: Insight from meter-scale rock friction experiments

    Science.gov (United States)

    Xu, Shiqing; Fukuyama, Eiichi; Yamashita, Futoshi; Mizoguchi, Kazuo; Takizawa, Shigeru; Kawakata, Hironori

    2018-05-01

    We conduct meter-scale rock friction experiments to study strain rate effect on fault slip and rupture evolution. Two rock samples made of Indian metagabbro, with a nominal contact dimension of 1.5 m long and 0.1 m wide, are juxtaposed and loaded in a direct shear configuration to simulate the fault motion. A series of experimental tests, under constant loading rates ranging from 0.01 mm/s to 1 mm/s and under a fixed normal stress of 6.7 MPa, are performed to simulate conditions with changing strain rates. Load cells and displacement transducers are utilized to examine the macroscopic fault behavior, while high-density arrays of strain gauges close to the fault are used to investigate the local fault behavior. The observations show that the macroscopic peak strength, strength drop, and the rate of strength drop can increase with increasing loading rate. At the local scale, the observations reveal that slow loading rates favor generation of characteristic ruptures that always nucleate in the form of slow slip at about the same location. In contrast, fast loading rates can promote very abrupt rupture nucleation and along-strike scatter of hypocenter locations. At a given propagation distance, rupture speed tends to increase with increasing loading rate. We propose that a strain-rate-dependent fault fragmentation process can enhance the efficiency of fault healing during the stick period, which together with healing time controls the recovery of fault strength. In addition, a strain-rate-dependent weakening mechanism can be activated during the slip period, which together with strain energy selects the modes of fault slip and rupture propagation. The results help to understand the spectrum of fault slip and rock deformation modes in nature, and emphasize the role of heterogeneity in tuning fault behavior under different strain rates.

  2. Effect of Mindfulness Meditation on Perceived Stress Scores and Autonomic Function Tests of Pregnant Indian Women.

    Science.gov (United States)

    Muthukrishnan, Shobitha; Jain, Reena; Kohli, Sangeeta; Batra, Swaraj

    2016-04-01

    Various pregnancy complications like hypertension, preeclampsia have been strongly correlated with maternal stress. One of the connecting links between pregnancy complications and maternal stress is mind-body intervention which can be part of Complementary and Alternative Medicine (CAM). Biologic measures of stress during pregnancy may get reduced by such interventions. To evaluate the effect of Mindfulness meditation on perceived stress scores and autonomic function tests of pregnant Indian women. Pregnant Indian women of 12 weeks gestation were randomised to two treatment groups: Test group with Mindfulness meditation and control group with their usual obstetric care. The effect of Mindfulness meditation on perceived stress scores and cardiac sympathetic functions and parasympathetic functions (Heart rate variation with respiration, lying to standing ratio, standing to lying ratio and respiratory rate) were evaluated on pregnant Indian women. There was a significant decrease in perceived stress scores, a significant decrease of blood pressure response to cold pressor test and a significant increase in heart rate variability in the test group (pwomen. The results of this study suggest that mindfulness meditation improves parasympathetic functions in pregnant women and is a powerful modulator of the sympathetic nervous system during pregnancy.

  3. Creep rupture strength and creep behavior of low-activation martensitic OPTIFER alloys. Final report

    International Nuclear Information System (INIS)

    Schirra, M.; Falkenstein, A.; Heger, S.; Lapena, J.

    2001-07-01

    The creep rupture strength and creep experiments performed on low-activation OPTIFER alloys in the temperature range of 450-700 C shall be summarized in the present report. Together with the reference alloy of the type 9.5Cr1W-Mn-V-Ta, W-free variants (+Ge) with a more favorable activation and decay behavior shall be studied. Their smaller strength values are compensated by far better toughness characteristics. Of each development line, several batches of slightly varying chemical composition have been investigated over service lives of up to 40,000 h. Apart from the impact of a reference thermal treatment at a hardening temperature of 1075 C and an annealing temperature of 750 C, the influence of reduced hardening temperatures (up to 950 C) has been determined. A long-term use at increased temperatures (max. 550 C-20,000 h) produces an aging effect with strength being decreased in the annealed state. To determine this aging effect quantitatively, creep rupture experiments have been performed using specimens that were subjected to variable types of T/t annealing (550 -650 C, 330-5000 h). Based on all test results, minimum values for the 1% time-strain limit and creep rupture in the T range of 400-600 C can be given as design curves for 20,000 h. The minimum creep rates obtained from the creep curves recorded as a function of the experimental stress yield the stress exponent n (n=Norton) for the individual test temperatures. Creep behavior as a function of the test temperature yields the values for the effective activation energy of creeping Q K . The influence of a preceding temperature transient up to 800 C (≤Ac 1b ) or 840 C (>Ac 1b ) with subsequent creep rupture tests at 500 C and 550 C, respectively, shall be described. The results obtained for the OPTIFER alloys shall be compared with the results achieved for the Japanese 2% W-containing F82H-mod. alloy. (orig.) [de

  4. Simultaneous bilateral patellar tendon rupture.

    Science.gov (United States)

    Moura, Diogo Lino; Marques, José Pedro; Lucas, Francisco Manuel; Fonseca, Fernando Pereira

    2017-01-01

    Bilateral patellar tendon rupture is a rare entity, often associated with systemic diseases and patellar tendinopathy. The authors report a rare case of a 34-year-old man with simultaneous bilateral rupture of the patellar tendon caused by minor trauma. The patient is a retired basketball player with no past complaints of chronic knee pain and a history of steroid use. Surgical management consisted in primary end-to-end tendon repair protected temporarily with cerclage wiring, followed by a short immobilization period and intensive rehabilitation program. Five months after surgery, the patient was able to fully participate in sport activities.

  5. Simultaneous bilateral patellar tendon rupture

    Directory of Open Access Journals (Sweden)

    Diogo Lino Moura

    Full Text Available ABSTRACT Bilateral patellar tendon rupture is a rare entity, often associated with systemic diseases and patellar tendinopathy. The authors report a rare case of a 34-year-old man with simultaneous bilateral rupture of the patellar tendon caused by minor trauma. The patient is a retired basketball player with no past complaints of chronic knee pain and a history of steroid use. Surgical management consisted in primary end-to-end tendon repair protected temporarily with cerclage wiring, followed by a short immobilization period and intensive rehabilitation program. Five months after surgery, the patient was able to fully participate in sport activities.

  6. Spontaneous rupture of vaginal enterocele

    DEFF Research Database (Denmark)

    Svendsen, J H; Galatius, H; Hansen, P K

    1985-01-01

    Spontaneous rupture of an enterocele is a rare complication. Only 24 cases including the present case have been reported in the literature. The patients were elderly and had had at least one vaginal operation. The patients were remarkably unaffected symptomatically on admission.......Spontaneous rupture of an enterocele is a rare complication. Only 24 cases including the present case have been reported in the literature. The patients were elderly and had had at least one vaginal operation. The patients were remarkably unaffected symptomatically on admission....

  7. Rupture luminescence from natural fibers

    Science.gov (United States)

    Li, W.; Haneman, D.

    1999-12-01

    Fibers of cotton and wool, and samples of paper, have been ruptured in tension in vacuum and in air, and give detectable luminescence in the visible range. All have a common emission peak at around 2.0 eV, which is ascribed to the deexcitation of states excited by the rupture of organic chain molecule bonds. Rubber bands give stronger emission in air, but no emission in vacuum, suggesting the material breaks only at weak interchain bonds. Mohair, cat, and horse hair also give emission in air. The phenomena reveal effects that would occur widely in nature.

  8. Model test study on propagation law of plane stress wave in jointed rock mass under different in-situ stresses

    Science.gov (United States)

    Dong, Qian

    2017-12-01

    The study of propagation law of plane stress wave in jointed rock mass under in-situ stress has important significance for safety excavation of underground rock mass engineering. A model test of the blasting stress waves propagating in the intact rock and jointed rock mass under different in-situ stresses was carried out, and the influencing factors on the propagation law, such as the scale of static loads and the number of joints were studied respectively. The results show that the transmission coefficient of intact rock is larger than that of jointed rock mass under the same loading condition. With the increase of confining pressure, the transmission coefficients of intact rock and jointed rock mass both show an trend of increasing first and then decreasing, and the variation of transmission coefficients in intact rock is smaller than that of jointed rock mass. Transmission coefficient of jointed rock mass decreases with the increase of the number of joints under the same loading condition, when the confining pressure is relatively small, the reduction of transmission coefficients decreases with the increasing of the number of joints, and the variation law of the reduction of transmission coefficients is contrary when the confining pressure is large.

  9. A Study on the Storage Reliability of LSINS Based on Step-stress Accelerated Life Test

    Directory of Open Access Journals (Sweden)

    Teng Fei

    2015-01-01

    Full Text Available Based on the step-stress accelerated life test and the laser strap-down inertial navigation system, this paper studies the accelerated life model and the test method, provides the likelihood function, the likelihood equation and the two-order derivative when the stress level is k, evaluates the effectiveness of the method with the simulation test model established by MATLAB, applies the research findings in the storage reliability study of the XX laser strap-down inertial navigation system, and puts forward an effective evaluation method of the storage life of the inertial navigation system.

  10. Standard test method for calibration of surface/stress measuring devices

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1997-01-01

    Return to Contents page 1.1 This test method covers calibration or verification of calibration, or both, of surface-stress measuring devices used to measure stress in annealed and heat-strengthened or tempered glass using polariscopic or refractometry based principles. 1.2 This test method is nondestructive. 1.3 This test method uses transmitted light, and therefore, is applicable to light-transmitting glasses. 1.4 This test method is not applicable to chemically tempered glass. 1.5 Using the procedure described, surface stresses can be measured only on the “tin” side of float glass. 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  11. Predischarge stress test after myocardial infarction in the old stage : results and prognostic value

    NARCIS (Netherlands)

    P.M. Fioretti (Paolo); J.W. Deckers (Jaap); R.W. Brower (Ronald); M.L. Simoons (Maarten); J.A.J.M. Beelen; P.G. Hugenholtz (Paul)

    1984-01-01

    textabstractThe aim of this study was to evaluate the results of predischarge stress testing in the elderly, and to assess the prognostic value of the test during one-year follow-up. The database consisted of 48 patients older than 64 years of age and 109 patients 55-64 years of age, who survived

  12. Analysis of 30 breast implant rupture cases.

    Science.gov (United States)

    Tark, Kwan Chul; Jeong, Hii Sun; Roh, Tae Suk; Choi, Jong Woo

    2005-01-01

    Breast implants used for augmentation mammoplasty or breast reconstruction could rupture from various causes such as trauma or spontaneous failure. The objectives of this study were to investigate the relationships between the causes of implant rupture and the degree of capsular contracture, and then to evaluate the relative efficacies of specific signs on magnetic resonance imaging (MRI) known to be beneficial for diagnosing the rupture. A retrospective review identified patients with prosthetic implant rupture or impending rupture treated by the senior author. The 30 cases of implant rupture available for review were classified into two groups: intracapsular and extracapsular ruptures. The 30 cases of breast implant ruptures were analyzed with respect to the clinical symptoms and signs, the causes of rupture, the degree of capsular contracture, and therapeutic plans. Among the 30 cases, 14 patients who had undergone MRI during the diagnostic period were analyzed with respect to the relationships between MRI readings and operative findings. Spontaneous rupture of membranes was most common (80%), followed by failure because of trauma (7%) and valve or implant base (4%). The symptoms during implant rupture were contour deformity, palpated mass-like lesions, pain, and focal inflammation. According to the analysis of specific MRI signs, the sensitivity and specificity of the linguine sign were 87% and 100%, respectively, for intracapsular rupture. For extracapsular rupture, the sensitivity and specificity of the linguine sign were, respectively, 67% and 75%. The sensitivity and specificity of the rat-tail sign and tear drop sign were 14% and 50%, respectively. Breast implant rupture was correlated with the degree of capsular contracture in our study. Among the various specific MRI signs used in diagnosing the rupture, the linguine sign was reliable and had a high sensitivity and specificity, especially in cases of intracapsular rupture. On the other hand, the rat

  13. Rupture of Achilles Tendon : Usefulness of Ultrasonography

    International Nuclear Information System (INIS)

    Kim, Nam Hyeon; Ki, Won Woo; Yoon, Kwon Ha; Kim, Song Mun; Shin, Myeong Jin; Kwon, Soon Tae

    1996-01-01

    To differentiate a complete rupture of Achilles tendon from an incomplete one which is important because its treatment is quite different. And it is necessary to know the exact site of the rupture preoperatively. Fifteen cases of fourteen patients which were diagnosed as Achilles tendon rupture by ultrasonography and surgery were reviewed. We compared sonographic rupture site with surgical findings. Ultrasonographic criteria for differentiation of complete and incomplete rupture was defined as follows : the discreteness, which means the proximal intervening hypoechogenicity to the interface echogenicity of distal margin of ruptured tendon : the slant sign, which represents the interface of ruptured distal margin which was seen over the 3/4 of the thickness of the tendon without intervening low echogeneicity : the invagination sign, which means the echogenic invagination from Kager triangle into posterior aspect of Achilles tendon over the half thickness of the tendon. The sites of complete tendon rupture were exactly corresponded to surgical finding in four cases of ten complete ruptures. And the discrepancy between sonographic and surgical findings in the site of complete rupture was 1.2 ± 0.4 cm in six cases. Three of ten complete ruptures showed the discreteness sign, all of ten showed the slant sign and two of ten showed the invagination sign. It is helpful to differentiate a complete from incomplete rupture of the Achilles tendon and to localize the site of the complete rupture with the ultrasonographic evaluation

  14. Tests on mechanical behavior of 304 L stainless steel under constant stress associated with cyclic strain

    International Nuclear Information System (INIS)

    Lebey, J.; Roche, R.

    1979-01-01

    Mechanical analyses of structures, to be efficient, must incorporate materials behavior data. Among the mechanisms liable to cause collapse, progressive distortion (or ratcheting) has been the subject of only a few basic experiments, most of the investigations being theoretical. In order to get meaningful results to characterize materials behavior, an experimental study on ratcheting of austenitic steels has been undertaken at the C.E.A. This paper gives the first results of tests at room temperature on thin tubes of 304L steel submitted to an axial constant stress (primary stress) to which is added a cyclic shearing strain (secondary stress). The tests cover a large combination of the two loading modes. The main results consist of curves of cumulative iso-deformation in the primary and secondary stress field (Bree type diagrams). Results are given for plastic deformations ranging from 0.1 to 2.5% up to N=100 cycles

  15. Stress Corrosion Cracking of Steel and Aluminum in Sodium Hydroxide: Field Failure and Laboratory Test

    Directory of Open Access Journals (Sweden)

    Y. Prawoto

    2012-01-01

    Full Text Available Through an investigation of the field failure analysis and laboratory experiment, a study on (stress corrosion cracking SCC behavior of steel and aluminum was performed. All samples were extracted from known operating conditions from the field failures. Similar but accelerated laboratory test was subsequently conducted in such a way as to mimic the field failures. The crack depth and behavior of the SCC were then analyzed after the laboratory test and the mechanism of stress corrosion cracking was studied. The results show that for the same given stress relative to ultimate tensile strength, the susceptibility to SCC is greatly influenced by heat treatment. Furthermore, it was also concluded that when expressed relative to the (ultimate tensile strength UTS, aluminum has similar level of SCC susceptibility to that of steel, although with respect to the same absolute value of applied stress, aluminum is more susceptible to SCC in sodium hydroxide environment than steel.

  16. Neutron measurements of stresses in a test artifact produced by laser-based additive manufacturing

    Energy Technology Data Exchange (ETDEWEB)

    Gnäupel-Herold, Thomas [Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg MD 20899-6102 (United States); Slotwinski, John; Moylan, Shawn [Intelligent Systems Division, National Institute of Standards and Technology, Gaithersburg MD 20899-8220 (United States)

    2014-02-18

    A stainless steel test artifact produced by Direct Metal Laser Sintering and similar to a proposed standardized test artifact was examined using neutron diffraction. The artifact contained a number of structures with different aspect ratios pertaining to wall thickness, height above base plate, and side length. Through spatial resolutions of the order of one millimeter the volumetric distribution of stresses in several was measured. It was found that the stresses peak in the tensile region around 500 MPa near the top surface, with balancing compressive stresses in the interior. The presence of a support structure (a one millimeter high, thin walled, hence weaker, lattice structure deposited on the base plate, followed by a fully dense AM structure) has only minor effects on the stresses.

  17. Stress-testing the Standard Model at the LHC

    CERN Document Server

    2016-01-01

    With the high-energy run of the LHC now underway, and clear manifestations of beyond-Standard-Model physics not yet seen in data from the previous run, the search for new physics at the LHC may be a quest for small deviations with big consequences. If clear signals are present, precise predictions and measurements will again be crucial for extracting the maximum information from the data, as in the case of the Higgs boson. Precision will therefore remain a key theme for particle physics research in the coming years. The conference will provide a forum for experimentalists and theorists to identify the challenges and refine the tools for high-precision tests of the Standard Model and searches for signals of new physics at Run II of the LHC. Topics to be discussed include: pinning down Standard Model corrections to key LHC processes; combining fixed-order QCD calculations with all-order resummations and parton showers; new developments in jet physics concerning jet substructure, associated jets and boosted je...

  18. A New Test Device for Characterization of Mechanical Stress Caused by Packaging Processes

    International Nuclear Information System (INIS)

    Hirsch, Soeren; Doerner, Steffen; Hauptmann, Peter; Schmidt, Bertram

    2006-01-01

    This paper reports on a new method for estimation and minimization of mechanical stress on MEMS sensor and actuator structures due to packaging processes based on flip chip technology. For studying mechanical stress a test chip with silicon membranes was fabricated. A network of piezo-resistive solid state resistors created by diffusion was used to measure the surface tension pattern between adjacent membranes. Finite element method simulation was used to calculate the stress profile and to determine the optimum positions for placing the resistive network

  19. Test plan for suitability assessment of five overcoring stress measurement techniques

    International Nuclear Information System (INIS)

    Gregory, E.C.; Rundle, T.A.; McCabe, W.M.; Kim, K.

    1982-08-01

    Tests are to be conducted at the Near-Surface Test Facility (NSTF) to assess the suitability of five overcoring techniques for in situ stress determination in a jointed basalt. The overcoring methods to be investigated use the following instrumentation to measure strain relief by overcoring a pilot borehole: USBM borehole deformation gage, CSIRO hollow inclusion stress cell, cast epoxy inclusion, the Lulea triaxial strain cell and the ''doorstopper'' biaxial strain cell. The tests are to provide data regarding the state of stress below the NSTF. This information is to be used in the evaluation of each method of overcoring. During the course of field testing, an attempt is to be made to adapt conventional overcoring techniques and analytical methods to the basalt medium. If overcoring stress determination in basalt is shown suitable, then additional studies will be identified to further adapt a technique for use at depth. In addition to the five overcoring techniques to be tested at the NSTF, stress measurements by Hydrofracturing are to be conducted to provide data for direct comparison with overcoring results. 16 refs., 18 figs

  20. Social Support for Divorced Fathers' Parenting: Testing a Stress-Buffering Model*

    OpenAIRE

    DeGarmo, David S.; Patras, Joshua; Eap, Sopagna

    2008-01-01

    A stress-buffering hypothesis for parenting was tested in a county-representative sample of 218 divorced fathers. Social support for parenting (emergency and nonemergency child care, practical support, financial support) was hypothesized to moderate effects of stress (role overload, coparental conflict, and daily hassles) on fathers’ quality parenting. No custody fathers relied more on relatives compared with custodial fathers, who relied more on new partners for parenting support. No differe...

  1. Work Stress and Alcohol Use: Developing and Testing a Biphasic Self-Medication Model

    OpenAIRE

    Frone, Michael R.

    2016-01-01

    This study developed and tested a moderated-mediation model of work stress and alcohol use, based on the biphasic (stimulant and sedative) effects of alcohol and the self-medication and stress-vulnerability models of alcohol use. The model proposes that exposure to work stressors can increase both negative affect and work fatigue, and that these two sources of strain can subsequently motivate the use of alcohol. However, the relations of negative affect and work fatigue to a...

  2. Stress Testing of the Philips 60W Replacement Lamp L Prize Entry

    Energy Technology Data Exchange (ETDEWEB)

    Poplawski, Michael E.; Ledbetter, Marc R.; Smith, Mark

    2012-04-24

    The Pacific Northwest National Laboratory, operated by Battelle for the U.S. Department of Energy, worked with Intertek to develop a procedure for stress testing medium screw-base light sources. This procedure, composed of alternating stress cycles and performance evaluation, was used to qualitatively compare and contrast the durability and reliability of the Philips 60W replacement lamp L Prize entry with market-proven compact fluorescent lamps (CFLs) with comparable light output and functionality. The stress cycles applied simultaneous combinations of electrical, thermal, vibration, and humidity stresses of increasing magnitude. Performance evaluations measured relative illuminance, x chromaticity and y chromaticity shifts after each stress cycle. The Philips L Prize entry lamps appear to be appreciably more durable than the incumbent energy-efficient technology, as represented by the evaluated CFLs, and with respect to the applied stresses. Through the course of testing, all 15 CFL samples permanently ceased to function as a result of the applied stresses, while only 1 Philips L Prize entry lamp exhibited a failure, the nature of which was minor, non-destructive, and a consequence of a known (and resolved) subcontractor issue. Given that current CFL technology appears to be moderately mature and no Philips L Prize entry failures could be produced within the stress envelope causing 100 percent failure of the benchmark CFLs, it seems that, in this particular implementation, light-emitting diode (LED) technology would be much more durable in the field than current CFL technology. However, the Philips L Prize entry lamps used for testing were carefully designed and built for the competition, while the benchmark CFLs were mass produced for retail sale—a distinction that should be taken into consideration. Further reliability testing on final production samples would be necessary to judge the extent to which the results of this analysis apply to production versions

  3. Fault roughness and strength heterogeneity control earthquake size and stress drop

    KAUST Repository

    Zielke, Olaf; Galis, Martin; Mai, Paul Martin

    2017-01-01

    An earthquake's stress drop is related to the frictional breakdown during sliding and constitutes a fundamental quantity of the rupture process. High-speed laboratory friction experiments that emulate the rupture process imply stress drop values

  4. Socioeconomic status and parenting in ethnic minority families: testing a minority family stress model.

    Science.gov (United States)

    Emmen, Rosanneke A G; Malda, Maike; Mesman, Judi; van Ijzendoorn, Marinus H; Prevoo, Mariëlle J L; Yeniad, Nihal

    2013-12-01

    According to the family stress model (Conger & Donnellan, 2007), low socioeconomic status (SES) predicts less-than-optimal parenting through family stress. Minority families generally come from lower SES backgrounds than majority families, and may experience additional stressors associated with their minority status, such as acculturation stress. The primary goal of this study was to test a minority family stress model with a general family stress pathway, as well as a pathway specific to ethnic minority families. The sample consisted of 107 Turkish-Dutch mothers and their 5- to 6-year-old children, and positive parenting was observed during a 7-min problem-solving task. In addition, mothers reported their daily hassles, psychological distress, and acculturation stress. The relation between SES and positive parenting was partially mediated by both general maternal psychological stress and maternal acculturation stress. Our study contributes to the argument that stressors specific to minority status should be considered in addition to more general demographic and family stressors in understanding parenting behavior in ethnic minority families.

  5. Earthquake Directivity, Orientation, and Stress Drop Within the Subducting Plate at the Hikurangi Margin, New Zealand

    Science.gov (United States)

    Abercrombie, Rachel E.; Poli, Piero; Bannister, Stephen

    2017-12-01

    We develop an approach to calculate earthquake source directivity and rupture velocity for small earthquakes, using the whole source time function rather than just an estimate of the duration. We apply the method to an aftershock sequence within the subducting plate beneath North Island, New Zealand, and investigate its resolution. We use closely located, highly correlated empirical Green's function (EGF) events to obtain source time functions (STFs) for this well-recorded sequence. We stack the STFs from multiple EGFs at each station, to improve the stability of the STFs. Eleven earthquakes (M 3.3-4.5) have sufficient azimuthal coverage, and both P and S STFs, to investigate directivity. The time axis of each STF in turn is stretched to find the maximum correlation between all pairs of stations. We then invert for the orientation and rupture velocity of both unilateral and bilateral line sources that best match the observations. We determine whether they are distinguishable and investigate the effects of limited frequency bandwidth. Rupture orientations are resolvable for eight earthquakes, seven of which are predominantly unilateral, and all are consistent with rupture on planes similar to the main shock fault plane. Purely unilateral rupture is rarely distinguishable from asymmetric bilateral rupture, despite a good station distribution. Synthetic testing shows that rupture velocity is the least well-resolved parameter; estimates decrease with loss of high-frequency energy, and measurements are best considered minimum values. We see no correlation between rupture velocity and stress drop, and spatial stress drop variation cannot be explained as an artifact of varying rupture velocity.

  6. PREMATURE RUPTURE OF THE MEMBRANES*

    African Journals Online (AJOL)

    In patients presenting with premature rupture of the membranes there are two factors which influence the foetal morbidity and mortality. These factors are prema- turity and intra-uterine infection. The purpose of this analysis was to elucidate which factor carried the greater risk to the foetus. Recently there has been a spate of.

  7. Ruptured Cervical Anellrysm with Neurofibromatosis

    African Journals Online (AJOL)

    rupture of an aneurysm of a lateral branch of the right thyrocervical trunk in a patient suffering from diffuse neurofibromatosis. The operative findings are reported. s. Air. Med. ... system demonstrated decreased power in all muscles of the right shoulder girdle and arm, without sensory change. The cranial nerves were normal.

  8. Spontaneous Splenic Rupture in Melanoma

    Directory of Open Access Journals (Sweden)

    Hadi Mirfazaelian

    2014-01-01

    Full Text Available Spontaneous rupture of spleen due to malignant melanoma is a rare situation, with only a few case reports in the literature. This study reports a previously healthy, 30-year-old man who came with chief complaint of acute abdominal pain to emergency room. On physical examination, abdominal tenderness and guarding were detected to be coincident with hypotension. Ultrasonography revealed mild splenomegaly with moderate free fluid in abdominopelvic cavity. Considering acute abdominal pain and hemodynamic instability, he underwent splenectomy with splenic rupture as the source of bleeding. Histologic examination showed diffuse infiltration by tumor. Immunohistochemical study (positive for S100, HMB45, and vimentin and negative for CK, CD10, CK20, CK7, CD30, LCA, EMA, and chromogranin confirmed metastatic malignant melanoma. On further questioning, there was a past history of a nasal dark skin lesion which was removed two years ago with no pathologic examination. Spontaneous (nontraumatic rupture of spleen is an uncommon situation and it happens very rarely due to neoplastic metastasis. Metastasis of malignant melanoma is one of the rare causes of the spontaneous rupture of spleen.

  9. A test case of the deformation rate analysis (DRA) stress measurement method

    Energy Technology Data Exchange (ETDEWEB)

    Dight, P.; Hsieh, A. [Australian Centre for Geomechanics, Univ. of WA, Crawley (Australia); Johansson, E. [Saanio and Riekkola Oy, Helsinki (Finland); Hudson, J.A. [Rock Engineering Consultants (United Kingdom); Kemppainen, K.

    2012-01-15

    As part of Posiva's site and ONKALO investigations, the in situ rock stress has been measured by a variety of techniques, including hydraulic fracturing, overcoring, and convergence measurements. All these techniques involve direct measurements in a drillhole or at the rock surface. An alternative method is to test drillhole core in a way that enables estimation of the magnitudes and orientations of the in situ rock stress. The Kaiser Effect (KE) and Deformation Rate Analysis (DRA) are two ways to do this. In the work reported here, a 'blind' DRA test was conducted on core obtained from the POSE (Posiva's Olkiluoto Spalling Experiment) niche in the ONKALO. The term 'blind' means that the two first authors of this report, who conducted the tests at the Australian Centre for Geomechanics, did not know the depths below surface at which the cores had been obtained. The results of this DRA Test Case are presented, together with an explanation of the DRA procedure. Also, additional information that would help in such DRA testing and associated analysis is explained. One of the problems in comparing the DRA results with the known Olkiluoto stress field is that the latter is highly variable across the site, as experienced by the previous in situ stress measurements and as predicted by numerical analysis. The variability is mainly caused by the presence of the large brittle deformation zones which perturb the local stress state. However, this variability reduces with depth and the stress field becomes more stable at the {approx} 350 m at which the drillhole cores were obtained. Another compounding difficulty is that the stress quantity, being a second order tensor, requires six independent components for its specification. In other words, comparison of the DRA results and the known stress field requires comparison of six different quantities. In terms of the major principal stress orientation, the DRA results predict an orientation completely

  10. A test case of the deformation rate analysis (DRA) stress measurement method

    International Nuclear Information System (INIS)

    Dight, P.; Hsieh, A.; Johansson, E.; Hudson, J.A.; Kemppainen, K.

    2012-01-01

    As part of Posiva's site and ONKALO investigations, the in situ rock stress has been measured by a variety of techniques, including hydraulic fracturing, overcoring, and convergence measurements. All these techniques involve direct measurements in a drillhole or at the rock surface. An alternative method is to test drillhole core in a way that enables estimation of the magnitudes and orientations of the in situ rock stress. The Kaiser Effect (KE) and Deformation Rate Analysis (DRA) are two ways to do this. In the work reported here, a 'blind' DRA test was conducted on core obtained from the POSE (Posiva's Olkiluoto Spalling Experiment) niche in the ONKALO. The term 'blind' means that the two first authors of this report, who conducted the tests at the Australian Centre for Geomechanics, did not know the depths below surface at which the cores had been obtained. The results of this DRA Test Case are presented, together with an explanation of the DRA procedure. Also, additional information that would help in such DRA testing and associated analysis is explained. One of the problems in comparing the DRA results with the known Olkiluoto stress field is that the latter is highly variable across the site, as experienced by the previous in situ stress measurements and as predicted by numerical analysis. The variability is mainly caused by the presence of the large brittle deformation zones which perturb the local stress state. However, this variability reduces with depth and the stress field becomes more stable at the ∼ 350 m at which the drillhole cores were obtained. Another compounding difficulty is that the stress quantity, being a second order tensor, requires six independent components for its specification. In other words, comparison of the DRA results and the known stress field requires comparison of six different quantities. In terms of the major principal stress orientation, the DRA results predict an orientation completely different to the NW-SE regional

  11. Endometriosis-related spontaneous diaphragmatic rupture.

    Science.gov (United States)

    Triponez, Frédéric; Alifano, Marco; Bobbio, Antonio; Regnard, Jean-François

    2010-10-01

    Non-traumatic, spontaneous diaphragmatic rupture is a rare event whose pathophysiology is not known. We report the case of endometriosis-related spontaneous rupture of the right diaphragm with intrathoracic herniation of the liver, gallbladder and colon. We hypothesize that the invasiveness of endometriotic tissue caused diaphragm fragility, which finally lead to its complete rupture without traumatic event. The treatment consisted of a classical management of diaphragmatic rupture, with excision of the endometriotic nodule followed by medical ovarian suppression for six months.

  12. ACL Rupture in Collegiate Wrestler

    Directory of Open Access Journals (Sweden)

    Lindsay A. Palmer

    2016-05-01

    Full Text Available Objective: To educate others on unique Anterior Cruciate Ligament tears and percentage of usage of the ACL in normal daily function. Background: Patient is an eighteen year old male participating in wrestling and football at the time of the injury. Patient now only participates in wrestling. No previous knee or chronic injuries were reported prior to this injury. Patient was playing football during the time of injury. The patient stated that he planted his foot down and was tackled at the same time when the injury occurred. The patient felt his knee twist and buckle. Patient complained of clicking inside the knee and had minimal swelling. He also complained of it being difficult to bear weight at the time. The patient did not seek further treatment until two months after the injury occurred when he received an MRI. His MRI showed a positive finding for an Anterior Cruciate Ligament rupture. His previous Athletic Trainer could not find a positive diagnosis for the patient prior to the MRI. Differential Diagnosis: Possible meniscal or ACL injury. Treatment: Doctors officially diagnosed the injury as a complete rupture of the ACL. The patient did not receive surgery immediately. Doctors have stated that he only uses about 50% of his ACL on a daily basis compared to a normal person who uses about 95% of their ACL daily. Because of this, the patient played on his rupture for seven months before receiving surgery. He played a whole season of high school football and a whole season of wrestling his senior year with the ACL ruptured. The patient only used a brace for better comfort during the seven months. The patient then received reconstructive surgery to repair the rupture. A hamstring tendon graft was used to repair the ruptured ACL. Because a tendon was taken from the hamstring, patient experienced a tight ACL and hamstring of the left leg post-surgery. The patient participated in Physical Therapy for five months to strengthen and stretch the new

  13. Synthetic sea water - An improved stress corrosion test medium for aluminum alloys

    Science.gov (United States)

    Humphries, T. S.; Nelson, E. E.

    1973-01-01

    A major problem in evaluating the stress corrosion cracking resistance of aluminum alloys by alternate immersion in 3.5 percent salt (NaCl) water is excessive pitting corrosion. Several methods were examined to eliminate this problem and to find an improved accelerated test medium. These included the addition of chromate inhibitors, surface treatment of specimens, and immersion in synthetic sea water. The results indicate that alternate immersion in synthetic sea water is a very promising stress corrosion test medium. Neither chromate inhibitors nor surface treatment (anodize and alodine) of the aluminum specimens improved the performance of alternate immersion in 3.5 percent salt water sufficiently to be classified as an effective stress corrosion test method.

  14. European stress tests for nuclear power plants. The Swedish National Report

    International Nuclear Information System (INIS)

    2011-01-01

    On 11 March 2011, the Tohoku region in north Honshu, Japan, suffered a severe earthquake with an ensuing tsunami and an accident at the Fukushima Dai-ichi nuclear power plant. Due to the accident the Council of the European Union declared in late March that Member States were prepared to begin reviewing safety at nuclear facilities in the European Union by means of a comprehensive assessment of risk and safety ('stress testing'). On 25 May, SSM ordered the licensees of the nuclear power plants to conduct renewed analyses of the facilities' resilience against different kinds of natural phenomena. They were also to analyse how the facilities would be capable of dealing with a prolonged loss of electrical power, regardless of cause. On 31 October, the licensees reported on their stress tests to SSM. After reviewing these reports, SSM produced a summary stress test report, which was submitted to the Government on the 15 December. The present report is the national report on Swedish stress tests of nuclear power plants. The report will be submit to the European Commission no later than 31 December. Based on the review SSM has drawn the conclusion that the stress tests carried out by Swedish licensees are largely performed in accordance with the specification resolved within the European Union. The scope and depth of these analyses and assessments are essentially in accordance with ENSREG's definition of 'a comprehensive assessment of risk and safety'. The stress tests show that Swedish facilities are robust, but the tests also identify a number of opportunities to further strengthen the facilities' robustness. SSM will order the respective licensees to present an action plan for dealing with the results from the stress tests. The Authority will then examine the plans and adopt a standpoint on proposed measures as well as check that the necessary safety improvements are made. In a number of cases, the stress tests indicate deficiencies in relation to, or alternatively

  15. Characterization Of Flow Stress Of Different AA6082 Alloys By Means Of Hot Torsion Test

    International Nuclear Information System (INIS)

    Donati, Lorenzo; El Mehtedi, Mohamad

    2011-01-01

    FEM simulations are become the most powerful tools in order to optimize the different aspects of the extrusion process and an accurate flow stress definition of the alloy is a prerequisite for a reliable effectiveness of the simulation. In the paper the determination of flow stress by means of hot torsion test is initially presented and discussed: the several approximations that are usually introduced in flow stress computation are described and computed for an AA6082 alloy in order to evidence the final effect on curves shapes. The procedure for regressing the parameters of the sinhyperbolic flow stress definition is described in detailed and applied to the described results. Then four different alloys, extracted by different casting batches but all namely belonging to the 6082 class, were hot torsion tested in comparable levels of temperature and strain rate up to specimen failure. The results are analyzed and discussed in order to understand if a mean flow stress behavior can be identified for the whole material class at the different tested conditions or if specific testing conditions (chemical composition of the alloy, specimen shape, etc) influence the materials properties to a higher degree.

  16. Numerical Methods for the Analysis of Power Transformer Tank Deformation and Rupture Due to Internal Arcing Faults.

    Science.gov (United States)

    Yan, Chenguang; Hao, Zhiguo; Zhang, Song; Zhang, Baohui; Zheng, Tao

    2015-01-01

    Power transformer rupture and fire resulting from an arcing fault inside the tank usually leads to significant security risks and serious economic loss. In order to reveal the essence of tank deformation or explosion, this paper presents a 3-D numerical computational tool to simulate the structural dynamic behavior due to overpressure inside transformer tank. To illustrate the effectiveness of the proposed method, a 17.3 MJ and a 6.3 MJ arcing fault were simulated on a real full-scale 360MVA/220kV oil-immersed transformer model, respectively. By employing the finite element method, the transformer internal overpressure distribution, wave propagation and von-Mises stress were solved. The numerical results indicate that the increase of pressure and mechanical stress distribution are non-uniform and the stress tends to concentrate on connecting parts of the tank as the fault time evolves. Given this feature, it becomes possible to reduce the risk of transformer tank rupture through limiting the fault energy and enhancing the mechanical strength of the local stress concentrative areas. The theoretical model and numerical simulation method proposed in this paper can be used as a substitute for risky and costly field tests in fault overpressure analysis and tank mitigation design of transformers.

  17. Numerical Methods for the Analysis of Power Transformer Tank Deformation and Rupture Due to Internal Arcing Faults

    Science.gov (United States)

    Yan, Chenguang; Hao, Zhiguo; Zhang, Song; Zhang, Baohui; Zheng, Tao

    2015-01-01

    Power transformer rupture and fire resulting from an arcing fault inside the tank usually leads to significant security risks and serious economic loss. In order to reveal the essence of tank deformation or explosion, this paper presents a 3-D numerical computational tool to simulate the structural dynamic behavior due to overpressure inside transformer tank. To illustrate the effectiveness of the proposed method, a 17.3MJ and a 6.3MJ arcing fault were simulated on a real full-scale 360MVA/220kV oil-immersed transformer model, respectively. By employing the finite element method, the transformer internal overpressure distribution, wave propagation and von-Mises stress were solved. The numerical results indicate that the increase of pressure and mechanical stress distribution are non-uniform and the stress tends to concentrate on connecting parts of the tank as the fault time evolves. Given this feature, it becomes possible to reduce the risk of transformer tank rupture through limiting the fault energy and enhancing the mechanical strength of the local stress concentrative areas. The theoretical model and numerical simulation method proposed in this paper can be used as a substitute for risky and costly field tests in fault overpressure analysis and tank mitigation design of transformers. PMID:26230392

  18. A Retrospective Analysis of Ruptured Breast Implants

    Directory of Open Access Journals (Sweden)

    Woo Yeol Baek

    2014-11-01

    Full Text Available BackgroundRupture is an important complication of breast implants. Before cohesive gel silicone implants, rupture rates of both saline and silicone breast implants were over 10%. Through an analysis of ruptured implants, we can determine the various factors related to ruptured implants.MethodsWe performed a retrospective review of 72 implants that were removed for implant rupture between 2005 and 2014 at a single institution. The following data were collected: type of implants (saline or silicone, duration of implantation, type of implant shell, degree of capsular contracture, associated symptoms, cause of rupture, diagnostic tools, and management.ResultsForty-five Saline implants and 27 silicone implants were used. Rupture was diagnosed at a mean of 5.6 and 12 years after insertion of saline and silicone implants, respectively. There was no association between shell type and risk of rupture. Spontaneous was the most common reason for the rupture. Rupture management was implant change (39 case, microfat graft (2 case, removal only (14 case, and follow-up loss (17 case.ConclusionsSaline implants have a shorter average duration of rupture, but diagnosis is easier and safer, leading to fewer complications. Previous-generation silicone implants required frequent follow-up observation, and it is recommended that they be changed to a cohesive gel implant before hidden rupture occurs.

  19. Stress test with adenosine in cerebral perfusion imaging for the diagnosis of ischemic cerebrovascular disease

    International Nuclear Information System (INIS)

    Yuan Gengbiao; Kuang Anren; Chen Xuehong; Li Xihuan; Feng Jianzhong

    2004-01-01

    Objective: This study purpose is to evaluate cerebrovascular response and reserve capacity (CVR, CVRC) by stress test with adenosine in cerebral perfusion imaging for the diagnosis of ischemic cerebrovascular diseases. Methods There were 25 patients suffered from transient ischemia attack and 16 patients suffered from occlusive cerebral artery in this study. The rest cerebral perfusion imaging was obtained 30 minutes post-injection of 99mTC-ethylene cysteinate dimmer. After 2-5 days, adenosine stress tests were performed. Adenosine (0.14 mg/kg min) was administered intravenously 3 minutes pre-injection of 99mTC-ECD.Under same condition, the rest and stress tests of cerebral perfusion imaging were performed. By visual and semiquantitative analysis, the results of the rest/stress imaging were divided into the following four patterns: A: The stress imaging showed an expand areas of hypoperfusion, asymmetry index (AI) was decreased; B: Rest imaging was normal but new hypoperfused areas appeared with AI index declining in stress test; C: The hypoperfused areas were decreased or disappeared in size with AI index increasing in stress test; D: No changes showed in cerebral perfusion imaging patterns and Al index between rest and stress tests. AI index was ratio of radio account of interest regions than average radio account of cerebella. Results It was found that A, B, C and D type were 24%,12%,56% and 8% respectively in the group of transient ischemia attack patients, and 31%,44%, 19% and 6% respectively in the group of occlusive cerebrovascular patients. In rest test, of 41 patients of cerebrovascular disease, there were 28 cases decreased of radio uptake, moreover in stress test, there were 38 case decreased of radio uptake, positive rate were 68.29% and 92.68% respectively. Compared to X±SD of AI index of rest/stress test, it is found to increasing and being significant statistics (p<0.01, Spass 8.0 statistics software). Conclusion: Adenosinal-induced vasodilatation

  20. Physical Stress Echocardiography: Prediction of Mortality and Cardiac Events in Patients with Exercise Test showing Ischemia

    Directory of Open Access Journals (Sweden)

    Ana Carla Pereira de Araujo

    2014-11-01

    Full Text Available Background: Studies have demonstrated the diagnostic accuracy and prognostic value of physical stress echocardiography in coronary artery disease. However, the prediction of mortality and major cardiac events in patients with exercise test positive for myocardial ischemia is limited. Objective: To evaluate the effectiveness of physical stress echocardiography in the prediction of mortality and major cardiac events in patients with exercise test positive for myocardial ischemia. Methods: This is a retrospective cohort in which 866 consecutive patients with exercise test positive for myocardial ischemia, and who underwent physical stress echocardiography were studied. Patients were divided into two groups: with physical stress echocardiography negative (G1 or positive (G2 for myocardial ischemia. The endpoints analyzed were all-cause mortality and major cardiac events, defined as cardiac death and non-fatal acute myocardial infarction. Results: G2 comprised 205 patients (23.7%. During the mean 85.6 ± 15.0-month follow-up, there were 26 deaths, of which six were cardiac deaths, and 25 non-fatal myocardial infarction cases. The independent predictors of mortality were: age, diabetes mellitus, and positive physical stress echocardiography (hazard ratio: 2.69; 95% confidence interval: 1.20 - 6.01; p = 0.016. The independent predictors of major cardiac events were: age, previous coronary artery disease, positive physical stress echocardiography (hazard ratio: 2.75; 95% confidence interval: 1.15 - 6.53; p = 0.022 and absence of a 10% increase in ejection fraction. All-cause mortality and the incidence of major cardiac events were significantly higher in G2 (p < 0. 001 and p = 0.001, respectively. Conclusion: Physical stress echocardiography provides additional prognostic information in patients with exercise test positive for myocardial ischemia.

  1. Verification of intraspecimen method using constant stress tension test of sensitized alloy 600

    International Nuclear Information System (INIS)

    Lee, Seung Ki; Choi, Hoi Su; Hwang, Il Soon

    2005-01-01

    Stress corrosion cracking (SCC) occurring at the Nibase alloy 600 used in the nuclear power plant SG tubes and CRDM penetration nozzles had been reported after long-term operation in the harsh environment. Intraspecimen method was developed to predict the SCC initiation time statistically. [1] By dividing a test area into a number of smaller regions (intraspecimens) having homogeneous physical and chemical condition each SCC initiation in each intraspecimen could be counted as an independent outcome to provide enough number of statistical data. Earlier work of intraspecimen method had many problems in test method and didn't agree with Weibull statistics which is the theoretical base of intraspecimen method. The test method is improved in this intraspecimen test. To find out the root causes of the problems in earlier work and improve the accuracy of intraspecimen method, two kinds of materials are introduced, which are different in grain size but same in chemical composition. Ni-base alloy 600, heat no. J313 and J323 are used as test materials. Specimens of sensitized Alloy 600 are tested under the condition of constant tensile stress and well defined chemical environment therefore we can easily observe typical intergranular stress corrosion cracking (IGSCC). Material with finer grain (J323) showed the areadependence in agreement with theoretical prediction. But material with coarser grain (J313) did not show any significant area-dependence. While SCC initiates earlier at grain boundaries that are oriented close to normal to the stress axis, crack initiation time showed no correlation with grain boundary misorientation estimated by Electron Back Scattered Diffraction (EBSD). From the SCC initiation tests with two test materials, it is concluded that the number of grains in an intraspecimen, degree of sensitization and uniform stress distribution are important parameters to meet Weibull statistics

  2. Effects of stress on memory in children and adolescents: testing causal connections.

    Science.gov (United States)

    Quas, Jodi A; Rush, Elizabeth B; Yim, Ilona S; Nikolayev, Mariya

    2014-01-01

    Although a sizeable body of research has examined children's memory for stressful prior experiences, relatively few studies have experimentally manipulated stress during a to-be-remembered event to draw causal inferences about the effects of stress, especially across wide age ranges. We exposed children and adolescents to a more or a less arousing version of the Trier Social Stress Test-Modified (TSST-M), a widely used laboratory stress task. Two weeks later, we tested their memory for what happened. Interviewers behaved in a supportive or non-supportive manner. In adolescents, those who completed the high-arousal TSST-M provided fewer correct responses to recognition questions and fewer incorrect responses to misleading questions for which any answer would have been incorrect, compared to those who completed the lower-arousal TSST-M. Thus, arousal seemed to have reduced the adolescents' willingness to answer questions rather than having influenced their memory per se. In children, across TSST-M conditions, greater physiological arousal during the TSST-M predicted enhanced recall. Finally, interviewer support reduced the amount of factual information provided in free recall but increased correct responses to misleading questions. Results highlight the complex ways in which event stress and interviewer demeanour shape recounting of prior experiences across development.

  3. Rupture of the atherosclerotic plaque: does a good animal model exist?

    NARCIS (Netherlands)

    Cullen, Paul; Baetta, Roberta; Bellosta, Stefano; Bernini, Franco; Chinetti, Giulia; Cignarella, Andrea; von Eckardstein, Arnold; Exley, Andrew; Goddard, Martin; Hofker, Marten; Hurt-Camejo, Eva; Kanters, Edwin; Kovanen, Petri; Lorkowski, Stefan; McPheat, William; Pentikäinen, Markku; Rauterberg, Jürgen; Ritchie, Andrew; Staels, Bart; Weitkamp, Benedikt; de Winther, Menno

    2003-01-01

    By its very nature, rupture of the atherosclerotic plaque is difficult to study directly in humans. A good animal model would help us not only to understand how rupture occurs but also to design and test treatments to prevent it from happening. However, several difficulties surround existing models

  4. Randomized test of an implementation intention-based tool to reduce stress-induced eating.

    Science.gov (United States)

    O'Connor, Daryl B; Armitage, Christopher J; Ferguson, Eamonn

    2015-06-01

    Stress may indirectly contribute to disease (e.g. cardiovascular disease, cancer) by producing deleterious changes to diet. The purpose of this study was to test the effectiveness of a stress management support (SMS) tool to reduce stress-related unhealthy snacking and to promote stress-related healthy snacking. Participants were randomized to complete a SMS tool with instruction to link stressful situations with healthy snack alternatives (experimental) or a SMS tool without a linking instruction (control). On-line daily reports of stressors and snacking were completed for 7 days. Daily stressors were associated with unhealthy snack consumption in the control condition but not in the experimental condition. Participants highly motivated towards healthy eating consumed a greater number of healthy snacks in the experimental condition on stressful days compared to participants in the experimental condition with low and mean levels of motivation. This tool is an effective, theory driven, intervention that helps to protect against stress-induced high-calorie snack consumption.

  5. Design of PH-based accelerated life testing plans under multiple-stress-type

    International Nuclear Information System (INIS)

    Elsayed, E.A.; Zhang Hao

    2007-01-01

    Accelerated life testing (ALT) is used to obtain failure time data quickly under high stress levels in order to predict product life performance under design stress conditions. Most of the previous work on designing ALT plans is focused on the application of a single stress. However, as components or products become more reliable due to technological advances, it becomes more difficult to obtain significant amount of failure data within reasonable amount of time using single stress only. Multiple-stress-type ALTs have been employed as a means of overcoming such difficulties. In this paper, we design optimum multiple-stress-type ALT plans based on the proportional hazards model. The optimum combinations of stresses and their levels are determined such that the variance of the reliability estimate of the product over a specified period of time is minimized. The use of the model is illustrated using numerical example, and sensitivity analysis shows that the resultant optimum ALT plan is robust to the deviation in model parameters

  6. A test procedure for determining the influence of stress ratio on fatigue crack growth

    Science.gov (United States)

    Fitzgerald, J. H.; Wei, R. P.

    1974-01-01

    A test procedure is outlined by which the rate of fatigue crack growth over a range of stress ratios and stress intensities can be determined expeditiously using a small number of specimens. This procedure was developed to avoid or circumvent the effects of load interactions on fatigue crack growth, and was used to develop data on a mill annealed Ti-6Al-4V alloy plate. Experimental data suggest that the rates of fatigue crack growth among the various stress ratios may be correlated in terms of an effective stress intensity range at given values of K max. This procedure is not to be used, however, for determining the corrosion fatigue crack growth characteristics of alloys when nonsteady-state effects are significant.

  7. Energia total de ruptura: um teste biomecânico para avaliação de material biológico com propriedade viscoelástica não linear Total energy of rupture: a biomechanical test to evaluate non-linear viscoelastic biological material

    Directory of Open Access Journals (Sweden)

    Feng Chung Wu

    2004-12-01

    Full Text Available Objetivo: Apresentação do teste biomecânico Energia Total de Ruptura para o estudo da resistência intrínseca de material biológico com propriedade viscoelástica não-linear representado neste trabalho por segmento íntegro de cólon descendente de rato. Métodos: Implementação do teste biomecânico Energia Total de Ruptura e do Sistema de Aquisição e Análise de dados Biomecânicos - SABI 2.0. Para esse fim, foram utilizados conceitos físico-mecânicos, computacionais e biomecânicos e como corpos de teste, 15 espécimes de cólon descendente de ratos. Resultados: O teste biomecânico Energia Total de Ruptura permitiu o cálculo da energia total acumulada necessária para promover a ruptura dos corpos de prova durante os ensaios mecânicos. Por meio da automatização e gerenciamento da aquisição e análise dos dados capturados foi possível a geração de gráficos e relatórios descritivos e estatísticos. Conclusão: Fundamentado em conceitos físico-mecânicos, computacionais e biomecânicos, o teste Energia Total de Ruptura pôde proporcionar análise matemática do comportamento dos segmentos de cólon descendente de ratos durante os ensaios, demonstrando ser um possível método de medição da resistência intrínseca desse material biológico com propriedade viscoelástica não-linear.Purpose: Presentation of the Total Energy of Rupture biomechanical test to evaluate the intrinsic resistance of the rat’s left colon which presents a non-linear viscoelastic property. Methods: Implementation of Total Energy of Rupture test (ETR and the Biomechanical Data Acquisition and Analysis System (SABI 2.0 based on physic-mechanical, computational and biomechanical concepts. Fifteen specimens of Wistar adults rat’s left colon where considered for experiments. Results: Using the TER biomechanical test it was possible calculate the accumulated total energy necessary to promote the specimens rupture during the mechanical trial. It was

  8. Effect of sodium on the creep-rupture behavior of type 304 stainless steel

    International Nuclear Information System (INIS)

    Natesan, K.; Chopra, O.K.; Kassner, T.F.

    1976-01-01

    Uniaxial creep-rupture data have been obtained for Type 304 stainless steel in the solution-annealed condition and after exposure to a flowing sodium environment at temperatures of 700, 650, and 600 0 C.The specimens were exposed to sodium for time periods between 120 and 5012 h to produce carbon penetration depths of approximately 0.010, 0.020, and 0.038 cm in the steel. Results showed that, as the depth of carbon penetration and the average carbon concentration in the steel increase, the rupture life increases and the minimum creep rate decreases. Creep correlations that relate rupture life, minimum creep rate, and time-to-tertiary creep were developed for the steel in both the solution-annealed and sodium-exposed conditions. Isochronous stress-creep strain curves and results on the calculations of the stress levels for 1 percent creep strain and long-term rupture life are also presented. 11 fig

  9. Spontaneous Extensor Tendon Rupture in the Rheumatoid Wrist: Risk Factors and Preventive Role of Extended Tenosynovectomy.

    Science.gov (United States)

    Hsueh, Jung-Hua; Liu, Wen-Chung; Yang, Kuo-Chung; Hsu, Kuei-Chang; Lin, Cheng-Ta; Chen, Lee-Wei

    2016-03-01

    Spontaneous extensor tendon rupture is often seen in rheumatoid arthritis (RA) patients, but the risk factors are not clearly defined. We therefore collected the data of RA patients with previous extensor tendon rupture and those with tenosynovitis and analyzed the relationship between extended tenosynovectomy and spontaneous extensor tendon rupture. We retrospectively reviewed 17 spontaneous extensor tendon rupture episodes in 15 RA patients and 14 tenosynovitis episodes that required tenosynovectomy in 12 RA patients from 1997 to 2013. Correlations between the incidence of tendon rupture, X-ray findings, and clinical findings in the affected wrists before tendon rupture were analyzed statistically using the test for proportion. The following parameters were significantly correlated with spontaneous extensor tendon rupture: disease duration longer than 8 years, persistent tenosynovitis longer than 1 year duration, and Larsen grade greater than 4 (P = 0.02, 0.03, and 0.01, respectively). Dislocation of the distal end of the ulna, carpal collapse, and the scallop sign on X-ray contributed to a higher spontaneous extensor tendon rupture rate among RA patients (P = 0.01, 0.05, and 0.03, respectively). Extended tenosynovectomy was performed on 14 wrists in 12 RA patients with persistent tenosynovitis longer than 6 months, and Larsen grade did not deteriorate in this group compared with those who did not undergo the surgery. No spontaneous extensor tendon rupture occurred following the surgery. Risk factors of spontaneous extensor tendon rupture included disease duration longer than 8 years, persistent tenosynovitis longer than 1 year, and wrist Larsen grade greater than 4. Dislocation of the distal end of the ulna, carpal collapse, and the scallop sign on X-ray indicated a higher probability of extensor tendon rupture. Rheumatologists should consult with hand surgeons promptly to preserve hand function before tendon rupture. Prophylactic extended tenosynovectomy

  10. Stress corrosion cracking tests on electron beam welded carbon steel specimens in carbonate-bicarbonate solution

    International Nuclear Information System (INIS)

    Parkins, R.N.

    1985-04-01

    Stress corrosion cracking tests have been performed on tapered carbon steel test pieces containing electron beam welds with a view to defining susceptibility to such cracking in a carbonate-bicarbonate solution at 90 C and an appropriate electrode potential. The tests involved applying cyclic loads to the specimens and it is shown that the threshold stress for cracking reduces linearly with increase in the magnitude of the cyclic load component. Extrapolation of these trends to zero fluctuating stress indicates static load threshold stresses in the vicinity of the yield stress (i.e. about 300 N/mm 2 for parent plate without a weld, 400 N/mm 2 for specimens with welds on one side only and 600 N/mm 2 for specimens having welds penetrating through the thickness of the specimen). The averages of the maximum crack velocities observed were least for parent plate material and greatest for weld metal, the former being essentially intergranular in morphology and the latter mostly transgranular, with heat affected zone material being intermediate between these extremes. (author)

  11. Creep-rupture behavior of iron superalloys in high-pressure hydrogen

    Science.gov (United States)

    Bhattacharyya, S.; Peterman, W.

    1984-01-01

    The creep-rupture properties of five iron-base and one cobalt-base high temperature alloys were investigated to assess the feasibility of using the alloys as construction materials in a Stirling engine. The alloys were heat treated and hardness measurements were taken. Typical microstructures of the alloys are shown. The creep-rupture properties of the alloys were determined at 760 and 815 C in 15.0 MPa H2 for 200 to 1000 hours. Plots of rupture life versus stress for the six superalloys are presented along with creep strain-time plots.

  12. Characterize kinematic rupture history of large earthquakes with Multiple Haskell sources

    Science.gov (United States)

    Jia, Z.; Zhan, Z.

    2017-12-01

    Earthquakes are often regarded as continuous rupture along a single fault, but the occurrence of complex large events involving multiple faults and dynamic triggering challenges this view. Such rupture complexities cause difficulties in existing finite fault inversion algorithms, because they rely on specific parameterizations and regularizations to obtain physically meaningful solutions. Furthermore, it is difficult to assess reliability and uncertainty of obtained rupture models. Here we develop a Multi-Haskell Source (MHS) method to estimate rupture process of large earthquakes as a series of sub-events of varying location, timing and directivity. Each sub-event is characterized by a Haskell rupture model with uniform dislocation and constant unilateral rupture velocity. This flexible yet simple source parameterization allows us to constrain first-order rupture complexity of large earthquakes robustly. Additionally, relatively few parameters in the inverse problem yields improved uncertainty analysis based on Markov chain Monte Carlo sampling in a Bayesian framework. Synthetic tests and application of MHS method on real earthquakes show that our method can capture major features of large earthquake rupture process, and provide information for more detailed rupture history analysis.

  13. Morphology parameters for intracranial aneurysm rupture risk assessment.

    Science.gov (United States)

    Dhar, Sujan; Tremmel, Markus; Mocco, J; Kim, Minsuok; Yamamoto, Junichi; Siddiqui, Adnan H; Hopkins, L Nelson; Meng, Hui

    2008-08-01

    The aim of this study is to identify image-based morphological parameters that correlate with human intracranial aneurysm (IA) rupture. For 45 patients with terminal or sidewall saccular IAs (25 unruptured, 20 ruptured), three-dimensional geometries were evaluated for a range of morphological parameters. In addition to five previously studied parameters (aspect ratio, aneurysm size, ellipticity index, nonsphericity index, and undulation index), we defined three novel parameters incorporating the parent vessel geometry (vessel angle, aneurysm [inclination] angle, and [aneurysm-to-vessel] size ratio) and explored their correlation with aneurysm rupture. Parameters were analyzed with a two-tailed independent Student's t test for significance; significant parameters (P 41; 95% confidence interval, 1.03-1.92) and undulation index (odds ratio, 1.51; 95% confidence interval, 1.08-2.11) had the strongest independent correlation with ruptured IA. From the receiver operating characteristic analysis, size ratio and aneurysm angle had the highest area under the curve values of 0.83 and 0.85, respectively. Size ratio and aneurysm angle are promising new morphological metrics for IA rupture risk assessment. Because these parameters account for vessel geometry, they may bridge the gap between morphological studies and more qualitative location-based studies.

  14. Estimation of Stresses in a Dry Sand Layer Tested on Shaking Table

    Science.gov (United States)

    Sawicki, Andrzej; Kulczykowski, Marek; Jankowski, Robert

    2012-12-01

    Theoretical analysis of shaking table experiments, simulating earthquake response of a dry sand layer, is presented. The aim of such experiments is to study seismic-induced compaction of soil and resulting settlements. In order to determine the soil compaction, the cyclic stresses and strains should be calculated first. These stresses are caused by the cyclic horizontal acceleration at the base of soil layer, so it is important to determine the stress field as function of the base acceleration. It is particularly important for a proper interpretation of shaking table tests, where the base acceleration is controlled but the stresses are hard to measure, and they can only be deduced. Preliminary experiments have shown that small accelerations do not lead to essential settlements, whilst large accelerations cause some phenomena typical for limit states, including a visible appearance of slip lines. All these problems should be well understood for rational planning of experiments. The analysis of these problems is presented in this paper. First, some heuristic considerations about the dynamics of experimental system are presented. Then, the analysis of boundary conditions, expressed as resultants of respective stresses is shown. A particular form of boundary conditions has been chosen, which satisfies the macroscopic boundary conditions and the equilibrium equations. Then, some considerations are presented in order to obtain statically admissible stress field, which does not exceed the Coulomb-Mohr yield conditions. Such an approach leads to determination of the limit base accelerations, which do not cause the plastic state in soil. It was shown that larger accelerations lead to increase of the lateral stresses, and the respective method, which may replace complex plasticity analyses, is proposed. It is shown that it is the lateral stress coefficient K0 that controls the statically admissible stress field during the shaking table experiments.

  15. Testing the accelerating moment release (AMR) hypothesis in areas of high stress

    Science.gov (United States)

    Guilhem, Aurélie; Bürgmann, Roland; Freed, Andrew M.; Ali, Syed Tabrez

    2013-11-01

    Several retrospective analyses have proposed that significant increases in moment release occurred prior to many large earthquakes of recent times. However, the finding of accelerating moment release (AMR) strongly depends on the choice of three parameters: (1) magnitude range, (2) area being considered surrounding the events and (3) the time period prior to the large earthquakes. Consequently, the AMR analysis has been criticized as being a posteriori data-fitting exercise with no new predictive power. As AMR has been hypothesized to relate to changes in the state of stress around the eventual epicentre, we compare here AMR results to models of stress accumulation in California. Instead of assuming a complete stress drop on all surrounding fault segments implied by a back-slip stress lobe method, we consider that stress evolves dynamically, punctuated by the occurrence of earthquakes, and governed by the elastic and viscous properties of the lithosphere. We study the seismicity of southern California and extract events for AMR calculations following the systematic approach employed in previous studies. We present several sensitivity tests of the method, as well as grid-search analyses over the region between 1955 and 2005 using fixed magnitude range, radius of the search area and period of time. The results are compared to the occurrence of large events and to maps of Coulomb stress changes. The Coulomb stress maps are compiled using the coseismic stress from all M > 7.0 earthquakes since 1812, their subsequent post-seismic relaxation, and the interseismic strain accumulation. We find no convincing correlation of seismicity rate changes in recent decades with areas of high stress that would support the AMR hypothesis. Furthermore, this indicates limited utility for practical earthquake hazard analysis in southern California, and possibly other regions.

  16. Test with different stress measurement methods in two orthogonal bore holes in Aespoe HRL

    Energy Technology Data Exchange (ETDEWEB)

    Janson, Thomas; Stigsson, Martin [Golder Associates AB, Stockholm (Sweden)

    2002-12-01

    Within the scope of work, to provide the necessary rock mechanics support for the site investigations, SKB has studied some available pieces of equipment for in situ stress measurements in deep boreholes. A project with the objective to compare three different pieces of equipment for in situ stress measurements under similar conditions has been carried out. The main objective for the project is to compare the three different pieces of equipment for in situ stress measurements and find a strategy for SKB's Site Investigations to determine the state of stress in the rock mass. Two units of equipment use the overcoring method while the third uses the hydraulic fracturing method. The overcoring was performed by AECL, using Deep Door stopper Gauge System (DDGS), and SwedPower, using their triaxial strain measuring instrument (Borre Probe). MeSy Geo Systeme GmbH performed the hydraulic fracturing. The DDGS system is a new method to SKB while the experience of the SwedPower overcoring and the hydraulic fracturing methods are long. The tests were performed in the same orthogonal boreholes at Aespoe Hard Rock Laboratory (HRL), Oskarshamn, Sweden. The measured results have been verified against known conditions at the Aespoe HRL. The results from the three in situ stress measurement methods rose more questions than answers. Which illustrate the complexity to determine the in situ stresses in a rock mass. To understand the difference in results and answer the questions, it was necessary to do deeper investigations such as laboratory tests and theoretical calculations such as geological structure model, analysis of the influence of a nearby fracture, P-wave measurements, uniaxial tests on small cores from the HQ-3 core, theoretical and numerical analyses of the hole bottom (theoretical strains, stress concentrations and microcracking), auditing of DDGS measurements results and assumptions in the DDGS analyse and microscopy investigations on the cores. The following

  17. Objective effect manifestation of pectus excavatum on load-stressed pulmonary function testing: a case report

    Directory of Open Access Journals (Sweden)

    Chan Jason

    2011-12-01

    Full Text Available Abstract Introduction Pectus excavatum is the most common congenital deformity of the anterior chest wall that, under certain conditions, may pose functional problems due to cardiopulmonary compromise and exercise intolerance. Case presentation We present the case of an otherwise physically-adept 21-year-old Chinese sportsman with idiopathic pectus excavatum, whose symptoms manifested only on bearing a loaded body vest and backpack during physical exercise. Corroborative objective evidence was obtained via load-stressed pulmonary function testing, which demonstrated restrictive lung function. Conclusion This report highlights the possible detrimental synergism of thoracic load stress and pectus excavatum on cardiopulmonary function. Thoracic load-stressed pulmonary function testing provides objective evidence in support of such a synergistic relationship.

  18. Developing the multiple stress-strain creep recovery (MS-SCR) test

    Science.gov (United States)

    Elnasri, Mahmoud; Airey, Gordon; Thom, Nick

    2018-04-01

    While most published work from Europe has been concerned with evaluating binders' resistance to rutting based on their stiffness (deformation resistance), work originating in the US has mainly been concerned with ranking binders based on their recoverability in a multiple stress form. This paper details the design of a new modified multiple stress-strain creep recovery (MS-SCR) test. The test is designed to evaluate binders' rutting resistance based on two rutting resistance mechanisms: stiffness and recoverability. A preliminary investigation is presented in this paper followed by details of the design of the new modified test. A 40/60 penetration grade bitumen and bitumen-filler mastics prepared with three filler concentrations (35%, 50%, and 65% filler content by mass of mastic) were tested. In addition, two polymer modified bitumens (PMBs) using the same base bitumen type were examined for validation. Two parameters are introduced to characterise the short and long recovery in the new test. In terms of stiffness, the test allows the behaviour of binders at different stress levels and loading cycles to be studied and produces a new parameter that can quantify the degree of modification. Finally, a relationship between nonlinearity and normal force in the test was investigated.

  19. Recent developments in small punch testing: Applications at elevated temperatures

    Czech Academy of Sciences Publication Activity Database

    Dymáček, Petr

    2016-01-01

    Roč. 86, DEC (2016), s. 25-33 ISSN 0167-8442 R&D Projects: GA MŠk(CZ) LQ1601 Institutional support: RVO:68081723 Keywords : Small punch test * Creep rupture * Stress relaxation Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 2.659, year: 2016

  20. Validity and Reliability of the Achilles Tendon Total Rupture Score

    DEFF Research Database (Denmark)

    Ganestam, Ann; Barfod, Kristoffer; Klit, Jakob

    2013-01-01

    study was to validate a Danish translation of the ATRS. The ATRS was translated into Danish according to internationally adopted standards. Of 142 patients, 90 with previous rupture of the Achilles tendon participated in the validity study and 52 in the reliability study. The ATRS showed moderately......The best treatment of acute Achilles tendon rupture remains debated. Patient-reported outcome measures have become cornerstones in treatment evaluations. The Achilles tendon total rupture score (ATRS) has been developed for this purpose but requires additional validation. The purpose of the present...... = .07). The limits of agreement were ±18.53. A strong correlation was found between test and retest (intercorrelation coefficient .908); the standard error of measurement was 6.7, and the minimal detectable change was 18.5. The Danish version of the ATRS showed moderately strong criterion validity...

  1. Developing Field Test Procedures for Chloride Stress Corrosion Cracking in the Arabian Gulf

    Directory of Open Access Journals (Sweden)

    Hanan Farhat

    2018-01-01

    Full Text Available Oil and gas production and petrochemical plants in the Arabian Gulf are exposed to severe environmental conditions of high temperature and humidity. This makes these plants susceptible to chloride-induced stress corrosion cracking (CSCC. The laboratory testing fails to provide the exact field environmental conditions. A cost efficient field test setup for CSCC was designed and developed for the Arabian Gulf. The setup included designing self-sustained loading devices, samples, and sample racks. The samples were exposed to a stress equivalent to 80% and 100% of their yield strength. This paper describes the developed test procedures to establish testing with high level of accuracy and repeatability. It also discusses the design aspects and the challenges that were met.

  2. Size ratio correlates with intracranial aneurysm rupture status: a prospective study.

    Science.gov (United States)

    Rahman, Maryam; Smietana, Janel; Hauck, Erik; Hoh, Brian; Hopkins, Nick; Siddiqui, Adnan; Levy, Elad I; Meng, Hui; Mocco, J

    2010-05-01

    The prediction of intracranial aneurysm (IA) rupture risk has generated significant controversy. The findings of the International Study of Unruptured Intracranial Aneurysms (ISUIA) that small anterior circulation aneurysms (IAs are small. These discrepancies have led to the search for better aneurysm parameters to predict rupture. We previously reported that size ratio (SR), IA size divided by parent vessel diameter, correlated strongly with IA rupture status (ruptured versus unruptured). These data were all collected retrospectively off 3-dimensional angiographic images. Therefore, we performed a blinded prospective collection and evaluation of SR data from 2-dimensional angiographic images for a consecutive series of patients with ruptured and unruptured IAs. We prospectively enrolled 40 consecutive patients presenting to a single institution with either ruptured IA or for first-time evaluation of an incidental IA. Blinded technologists acquired all measurements from 2-dimensional angiographic images. Aneurysm rupture status, location, IA maximum size, and parent vessel diameter were documented. The SR was calculated by dividing the aneurysm size (mm) by the average parent vessel size (mm). A 2-tailed Mann-Whitney test was performed to assess statistical significance between ruptured and unruptured groups. Fisher exact test was used to compare medical comorbidities between the ruptured and unruptured groups. Significant differences between the 2 groups were subsequently tested with logistic regression. SE and probability values are reported. Forty consecutive patients with 24 unruptured and 16 ruptured aneurysms met the inclusion criteria. No significant differences were found in age, gender, smoking status, or medical comorbidities between ruptured and unruptured groups. The average maximum size of the unruptured IAs (6.18 + or - 0.60 mm) was significantly smaller compared with the ruptured IAs (7.91 + or - 0.47 mm; P=0.03), and the unruptured group had

  3. Stress

    Science.gov (United States)

    ... taking care of an aging parent. With mental stress, the body pumps out hormones to no avail. Neither fighting ... with type 1 diabetes. This difference makes sense. Stress blocks the body from releasing insulin in people with type 2 ...

  4. Simulated Service and Stress Corrosion Cracking Testing for Friction Stir Welded Spun Formed Domes

    Science.gov (United States)

    Stewart, Thomas J.; Torres, Pablo D.; Caratus, Andrei A.; Curreri, Peter A.

    2010-01-01

    Simulated service testing (SST) development was required to help qualify a new 2195 aluminum lithium (Al-Li) alloy spin forming dome fabrication process for the National Aeronautics and Space Administration (NASA) Exploration Development Technology Program. The application for the technology is to produce high strength low weight tank components for NASA s next generation launch vehicles. Since plate material is not currently manufactured large enough to fabricate these domes, two plates are joined by means of friction stir welding. The plates are then pre-contour machined to near final thicknesses allowing for a thicker weld land and anticipating the level of stretch induced by the spin forming process. The welded plates are then placed in a spin forming tool and hot stretched using a trace method producing incremental contours. Finally the dome receives a room temperature contour stretch to final dimensions, heat treatment, quenching, and artificial aging to emulate a T-8 condition of temper. Stress corrosion cracking (SCC) tests were also performed by alternate immersion in a sodium chloride (NaCl) solution using the typical double beam assembly and with 4-point loaded specimens and use of bent-beam stress-corrosion test specimens under alternate immersion conditions. In addition, experiments were conducted to determine the threshold stress intensity factor for SCC (K(sub ISCC)) which to our knowledge has not been determined previously for Al-Li 2195 alloy. The successful simulated service and stress corrosion testing helped to provide confidence to continue to Ares 1 scale dome fabrication

  5. Lessons learned from EU stress tests evaluations with regard to external hazards

    International Nuclear Information System (INIS)

    Misak, J.

    2014-01-01

    The presentation was oriented to critical review of the lessons learned from the European Union (EU) Stress Test focusing on NPP robustness against external hazards. These lessons addressed: - organization of the stress tests, - scope and objectives of the stress tests, - peer review findings, recommendations and implications on the design in the area of external hazards, - further studies recommended in the area of external hazards and PSA, - relevant research areas identified by the SNETP Task Group in response to Fukushima accident. Some important conclusions were made in the final part of the presentation: - Vulnerability to the Fukushima Dai-ichi reactor accidents caused by external hazards and including their secondary effects was underestimated, - Lessons learned from Fukushima Dai-ichi reactor accidents, from the EU Stress Test and from peer reviews are to be reflected in safety improvements of operating plants and considered in new designs, - while no completely new phenomena were revealed from the Fukushima Dai-ichi reactor accidents, improvements in specific research areas (including external hazards and use of PSA) should be considered with high priority

  6. Optimal Constant-Stress Accelerated Degradation Test Plans Using Nonlinear Generalized Wiener Process

    Directory of Open Access Journals (Sweden)

    Zhen Chen

    2016-01-01

    Full Text Available Accelerated degradation test (ADT has been widely used to assess highly reliable products’ lifetime. To conduct an ADT, an appropriate degradation model and test plan should be determined in advance. Although many historical studies have proposed quite a few models, there is still room for improvement. Hence we propose a Nonlinear Generalized Wiener Process (NGWP model with consideration of the effects of stress level, product-to-product variability, and measurement errors for a higher estimation accuracy and a wider range of use. Then under the constraints of sample size, test duration, and test cost, the plans of constant-stress ADT (CSADT with multiple stress levels based on the NGWP are designed by minimizing the asymptotic variance of the reliability estimation of the products under normal operation conditions. An optimization algorithm is developed to determine the optimal stress levels, the number of units allocated to each level, inspection frequency, and measurement times simultaneously. In addition, a comparison based on degradation data of LEDs is made to show better goodness-of-fit of the NGWP than that of other models. Finally, optimal two-level and three-level CSADT plans under various constraints and a detailed sensitivity analysis are demonstrated through examples in this paper.

  7. Economic Crisis and Marital Problems in Turkey: Testing the Family Stress Model

    Science.gov (United States)

    Aytac, Isik A.; Rankin, Bruce H.

    2009-01-01

    This paper applied the family stress model to the case of Turkey in the wake of the 2001 economic crisis. Using structural equation modeling and a nationally representative urban sample of 711 married women and 490 married men, we tested whether economic hardship and the associated family economic strain on families resulted in greater marital…

  8. 12 CFR Appendix A to Subpart B of... - Risk-Based Capital Stress Test

    Science.gov (United States)

    2010-01-01