Uncertainty Quantification and Comparison of Weld Residual Stress Measurements and Predictions.

Energy Technology Data Exchange (ETDEWEB)

Lewis, John R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Brooks, Dusty Marie [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2016-10-01

In pressurized water reactors, the prevention, detection, and repair of cracks within dissimilar metal welds is essential to ensure proper plant functionality and safety. Weld residual stresses, which are difficult to model and cannot be directly measured, contribute to the formation and growth of cracks due to primary water stress corrosion cracking. Additionally, the uncertainty in weld residual stress measurements and modeling predictions is not well understood, further complicating the prediction of crack evolution. The purpose of this document is to develop methodology to quantify the uncertainty associated with weld residual stress that can be applied to modeling predictions and experimental measurements. Ultimately, the results can be used to assess the current state of uncertainty and to build confidence in both modeling and experimental procedures. The methodology consists of statistically modeling the variation in the weld residual stress profiles using functional data analysis techniques. Uncertainty is quantified using statistical bounds (e.g. confidence and tolerance bounds) constructed with a semi-parametric bootstrap procedure. Such bounds describe the range in which quantities of interest, such as means, are expected to lie as evidenced by the data. The methodology is extended to provide direct comparisons between experimental measurements and modeling predictions by constructing statistical confidence bounds for the average difference between the two quantities. The statistical bounds on the average difference can be used to assess the level of agreement between measurements and predictions. The methodology is applied to experimental measurements of residual stress obtained using two strain relief measurement methods and predictions from seven finite element models developed by different organizations during a round robin study.

Correlation between electron-irradiation defects and applied stress in graphene: A molecular dynamics study

Energy Technology Data Exchange (ETDEWEB)

Kida, Shogo; Yamamoto, Masaya; Kawata, Hiroaki; Hirai, Yoshihiko; Yasuda, Masaaki, E-mail: yasuda@pe.osakafu-u.ac.jp [Department of Physics and Electronics, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Tada, Kazuhiro [Department of Electrical and Control Systems Engineering, National Institute of Technology, Toyama College, Toyama 939-8630 (Japan)

2015-09-15

Molecular dynamics (MD) simulations are performed to study the correlation between electron irradiation defects and applied stress in graphene. The electron irradiation effect is introduced by the binary collision model in the MD simulation. By applying a tensile stress to graphene, the number of adatom-vacancy (AV) and Stone–Wales (SW) defects increase under electron irradiation, while the number of single-vacancy defects is not noticeably affected by the applied stress. Both the activation and formation energies of an AV defect and the activation energy of an SW defect decrease when a tensile stress is applied to graphene. Applying tensile stress also relaxes the compression stress associated with SW defect formation. These effects induced by the applied stress cause the increase in AV and SW defect formation under electron irradiation.

Magnetic hysteresis measurements of thin films under isotropic stress.

Science.gov (United States)

Holland, Patrick; Dubey, Archana; Geerts, Wilhelmus

2000-10-01

Nowadays, ferromagnetic thin films are widely applied in devices for information technology (credit cards, video recorder tapes, floppies, hard disks) and sensors (air bags, anti-breaking systems, navigation systems). Thus, with the increase in the use of magnetic media continued investigation of magnetic properties of materials is necessary to help in determining the useful properties of materials for new or improved applications. We are currently interested in studying the effect of applied external stress on Kerr hysteresis curves of thin magnetic films. The Ni and NiFe films were grown using DC magnetron sputtering with Ar as the sputter gas (pAr=4 mTorr; Tsub=55-190 C). Seed and cap layers of Ti were used on all films for adhesion and oxidation protection, respectively. A brass membrane pressure cell was designed to apply in-plane isotropic stress to thin films. In this pressure cell, gas pressure is used to deform a flexible substrate onto which a thin magnetic film has been sputtered. The curvature of the samples could be controlled by changing the gas pressure to the cell. Magneto-Optical in-plane hysteresis curves at different values of strain were measured. The results obtained show that the stress sensitivity is dependent on the film thickness. For the 500nm NiFe films, the coercivity strongly decreased as a function of the applied stress.

High precision stress measurements in semiconductor structures by Raman microscopy

Energy Technology Data Exchange (ETDEWEB)

Uhlig, Benjamin

2009-07-01

Stress in silicon structures plays an essential role in modern semiconductor technology. This stress has to be measured and due to the ongoing miniaturization in today's semiconductor industry, the measuring method has to meet certain requirements. The present thesis deals with the question how Raman spectroscopy can be used to measure the state of stress in semiconductor structures. In the first chapter the relation between Raman peakshift and stress in the material is explained. It is shown that detailed stress maps with a spatial resolution close to the diffraction limit can be obtained in structured semiconductor samples. Furthermore a novel procedure, the so called Stokes-AntiStokes-Difference method is introduced. With this method, topography, tool or drift effects can be distinguished from stress related influences in the sample. In the next chapter Tip-enhanced Raman Scattering (TERS) and its application for an improvement in lateral resolution is discussed. For this, a study is presented, which shows the influence of metal particles on the intensity and localization of the Raman signal. A method to attach metal particles to scannable tips is successfully applied. First TERS scans are shown and their impact on and challenges for high resolution stress measurements on semiconductor structures is explained. (orig.)

Measuring multiple residual-stress components using the contour method and multiple cuts

Energy Technology Data Exchange (ETDEWEB)

Prime, Michael B [Los Alamos National Laboratory; Swenson, Hunter [Los Alamos National Laboratory; Pagliaro, Pierluigi [U. PALERMO; Zuccarello, Bernardo [U. PALERMO

2009-01-01

The conventional contour method determines one component of stress over the cross section of a part. The part is cut into two, the contour of the exposed surface is measured, and Bueckner's superposition principle is analytically applied to calculate stresses. In this paper, the contour method is extended to the measurement of multiple stress components by making multiple cuts with subsequent applications of superposition. The theory and limitations are described. The theory is experimentally tested on a 316L stainless steel disk with residual stresses induced by plastically indenting the central portion of the disk. The stress results are validated against independent measurements using neutron diffraction. The theory has implications beyond just multiple cuts. The contour method measurements and calculations for the first cut reveal how the residual stresses have changed throughout the part. Subsequent measurements of partially relaxed stresses by other techniques, such as laboratory x-rays, hole drilling, or neutron or synchrotron diffraction, can be superimposed back to the original state of the body.

A study of x-ray microbeam stress measurement for local area

International Nuclear Information System (INIS)

Natsume, Yoshitaka; Miyakawa, Susumu

1987-01-01

A new type X-ray microbeam equipment which is capable of three-dimensional oscillation at an X-ray radiation position was used to measure the residual stress of pure iron powder and bending plate specimens as well as that in the vicinity of fatigue crack tip of 1/2 CT specimen. The results obtained are summerized as follows. (1) Diffraction profiles of pure iron powder with diameter 0.02 ∼ 0.03 μm particle size obtained by the present microbeam technique in the beam area of 80 μm in diamether and measuring time more than 800 sec showed Kα 1 and Kα 2 peaks clearly, so that these profiles are good enough for stress measurement. (2) The measured stress of pure iron powder with diameter 10 ∼ 25 μm particle size in the beam area of 80 μm in diameter was not equal to 0 MPa. The measured stress varied greatly and was independent of measuring time. (3) The measured stress of pure iron powder with diameter 0.02 ∼ 0.03 μm particle size in the beam area of 80 μm in diameter was almost 1 MPa, which shows the good accuracy of this X-ray micro-beam equipment. (4) The relation between the X-ray measured stress and the mechanically applied stress showed good agreement. (5) The distribution of residual stress at the vicinity of fatigue crack tip showed that the residual stress at the fatigue crack tip was compression and the residual stress in front of crack tip was tension. This tensile residual stress in front of crack tip existed in the area from 0.02 mm to 2 mm. (6) The above results show that the present equipment is advantageous in the investigation of local stress, shortening the measuring time without sacrificing the accuracy. (author)

Residual stress measurement with focused acoustic waves and direct comparison with X-ray diffraction stress measurements

International Nuclear Information System (INIS)

Sathish, Shamachary; Moran, Thomas J.; Martin, Richard W.; Reibel, Richard

2005-01-01

The technique of measuring small changes in acoustic wave velocity due to external or internal stress has been used for quantitative determination of residual stress in materials during the last decade. Application of similar methodology with focused acoustic waves leads to residual stress measurement with spatial resolution of a few millimeters to a few microns. The high spatial resolution residual stress measurement required development of new methodologies in both the design of acoustic lenses and the instrumentation for acoustic wave velocity determination. This paper presents two new methodologies developed for the measurement of residual stress with spatial resolution of a few millimeters. The design of new type of acoustic lens for achieving higher spatial resolution in residual stress measurement is introduced. Development of instrumentation for high precision local surface wave velocity measurement will be presented. Residual stresses measured around a crack tip in a sample of Ti-6A1-4V using a focused beam will be compared with X-ray diffraction measurements performed on the same region of the sample. Results of residual stress measurements along a direction perpendicular to the electron beam weld in a sample of Ti-6A1-4V, determined using focused acoustic waves and X-ray diffraction technique, are also presented. The spatial resolution and penetration depth of X-rays and focused acoustic beams with reference to residual stress measurements are discussed

Background Stress Inventory: Developing a Measure of Understudied Stress.

Science.gov (United States)

Terrill, Alexandra L; Gjerde, Jill M; Garofalo, John P

2015-10-01

Background stress is an understudied source of stress that involves both ambient stress and daily hassles upon which new stressors are superimposed. To date, an accurate measure of the background stress construct has not been available. We developed the Background Stress Inventory, a 25-item self-report measure that asks respondents to indicate how distressed they have felt over the past month and the majority of the past year across five domains: financial, occupation, environment, health and social. Seven hundred seventy-two participants completed the paper-and-pencil measure; the sample was randomly split into two separate subsamples for analyses. Exploratory factor analysis suggested five factors corresponding to these domains, and confirmatory factor analysis showed acceptable global fit (X(2)(255) = 456.47, comparative fit index = 0.94, root mean square error of approximation = 0.045). Cronbach's alpha (0.89) indicated good internal reliability. Construct validity analyses showed significant positive relationships with measures of perceived stressfulness (r = 0.62) and daily hassles (0.41), p's < 0.01. Depressive symptoms (0.62) and basal blood pressure (0.21) were both significantly associated with background stress, p's < 0.01. The importance of the proposed measure is reflected in the limited research base on the impact of background stress. Systematic investigation of this measure will provide insight into this understudied form of chronic stress and its potential influence on both psychological and physical endpoints. Copyright © 2013 John Wiley & Sons, Ltd.

Development of a stress sensor based on the piezoelectric lead zirconate titanate for impact stress measurement

Science.gov (United States)

Liu, Yiming; Xu, Bin; Li, Lifei; Li, Bing

2012-04-01

The measurement of stress of concrete structures under impact loading and other strong dynamic loadings is crucial for the monitoring of health and damage detection. Due to its main advantages including availability, extremely high rigidity, high natural frequency, wide measuring range, high stability, high reproducibility, high linearity and wide operating temperature range, piezoelectric (Lead Zirconate Titanate, PZT) ceramic materials has been a widely used smart material for both sensing and actuation for monitoring and control in engineering structures. In this paper, a kind of stress sensor based on piezoelectric ceramics for impact stress measuring of concrete structures is developed. Because the PZT is fragile, in order to employ it for the health monitoring of concrete structures, special handling and treatment should be taken to protect the PZT and to make it survive and work properly in concrete. The commercially available PZT patch with lead wires is first applied with an insulation coating to prevent water and moisture damage, and then is packaged by jacketing it by two small precasted cylinder concrete blocks with enough strength to form a smart aggregate (SA). The employed PZT patch has a dimension of 10mm x 10mm x 0.3mm. In order to calibrate the PZT based stress sensor for impact stress measuring, a dropping hammer was designed and calibration test on the sensitivity of the proposed transducer was carried out with an industry charge amplifier. The voltage output of the stress sensor and the impact force under different free falling heights and impact mass were recorded with a high sampling rate data acquisition system. Based on the test measurements, the sensibility of the PZT based stress sensor was determined. Results show that the output of the PZT based stress sensor is proportional to the stress level and the repeatability of the measurement is very good. The self-made piezoelectric stress sensor can be easily embedded in concrete and provide

Modeling of stress-strain diagram on the basis of magnetic measurements

International Nuclear Information System (INIS)

Gorkunov, Eh.S.; Fedotov, V.P.; Bukhvalov, A.B.; Veselov, I.N.

1997-01-01

The model of a stress-strain diagram with taking into account the strain hardening and the growth of metal damageing is proposed. The model is applied to calculate a stress-strain curve for continuous cast 45 steel using the results of magnetic properties measuring. The latter permits predicting the durability of construction elements with the use of nondestructive magnetic testing

Residual stress measurement method in MEMS microbeams using frequency shift data

International Nuclear Information System (INIS)

Somà, Aurelio; Ballestra, Alberto

2009-01-01

The dynamical behaviour of a set of gold microbeams affected by residual stress has been studied. Experimental frequency shift curves were obtained by increasing the dc voltage applied to the specimens. Comparison with different analytical and numerical models has been carried out in order to identify both analytical and finite element models in the presence of residual stress. Residual strain and stress, due to the fabrication process, have been widely reported in the literature in both out-of-plane microcantilevers and clamped–clamped microbeams by using mainly the value of pull-in voltage and static deflection data. In the case of a microcantilever, an accurate modelling includes the effect of the initial curvature due to microfabrication. In double-clamped microbeams, a pre-load applied by tensile stress is considered. A good correspondence is pointed out between measurements and numerical models so that the residual stress effect can be evaluated for different geometrical configurations

Neutron stress measurement using image plate and the cos α method

International Nuclear Information System (INIS)

Sasaki, Toshihiko; Hirose, Yukio; Minakawa, Nobuaki; Morii, Yukio

2004-01-01

A new type of the neutron stress measurement method, in which the stress is determined by the cos α method, was studied. A neutron image plate was used in this study for detecting the diffraction image. Steel specimens of 5 mm thickness were used for the tensile stress test. The stresses obtain from the experiment showed one-to-one ratio with respect to the applied stresses, though the misfit stress of about 400 MPa was also observed in the result. A simple correction technique for calibrating raw data was proposed to obtain the true stress. A simulation study was carried out to check the experimental result on the peak positions in the diffraction ring and the stress calculation by the cos α method. (author)

Quantitative stress measurement of elastic deformation using mechanoluminescent sensor: An intensity ratio model

Science.gov (United States)

Cai, Tao; Guo, Songtao; Li, Yongzeng; Peng, Di; Zhao, Xiaofeng; Liu, Yingzheng

2018-04-01

The mechanoluminescent (ML) sensor is a newly developed non-invasive technique for stress/strain measurement. However, its application has been mostly restricted to qualitative measurement due to the lack of a well-defined relationship between ML intensity and stress. To achieve accurate stress measurement, an intensity ratio model was proposed in this study to establish a quantitative relationship between the stress condition and its ML intensity in elastic deformation. To verify the proposed model, experiments were carried out on a ML measurement system using resin samples mixed with the sensor material SrAl2O4:Eu2+, Dy3+. The ML intensity ratio was found to be dependent on the applied stress and strain rate, and the relationship acquired from the experimental results agreed well with the proposed model. The current study provided a physical explanation for the relationship between ML intensity and its stress condition. The proposed model was applicable in various SrAl2O4:Eu2+, Dy3+-based ML measurement in elastic deformation, and could provide a useful reference for quantitative stress measurement using the ML sensor in general.

Speed of human tooth movement in growers and non-growers: Selection of applied stress matters.

Science.gov (United States)

Iwasaki, L R; Liu, Y; Liu, H; Nickel, J C

2017-06-01

To test that the speed of tooth translation is not affected by stress magnitude and growth status. Advanced Education Orthodontic clinics at the Universities of Nebraska Medical Center and Missouri-Kansas City. Forty-six consenting subjects with orthodontic treatment plans involving maxillary first premolar extractions. This randomized split-mouth study used segmental mechanics with definitive posterior anchorage and individual vertical-loop maxillary canine retraction appliances and measured three-dimensional tooth movements. Height and cephalometric superimposition changes determined growing (G) and non-growing (NG) subjects. Subjects were appointed for 9-11 visits over 84 days for maxillary dental impressions to measure three-dimensional tooth movement and to ensure retraction forces were continuously applied via calibrated nitinol coil springs. Springs were custom selected to apply two different stresses of 4, 13, 26, 52 or 78 kPa to maxillary canines in each subject. Statistical analyses (α=0.050) included ANOVA, effect size (partial η 2 ) and Tukey's Honest Significant Difference (HSD) and two-group t tests. Distolateral translation speeds were 0.034±0.015, 0.047±0.019, 0.066±0.025, 0.068±0.016 and 0.079±0.030 mm/d for 4, 13, 26, 52 and 78 kPa, respectively. Stress significantly affected speed and partial η 2 =0.376. Overall, more distopalatal rotation was shown by teeth moved by 78 kPa (18.03±9.50º) compared to other stresses (3.86±6.83º), and speeds were significantly higher (P=.001) in G (0.062±0.026 mm/d) than NG subjects (0.041±0.019 mm/d). Stress magnitude and growth status significantly affected the speed of tooth translation. Optimal applied stresses were 26-52 kPa, and overall speeds were 1.5-fold faster in G compared to NG subjects. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

A computer program (COSTUM) to calculate confidence intervals for in situ stress measurements. V. 1

International Nuclear Information System (INIS)

Dzik, E.J.; Walker, J.R.; Martin, C.D.

1989-03-01

The state of in situ stress is one of the parameters required both for the design and analysis of underground excavations and for the evaluation of numerical models used to simulate underground conditions. To account for the variability and uncertainty of in situ stress measurements, it is desirable to apply confidence limits to measured stresses. Several measurements of the state of stress along a borehole are often made to estimate the average state of stress at a point. Since stress is a tensor, calculating the mean stress and confidence limits using scalar techniques is inappropriate as well as incorrect. A computer program has been written to calculate and present the mean principle stresses and the confidence limits for the magnitudes and directions of the mean principle stresses. This report describes the computer program, COSTUM

Influence of applied stress on swelling behavior in Type 304 stainless steel

International Nuclear Information System (INIS)

Igata, N.; Fujihira, T.; Kohno, Y.; Tsunakawa, M.

1984-01-01

The swelling behavior of Type 304 stainless steel during stress application was investigated by means of electron irradiation using a high-voltage electron microscope (HVEM). The dose dependence of swelling under stress is similar to the linearafter-incubation swelling scheme of other electron irradiation studies. The effect of applied stress on the swelling characteristics appeared through the control of incubation regime of swelling rather than of the swelling rate. The incubation dose first increases, then decreases, and increases again with increasing applied stress. The prominent finding in this study, based on the advantage of HVEM in situ observation, is that the saturated void density is equal to the number density of interstitial dislocation loops observed in the early stage of irradiation. Essentially, applied stress affects the loop nucleation process. The dislocation loop density then affects the incubation dose of swelling through its control of dislocation behavior and the saturation dose of dislocation density

Residual-stress measurements

Energy Technology Data Exchange (ETDEWEB)

Ezeilo, A N; Webster, G A [Imperial College, London (United Kingdom); Webster, P J [Salford Univ. (United Kingdom)

1997-04-01

Because neutrons can penetrate distances of up to 50 mm in most engineering materials, this makes them unique for establishing residual-stress distributions non-destructively. D1A is particularly suited for through-surface measurements as it does not suffer from instrumental surface aberrations commonly found on multidetector instruments, while D20 is best for fast internal-strain scanning. Two examples for residual-stress measurements in a shot-peened material, and in a weld are presented to demonstrate the attractive features of both instruments. (author).

Stress measurements using the CFDF

International Nuclear Information System (INIS)

Maayouf, R.M.A.; Abdel-Latif, I.A.; Khalil, M.I.

2000-01-01

The present work deals with neutron diffraction measurements performed using the Cairo Fourier Diffractometer Facility (CFDF) for stress analysis.The CFDF has 0.45% resolution and a value l.lxl0 6 neutrons . cm -2 , s -1 of integral neutron flux at the sample position. While one of the two samples used for the present measurements was made from two steel cylindrical rods ( 5.5 mm in diameter) electrically welded together, the second one was a stress free steel rod of the same material. The stress distribution after welding was studied from the measured, by the CFDF, diffraction patterns . It has been found from the present measurements that the strain at the welding point is higher than any point far from it; verifying that the CFDF can be successfully used for stress measurement

Critical applied stresses for a crack initiation from a sharp V-notch

Directory of Open Access Journals (Sweden)

L. Náhlík

2014-10-01

Full Text Available The aim of the paper is to estimate a value of the critical applied stress for a crack initiation from a sharp V-notch tip. The classical approach of the linear elastic fracture mechanics (LELM was generalized, because the stress singularity exponent differs from 0.5 in the studied case. The value of the stress singularity exponent depends on the V-notch opening angle. The finite element method was used for a determination of stress distribution in the vicinity of the sharp V-notch tip and for the estimation of the generalized stress intensity factor depending on the V-notch opening angle. Critical value of the generalized stress intensity factor was obtained using stability criteria based on the opening stress component averaged over a critical distance d from the V-notch tip and generalized strain energy density factor. Calculated values of the critical applied stresses were compared with experimental data from the literature and applicability of the LEFM concept is discussed.

Applied rolling and sensitivity of Bi(2223)/Ag tapes on Ic degradation by mechanical stress

International Nuclear Information System (INIS)

Kovac, P.; Bukva, P.; Husek, I.; Richens, P.E.; Jones, H.

1999-01-01

An experimental study of multicore Bi(2223)/Ag tapes, roll-sintered by different methods and subjected to bending and tension stresses has been performed. The tapes, of various technological histories, were bent and tensioned and subsequently the transport current was measured at each stressed state. Comparison of I c degradation curves shows that applied rolling may influence the sensitivity of Bi-2223 filaments against the mechanical stress. The existence of transverse microcracks caused by intermediate rolling leads to a higher sensitivity of the tape to bending. A lowering of critical current degradation was observed for two-axially rolled tapes having a higher filament density and better homogeneity prior to sintering treatment. (author)

Stress measurements in the Naesliden Mine

Energy Technology Data Exchange (ETDEWEB)

Leijon, B. [Univ. of Luleaa, Sweden; Carlsson, H.; Myrvang, A.

1980-05-15

Determinations of virgin stresses were performed at an early stage of the Naesliden Project in order to obtain input data for the finite element models of the mine. The Leeman three-dimensional overcoring technique was used at five locations on levels ranging from 210 m to 460 m below surface. Stress data were obtained at four of these locations. The results show an excess of horizontal stresses whilst the vertical stress is in accordance with the gravitational load from the overburden. The major and intermediate principal stresses are sub-horizontal and directed respectively perpendicular and parallel to the schisotsity of the wall rock and the strike of the tabular ore body. The minor principal stress is directed almost vertically. Stresses were also measured close to a stope on 300 m level in the mine. Biaxial and triaxial overcoring measurements were made at eighteen points between 0.25 m and 7.2 m above the roof of the stope. The stresses were found to have magnitudes of about 70 MPa close to the roof and to decrease rapidly with the distance from the roof. Stress measurements were made in connection with slot blastings in the foot wall, the latter measure being made in an attempt to de-stress the roof of stope 3. Two methods were used for stress monitorings, both showing that expected stress changes did not take place. Long-term stress guages have been installed in the ore body in order to monitor expected re-distributions of stresses due to mining. So far, the recorded stress changes are below 5 MPa.

The measurement of residual stresses in claddings

International Nuclear Information System (INIS)

Hofer, G.; Bender, N.

1978-01-01

The ring core method, a variation of the hole drilling method for the measurement of biaxial residual stresses, has been extended to measure stresses from depths of about 5 to 25mm. It is now possible to measure the stress profiles of clad material. Examples of measured stress profiles are shown and compared with those obtained with a sectioning technique. (author)

Determining Quiescent Colloidal Suspension Viscosities Using the Green-Kubo Relation and Image-Based Stress Measurements

Science.gov (United States)

Lin, Neil Y. C.; Bierbaum, Matthew; Cohen, Itai

2017-09-01

By combining confocal microscopy and stress assessment from local structural anisotropy, we directly measure stresses in 3D quiescent colloidal liquids. Our noninvasive and nonperturbative method allows us to measure forces ≲50 fN with a small and tunable probing volume, enabling us to resolve the stress fluctuations arising from particle thermal motions. We use the Green-Kubo relation to relate these measured stress fluctuations to the bulk Brownian viscosity at different volume fractions, comparing against simulations and conventional rheometry measurements. We find that the Green-Kubo analysis gives excellent agreement with these prior results, suggesting that similar methods could be applied to investigations of local flow properties in many poorly understood far-from-equilibrium systems, including suspensions that are glassy, strongly sheared, or highly confined.

Development of technique to apply induction heating stress improvement to recirculation inlet nozzle

International Nuclear Information System (INIS)

Chiba, Kunihiko; Nihei, Kenichi; Ootaka, Minoru

2009-01-01

Stress corrosion cracking (SCC) have been found in the primary loop recirculation (PLR) systems of boiling water reactors (BWR). Residual stress in welding heat-affected zone is one of the factors of SCC, and the residual stress improvement is one of the most effective methods to prevent SCC. Induction heating stress improvement (IHSI) is one of the techniques to improve reduce residual stress. However, it is difficult to apply IHSI to the place such as the recirculation inlet nozzle where the flow stagnates. In this present study, the technique to apply IHSI to the recirculation inlet nozzle was developed using water jet which blowed into the crevice between the nozzle safe end and the thermal sleeve. (author)

In-situ X-ray residual stress measurement on a peened alloy 600 weld metal at elevated temperature under tensile load

International Nuclear Information System (INIS)

Yunomura, Tomoaki; Maeguchi, Takaharu; Kurimura, Takayuki

2014-01-01

In order to verify stability of residual stress improvement effect of peeing for mitigation of stress corrosion cracking in components of PWR plant, relaxation behavior of residual stress induced by water jet peening (WJP) on surface of alloy 600 weld metal (alloy 132) was investigated by in-situ X-ray residual stress measurement under thermal aging and stress condition considered for actual plant operation. Surface residual stress change was observed at the early stage of thermal aging at 360°C, but no significant further stress relaxation was observed after that. Applied stress below yield stress does not significantly affect stress relaxation behavior of surface residual stress. For the X-ray residual stress measurement, X-ray stress constant at room temperature for alloy 600 was determined experimentally with several surface treatment and existence of applied strain. The X-ray stress constant at elevated temperatures were extrapolated theoretically based on the X-ray stress constant at room temperature for alloy 600. (author)

A study for high accuracy measurement of residual stress by deep hole drilling technique

Science.gov (United States)

Kitano, Houichi; Okano, Shigetaka; Mochizuki, Masahito

2012-08-01

The deep hole drilling technique (DHD) received much attention in recent years as a method for measuring through-thickness residual stresses. However, some accuracy problems occur when residual stress evaluation is performed by the DHD technique. One of the reasons is that the traditional DHD evaluation formula applies to the plane stress condition. The second is that the effects of the plastic deformation produced in the drilling process and the deformation produced in the trepanning process are ignored. In this study, a modified evaluation formula, which is applied to the plane strain condition, is proposed. In addition, a new procedure is proposed which can consider the effects of the deformation produced in the DHD process by investigating the effects in detail by finite element (FE) analysis. Then, the evaluation results obtained by the new procedure are compared with that obtained by traditional DHD procedure by FE analysis. As a result, the new procedure evaluates the residual stress fields better than the traditional DHD procedure when the measuring object is thick enough that the stress condition can be assumed as the plane strain condition as in the model used in this study.

Application of advanced one sided stress wave velocity measurement in concrete

International Nuclear Information System (INIS)

Lee, Joon Hyun; Song, Won Joon; Popovices, J. S.; Achenbach, J. D.

1997-01-01

It is of interest to reliably measure the velocity of stress waves in concrete. At present, reliable measurement is not possible for dispersive and attenuating materials such as concrete when access to only one surface of the structure is available, such as in the case of pavement structures. In this paper, a new method for one-sided stress wave velocity determination in concrete is applied to investigate the effects of composition, age and moisture content. This method uses a controlled impact as a stress wave source and two sensitive receivers mounted on the same surface as the impact sites. The novel aspect of the technique is the data collection system which automatically determines the arrival of the generated longitudinal and surface wave arrivals. A conventional ultrasonic through transmission method is used to compare with the results determined by the one-sided method.

Development of stress relaxation measurement by a small size C-ring specimen method

International Nuclear Information System (INIS)

Shimanuki, Shizuka; Nakata, Kiyotomo; Kasahara, Shigeki; Kuniya, Jiro

2002-01-01

A stress relaxation measurement method has been developed by using C-ring specimens, and a specimen size effect has been evaluated taking radiation-induced stress relaxation into consideration. C-ring specimens were stressed by forcing a wedge in the gap. Giving an appropriate eccentric configuration in the half of the ring opposite the gap, the stress gradient along the circumference was eliminated in the section and the stress level could be varied by changing the gap spacing. The validity of the C-ring test method was confirmed by thermally stress relaxation experiments at annealing temperatures from 300 to 600degC for 1 min to 200 h in carbon steel: considerable stress relaxation could be measured for all levels of applied stress even at relatively low annealing temperatures. The relaxation results obtained from the C-ring test were in good agreement with those from a uniaxial tensile stress relaxation test. The smaller C-ring specimen with about 40 mm diameter, which is required for radiation-induced stress relaxation test, also showed adequate accuracy on stress relaxation at 600 to 830degC in stainless steel, compared with the large size C-ring specimen test. (author)

Measurement of residual stress in textured Al alloy by neutron diffraction method

International Nuclear Information System (INIS)

Okido, S.; Hayashi, M.; Tanaka, K.; Akiniwa, Y.; Minakawa, N.; Morii, Y.

1999-01-01

Residual stress generated in a shrunken aluminum alloy specimen, which was prepared for the round robin test conducted by VAMAS (Versailles Project on Advanced Materials and Standards) TWA-20 organized for the purpose of standardizing residual stress measurement methods, was evaluated by a neutron diffraction method. The main purpose of the round robin test was to assess the reproducibility of data obtained with the measurement facilities of the participants. The general standard of the Residual Stress Analyzer (RESA) constructed in the Japan Atomic Energy Research Institute was verified from the measured residual strains, which were equivalent to the values calculated by FEM and values measured by the research facilities in North America. Residual stress was calculated from residual strain in three perpendicular directions. The diffraction intensities were dependent on measurement directions since the prepared specimen possessed texture. Diffraction profiles in directions having a weak diffraction intensity caused an inaccurate evaluation of the residual stress. To solve this problem, a new method for evaluating residual stress with respect to diffraction plane dependency of the elastic constant was applied. The diffraction plane giving the highest intensity among 110, 200, and 220 diffraction was used to evaluate the residual strain in each of three directions. The residual strain obtained on the used diffraction plane was converted to the equivalent strain for the defined diffraction plane using the ratio of elastic constants of these two planes. The developed evaluation method achieved highly accurate measurement and remarkable efficiency in the measurement process. (author)

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

Experimental Measurement of In Situ Stress

Science.gov (United States)

Tibbo, Maria; Milkereit, Bernd; Nasseri, Farzine; Schmitt, Douglas; Young, Paul

2016-04-01

The World Stress Map data is determined by stress indicators including earthquake focal mechanisms, in situ measurement in mining, oil and gas boreholes as well as the borehole cores, and geologic data. Unfortunately, these measurements are not only infrequent but sometimes infeasible, and do not provide nearly enough data points with high accuracy to correctly infer stress fields in deep mines around the world. Improvements in stress measurements of Earth's crust is fundamental to several industries such as oil and gas, mining, nuclear waste management, and enhanced geothermal systems. Quantifying the state of stress and the geophysical properties of different rock types is a major complication in geophysical monitoring of deep mines. Most stress measurement techniques involve either the boreholes or their cores, however these measurements usually only give stress along one axis, not the complete stress tensor. The goal of this project is to investigate a new method of acquiring a complete stress tensor of the in situ stress in the Earth's crust. This project is part of a comprehensive, exploration geophysical study in a deep, highly stressed mine located in Sudbury, Ontario, Canada, and focuses on two boreholes located in this mine. These boreholes are approximately 400 m long with NQ diameters and are located at depths of about 1300 - 1600 m and 1700 - 2000 m. Two borehole logging surveys were performed on both boreholes, October 2013 and July 2015, in order to perform a time-lapse analysis of the geophysical changes in the mine. These multi-parameter surveys include caliper, full waveform sonic, televiewer, chargeability (IP), and resistivity. Laboratory experiments have been performed on borehole core samples of varying geologies from each borehole. These experiments have measured the geophysical properties including elastic modulus, bulk modulus, P- and S-wave velocities, and density. The apparatus' used for this project are geophysical imaging cells capable

Neutron measurement of residual stresses in a used railway rail

International Nuclear Information System (INIS)

Webster, P.J.; Low, K.S.; Mills, G.; Webster, G.A.

1990-01-01

The high resolution neutron diffraction technique has been applied to determine, non-destructively, the residual stress distribution developed in the head of a railway rail after normal service. Measurements were made, using the neutron strain scanner at the Institute Laue Langevin, Grenoble, on a transverse slice of rail 12mm thick taken from a section of straight track. The rail head was scanned in the three principal orientations in a series of parallel traverses sufficiently close to enable a two-dimensional matrix of data to be accumulated and vertical, transverse and longitudinal residual stress contours to be drawn. The results demonstrate the effectiveness and unique characteristics of the neutron technique to determine nondestructively and continuously the residual stresses inside engineering components

Stress Measurement by Geometrical Optics

Science.gov (United States)

Robinson, R. S.; Rossnagel, S. M.

1986-01-01

Fast, simple technique measures stresses in thin films. Sample disk bowed by stress into approximately spherical shape. Reflected image of disk magnified by amount related to curvature and, therefore, stress. Method requires sample substrate, such as cheap microscope cover slide, two mirrors, laser light beam, and screen.

Investigations of some rock stress measuring techniques and the stress field in Norway

Energy Technology Data Exchange (ETDEWEB)

Hanssen, Tor Harald

1998-12-31

Rock stresses are important to the safe construction and operation of all man-made structures in rock, whether In mining, civil or petroleum engineering. The crucial issue is their relative magnitude and orientation. This thesis develops equipment and methods for further rock stress assessment and reevaluates existing overcoring rock stress measurements, and relates this information to the present geological setting. Both laboratory work and field work are involved. In the field, rock stresses are measured by the overcoring and the hydraulic fracturing technique. An observation technique for assessing likely high stresses is developed. The field data refer to several hydropower projects and to some offshore hydrocarbon fields. The principal sections are: (1) Tectonic setting in the western Fennoscandia, (2) Triaxial rock stress measurements by overcoring using the NTH cell (a strain gauge cell developed at the Norwegian technical university in Trondheim and based on the CSIR cell of the South African Council for Scientific and Industrial Research), (3) Laboratory testing of the NTH cell, (4) Quality ranking of stresses measured by the NTH cell, (4) Recalculated rock stresses and implications to the regional stress field, (5) Hydraulic fracturing stress measurements. 113 refs., 98 figs., 62 tabs.

Investigations of some rock stress measuring techniques and the stress field in Norway

Energy Technology Data Exchange (ETDEWEB)

Hanssen, Tor Harald

1997-12-31

Rock stresses are important to the safe construction and operation of all man-made structures in rock, whether In mining, civil or petroleum engineering. The crucial issue is their relative magnitude and orientation. This thesis develops equipment and methods for further rock stress assessment and reevaluates existing overcoring rock stress measurements, and relates this information to the present geological setting. Both laboratory work and field work are involved. In the field, rock stresses are measured by the overcoring and the hydraulic fracturing technique. An observation technique for assessing likely high stresses is developed. The field data refer to several hydropower projects and to some offshore hydrocarbon fields. The principal sections are: (1) Tectonic setting in the western Fennoscandia, (2) Triaxial rock stress measurements by overcoring using the NTH cell (a strain gauge cell developed at the Norwegian technical university in Trondheim and based on the CSIR cell of the South African Council for Scientific and Industrial Research), (3) Laboratory testing of the NTH cell, (4) Quality ranking of stresses measured by the NTH cell, (4) Recalculated rock stresses and implications to the regional stress field, (5) Hydraulic fracturing stress measurements. 113 refs., 98 figs., 62 tabs.

Laser-induced stresses versus mechanical stress power measurements during laser ablation of solids

International Nuclear Information System (INIS)

Shannon, M.A.; Russo, R.E.

1995-01-01

Laser-induced stresses resulting from high-power laser-material interactions have been studied extensively. However, the rate of change in mechanical energy, or stress power, due to laser-induced stresses has only recently been investigated. An unanswered question for monitoring laser-material interactions in the far-field is whether stress power differs from stresses measured, particularly with respect to laser-energy coupling to a solid target. This letter shows experimental acoustic data which demonstrate that stress power measured in the far field of the target shows changes in laser-energy coupling, whereas the stresses measured do not. For the ambient medium above the target, stress power and stress together reflect changes in laser-energy coupling. copyright 1995 American Institute of Physics

Measurements for stresses in machine components

CERN Document Server

Yakovlev, V F

1964-01-01

Measurements for Stresses in Machine Components focuses on the state of stress and strain of components and members, which determines the service life and strength of machines and structures. This book is divided into four chapters. Chapter I describes the physical basis of several methods of measuring strains, which includes strain gauges, photoelasticity, X-ray diffraction, brittle coatings, and dividing grids. The basic concepts of the electric strain gauge method for measuring stresses inside machine components are covered in Chapter II. Chapter III elaborates on the results of experim

Grain boundary cavity growth under applied stress and internal pressure

International Nuclear Information System (INIS)

Mancuso, J.F.

1977-08-01

The growth of grain boundary cavities under applied stress and internal gas pressure was investigated. Methane gas filled cavities were produced by the C + 4H reversible CH4 reaction in the grain boundaries of type 270 nickel by hydrogen charging in an autoclave at 500 0 C with a hydrogen pressure of either 3.4 or 14.5 MPa. Intergranular fracture of nickel was achieved at a charging temperature of 300 0 C and 10.3 MPa hydrogen pressure. Cavities on the grain boundaries were observed in the scanning electron microscope after fracture. Photomicrographs of the cavities were produced in stereo pairs which were analyzed so as to correct for perspective distortion and also to determine the orientational dependence of cavity growth under an applied tensile stress

Measurement of stress-strain behaviour of human hair fibres using optical techniques.

Science.gov (United States)

Lee, J; Kwon, H J

2013-06-01

Many studies have presented stress-strain relationship of human hair, but most of them have been based on an engineering stress-strain curve, which is not a true representation of stress-strain behaviour. In this study, a more accurate 'true' stress-strain curve of human hair was determined by applying optical techniques to the images of the hair deformed under tension. This was achieved by applying digital image cross-correlation (DIC) to 10× magnified images of hair fibres taken under increasing tension to estimate the strain increments. True strain was calculated by summation of the strain increments according to the theoretical definition of 'true' strain. The variation in diameter with the increase in longitudinal elongation was also measured from the 40× magnified images to estimate the Poisson's ratio and true stress. By combining the true strain and the true stress, a true stress-strain curve could be determined, which demonstrated much higher stress values than the conventional engineering stress-strain curve at the same degree of deformation. Four regions were identified in the true stress-strain relationship and empirical constitutive equations were proposed for each region. Theoretical analysis on the necking condition using the constitutive equations provided the insight into the failure mechanism of human hair. This analysis indicated that local thinning caused by necking does not occur in the hair fibres, but, rather, relatively uniform deformation takes place until final failure (fracture) eventually occurs. © 2012 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Sensor for direct measurement of the boundary shear stress in fluid flow

Science.gov (United States)

Bao, Xiaoqi; Badescu, Mircea; Bar-Cohen, Yoseph; Lih, Shyh-Shiuh; Sherrit, Stewart; Chang, Zensheu; Chen, Beck; Widholm, Scott; Ostlund, Patrick

2011-04-01

The formation of scour patterns at bridge piers is driven by the forces at the boundary of the water flow. In most experimental scour studies, indirect processes have been applied to estimate the shear and normal stress using measured velocity profiles. The estimations are based on theoretical models and associated assumptions. However, the turbulence flow fields and boundary layer in the pier-scour region are very complex. In addition, available turbulence models cannot account accurately for the bed roughness effect. Direct measurement of the boundary shear and normal stress and their fluctuations are attractive alternatives. However, this approach is a challenging one especially for high spatial resolution and high fidelity measurements. The authors designed and fabricated a prototype miniature shear stress sensor including an EDM machined floating plate and a high-resolution optical encoder. Tests were performed both in air as well as operation in water with controlled flow. The sensor sensitivity, stability and signal-to-noise level were measured and evaluated. The detailed test results and a discussion of future work will be presented in this paper.

Material Stress Fringe Constant Measurement of Specimen under Pure Bending Load by Use of Photoelastic Phase Shifting Method

International Nuclear Information System (INIS)

Liu, Guan Yong; Kim, Myung Soo; Baek, Tae Hyun

2014-01-01

In a photoelastic experiment, it is necessary to know the material stress fringe constant of the photoelastic specimen to determine the stresses from the measured isochromatic fringe orders. The material stress fringe constant can be obtained using a simple tension specimen and/or a circular disk under diametric compression. In these methods, there is generally a need to apply numerous loads to the specimen in response to the relationship of the fringe order. Then, the least squares method is used to obtain the material constant. In this paper, the fringe orders that appear on a four-point bending specimen are used to determine the fringe constant. This method requires four photoelastic fringes obtained from a circular polariscope by rotating the analyzer to 0, π/4, π/2, and 3π/4 radians. Using the four-point bending specimen to determine the material stress fringe constant has an advantage because measurements can be made at different locations by applying a constant load. The stress fringe constant measured with this method is within the range suggested by the manufacturer of the photoelastic material

Neutron stress measurement of W-fiber reinforced Cu composite

International Nuclear Information System (INIS)

Nishida, M.; Hanabusa, T.; Ikeuchi, Y.; Minakawa, N.

2003-01-01

Stress measurement methods using neutron and X-ray diffraction were examined by comparing the surface stresses with internal stresses in the continuous tungsten-fiber reinforced copper-matrix composite. Surface stresses were measured by X-ray stress measurement with the sin 2 ψ method. Furthermore, the sin 2 ψ method and the most common triaxal measurement method using Hooke's equation were employed for internal stress measurement by neutron diffraction. On the other hand, microstress distributions developed by the difference in the thermal expansion coefficients between these two phases were calculated by FEM. The weighted average strains and stresses were compared with the experimental results. The FEM results agreed with the experimental results qualitatively and confirmed the importance of the triaxial stress analysis in the neutron stress measurement. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

Stress assessment based on EEG univariate features and functional connectivity measures.

Science.gov (United States)

Alonso, J F; Romero, S; Ballester, M R; Antonijoan, R M; Mañanas, M A

2015-07-01

The biological response to stress originates in the brain but involves different biochemical and physiological effects. Many common clinical methods to assess stress are based on the presence of specific hormones and on features extracted from different signals, including electrocardiogram, blood pressure, skin temperature, or galvanic skin response. The aim of this paper was to assess stress using EEG-based variables obtained from univariate analysis and functional connectivity evaluation. Two different stressors, the Stroop test and sleep deprivation, were applied to 30 volunteers to find common EEG patterns related to stress effects. Results showed a decrease of the high alpha power (11 to 12 Hz), an increase in the high beta band (23 to 36 Hz, considered a busy brain indicator), and a decrease in the approximate entropy. Moreover, connectivity showed that the high beta coherence and the interhemispheric nonlinear couplings, measured by the cross mutual information function, increased significantly for both stressors, suggesting that useful stress indexes may be obtained from EEG-based features.

Residual stress relaxation measurements across interfaces at macro-and micro-scales using slitting and DIC

Energy Technology Data Exchange (ETDEWEB)

Blair, A; Daynes, N; Hamilton, D; Horne, G; Hodgson, D Z L; Shterenlikht, A [Department of Mechanical Engineering, University of Bristol, Bristol BS8 1TR (United Kingdom); Heard, P J; Scott, T B, E-mail: mexas@bristol.ac.u [Interface Analysis Centre, University of Bristol, Bristol BS2 8BS (United Kingdom)

2009-08-01

In this paper digital image correlation is used to measure relaxation of residual stresses across an interface. On the macro scale the method is applied to a tri-layer bonded aluminium sample, where the middle layer is in tension and the top and the bottom layers are in compression. High contrast speckle pattern was sprayed onto the surface. The relaxation was done with the slitting saw. Three dimensional image correlation was used. On the micro scale the technique was applied to a heat treated large grain brass loaded in tension. Mechanical and electro polishing was used for surface preparation. A focused ion beam was used for slitting across a grain boundary and for imaging. Grain orientation was measured using electron back-scattering diffraction. Two dimensional image correlation was employed. In all macro- and micro-scale experiments the range of measured relaxation was sub-pixel, almost at the limit of the resolution of the image correlation algorithms. In the macro-scale experiments, the limiting factor was low residual stress, due to low shear strength of the Araldite glue used for bonding. Finite element simulation of the relaxation agreed only qualitatively with the experimental results at both size scales. The methodology is intended for use with inverse methods, i.e. the measured relaxation is applied as the boundary conditions to an appropriate FE model which produces stresses equal to the relaxed residual stresses, but with opposite sign. The main conclusion is that the digital image correlation method could be used to measure relaxation caused by slitting in heterogeneous materials and structures at both macro- and micro-scales. However, the repeatability of the techniques needs to be improved before residual stresses can be determined confidently. Acknowledgments The authors gratefully acknowledge Airbus UK for provision of materials. They thank Dr Richard Burguete, Airbus UK, and Prof Peter Flewitt, Department of Physics, University of Bristol, for

Residual stress relaxation measurements across interfaces at macro-and micro-scales using slitting and DIC

International Nuclear Information System (INIS)

Blair, A; Daynes, N; Hamilton, D; Horne, G; Hodgson, D Z L; Shterenlikht, A; Heard, P J; Scott, T B

2009-01-01

In this paper digital image correlation is used to measure relaxation of residual stresses across an interface. On the macro scale the method is applied to a tri-layer bonded aluminium sample, where the middle layer is in tension and the top and the bottom layers are in compression. High contrast speckle pattern was sprayed onto the surface. The relaxation was done with the slitting saw. Three dimensional image correlation was used. On the micro scale the technique was applied to a heat treated large grain brass loaded in tension. Mechanical and electro polishing was used for surface preparation. A focused ion beam was used for slitting across a grain boundary and for imaging. Grain orientation was measured using electron back-scattering diffraction. Two dimensional image correlation was employed. In all macro- and micro-scale experiments the range of measured relaxation was sub-pixel, almost at the limit of the resolution of the image correlation algorithms. In the macro-scale experiments, the limiting factor was low residual stress, due to low shear strength of the Araldite glue used for bonding. Finite element simulation of the relaxation agreed only qualitatively with the experimental results at both size scales. The methodology is intended for use with inverse methods, i.e. the measured relaxation is applied as the boundary conditions to an appropriate FE model which produces stresses equal to the relaxed residual stresses, but with opposite sign. The main conclusion is that the digital image correlation method could be used to measure relaxation caused by slitting in heterogeneous materials and structures at both macro- and micro-scales. However, the repeatability of the techniques needs to be improved before residual stresses can be determined confidently. Acknowledgments The authors gratefully acknowledge Airbus UK for provision of materials. They thank Dr Richard Burguete, Airbus UK, and Prof Peter Flewitt, Department of Physics, University of Bristol, for

A flexible method for residual stress measurement of spray coated layers by laser made hole drilling and SLM based beam steering

Science.gov (United States)

Osten, W.; Pedrini, G.; Weidmann, P.; Gadow, R.

2015-08-01

A minimum invasive but high resolution method for residual stress analysis of ceramic coatings made by thermal spraycoating using a pulsed laser for flexible hole drilling is described. The residual stresses are retrieved by applying the measured surface data for a model-based reconstruction procedure. While the 3D deformations and the profile of the machined area are measured with digital holography, the residual stresses are calculated by FE analysis. To improve the sensitivity of the method, a SLM is applied to control the distribution and the shape of the holes. The paper presents the complete measurement and reconstruction procedure and discusses the advantages and challenges of the new technology.

Indirect Measurement of Energy Density of Soft PZT Ceramic Utilizing Mechanical Stress

Science.gov (United States)

Unruan, Muangjai; Unruan, Sujitra; Inkong, Yutthapong; Yimnirun, Rattikorn

2017-11-01

This paper reports on an indirect measurement of energy density of soft PZT ceramic utilizing mechanical stress. The method works analogous to the Olsen cycle and allows for a large amount of electro-mechanical energy conversion. A maximum energy density of 350 kJ/m3/cycle was found under 0-312 MPa and 1-20 kV/cm of applied mechanical stress and electric field, respectively. The obtained result is substantially higher than the results reported in previous studies of PZT materials utilizing a direct piezoelectric effect.

Stress measurement by x-ray diffractometry

Energy Technology Data Exchange (ETDEWEB)

Mitchell, C M

1985-10-22

This invention relates to x-ray diffractometry and more particularly to apparatus and methods for the measurement of residual stress in polycrystalline, e.g. metallic, specimens. The procedure is based on measurement of the lattice strain of crystals by x-ray diffraction, in which change in the interplanar spacing of a set of crystal lattice planes due to strain causes a change in the diffraction angle of the scattered x-ray beam, from which latter change the magnitude of the strain can be determined. In a polycrystalline specimen, from well know relations for elastic behaviour in isotropic materials, the stress on a plane normal to a given direction in the surface has a component in the given direction which can be calculated from measurement of lattice strain in two directions in a plane containing the given direction and the normal to the specimen surface. In general three such stress components in three directions in the surface are required to determine the principal stresses and thus express the state of stress in the surface. (author). 2 tabs., 9 figs.

Hole Drilling Technique – on site stress measurement

OpenAIRE

Schueremans, Luc

2009-01-01

2. Hole Drilling Technique for onsite stress measurement has been used to validate the stress level at 2 pillars of the Sint-Jacobschurch (Leuven, B). The technique allows estimating the stress in a stone from measuring deformation when a small hole is made. It is a low intrusive technique. The application of it is limited to local stress measurements and is a complement to stress estimate from calculations of from the use of –for example- flat jacks. In addition to the flat-jack technique...

A Shortened Stress Measure in Military Nursing Personnel

Science.gov (United States)

2017-10-17

REPORT TYPE 3. DATES COVERED (From- To) 10/17/2017 Abstract 4. TITLE AND SUBTITLE Sa. CONTRACT NUMBER A Shortened Stress Measure in Military...Psychology 14. ABSTRACT A Shortened Stress Measure with Military Nursing Personnel Abstract Stress is a psychological construct with important...consequences for human health. A substantial number of stress measures are available that vary in length and dimensionality. The purpose of this study was to

Method for evaluationo of the 3D residual stress field from X-ray diffraction measurements on heavy weldments

International Nuclear Information System (INIS)

Larsson, L.E.; Sandstroem, R.

1982-03-01

A method for evaluation of the three dimensional residual 30 stress distribution in heavy weldmwents has been developed. The evaluation is based on measured stress data at a number of depth levels below the plate surface. The method has been applied to two measurements on heavy weldments of A 553 B steel. Comparison to a previous evaluation shows good agreement. (Authors)

THE EFFECT OF APPLIED STRESS ON THE GRAPHITIZATION OF PYROLYTIC GRAPHITE

Energy Technology Data Exchange (ETDEWEB)

Bragg, R H; Crooks, D D; Fenn, Jr, R W; Hammond, M L

1963-06-15

Metallographic and x-ray diffraction studies were made of the effect of applied stress at high temperature on the structure of pyrolytic graphite (PG). The dominant factor was whether the PG was above or below its graphitization temperature, which, in turn, was not strongly dependent on applied stress. Below the graphitization temperature, the PG showed a high proportion of disordered layers (0.9), a fairly large mean tilt angle (20 deg ) and a small crystailite size (La --150 A). Fracture occurred at low stress and strain and the materiai exhibited a high apparent Young's modulus ( approximates 4 x 10/sup 6/ psi). Above the graphitization temperature, graphitization was considerably enhanced by strain up to about 8%. The disorder parameter was decreased from a zero strain value of 0.3 to 0.l5 with strain, the mean tilt angle was decreased to 4 deg , and a fivefold increase in crystallite size occurred. When the strainenhanced graphitization was complete, the material exhibited a low apparent modulus ( approximates 0.5 x 10/sup 6/ psi) and large plastic strains (>100%) for a constant stress ( approximates 55 ksi). Graphitization was shown to be a spontaneous process that is promoted by breaking cross-links thermally, and the process is furthered by chemical attack and plastic strain. (auth)

Development of the apparatus for measuring magnetic properties of electrical steel sheets in arbitrary directions under compressive stress normal to their surface

Science.gov (United States)

Maeda, Yoshitaka; Urata, Shinya; Nakai, Hideo; Takeuchi, Yuuya; Yun, Kyyoul; Yanase, Shunji; Okazaki, Yasuo

2017-05-01

In designing motors, one must grasp the magnetic properties of electrical steel sheets considering actual conditions in motors. Especially important is grasping the stress dependence of magnetic power loss. This paper describes a newly developed apparatus to measure two-dimensional (2-D) magnetic properties (properties under the arbitrary alternating and the rotating flux conditions) of electrical steel sheets under compressive stress normal to the sheet surface. The apparatus has a 2-D magnetic excitation circuit to generate magnetic fields in arbitrary directions in the evaluation area. It also has a pressing unit to apply compressive stress normal to the sheet surface. During measurement, it is important to apply uniform stress throughout the evaluation area. Therefore, we have developed a new flux density sensor using needle probe method. It is composed of thin copper foils sputtered on electrical steel sheets. By using this sensor, the stress can be applied to the surface of the specimen without influence of this sensor. This paper described the details of newly developed apparatus with this sensor, and measurement results of iron loss by using are shown.

Recent advances in residual stress measurement

International Nuclear Information System (INIS)

Withers, P.J.; Turski, M.; Edwards, L.; Bouchard, P.J.; Buttle, D.J.

2008-01-01

Until recently residual stresses have been included in structural integrity assessments of nuclear pressure vessels and piping in a very primitive manner due to the lack of reliable residual stress measurement or prediction tools. This situation is changing the capabilities of newly emerging destructive (i.e. the contour method) and non-destructive (i.e. magnetic and high-energy synchrotron X-ray strain mapping) residual stress measurement techniques for evaluating ferritic and austenitic pressure vessel components are contrasted against more well-established methods. These new approaches offer the potential for obtaining area maps of residual stress or strain in welded plants, mock-up components or generic test-pieces. The mapped field may be used directly in structural integrity calculations, or indirectly to validate finite element process/structural models on which safety cases for pressurised nuclear systems are founded. These measurement methods are complementary in terms of application to actual plant, cost effectiveness and measurements in thick sections. In each case an exemplar case study is used to illustrate the method and to highlight its particular capabilities

Neutron residual stress measurements in linepipe

International Nuclear Information System (INIS)

Law, Michael; Gnaepel-Herold, Thomas; Luzin, Vladimir; Bowie, Graham

2006-01-01

Residual stresses in gas pipelines are generated by manufacturing and construction processes and may affect the subsequent pipe integrity. In the present work, the residual stresses in eight samples of linepipe were measured by neutron diffraction. Residual stresses changed with some coating processes. This has special implications in understanding and mitigating stress corrosion cracking, a major safety and economic problem in some gas pipelines

Magnetically applied pressure-shear : a new technique for direct strength measurement at high pressure (final report for LDRD project 117856).

Energy Technology Data Exchange (ETDEWEB)

Lamppa, Derek C.; Haill, Thomas A.; Alexander, C. Scott; Asay, James Russell

2010-09-01

A new experimental technique to measure material shear strength at high pressures has been developed for use on magneto-hydrodynamic (MHD) drive pulsed power platforms. By applying an external static magnetic field to the sample region, the MHD drive directly induces a shear stress wave in addition to the usual longitudinal stress wave. Strength is probed by passing this shear wave through a sample material where the transmissible shear stress is limited to the sample strength. The magnitude of the transmitted shear wave is measured via a transverse VISAR system from which the sample strength is determined.

Stress coupling in the seismic cycle indicated from geodetic measurements

Science.gov (United States)

Wang, L.; Hainzl, S.; Zoeller, G.; Holschneider, M.

2012-12-01

The seismic cycle includes several phases, the interseismic, coseismic and postseismic phase. In the interseismic phase, strain gradually builds up around the overall locked fault in tens to thousands of years, while it is coseismically released in seconds. In the postseismic interval, stress relaxation lasts months to years, indicated by evident aseismic deformations which have been indicated to release comparable or even higher strain energy than the main shocks themselves. Benefiting from the development of geodetic observatory, e.g., Global Positioning System (GPS) and Interferometric Synthetic Aperture Radar (InSAR) in the last two decades, the measurements of surface deformation have been significantly improved and become valuable information for understanding the stress evolution on the large fault plane. In this study, we utilize the GPS/InSAR data to investigate the slip deficit during the interseismic phase, the coseismic slip and the early postseismic creep on the fault plane. However, it is already well-known that slip inversions based only on the surface measurements are typically non-unique and subject to large uncertainties. To reduce the ambiguity, we utilize the assumption of stress coupling between interseismic and coseismic phases, and between coseismic and postseismic phases. We use a stress constrained joint inversion in Bayesian approach (Wang et al., 2012) to invert simultaneously for (1) interseismic slip deficit and coseismic slip, and (2) coseismic slip and postseismic creep. As case studies, we analyze earthquakes occurred in well-instrumented regions such as the 2004 M6.0 Parkfield earthquake, the 2010 M8.7 earthquake and the 2011 M9.1 Tohoku-Oki earthquake. We show that the inversion with the stress-coupling constraint leads to better constrained slip distributions. Meanwhile, the results also indicate that the assumed stress coupling is reasonable and can be well reflected from the available geodetic measurements. Reference: Lifeng

A pulsed magnetic stress applied to Drosophila melanogaster flies

International Nuclear Information System (INIS)

Delle Side, D; Giuffreda, E; Nassisi, V; Velardi, L; Bozzetti, M P; Friscini, A; Specchia, V

2014-01-01

We report the development of a system to feed pulsed magnetic stress to biological samples. The device is based on a RLC circuit that transforms the energy stored in a high voltage capacitor into a magnetic field inside a coil. The field has been characterized and we found that charging the capacitor with 24 kV results in a peak field of 0.4 T. In order to test its effect, we applied such a stress to the Drosophila melanogaster model and we examined its bio-effects. We analysed, in the germ cells, the effects on the control of specific DNA repetitive sequences that are activated after different environmental stresses. The deregulation of these sequences causes genomic instability and chromosomes breaks leading to sterility. The magnetic field treatment did not produce effects on repetitive sequences in the germ cells of Drosophila. Hence, this field doesn't produce deleterious effects linked to repetitive sequences derepression.

A pulsed magnetic stress applied to Drosophila melanogaster flies

Science.gov (United States)

Delle Side, D.; Bozzetti, M. P.; Friscini, A.; Giuffreda, E.; Nassisi, V.; Specchia, V.; Velardi, L.

2014-04-01

We report the development of a system to feed pulsed magnetic stress to biological samples. The device is based on a RLC circuit that transforms the energy stored in a high voltage capacitor into a magnetic field inside a coil. The field has been characterized and we found that charging the capacitor with 24 kV results in a peak field of 0.4 T. In order to test its effect, we applied such a stress to the Drosophila melanogaster model and we examined its bio-effects. We analysed, in the germ cells, the effects on the control of specific DNA repetitive sequences that are activated after different environmental stresses. The deregulation of these sequences causes genomic instability and chromosomes breaks leading to sterility. The magnetic field treatment did not produce effects on repetitive sequences in the germ cells of Drosophila. Hence, this field doesn't produce deleterious effects linked to repetitive sequences derepression.

Stress strain tensors with their application to x-ray stress measurement

International Nuclear Information System (INIS)

Kurita, Masanori

2015-01-01

This paper describes in detail the method of obtaining the formulas of stress-strain tensor that express the directional dependence of stress-strain, that is, how these values change in response to coordinate transformation, and clarifies the preconditions for supporting both formulas. The two conversion formulas are both the second order of tensor, and the formula of strain tensor not only does not use the relational expression of stress and strain at all, but also is obtained completely independently of the formula of stress tensor. Except for the condition that the strain is very small (elastic deformation) in the conversion formula of strain, both formulas unconditionally come into effect. In other words, both formulas hold true even in the isotropic elastic body or anisotropic elastic body. It was shown that the conversion formula of strain can be derived from the conversion formula of stress using the formula of Hooke for isotropic elastic body. From these three-dimensional expressions, the two-dimensional stress-strain coordinate conversion formula that is used for Mohr's stress-strain circle was derived. It was shown that these formulas hold true for three-dimensional stress condition with stress-strain components in the three-axial direction that are not plane stress nor plane strain condition. In addition, as an application case of this theory, two-dimensional and three-dimensional X-ray stress measurements that are effective for residual stress measurement were shown. (A.O.)

Hydraulic fracturing stress measurements at Yucca Mountain, Nevada, and relationship to the regional stress field

International Nuclear Information System (INIS)

Stock, J.M.; Healy, J.H.; Hickman, S.H.; Zoback, M.D.

1985-01-01

Hydraulic fracturing stress measurements and acoustic borehole televiewer logs were run in holes USW G-1 and USW G-2 at Yucca Mountain as part of the Nevada Nuclear Waste Storage Investigations for the U. S. Department of Energy. Eight tests in the saturated zone, at depths from 646 to 1288 m, yielded values of the least horizontal stress S/sub h/ that are considerably lower than the vertical principal stress S/sub v/. In tests for which the greatest horizontal principal stress S/sub H/ could be determined, it was found to be less than S/sub v/, indicating a normal faulting stress regime. The borehole televiewer logs showed the presence of long (in excess of 10 m), vertical, drilling-induced fractures in the first 300 m below the water table. These are believed to form by the propagation of small preexisting cracks under the excess downhole fluid pressures (up to 5.2 MPa) applied during drilling. The presence of these drilling-induced hydrofractures provides further confirmation of the low value of the least horizontal stresses. A least horizontal principal stress direction of N60 0 W--N65 0 W is indicated by the orientation of the drilling-induced hydrofractures (N25 0 E--N30 0 E), and the orientation of stress-induced well bore breakouts in the lower part of USW G-2 (N65 0 W). This direction is in good agreement with indicators of stress direction from elsewhere at the Nevada Test Site. The observed stress magnitudes and directions were examined for the possibility of slip on preexisting faults. Using these data, the Coulomb criterion for frictional sliding suggests that for coefficients of friction close to 0.6, movement on favorably oriented faults could be expected

Results and conclusions of stress measurements at Stripa

International Nuclear Information System (INIS)

Doe, T.W.; Hustrulid, W.A.; Leijon, B.; Ingevald, K.; Strindell, L.; Carlsson, Hans

1983-01-01

This paper describes the results of stress measurements at Stripa, compares the results obtained by different techniques, and recommends a stress measurement program for a hard rock repository site. The state of stress at the Stripa Mine has been measured both in a 381m deep hole drilled from the surface and in holes drilled from the drifts underground. The results of overcoring and hydraulic fracturing agree well, particularly for the magnitude and orientation of the greatest stress. A recommended program for stress measurement at a repository site would include hydraulic fracturing and deep-hole overcoring in a deep hole drilled from surface, and ovecoring and hydraulic fracturing from holes drilled from underground openings when access is available. Propagation of the hydraulic fractures should be monitored acoustically to determine their location and orientation

A modeling of radiation induced microstructural evolution under applied stress in austenitic alloys

Energy Technology Data Exchange (ETDEWEB)

Tanigawa, Hiroyasu; Kohyama, Akira [Kyoto Univ., Uji (Japan). Inst. of Advanced Energy; Katoh, Yutai; Kohno, Yutaka

1996-10-01

Effects of applied stress on interstitial type Frank loop evolution at early stages of irradiation were investigated by both numerical calculation and irradiation experiments. In the experimental part of this work, microstructural inspection has been made by transmission electron microscopy with a special emphasis on Frank loops and perfect loops on every {l_brace}111{r_brace} plane. The results of the TEM observation revealed that Frank loop concentration on a {l_brace}111{r_brace} plane increased as the resolved normal stress to a {l_brace}111{r_brace} plane increased and that small perfect loops were more likely produced on {l_brace}111{r_brace} planes where larger resolved shear stress was applied. The model of a stress effect on Frank loop unfaulting was provided, which is triggered by nucleation of a Shockley partial dislocation loop in a Frank loop, was proposed. The results of the numerical calculation was successful to predict the strong dependence of Frank loop concentration on the resolved normal stress to {l_brace}111{r_brace} plane, which was the characteristic feature seen in the irradiation experiments. (author)

Development of the apparatus for measuring magnetic properties of electrical steel sheets in arbitrary directions under compressive stress normal to their surface

Directory of Open Access Journals (Sweden)

Yoshitaka Maeda

2017-05-01

Full Text Available In designing motors, one must grasp the magnetic properties of electrical steel sheets considering actual conditions in motors. Especially important is grasping the stress dependence of magnetic power loss. This paper describes a newly developed apparatus to measure two-dimensional (2-D magnetic properties (properties under the arbitrary alternating and the rotating flux conditions of electrical steel sheets under compressive stress normal to the sheet surface. The apparatus has a 2-D magnetic excitation circuit to generate magnetic fields in arbitrary directions in the evaluation area. It also has a pressing unit to apply compressive stress normal to the sheet surface. During measurement, it is important to apply uniform stress throughout the evaluation area. Therefore, we have developed a new flux density sensor using needle probe method. It is composed of thin copper foils sputtered on electrical steel sheets. By using this sensor, the stress can be applied to the surface of the specimen without influence of this sensor. This paper described the details of newly developed apparatus with this sensor, and measurement results of iron loss by using are shown.

Parent Perspectives of Applying Mindfulness-Based Stress Reduction Strategies to Special Education.

Science.gov (United States)

Burke, Meghan M; Chan, Neilson; Neece, Cameron L

2017-06-01

Parents of children with (versus without) intellectual and developmental disabilities report greater stress; such stress may be exacerbated by dissatisfaction with school services, poor parent-school partnerships, and the need for parent advocacy. Increasingly, mindfulness interventions have been used to reduce parent stress. However, it is unclear whether parents apply mindfulness strategies during the special education process to reduce school-related stress. To investigate whether mindfulness may reduce school-related stress, interviews were conducted with 26 parents of children with intellectual and developmental disabilities who completed a mindfulness-based stress reduction intervention. Participants were asked about their stress during meetings with the school, use of mindfulness strategies in communicating with the school, and the impact of such strategies. The majority of parent participants reported: special education meetings were stressful; they used mindfulness strategies during IEP meetings; and such strategies affected parents' perceptions of improvements in personal well-being, advocacy, family-school relationships, and access to services for their children. Implications for future research, policy, and practice are discussed.

NPE - close-in stress and motion measurements

Energy Technology Data Exchange (ETDEWEB)

Smith, C.W. [Sandia National Labs., Albuquerque, NM (United States)

1994-12-31

On the Non-Proliferation Experiment we measured stresses and accelerations in the nonlinear regime. Measurements were made in the host rock and in the grout stemming of the access drift. The thrust of the measurements was to provide data for a comparison with waveforms from nuclear events and with calculations of the process. Measured stress waveforms show greater amplitudes than yield-scaled waveforms from nearby nuclear events. Specifically, the five stress peaks suggest an equivalent nuclear yield of more than two kilotons. Material velocity data from NPE also show amplitudes greater than nuclear data. The risetimes of the NPE data are slower than risetimes of scaled nuclear data. The ratio of risetimes is about two; this difference may prove useful in discriminating between nuclear and chemical explosions. Non-radical accelerations show some departure from symmetric wave propagation. Tuff strengths-inferred from differences between radial and hoop stresses-show values that are about twice laboratory determined values.

Analysis of rock stress and rock stress measurements with application to Aespoe HRL

International Nuclear Information System (INIS)

Lundholm, Beatrice

2000-11-01

The process of choosing a site for a nuclear waste repository means that many aspects have to be taken into consideration. One of these is that the repository has to be mechanically stable for a long time. The mechanical stability of the rock is very difficult to determine. One of several factors, which determine the mechanical stability, is the virgin state of stress. The thesis project consists of two parts. In the first part the state of stress at Aespoe Hard Rock Laboratory had to be defined. This was done based on earlier rock stress measurements conducted during the years 1988 to 1997. Two different measurement techniques have been used, hydraulic fracturing and overcoring. During the overcoring two types of cells have been used, CSIRO HI-cell and a cell developed by the Swedish State Power Board (SSPB). In the second part of the project, investigation of the correlation between the stress and geological structures are made using numerical modelling tools such as FLAC, UDEC and 3DEC. The rock stress measurements using the hydraulic fracturing gave orientations of the horizontal stress that coincide with earlier hydraulic fracturing measurements conducted in Scandinavia. The magnitudes of rock stresses are slightly lower than the earlier reported stress magnitudes for the Scandinavian part of the earth crust. The rock stresses obtained from the overcoring resulted in higher stresses than what was predicted by the hydraulic fracturing measurements. However, the orientation of the maximum horizontal stresses coincides well between the two techniques. The orientation is also more or less constant with respect to increasing depth. The state of stress at Aespoe is defined by using the results from the hydraulic fracturing and the measurements conducted by SSPB-cell. The measurements from the SSPB-cell are used since these have a Poisson's ratio that corresponds well with the uniaxial tests of rock samples and since the measurements have been done at a distance from

Diffraction grating strain gauge method: error analysis and its application for the residual stress measurement in thermal barrier coatings

Science.gov (United States)

Yin, Yuanjie; Fan, Bozhao; He, Wei; Dai, Xianglu; Guo, Baoqiao; Xie, Huimin

2018-03-01

Diffraction grating strain gauge (DGSG) is an optical strain measurement method. Based on this method, a six-spot diffraction grating strain gauge (S-DGSG) system has been developed with the advantages of high and adjustable sensitivity, compact structure, and non-contact measurement. In this study, this system is applied for the residual stress measurement in thermal barrier coatings (TBCs) combining the hole-drilling method. During the experiment, the specimen’s location is supposed to be reset accurately before and after the hole-drilling, however, it is found that the rigid body displacements from the resetting process could seriously influence the measurement accuracy. In order to understand and eliminate the effects from the rigid body displacements, such as the three-dimensional (3D) rotations and the out-of-plane displacement of the grating, the measurement error of this system is systematically analyzed, and an optimized method is proposed. Moreover, a numerical experiment and a verified tensile test are conducted, and the results verify the applicability of this optimized method successfully. Finally, combining this optimized method, a residual stress measurement experiment is conducted, and the results show that this method can be applied to measure the residual stress in TBCs.

Measurement of residual stress in a sphere by x-ray under the consideration of its penetration depth

International Nuclear Information System (INIS)

Doi, Osamu; Ukai, Takayoshi

1981-01-01

It was pointed out in the case of a plate that when stress gradient is large, the use of the X-ray with large penetration depth caused large measurement error. In this paper, the theoretical equations for measuring the residual stress in a sphere with X-ray, taking penetration depth into account, are proposed, and the example of application is shown. As the method of measuring the residual stress in a hollow sphere with X-ray, only the method of combining external surface removal and external surface irradiation is practically in use. It was assumed that a sphere is isotropic, and that the residual stress is a function of the radius only. First, the theory of measuring the residual stress in a sphere with X-ray taking penetration depth into account is explained, and the equations for calculating the residual stresses in tangential and radial directions are derived. As the example of applying this theory, the distribution of the residual stress in a steel ball for a ball bearing was measured with Cr characteristic X-ray. The ball of 30 mm diameter was made of high-carbon chromium bearing steel, grade 2, (JIS SUJ2) and quenched and tempered. The removal of the thin layer was made by chemical etching and electrolysis. The measured values and the calculated values are shown. (Kako, I.)

Methods of measuring residual stresses in components

International Nuclear Information System (INIS)

Rossini, N.S.; Dassisti, M.; Benyounis, K.Y.; Olabi, A.G.

2012-01-01

Highlights: ► Defining the different methods of measuring residual stresses in manufactured components. ► Comprehensive study on the hole drilling, neutron diffraction and other techniques. ► Evaluating advantage and disadvantage of each method. ► Advising the reader with the appropriate method to use. -- Abstract: Residual stresses occur in many manufactured structures and components. Large number of investigations have been carried out to study this phenomenon and its effect on the mechanical characteristics of these components. Over the years, different methods have been developed to measure residual stress for different types of components in order to obtain reliable assessment. The various specific methods have evolved over several decades and their practical applications have greatly benefited from the development of complementary technologies, notably in material cutting, full-field deformation measurement techniques, numerical methods and computing power. These complementary technologies have stimulated advances not only in measurement accuracy and reliability, but also in range of application; much greater detail in residual stresses measurement is now available. This paper aims to classify the different residual stresses measurement methods and to provide an overview of some of the recent advances in this area to help researchers on selecting their techniques among destructive, semi destructive and non-destructive techniques depends on their application and the availabilities of those techniques. For each method scope, physical limitation, advantages and disadvantages are summarized. In the end this paper indicates some promising directions for future developments.

Stress measurement by neutron diffraction method. Standard method using angular dispersion method and trial of using neutron IP

International Nuclear Information System (INIS)

Sasaki, Toshihiko; Takago, Shigeki

2016-01-01

This paper outlined a stress measurement method using neutrons, and introduced the application examples to stress measurement for metal-based composite materials. In the angular dispersion type measurement using a steady-state reactor type neutron source, the white beams taken out from a nuclear reactor are monochromatized (wavelength λ is a constant value) with a single crystal monochromator and utilized. As an example of measurement, there was the case as follows: the stress of a sintered material which has been put to practical use as valve seat part for automobiles was measured by the neutron method, and the deformation behavior during load was studied. This study performed neutron diffraction measurement using a residual stress analyzer (RESA: Diffractometer for Residual Stress Analysis) installed at JAEA's experimental reactor JRR-3. As a result, it was found that the stress state of the sintered composite material of Fe-Cr and TiN can be predicted with a micromechanics model. A neutron diffraction ring can be obtained using a neutron image plate (IP), where fine powder of gadolinium (Gd) was incorporated into IP for X-rays, and it can be used as an IP reader in the same way as the case of X-rays. A report has been introduced on the examination results of the highly accurate stress measurement by applying the cos α method devised for X-ray stress measurement to neutron diffraction ring. (A.O.)

The effect of stress, applied immediately before stunning, on pork quality

NARCIS (Netherlands)

Wal, van der P.G.; Engel, B.; Reimert, H.G.M.

1999-01-01

The effect on meat quality characteristics of stress, applied during a short period just before stunning, was studied on slaughterpigs (113 boars, 85 gilts). Sexes were kept separately and only pigs that had been stunned correctly were included. Aggressive behaviour during lairage occurred more

Results and conclusions of stress measurements at Stripa

International Nuclear Information System (INIS)

Doe, T.W.; Hustrulid, W.A.; Leijon, B.; Ingevald, K.; Strindell, L.; Carlsson, H.

1982-10-01

This paper describes the results of stress measurements at Stripa, compares the results obtained by different techniques, and recommends a stress measurement program for a hard rock repository site. The state of stress at the Stripa Mine has been measured both in a 381-m-deep hole drilled from the surface and in holes drilled from the drifts underground. Hydraulic fracturing and several overcoring methods have been used (Lulea triaxial gauge, CSIRO gauge, USBM gauge, Swedish State Power Board deep-hole Leeman triaxial gauge). The results of overcoring and hydraulic fracturing agree well, particularly for the magnitude and orientation of the greatest stress. A recommended program for stress measurement at a repository site would include hydraulic fracturing and deep-hole overcoring in a deep hole drilled from surface, and overcoring (Lulea gauge and USBM gauge) and hydraulic fracturing from holes drilled from underground openings when access is available. Propagation of the hydraulic fractures should be monitored acoustically to determine their location and orientation

Optical residual stress measurement in TFT-LCD panels

Science.gov (United States)

Wang, Wei-Chung; Sung, Po-Chi

2017-06-01

The residual stress of the glass substrate might be one of causes to produce the non-uniform light distribution defect, i.e. Mura, in thin film transistor-liquid crystal display (TFT-LCD) panels. Glass is a birefringent material with very low birefringence. Furthermore, the thinner and thinner thickness request from the market makes the traditional photoelasticity almost impossible to measure the residual stresses produced in thin glass plates. Recently, a low-level stress measurement method called transmissivity extremities theory of photoelasticity (TEToP) was successfully developed to measure the residual stress in glass plate. Besides, to measure the stress of the glass plate in the TFT-LCD panel whose rear surface may has different kinds of coatings, an advanced reflection photoelasticity was also developed. In this paper, three commercially available glass plates with 0.33mm nominal thickness and three glass circular disks with different coatings were inspected to verify the feasibility of the TEToP and the advanced reflection photoelasticity, respectively.

The Impact of Simultaneously Applying Normal Stress and Vibrotactile Stimulation for Feedback of Exteroceptive Information.

Science.gov (United States)

Reza Motamedi, M; Otis, Martin; Duchaine, Vincent

2017-06-01

Commercially available prosthetic hands do not convey any tactile information, forcing amputees to rely solely on visual attention. A promising solution to this problem is haptics, which could lead to new prostheses in which tactile information is conveyed between the amputee and the artificial limb. However, the haptic feedback must be optimized so that amputees can use it effectively; and although several studies have examined how specific haptic feedback systems can transmit certain types of tactile information, there has not yet been much research on the effects of superposing two or more types of feedback at the same location, which might prove to be more effective than using a single type of feedback alone. This paper investigates how the simultaneous application of two different types of haptic feedback-vibration and normal stress-impacts the human sensory perception of each separate feedback type. These stimuli were applied to glabrous skin on the forearms of 14 participants. Our experiments tested whether participants experienced more accurate sensory perception, compared to vibration or normal stress alone, when vibration was applied at the same time as the normal stress, at either the same location, or at a different location 6 cm away. Results indicate that although participants' perception of the normal stress diminished when vibration was applied at the same location, the same combination improved their perception of the vibration. Apparently, vibration has a negative impact upon the ability to perceive normal stress, whether applied at the same or a different location; whereas the opposite is true for the effect of normal stress upon the perception of vibration.

Development of two short measures for recovery and stress in sport.

Science.gov (United States)

Nässi, Anu; Ferrauti, Alexander; Meyer, Tim; Pfeiffer, Mark; Kellmann, Michael

2017-08-01

The Acute Recovery and Stress Scale (ARSS) and the Short Recovery and Stress Scale were first established in German for the purposes of monitoring athletes' current recovery-stress states in an economical and multidimensional manner. The aim of this paper is to document the development and initial validation of the English versions of these two psychometric monitoring tools. A total of 267 English-speaking athletes from a variety of team and individual sports participated in the study. The English versions demonstrated satisfactory internal consistency for both instruments (Cronbach α of .74-.89). Furthermore, good model fit was found for the eight scales of the ARSS, matching the structure and results of the German counterparts. Correlations among and between the scales reciprocate the theoretical constructs of stress and recovery, supporting the construct validity of the scales. Correlation coefficients within stress and recovery ranged between r s  = .29 and .68. The correlations between stress and recovery varied between r s  = -.29 and -.64. These constructs were further supported by correlations with the scores of the Recovery-Stress Questionnaire for Athletes, thereby showing convergent validity. The findings demonstrate initial validity and reliability of the two measures and reflect the results of the German versions. However, further research is needed before applying these scales in practical settings.

Measurement of stress using synchrotron x-rays

International Nuclear Information System (INIS)

Weidner, Donald J; Li Li

2006-01-01

Stress analysis in polycrystalline materials reveals that stress can vary considerably among different subpopulations of grains. Samples of MgO and mixtures of MgO and spinel have been studied. After the onset of plastic flow, stronger grains or orientations will support more stress than the weaker grains. A grain to grain fabric develops that enables this stress partitioning. The stress partitioning and the resulting fabric can invalidate static measurements of elastic moduli. However, high temperature flow mechanisms reveal a more isotropic strength behaviour resulting in a more uniform variation of stress with orientation

Measurements of the residual stresses in the welded steel columns based on the x-ray diffraction method, 2

International Nuclear Information System (INIS)

Kaneta, Kiyoshi; Nishizawa, Hidekazu; Arashiyama, Masaki.

1982-01-01

In order to evaluate the applicability of two kinds of techniques of the X-ray stress analysis, namely, the standard sin 2 psi method and the newly developed phi-sin 2 psi method, bending tests have been performed. The test results have proved that the values of the stresses measured by means of the mechanical devices and of those measured by the two kinds of the X-ray techniques coincide each other. Then, these two methods have been applied to measure the surface residual stresses of the box-typed, welded steel columns and the following conclusions have been drawn. 1. The principal stress of the surface residural stresses is, in most cases, oriented to the rolled directions at the center of the steel plates, and it tends to rotate in the neighborhood of the heat affected zones. 2. Tensile residual stresses of a large magnitude have been observed in the direction parallel to the beads of the weld, and the moderate compressive residual stresses can be detected in the direction normal to the beads. (author)

Effects of applied stress ratio on the fatigue behavior of additively manufactured porous biomaterials under compressive loading.

Science.gov (United States)

de Krijger, Joep; Rans, Calvin; Van Hooreweder, Brecht; Lietaert, Karel; Pouran, Behdad; Zadpoor, Amir A

2017-06-01

Additively manufactured (AM) porous metallic biomaterials are considered promising candidates for bone substitution. In particular, AM porous titanium can be designed to exhibit mechanical properties similar to bone. There is some experimental data available in the literature regarding the fatigue behavior of AM porous titanium, but the effect of stress ratio on the fatigue behavior of those materials has not been studied before. In this paper, we study the effect of applied stress ratio on the compression-compression fatigue behavior of selective laser melted porous titanium (Ti-6Al-4V) based on the diamond unit cell. The porous titanium biomaterial is treated as a meta-material in the context of this work, meaning that R-ratios are calculated based on the applied stresses acting on a homogenized volume. After morphological characterization using micro computed tomography and quasi-static mechanical testing, the porous structures were tested under cyclic loading using five different stress ratios, i.e. R = 0.1, 0.3, 0.5, 0.7 and 0.8, to determine their S-N curves. Feature tracking algorithms were used for full-field deformation measurements during the fatigue tests. It was observed that the S-N curves of the porous structures shift upwards as the stress ratio increases. The stress amplitude was the most important factor determining the fatigue life. Constant fatigue life diagrams were constructed and compared with similar diagrams for bulk Ti-6Al-4V. Contrary to the bulk material, there was limited dependency of the constant life diagrams to mean stress. The notches present in the AM biomaterials were the sites of crack initiation. This observation and other evidence suggest that the notches created by the AM process cause the insensitivity of the fatigue life diagrams to mean stress. Feature tracking algorithms visualized the deformation during fatigue tests and demonstrated the root cause of inclined (45°) planes of specimen failure. In conclusion, the R

Design and analysis of a toroidal tester for the measurement of core losses under axial compressive stress

Energy Technology Data Exchange (ETDEWEB)

Alatawneh, Natheer, E-mail: natheer80@yahoo.com [Department of Mining and Materials Engineering, McGill University, QC H3A 0G4 (Canada); Rahman, Tanvir; Lowther, David A. [Department of Electrical and Computer Engineering, McGill University, QC H3A 0E9 (Canada); Chromik, Richard [Department of Mining and Materials Engineering, McGill University, QC H3A 0G4 (Canada)

2017-06-15

Highlights: • Develop a toroidal tester for magnetic measurements under compressive axial stress. • The shape of the toroidal ring has been verified using 3D stress analysis. • The developed design has been prototyped, and measurements were carried out. • Physical explanations for the core loss trend due to stress are provided. - Abstract: Electric machine cores are subjected to mechanical stresses due to manufacturing processes. These stresses include radial, circumferential and axial components that may have significant influences on the magnetic properties of the electrical steel and hence, on the output and efficiencies of electrical machines. Previously, most studies of iron losses due to mechanical stress have considered only radial and circumferential components. In this work, an improved toroidal tester has been designed and developed to measure the core losses and the magnetic properties of electrical steel under a compressive axial stress. The shape of the toroidal ring has been verified using 3D stress analysis. Also, 3D electromagnetic simulations show a uniform flux density distribution in the specimen with a variation of 0.03 T and a maximum average induction level of 1.5 T. The developed design has been prototyped, and measurements were carried out using a steel sample of grade 35WW300. Measurements show that applying small mechanical stresses normal to the sample thickness rises the delivered core losses, then the losses decrease continuously as the stress increases. However, the drop in core losses at high stresses does not go lower than the free-stress condition. Physical explanations for the observed trend of core losses as a function of stress are provided based on core loss separation to the hysteresis and eddy current loss components. The experimental results show that the effect of axial compressive stress on magnetic properties of electrical steel at high level of inductions becomes less pronounced.

Development of an on-site measurement method for residual stress in primary system piping of nuclear power plants

International Nuclear Information System (INIS)

Maekawa, Akira; Takahashi, Shigeru; Fujiwara, Masaharu

2014-01-01

In residual stress measurement for large-scale pipes and vessels in high radiation areas and highly contaminated areas of nuclear plants, it is difficult to bring the radioactivated pipes and vessels out of the areas as they are. If they can brought out, it is very burdensome to handle them for the measurement. Development of an on-site measurement method of residual stress which can be quickly applied and has sufficient measurement accuracy is desirable. In this study, a new method combining an electric discharge skim-cut method with a microscopic strain measurement method using markers was proposed to realize the on-site residual stress measurement on pipes in high radiation areas and highly contaminated areas. In the electric discharge skim-cut method, a boat-type sample is skimmed out of a pipe outer/inner surface using electric discharge machining and released residual stress is measured. The on-site measurement of residual stress by the method can be done using a small, portable electric discharge machine. In the microscopic strain measurement method using markers, the residual stress is estimated by microscopic measurement of the distance between markers after the stress release. The combination of both methods can evaluate the residual stress with the same accuracy as conventional methods offer and it can achieve reduction of radiation exposure in the measurement because the work is done simply and rapidly. In this study, the applicability of the electric discharge skim-cut method was investigated because the applicability of the microscopic strain measurement method using markers was confirmed previously. The experimental examination clarified the applicable conditions for the residual stress measurement with the same accuracy as the conventional methods. Furthermore, the electric discharge machining conditions using pure water as the machining liquid was found to eliminate the amount of liquid radioactive waste completely. (author)

The Effect of Applied Tensile Stress on Localized Corrosion in Sensitized AA5083

Science.gov (United States)

2015-09-01

corrosion, but if exposed to elevated temperature for prolonged periods of time the alloy becomes sensitized. Since the β phase is more anodic than the...degree of localized corrosion for sensitized AA5083 under an applied tensile stress. AA5083 is an aluminum -magnesium alloy that experiences severe...direction. 14. SUBJECT TERMS Aluminum alloy , AA5083, IGSCC, intergranular stress corrosion cracking, localized corrosion, sensitized aluminum 15

Measuring depth profiles of residual stress with Raman spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Enloe, W.S.; Sparks, R.G.; Paesler, M.A.

1988-12-01

Knowledge of the variation of residual stress is a very important factor in understanding the properties of machined surfaces. The nature of the residual stress can determine a part`s susceptibility to wear deformation, and cracking. Raman spectroscopy is known to be a very useful technique for measuring residual stress in many materials. These measurements are routinely made with a lateral resolution of 1{mu}m and an accuracy of 0.1 kbar. The variation of stress with depth; however, has not received much attention in the past. A novel technique has been developed that allows quantitative measurement of the variation of the residual stress with depth with an accuracy of 10nm in the z direction. Qualitative techniques for determining whether the stress is varying with depth are presented. It is also demonstrated that when the stress is changing over the volume sampled, errors can be introduced if the variation of the stress with depth is ignored. Computer aided data analysis is used to determine the depth dependence of the residual stress.

Standard test method for determining the effective elastic parameter for X-ray diffraction measurements of residual stress

CERN Document Server

American Society for Testing and Materials. Philadelphia

1998-01-01

1.1 This test method covers a procedure for experimentally determining the effective elastic parameter, Eeff, for the evaluation of residual and applied stresses by X-ray diffraction techniques. The effective elastic parameter relates macroscopic stress to the strain measured in a particular crystallographic direction in polycrystalline samples. Eeff should not be confused with E, the modulus of elasticity. Rather, it is nominally equivalent to E/(1 + ν) for the particular crystallographic direction, where ν is Poisson's ratio. The effective elastic parameter is influenced by elastic anisotropy and preferred orientation of the sample material. 1.2 This test method is applicable to all X-ray diffraction instruments intended for measurements of macroscopic residual stress that use measurements of the positions of the diffraction peaks in the high back-reflection region to determine changes in lattice spacing. 1.3 This test method is applicable to all X-ray diffraction techniques for residual stress measurem...

Internal stresses in α-plutonium during deformation

International Nuclear Information System (INIS)

Merz, M.D.

1975-01-01

Internal stresses were measured in fine-grained (2 μm) and coarse-grained (20 μm) α-plutonium. A stress drop technique (strain transient dip test) was used and the measurements were made for applied creep stresses, sigma/sub a/, from 45 MPa (6250 psi) to 207 MPa (30000 psi) and temperatures from 60 to 113 0 C. The internal stress sigma/sub i/ varied from 17 to 84 MPa and had a weak dependence on applied stress. The effective stress, given by sigma/sub e/ = sigma/sub a/-sigma/sub i/, which is associated with the stress to move dislocations, increased nearly one to one with applied stress, especially at high stresses. The strain rate obeyed the relation epsilon = K(T)sigma/sub e//sup n/ where K(T) is a temperature-dependent term given approximately by Kexp (-104 KJ/mol/RT) and n approximately equal to 3. In fine-grained α-plutonium, the internal stress was interpreted as the stress driving recovery processes near grain boundaries. Measurements of internal stress in α- plutonium with 20-μm grain size indicated a much higher internal stress than for the 2-μm grain size. (5 fig) (auth)

A New Method of Stress Measurement Based upon Elastic Deformation of Core Sample with Stress Relief by Drilling

Science.gov (United States)

Ito, T.; Funato, A.; Tamagawa, T.; Tezuka, K.; Yabe, Y.; Abe, S.; Ishida, A.; Ogasawara, H.

2017-12-01

When rock is cored at depth by drilling, anisotropic expansion occurs with the relief of anisotropic rock stresses, resulting in a sinusoidal variation of core diameter with a period of 180 deg. in the core roll angle. The circumferential variation of core diameter is given theoretically as a function of rock stresses. These new findings can lead various ideas to estimate the rock stress from circumferential variation of core diameter measured after the core retrieving. In the simplest case when a single core sample is only available, the difference between the maximum and minimum components of rock stress in a plane perpendicular to the drilled hole can be estimated from the maximum and minimum core diameters (see the detail in, Funato and Ito, IJRMMS, 2017). The advantages of this method include, (i) much easier measurement operation than those in other in-situ or in-lab estimation methods, and (ii) applicability in high stress environment where stress measurements need pressure for packers or pumping system for the hydro-fracturing methods higher than their tolerance levels. We have successfully tested the method at deep seismogenic zones in South African gold mines, and we are going to apply it to boreholes collared at 3 km depth and intersecting a M5.5 rupture plane several hundred meters below the mine workings in the ICDP project of "Drilling into Seismogenic zones of M2.0 - M5.5 earthquakes in deep South African gold mines" (DSeis) (e.g., http://www.icdp-online.org/projects/world/africa/orkney-s-africa/details/). If several core samples with different orientation are available, all of three principal components of 3D rock stress can be estimated. To realize this, we should have several boreholes drilled in different directions in a rock mass where the stress field is considered to be uniform. It is commonly carried out to dill boreholes in different directions from a mine gallery. Even in a deep borehole drilled vertically from the ground surface, the

Enhancement of power output by a new stress-applied mode on circular piezoelectric energy harvester

Science.gov (United States)

Shu, Fangming; Yang, Tongqing; Liu, Yaoze

2018-04-01

A new stress-applied mode is proposed on piezoelectric circular diaphragm energy harvester. Differing from the usual mode used in previous researches, the mass stick at the center of the diaphragm (PZT-51) is designed into an annular hollow shape. In this case, stress of the mass is applied along the edge of the copper sheet. A screw bonded with the undersurface of the diaphragm transfers force from the vibrator to the diaphragm. This device has a cylindrical shape and its volume is ˜7.9 cm3. With this new stress-applied mode, the piezoelectric energy harvester (with an optimal load of 18 kΩ, a mass of 30 g) could generate a maximum power output of ˜20.8 mW under 9.8 m.s-2 at its resonant frequency of ˜237 Hz. Meanwhile, the greater the hardness ratio between the ceramic and the copper sheet, the greater the advantages of the new structure.

Application of x-ray residual stress measurement to products

International Nuclear Information System (INIS)

Goto, T.; Iwamura, T.

1975-01-01

The X-ray residual stress measuring method is the only nondestructive method for measuring residual stress in polycrystalline materials. It is capable of obtaining information not only on macroscopic stress but also microscopic stress. The authors are employing this method for the development of pre-service and in-service inspection methods and for the improvement of various manufacturing techniques. In this paper, the results of measurement of some products as examples of its application are described. The examples introduced concern the following: (1) Selection of optimum conditions in heat treatment and stress-relief treatment. (2) Residual stress produced by mechanical processes such as autofrettage and flow form. (3) Check of manufacturing processes of rotary shaft and welded parts. (4) Estimation of fatigue strength of shot-peened part. (5) Detection of fatigue damage of shot-peened part. (auth.)

An automated x-ray stress measurement system using a microcomputer

International Nuclear Information System (INIS)

Kurita, Masanori; Miyagawa, Matsuo; Sato, Fumiyoshi; Sugiharai, Shigeru; Ishii, Masami; Sumiyoshi, Michio.

1985-01-01

An automated system for a rapid and precise X-ray stress measurement using a microcomputer has been developed. A block diagram of the system and a flowchart for the stress measurement method are shown. Of the various methods, the one most suitable for the material to be measured can be programmed in this system. The residual stress in a hardened steel having a broad diffraction profile (half-width of 7.2 deg ) could be measured in six minutes with a small standard deviation of 13 MPa by the Gaussian curve method using the sin 2 ψ method. Both the oscillation and the fixed ψ methods, using the Gaussian curve method, allow the X-ray stress measurement of coarse-grained steels; the sin 2 ψ diagram obtained by these methods had a good linearity. The residual stress measurement of an annealed chromium powder gave almost zero stress values, -3.2 to 2.9 MPa depending on the method used, showing a high accuracy of the system. (author)

The method for measuring residual stress in stainless steel pipes

International Nuclear Information System (INIS)

Shimov, Georgy; Rozenbaum, Mikhail; Serebryakov, Alexandr; Serebryakov, Andrey

2016-01-01

The main reason of appearance and growth of corrosion damages of the nuclear steam generator heat exchanger tubes is the process of stress-corrosion cracking of metal under the influence of residual tensile stress. Methods used in the production for estimating residual stresses (such as a method of ring samples) allow measuring only the average tangential stress of the pipe wall. The method of ring samples does not allow to assess the level of residual stress in the surface layer of the pipe. This paper describes an experimental method for measuring the residual stresses on the pipe surface by etching a thin surface layer of the metal. The construction and working principle of a trial installation are described. The residual stresses in the wall of the tubes 16 × 1.5 mm (steel AISI 321) for nuclear steam generators is calculated. Keywords: heat exchange pipes, stress corrosion cracking, residual stresses, stress distribution, stress measurement.

Concurrent grain boundary motion and grain rotation under an applied stress

International Nuclear Information System (INIS)

Gorkaya, Tatiana; Molodov, Konstantin D.; Molodov, Dmitri A.; Gottstein, Guenter

2011-01-01

Simultaneous shear coupling and grain rotation were observed experimentally during grain boundary migration in high-purity Al bicrystals subjected to an external mechanical stress at elevated temperatures. This behavior is interpreted in terms of the structure of the investigated planar 18.2 o non-tilt grain boundary with a 20 o twist component. For characterization of the grain rotation after annealing under stress the bicrystal surface topography across the boundary was measured by atomic force microscopy. The temperature dependence of the boundary migration rate was measured and the migration activation energy determined.

Residual stress measurement in a metal microdevice by micro Raman spectroscopy

International Nuclear Information System (INIS)

Song, Chang; Du, Liqun; Qi, Leijie; Li, Yu; Li, Xiaojun; Li, Yuanqi

2017-01-01

Large residual stress induced during the electroforming process cannot be ignored to fabricate reliable metal microdevices. Accurate measurement is the basis for studying the residual stress. Influenced by the topological feature size of micron scale in the metal microdevice, residual stress in it can hardly be measured by common methods. In this manuscript, a methodology is proposed to measure the residual stress in the metal microdevice using micro Raman spectroscopy (MRS). To estimate the residual stress in metal materials, micron sized β -SiC particles were mixed in the electroforming solution for codeposition. First, the calculated expression relating the Raman shifts to the induced biaxial stress for β -SiC was derived based on the theory of phonon deformation potentials and Hooke’s law. Corresponding micro electroforming experiments were performed and the residual stress in Ni–SiC composite layer was both measured by x-ray diffraction (XRD) and MRS methods. Then, the validity of the MRS measurements was verified by comparing with the residual stress measured by XRD method. The reliability of the MRS method was further validated by the statistical student’s t -test. The MRS measurements were found to have no systematic error in comparison with the XRD measurements, which confirm that the residual stresses measured by the MRS method are reliable. Besides that, the MRS method, by which the residual stress in a micro inertial switch was measured, has been confirmed to be a convincing experiment tool for estimating the residual stress in metal microdevice with micron order topological feature size. (paper)

Residual stress measurement in a metal microdevice by micro Raman spectroscopy

Science.gov (United States)

Song, Chang; Du, Liqun; Qi, Leijie; Li, Yu; Li, Xiaojun; Li, Yuanqi

2017-10-01

Large residual stress induced during the electroforming process cannot be ignored to fabricate reliable metal microdevices. Accurate measurement is the basis for studying the residual stress. Influenced by the topological feature size of micron scale in the metal microdevice, residual stress in it can hardly be measured by common methods. In this manuscript, a methodology is proposed to measure the residual stress in the metal microdevice using micro Raman spectroscopy (MRS). To estimate the residual stress in metal materials, micron sized β-SiC particles were mixed in the electroforming solution for codeposition. First, the calculated expression relating the Raman shifts to the induced biaxial stress for β-SiC was derived based on the theory of phonon deformation potentials and Hooke’s law. Corresponding micro electroforming experiments were performed and the residual stress in Ni-SiC composite layer was both measured by x-ray diffraction (XRD) and MRS methods. Then, the validity of the MRS measurements was verified by comparing with the residual stress measured by XRD method. The reliability of the MRS method was further validated by the statistical student’s t-test. The MRS measurements were found to have no systematic error in comparison with the XRD measurements, which confirm that the residual stresses measured by the MRS method are reliable. Besides that, the MRS method, by which the residual stress in a micro inertial switch was measured, has been confirmed to be a convincing experiment tool for estimating the residual stress in metal microdevice with micron order topological feature size.

An atomic resolution scanning tunneling microscope that applies external tensile stress and strain in an ultrahigh vacuum

International Nuclear Information System (INIS)

Fujita, D; Kitahara, M; Onishi, K; Sagisaka, K

2008-01-01

We have developed an ultrahigh vacuum scanning tunneling microscope with an in situ external stress application capability in order to determine the effects of stress and strain on surface atomistic structures. It is necessary to understand these effects because controlling them will be a key technology that will very likely be used in future nanometer-scale fabrication processes. We used our microscope to demonstrate atomic resolution imaging under external tensile stress and strain on the surfaces of wafers of Si(111) and Si(001). We also successfully observed domain redistribution induced by applying uniaxial stress at an elevated temperature on the surface of a wafer of vicinal Si(100). We confirmed that domains for which an applied tensile stress is directed along the dimer bond become less stable and shrink. This suggests that it may be feasible to fabricate single domain surfaces in a process that controls surface stress and strain

Project ES3: attempting to quantify and measure the level of stress.

Science.gov (United States)

Aguiló, Jordi; Ferrer-Salvans, Pau; García-Rozo, Antonio; Armario, Antonio; Corbí, Ángel; Cambra, Francisco J; Bailón, Raquel; González-Marcos, Ana; Caja, Gerardo; Aguiló, Sira; López-Antón, Raúl; Arza-Valdés, Adriana; Garzón-Rey, Jorge M

2015-11-01

The WHO has qualified stress as a 'world epidemic' due to its increasingly greater incidence on health. The work described in this paper represents an attempt to objectively quantify the level of stress. The aim of the method developed here is to measure how close or how far a subject is from a situation that can be considered 'normal' in medical and social terms. The literature on the pathophysiology of stress and its methods of study in experiments on both animals and humans was reviewed. Nine prospective observational studies were undertaken with different types of subjects and stressors covering the different types of stress. The results of the literature review made it possible to identify the different types of stress, the indicators that yield significant results, the psychometric tests and the well-documented 'stressors'. This material was then used to design the general method and the details of the nine clinical trials. The preliminary results obtained in some of the studies were used to validate the indicators as well as the efficacy of the techniques used experimentally to diminish stress or to produce it. The early results obtained in the experimental trials show that we are on the right path towards defining and validating multivariable markers for quantifying levels of stress and also suggest that the method can be applied in a similar way to the study of mental disorders.

Phase Transition Mapping by Means of Neutron Imaging in SOFC Anode Supports During Reduction Under Applied Stress

DEFF Research Database (Denmark)

Makowska, Malgorzata; Strobl, M.; Lauridsen, E. M.

2015-01-01

Mechanical and electrochemical performance of layers composed of Ni-YSZ cermet in solid oxide fuel and electrolysis cells (SOC) depends on their microstructure and initial internal stresses. After sintering, the manufacturing conditions, i.e. temperature, atmosphere and loads, can influence...... the microstructure and in particular the internal stresses in the Ni-YSZ layer and thereby the cell performance. Spatially resolved observation of the phase transition during reduction can provide information on how parameters like temperature and external load influence the reaction progress. This information...... is crucial for optimization of the SOC performance. In this work the measurements with energy resolved neutron imaging of the phase transition during the NiOYSZ reduction performed at different temperatures with and without applied load, are presented. The results indicate a link between reduction rate...

Residual stress measurement in veneering ceramic by hole-drilling.

Science.gov (United States)

Mainjot, Amélie K; Schajer, Gary S; Vanheusden, Alain J; Sadoun, Michaël J

2011-05-01

Mismatch in thermal expansion properties between veneering ceramic and metallic or high-strength ceramic cores can induce residual stresses and initiate cracks when combined with functional stresses. Knowledge of the stress distribution within the veneering ceramic is a key factor for understanding and predicting chipping failures, which are well-known problems with Yttria-tetragonal-zirconia-polycrystal based fixed partial dentures. The objectives of this study are to develop a method for measuring the stress profile in veneering ceramics and to compare ceramic-fused-to-metal compounds to veneered Yttria-tetragonal-zirconia-polycrystal ceramic. The hole-drilling method, often used for engineering measurements, was adapted for use with veneering ceramic. Because of the high sensitivity needed in comparison with industrial applications, a high sensitivity electrical measurement chain was developed. All samples exhibited the same type of stress vs. depth profile, starting with compressive at the ceramic surface, decreasing with depth and becoming tensile at 0.5-1.0mm from the surface, and then becoming slightly compressive again. The zirconia samples exhibited a stress depth profile of larger magnitude. The hole drilling method was shown be a practical tool for measuring residual stresses in veneering ceramics. Copyright © 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Effects of emotional and perceptual-motor stress on a voice recognition system's accuracy: An applied investigation

Science.gov (United States)

Poock, G. K.; Martin, B. J.

1984-02-01

This was an applied investigation examining the ability of a speech recognition system to recognize speakers' inputs when the speakers were under different stress levels. Subjects were asked to speak to a voice recognition system under three conditions: (1) normal office environment, (2) emotional stress, and (3) perceptual-motor stress. Results indicate a definite relationship between voice recognition system performance and the type of low stress reference patterns used to achieve recognition.

Accuracy of soil stress measurements as affected by transducer dimensions and shape

DEFF Research Database (Denmark)

Lamandé, Mathieu; Keller, Thomas; Berisso, Feto Esimo

2015-01-01

Accurate measurements of soil stress are needed to evaluate the impact of traffic on soil properties and prevent soil compaction. Four types of transducer commonly used to measure vertical stress were calibrated in realistic traffic conditions in the field. The four transducer types differed...... in shape and dimensions, which are important factors influencing stress. Deviation of measured stress from true stress ranged from 15% underestimation to 18% overestimation, with transducer thickness to width ratio being the most important shape factor influencing the stress recorded. Changes in physical...... conditions in the soil above the transducers due to their installation did not influence the accuracy of vertical stress measurements. The results of this calibration are valid for correcting stress measurements in topsoil, but should be used with caution for vertical stress measurements in subsoil. All...

Design and analysis of a toroidal tester for the measurement of core losses under axial compressive stress

Science.gov (United States)

Alatawneh, Natheer; Rahman, Tanvir; Lowther, David A.; Chromik, Richard

2017-06-01

Electric machine cores are subjected to mechanical stresses due to manufacturing processes. These stresses include radial, circumferential and axial components that may have significant influences on the magnetic properties of the electrical steel and hence, on the output and efficiencies of electrical machines. Previously, most studies of iron losses due to mechanical stress have considered only radial and circumferential components. In this work, an improved toroidal tester has been designed and developed to measure the core losses and the magnetic properties of electrical steel under a compressive axial stress. The shape of the toroidal ring has been verified using 3D stress analysis. Also, 3D electromagnetic simulations show a uniform flux density distribution in the specimen with a variation of 0.03 T and a maximum average induction level of 1.5 T. The developed design has been prototyped, and measurements were carried out using a steel sample of grade 35WW300. Measurements show that applying small mechanical stresses normal to the sample thickness rises the delivered core losses, then the losses decrease continuously as the stress increases. However, the drop in core losses at high stresses does not go lower than the free-stress condition. Physical explanations for the observed trend of core losses as a function of stress are provided based on core loss separation to the hysteresis and eddy current loss components. The experimental results show that the effect of axial compressive stress on magnetic properties of electrical steel at high level of inductions becomes less pronounced.

Thermal input control and enhancement for laser based residual stress measurements using liquid temperature indicating coatings

Science.gov (United States)

Pechersky, Martin J.

1999-01-01

An improved method for measuring residual stress in a material comprising the steps of applying a spot of temperature indicating coating to the surface to be studied, establishing a speckle pattern surrounds the spot of coating with a first laser then heating the spot of coating with a far infrared laser until the surface plastically deforms. Comparing the speckle patterns before and after deformation by subtracting one pattern from the other will produce a fringe pattern that serves as a visual and quantitative indication of the degree to which the plasticized surface responded to the stress during heating and enables calculation of the stress.

Mean wall-shear stress measurements using the micro-pillar shear-stress sensor MPS3

International Nuclear Information System (INIS)

Große, S; Schröder, W

2008-01-01

A new sensor to measure the mean turbulent wall-shear stress in turbulent flows is described. The wall-shear stress sensor MPS 3 has been tested in a well-defined fully developed turbulent pipe flow at Reynolds numbers Re b based on the bulk velocity U b and the pipe diameter D in the range of Re b = 10 000–20 000. The results demonstrate a convincing agreement of the mean wall-shear stress obtained with the new sensor technique with analytical and experimental results from the literature. The sensor device consists of a flexible micro-pillar that extends from the wall into the viscous sublayer. Bending due to the exerting fluid forces, the pillar-tip deflection serves as a measure for the local wall-shear stress. The sensor concept, calibration techniques, the achievable accuracy and error estimates, the fields of application and the sensor limits will be discussed. Furthermore, a first estimate of the pillar dynamic response will be derived showing the potential of the sensor to also measure the turbulent fluctuating wall-shear stress

A Hydraulic Stress Measurement System for Investigations at Depth in Slim Boreholes

Science.gov (United States)

Ask, M. V. S.; Ask, D.; Cornet, F. H.; Nilsson, T.; Talib, M.; Sundberg, J.

2017-12-01

Knowledge of the state of stress is essential to most underground work in rock mechanics as it provides means to analyze the mechanical behavior of a rock mass, serve as boundary condition in rock engineering problems, and help understand rock mass stability and groundwater flow. Luleå University of Technology (LTU) has developed and built a wire-line system for hydraulic rock stress measurements in slim boreholes together with the University of Strasbourg and Geosigma AB. The system consists of a downhole- and a surface unit. The downhole unit consists of hydraulic fracturing equipment (straddle packers and downhole imaging tool) and their associated data acquisition systems. The surface unit comprises of a 40-foot container permanently mounted on a trailer, which is equipped with a tripod, wire-line winches, water hydraulics, and a generator. The surface unit serves as a climate-independent on-site operations center, as well as a self-supporting transport vessel for the entire system. Three hydraulic stress testing methods can be applied: hydraulic fracturing, sleeve fracturing and hydraulic testing of pre-existing fractures. The three-dimensional stress tensor and its variation with depth within a continuous rock mass can be determined in a scientific unambiguously way by integrating results from the three test methods. The testing system is state of the art in several aspects including: (1) Large depth range (3 km), (2) Ability to test three borehole dimensions, (3) Resistivity imager maps the orientation of tested fracture (which is highlighted); (4) Highly stiff and resistive to corrosion downhole testing equipment; and (5) Very detailed control on the injection flow rate and cumulative volume is obtained by a hydraulic injection pump with variable piston rate, and a highly sensitive flow-meter. These aspects highly reduce measurement-related uncertainties of stress determination. Commissioning testing and initial field tests are scheduled to occur in a 1200

Improvement in accuracy of the measurements of residual stresses due to circumferential welds in thin-walled pipe using Rayleigh wave method

International Nuclear Information System (INIS)

Akhshik, Siamak; Moharrami, Rasool

2009-01-01

To achieve an acceptable safety in many industrial applications such as nuclear power plants and power generation, it is extremely important to gain an understanding of the magnitudes and distributions of the residual stresses in a pipe formed by joining two sections with a girth butt weld. Most of the methods for high-accuracy measurement of residual stress are destructive. These destructive measurement methods cannot be applied to engineering systems and structures during actual operation. In this paper, we present a method based on the measurement of ultrasonic Rayleigh wave velocity variations versus the stress state for nondestructive evaluation of residual stress in dissimilar pipe welded joint. We show some residual stress profile obtained by this method. These are then compared with other profiles determined using a semi-destructive technique (hole-drilling) that makes it possible to check our results. According to the results, we also present a new method for adjusting the ultrasonic measurements to improve the agreement with the results obtained from other techniques.

Flexible Micropost Arrays for Shear Stress Measurement

Science.gov (United States)

Wohl, Christopher J.; Palmieri, Frank L.; Hopkins, John W.; Jackson, Allen M.; Connell, John W.; Lin, Yi; Cisotto, Alexxandra A.

2015-01-01

Increased fuel costs, heightened environmental protection requirements, and noise abatement continue to place drag reduction at the forefront of aerospace research priorities. Unfortunately, shortfalls still exist in the fundamental understanding of boundary-layer airflow over aerodynamic surfaces, especially regarding drag arising from skin friction. For example, there is insufficient availability of instrumentation to adequately characterize complex flows with strong pressure gradients, heat transfer, wall mass flux, three-dimensionality, separation, shock waves, and transient phenomena. One example is the acoustic liner efficacy on aircraft engine nacelle walls. Active measurement of shear stress in boundary layer airflow would enable a better understanding of how aircraft structure and flight dynamics affect skin friction. Current shear stress measurement techniques suffer from reliability, complexity, and airflow disruption, thereby compromising resultant shear stress data. The state-of-the-art for shear stress sensing uses indirect or direct measurement techniques. Indirect measurements (e.g., hot-wire, heat flux gages, oil interferometry, laser Doppler anemometry, small scale pressure drag surfaces, i.e., fences) require intricate knowledge of the studied flow, restrictive instrument arrangements, large surface areas, flow disruption, or seeding material; with smaller, higher bandwidth probes under development. Direct measurements involve strain displacement of a sensor element and require no prior knowledge of the flow. Unfortunately, conventional "floating" recessed components for direct measurements are mm to cm in size. Whispering gallery mode devices and Fiber Bragg Gratings are examples of recent additions to this type of sensor with much smaller (?m) sensor components. Direct detection techniques are often single point measurements and difficult to calibrate and implement in wind tunnel experiments. In addition, the wiring, packaging, and installation

Measurement of the forming limit stress curve using a multi-axial tube expansion test with a digital image correlation system

Energy Technology Data Exchange (ETDEWEB)

Hakoyama, Tomoyuki [Department of Mechanical Systems Engineering, Graduate school of Engineering, Tokyo University of Agriculture and Technology, 2-24-16, Nakacho, Koganei-shi, Tokyo, 184-8588 (Japan); Kuwabara, Toshihiko [Division of Advanced Mechanical Systems Engineering, Institute of Engineering, Tokyo University of Agriculture and Technology, 2-24-16, Nakacho, Koganei-shi, Tokyo, 184-8588 (Japan)

2013-12-16

A servo-controlled tension-internal pressure testing machine with an optical 3D deformation analysis system (ARAMIS) was used to measure the multi-axial plastic deformation behavior of a high-strength steel sheet for a range of strain from initial yield to fracture. The testing machine is capable of applying arbitrary principal stress or strain paths to a tubular specimen using an electrical, closed-loop servo-control system for axial force and internal pressure. Tubular specimens with an inner diameter of 44.6 mm were fabricated from a high-strength steel sheet with a tensile strength of 590 MPa and a thickness of 1.2 mm by roller bending and laser welding. Several linear and non-linear stress paths in the first quadrant of the stress space were applied to the tubular specimens in order to measure the forming limit curve (FLC) and forming limit stress curve (FLSC) of the as-received test material, in addition to the contours of plastic work and the directions of plastic strain rates. The contours of plastic work and the directions of plastic strain rates measured for the linear stress path experiments were compared with those calculated using selected yield functions in order to identify the most appropriate yield function for the test material. Moreover, a Marciniak-Kuczyński type (M-K) forming limit analysis was performed using the most appropriate yield function. The calculated and measured FLC and FLSC were compared in order to validate the M-K approach. The path-dependence of the FLC and FLSC was also investigated.

The role of cold work and applied stress on surface oxidation of 304 stainless steel

Energy Technology Data Exchange (ETDEWEB)

Lozano-Perez, Sergio, E-mail: sergio.lozano-perez@materials.ox.ac.uk [Department of Materials, University of Oxford, Parks Rd., Oxford OX1 3PH (United Kingdom); Kruska, Karen [Department of Materials, University of Oxford, Parks Rd., Oxford OX1 3PH (United Kingdom); Iyengar, Ilya [Winchester College, College Street, Winchester SO23 9LX (United Kingdom); Terachi, Takumi; Yamada, Takuyo [Institute of Nuclear Safety System (INSS), 64 Sata, Mihama-cho, Mikata-gun, Fukui 919-1205 (Japan)

2012-03-15

Highlights: Black-Right-Pointing-Pointer FIB 3D sequential sectioning is an ideal technique to characterize surface oxidation. Black-Right-Pointing-Pointer 3D models of the oxide can be produced with nanometre resolution. Black-Right-Pointing-Pointer The effects of stress and cold work in grain boundary oxidation have been analysed. Black-Right-Pointing-Pointer At least three different oxidation modes are observed when stress is applied. - Abstract: FIB 3-dimensional (3D) sequential sectioning has been used to characterize environmental degradation of 304 stainless steels in pressurized water reactor (PWR) simulated primary water. In particular, the effects of cold work and applied stress on oxidation have been studied in detail. It was found that a description of the oxidation behaviour of this alloy is only complete if it is treated statistically, since it can suffer from high variability depending on the feature described.

Molecular force sensors to measure stress in cells

International Nuclear Information System (INIS)

Prabhune, Meenakshi; Rehfeldt, Florian; Schmidt, Christoph F

2017-01-01

Molecularly generated forces are essential for most activities of biological cells, but also for the maintenance of steady state or homeostasis. To quantitatively understand cellular dynamics in migration, division, or mechanically guided differentiation, it will be important to exactly measure stress fields within the cell and the extracellular matrix. Traction force microscopy and related techniques have been established to determine the stress transmitted from adherent cells to their substrates. However, different approaches are needed to directly assess the stress generated inside the cell. This has recently led to the development of novel molecular force sensors. In this topical review, we briefly mention methods used to measure cell-external forces, and then summarize and explain different designs for the measurement of cell-internal forces with their respective advantages and disadvantages. (topical review)

Measuring in-situ stress in deep boreholes

International Nuclear Information System (INIS)

1985-08-01

The hydrofracturing method of in-situ stress measurement is the only technique which has been proven to be reliable in boreholes below depths of 300 m. The method has been used in a variety of applications at depths of up to 5000m, and in a range of borehole diameters. The equipment used is composed of standard components from proven and long-established oil industry well-logging tools and is simple to operate. This is preferable to the delicate electrical devices used in the overcoring stress measurement method. Electrical components are difficult to waterproof, very small strains are monitored and the tendency of electrical circuits to drift, due to a variety of effects, makes interpretation of the results difficult. However, the interpretation of hydrofracturing test results is often not easy. Many factors can prevent ideal fracturing behaviour from occurring, in which case conventional analyses will yield incorrect answers. The complete state of stress can often not be determined and sweeping assumptions are commonly made about principal stress direction, which cannot always be subsequently verified. (author)

Ultrasonic measurements on residual stress in autofrettged thick walled petroleum pipes

International Nuclear Information System (INIS)

Woias, G.; Mizera, J.

2008-01-01

The residual stresses in a component or structure are caused by incompatible permanent deformation and related gradient of plastic/elastic strains. They may be generated or modified at every stage in the components life cycle, from original material production to final disposal. Residual stresses can be measured by non-destructive techniques, including X-ray and neutron diffraction, magnetic and ultrasonic methods. The selection of the optimum measurement technique should take account volumetric resolution, material, geometry and access to the component. For large metallic components neutron diffraction is of prime importance as it provides quantitative information on stresses in relatively large volume of methods disregarding its shape complexity. Residual stresses can play a significant role in explaining or preventing failure of components of industrial installations. One example of residual stresses preventing failure are the ones generated by shot peening, inducing surface compressive stresses that improve the fatigue life. Petroleum refinery piping is generally characterized by large-diameters, operated at elevated temperature and under high pressure. Pipelines of a polyethylene plant working in one of the Polish refineries are subjected to pressures exceeding 300 MPa at temperatures above 200 o C. The pipes considered here were pressurized with pressure of 600 MPa. The wall thickness of the pipes is 27 mm and pipe dimensions are 46 x 100 mm. The material is steel with Re=580 MPa. Due to pressurizing, the components retain compressive stresses at the internal surface. These stresses increase resistance to cracking of the pipes. Over the period of exploitation these stresses diminish due to temperature activated relaxation or creep. The purpose of the project is to verify kinetics of such a relaxation process and calibrate alternative methods of their measurements. To avoid stress relaxation, numerical analysis from Finite Element Modelling (FEM)gave an

Applied methods for mitigation of damage by stress corrosion in BWR type reactors

International Nuclear Information System (INIS)

Hernandez C, R.; Diaz S, A.; Gachuz M, M.; Arganis J, C.

1998-01-01

The Boiling Water nuclear Reactors (BWR) have presented stress corrosion problems, mainly in components and pipes of the primary system, provoking negative impacts in the performance of energy generator plants, as well as the increasing in the radiation exposure to personnel involucred. This problem has caused development of research programs, which are guided to find solution alternatives for the phenomena control. Among results of greater relevance the control for the reactor water chemistry stands out particularly in the impurities concentration and oxidation of radiolysis products; as well as the supervision in the materials selection and the stresses levels reduction. The present work presents the methods which can be applied to diminish the problems of stress corrosion in BWR reactors. (Author)

The Community Child Health Network Life Stress Interview: a brief chronic stress measure for community health research.

Science.gov (United States)

Tanner Stapleton, Lynlee R; Dunkel Schetter, Christine; Dooley, Larissa N; Guardino, Christine M; Huynh, Jan; Paek, Cynthia; Clark-Kauffman, Elizabeth; Schafer, Peter; Woolard, Richard; Lanzi, Robin Gaines

2016-07-01

Chronic stress is implicated in many theories as a contributor to a wide range of physical and mental health problems. The current study describes the development of a chronic stress measure that was based on the UCLA Life Stress Interview (LSI) and adapted in collaboration with community partners for use in a large community health study of low-income, ethnically diverse parents of infants in the USA (Community Child Health Network [CCHN]). We describe the instrument, its purpose and adaptations, implementation, and results of a reliability study in a subsample of the larger study cohort. Interviews with 272 mothers were included in the present study. Chronic stress was assessed using the CCHN LSI, an instrument designed for administration by trained community interviewers to assess four domains of chronic stress, each rated by interviewers. Significant correlations ranging from small to moderate in size between chronic stress scores on this measure, other measures of stress, biomarkers of allostatic load, and mental health provide initial evidence of construct and concurrent validity. Reliability data for interviewer ratings are also provided. This relatively brief interview (15 minutes) is available for use and may be a valuable tool for researchers seeking to measure chronic stress reliably and validly in future studies with time constraints.

Measuring occupational stress: development of the pressure management indicator.

Science.gov (United States)

Williams, S; Cooper, C L

1998-10-01

The study of occupational stress is hindered by the lack of compact and comprehensive standardized measurement tools. The Pressure Management Indicator (PMI) is a 120-item self-report questionnaire developed from the Occupational Stress Indicator (OSI). The PMI is more reliable, more comprehensive, and shorter than the OSI. It provides an integrated measure of the major dimensions of occupational stress. The outcome scales measure job satisfaction, organizational satisfaction, organizational security, organizational commitment, anxiety--depression, resilience, worry, physical symptoms, and exhaustion. The stressor scales cover pressure from workload, relationships, career development, managerial responsibility, personal responsibility, home demands, and daily hassles. The moderator variables measure drive, impatience, control, decision latitude, and the coping strategies of problem focus, life work balance, and social support.

Diffraction measurements of residual stress in titanium matrix composites

International Nuclear Information System (INIS)

James, M.R.; Bourke, M.A.; Goldstone, J.A.; Lawson, A.C.

1993-01-01

Metal matrix composites develop residual strains after consolidation due to the thermal expansion mismatch between the reinforcement fiber and the matrix. X-ray and neutron diffraction measured values for the longitudinal residual stress in the matrix of four titanium MMCs are reported. For thick composites (> 6 plies) the surface stress measured by x-ray diffraction matches that determined by neutron diffraction and therefore represents the stress in the bulk region consisting of the fibers and matrix. For thin sheet composites, the surface values are lower than in the interior and increase as the outer rows of fibers are approached. While a rationale for the behavior in the thin sheet has yet to be developed, accounting for composite thickness is important when using x-ray measured values to validate analytic and finite element calculations of the residual stress state

A Study on Residual Stress Measurements by Using Laser Speckle Interferometry

International Nuclear Information System (INIS)

Rho, Kyung Wan; Kang, Young June; Hong, Seong Jin; Kang, Hyung Soo

1999-01-01

Residual stress is one of the causes which make defects in engineering components and materials. And interest in the measurement of residual stress exists in many industries. There are commonly used methods by which residual stresses are currently measured. But these methods have a little demerits: time consumption and other problems. Therefore we devised a new experimental technique to measure residual stress in materials with a combination of laser speckle pattern interferometry, finite element method and spot heating. The speckle pattern interferometer measures in-plane deformations while the heating provides for very localized stress relief. FEM is used for determining heat temperature and other parameters. The residual stresses are determined by the amount of strain that is measured subsequent to the heating and cool-down of the region being interrogated. A simple model is presented to provide a description of the method. In this paper, the ambiguity problem for the fringe patterns has solved by a phase shifting method

Stress Measurement around a Circular Role in a Cantilever Beam under Bending Moment Using Strain Gage and Reflective Photoelasticity

Energy Technology Data Exchange (ETDEWEB)

Baek, Tae Hyun; Park, Tae Geun; Yang, Min Bok [Kunsan National University, Gunsan (Korea, Republic of)

2006-10-15

It is necessary to study on the stress concentration experimentally, which is the main reason to avoid mechanical dilapidation and failure, when designing a mechanical structure. Stress concentration factor of a specimen of cantilever beam with a circular hole in the center was measured using both strain gage and photoelastic methods in this paper. In strain-gage measurement, three strain gages along the line near a hole of the specimen were installed and maximum strain was extrapolated from three measurements. In photoelastic measurement, two methods were employed. First, the Babinet-Soleil compensation method was used to measure the maximum strain. Secondly, photoelastic 4-step phase shilling method was applied to observe the strain distribution around the hole. Measurements obtained by different experiments were comparable within the range of experimental error

Stress Measurement around a Circular Role in a Cantilever Beam under Bending Moment Using Strain Gage and Reflective Photoelasticity

International Nuclear Information System (INIS)

Baek, Tae Hyun; Park, Tae Geun; Yang, Min Bok

2006-01-01

It is necessary to study on the stress concentration experimentally, which is the main reason to avoid mechanical dilapidation and failure, when designing a mechanical structure. Stress concentration factor of a specimen of cantilever beam with a circular hole in the center was measured using both strain gage and photoelastic methods in this paper. In strain-gage measurement, three strain gages along the line near a hole of the specimen were installed and maximum strain was extrapolated from three measurements. In photoelastic measurement, two methods were employed. First, the Babinet-Soleil compensation method was used to measure the maximum strain. Secondly, photoelastic 4-step phase shilling method was applied to observe the strain distribution around the hole. Measurements obtained by different experiments were comparable within the range of experimental error

X-ray measurement of residual stress in metals at Chalk River Nuclear Laboratories

International Nuclear Information System (INIS)

Winegar, J.E.

1980-06-01

X-ray diffraction is used at CRNL to measure residual stress in metals. This report summarizes the basic principles of stress measurement, and reviews factors affecting accuracy of measurement. The technique and equipment described were developed at CRNL to give reliable measurements. Accuracy of measurement is achieved by using fixed-count step-scanning and by computer analysis of intensity data using a cubic spline curve smoothing routine. Specific reference is made to the measurement of residual stress in Inconel-600 and Incoloy-800 boiler tubing. Because it measures stress in thin surface layers, the X-ray method can also be used to measure the depth profile of stresses. As there are no standardized procedures for measuring residual stress, this report will be useful both to those unfamiliar with the measurement of residual stress and to those already making such measurements in other laboratories. (auth)

Comparison of residual stress measurement in thin films using surface micromachining method

International Nuclear Information System (INIS)

He, Q.; Luo, Z.X.; Chen, X.Y.

2008-01-01

Conductive, dielectric, semiconducting, piezoelectric and ferroelectric thin films are extensively used for MEMS/NEMS applications. One of the important parameters of thin films is residual stress. The residual stress can seriously affect the properties, performance and long-term stability of the films. Excessive compressive or tensile stress results in buckling, cracking, splintering and sticking problems. Stress measurement techniques are therefore essential for both process development and process monitoring. Many suggestions for stress measurement in thin films have been made over the past several decades. This paper is concentrated on the in situ stress measurement using surface micromachining techniques to determine the residual stress. The authors review and compare several types of stress measurement methods including buckling technique, rotating technique, micro strain gauge and long-short beam strain sensor

Measurements of wall-shear-stress distribution on an NACA0018 airfoil by liquid-crystal coating and near-wall particle image velocimetry (PIV)

International Nuclear Information System (INIS)

Fujisawa, N; Oguma, Y; Nakano, T

2009-01-01

Measurements of wall-shear-stress distributions along curved surfaces are carried out using non-intrusive experimental methods, such as liquid-crystal coating and near-wall particle image velocimetry (PIV). The former method relies on the color change of the liquid-crystal coating sensitive to the wall shear stress, while the latter is based on the direct evaluation of shear stresses through the near-wall PIV measurement in combination with the image deformation technique. These experimental methods are applied to the measurement of wall-shear-stress distributions of air flow at a free-stream velocity of 15 m s −1 on a flat plate and an NACA0018 airfoil. The experiments are carried out at zero angle of attack for the flat plate and at 0° and ±6° angles of attack for the airfoil, and then the variations of shear-stress distribution along these surfaces are studied. These measurements in wall shear stresses agree with each other within their experimental uncertainties, suggesting the validity of experimental methods for non-intrusive shear-stress measurements. It is found that the wall-shear-stress distribution shows a small negative value upstream of the reattachment point on the NACA0018 airfoil, which is followed by an increase in shear stresses downstream due to laminar–turbulent transition of boundary layers. Such behavior of wall-shear-stress distribution is well correlated with the mean flow and turbulence characteristics along the airfoil surfaces, which are measured by PIV

Measurements of the state of stress in deep drill holes

International Nuclear Information System (INIS)

Vaeaetaeinen, A.; Saerkkae, P.

1985-05-01

The state of stress in rock is one of the most important parameters in the safe planning of stable underground openings in rock. At the same time, it is very difficult to be determined from a great distance. The common methods for the determination of state of stress in bedrock are usually not able to do this from a distance over 30 m. This work is a survey on rock stress determination methods usable in deep, over 500 m, drill holes. It also contains a recommendation for a method to determine the state of stress in Lavia test hole. The presented recommendation for the measurement of the state of stress contains an estimation on the working time for the measurement as well as the amount and location of the measuring points. The examination of the methods has been concentrated on three methods, hydraulic fracturing, overcoring by Vattenfall and differential strain analysis. Theoretical background of these methods has been analyzed. A special interest has been laid on the fundamental assumptions of different methods and their influence on the reliability of the results and the interpretation of the state of stress. The comparison of the methods has been made by literature and user interviews. Equipment and personnel needed, and way of measurement are described for the methods. The parameters measured and their possible sources of errors are described, too, as well as the fundamental assumptions and potential difficulties in the measurement. The organizations in Scandinavia performing measurements and their abilities to do measurements and interpretation are presented. Readiness to interpretation in Finland is described shortly

Application of one-sided stress wave velocity measurement technique to evaluate freeze-thaw damage in concrete

International Nuclear Information System (INIS)

Lee, Joon Hyun; Park, Won Su

1998-01-01

It is well recognized that damage resulting from freeze-thaw cycles is a serious problems causing deterioration and degradation of concrete. In general, freeze-thaw cycles change the microstructure of the concrete ultimately leading to internal stresses and cracking. In this study, a new method for one-sided stress wave velocity measurement has been applied to evaluate freeze-thaw damage in concrete by monitoring the velocity change of longitudinal and surface waves. The freeze-thaw damage was induced in a 400 x 150 x 100 mm concrete specimen in accordance with ASTM C666 using s commercial testing apparatus. A cycle consisted of a variation of the temperature from -14 to 4 degrees Celsius. A cycle takes 4-5 hours with approximately equal times devoted to freezing-thawing. Measurement of longitudinal and surface wave velocities based on one-sided stress wave velocity measurement technique was made every 5 freeze-thaw cycle. The variation of longitudinal and surface wave velocities due to increasing freeze-thaw damage is demonstrated and compared to determine which one is more effective to monitor freeze-thaw cyclic damage progress. The variation in longitudinal wave velocity measured by one-sided technique is also compared with that measured by the conventional through transmission technique.

Hydraulic fracturing rock stress measurement at Haestholmen, Finland

International Nuclear Information System (INIS)

Ljunggren, C.; Klasson, H.

1992-12-01

This report presents hydraulic fracturing measurements in two boreholes located on the Haestholmen island near Loviisa, Finland. The aim of the measurements was to provide stress data, forming input for the design of an underground facility for disposal of low- and medium-level waste as well as future plant decommissioning radioactive waste from the IVO reactor units situated on Haestholmen. The theoretical background to the hydrofracturing method is summarized, as is the equipment and experimental procedures used in the present case. All results obtained are presented and critically discussed. The final stress parameters presented are magnitudes and directions of the maximum and minimum horizontal stresses. Testing was successfully completed according to schedule in both boreholes.(orig.)

Controlled drilling technology for HLW management. Directional drilling and mechanics/stress measurements in the borehole

International Nuclear Information System (INIS)

Kiho, Kenzo; Shin, Koichi; Okada, Tetsuji; Obuchi, Yasuyoshi; Sunaga, Takayuki; Hase, Kazunori

2013-01-01

Since 2000, Central Research Institute of Electric Power Industry (CRIEPI) has been conducting the project on controlled drilling and the logging/measurement technologies in its boreholes. Especially borehole pressure meter and bore hole stress measurement apparatus which can apply to the controlled drilling system was developed. The bore hole was drilled to the 1000 m long in order to intersect the Omagari fault located at Horonobe town in Hokkaido and its core recovery was 99.8% as of FY. 2011. Using borehole logging/measurement/survey, the geological, hydrological, geo-mechanical, geophysical and geochemical data were collected and the Omagari fault was characterized. (author)

3D Tyre/Road pavement contact stress measurements

CSIR Research Space (South Africa)

De Beer, Morris

2010-10-01

Full Text Available The CSIR’s proprietary Stress-in-Motion (SIM) measurements provide rational descriptions of 1D, 2D and 3D tyre/road pavement stresses for: Road pavement design testing and evaluation, as well as tyre design, testing and evaluation....

Lattice strain evolution in IMI 834 under applied stress

International Nuclear Information System (INIS)

Daymond, Mark R.; Bonner, Neil W.

2003-01-01

The effect of elastic and plastic anisotropy on the evolution of lattice strains in the titanium alloy IMI834 has been examined during a uniaxial tensile test, by in situ monitoring on the Engin instrument at the ISIS pulsed neutron source. Measurements were made at load during an incremental loading test. The data is analysed in the light of the requirements for engineering residual stress scanning measurements performed at polychromatic neutron and synchrotron diffraction sources. Comparisons between the measured strains from different lattice families and the predictions from an elasto-plastic self-consistent model are made. Agreement is good in the elastic regime and for most diffraction planes in the plastic regime

[Measurement of unemployment-related psychological stress: Validation of the Unemployment Stress (USS)].

Science.gov (United States)

Szabóné Kapuvári, Virág; Martos, Tamás

2016-01-01

Nowadays the theme of unemployment and the given answers of it are up to date questions in psychology. In spite of this fact, the psychological methods measuring this phenomenon are often missing. That is why the Unemployment Stress Scale (USS) is presented in this article. The aim of our study is to develop a scale called USS and test it's validity and reliability. There were 287 adult unemployed persons asked in this study. Besides the USS we used the Beck Depression Scale, the Spielberger Anxiety Scale (TRAIT), the Sense of Coherence Scale (Hungarian version) and the Rosenberg Self Esteem Scale. According to our results, USS has showed an excellent criterion and construct validity. A useful scale has been formed according to test-retest results. (Cronbach-alfa: 0.88 and 0.86 according to the samples). Moreover our scale has a strong correlation with the Spielberger Anxiety Scale (TRAIT) and the Beck Depression Scale. These chracteristics of the new scale proved that we fond a factor, independent from the self esteem and the sense of coherence, which represents the stress level in the situation of unemployment. This scale is a professional construction to measure stress contributed to unemployment. The USS can be a useful scale in clinical practice because after measuring with this scale we can protect the personality of the unemployed by representing the actual unemployment stress level. That is why professionals can help earlier in a crisis like this.

X-ray stress measurement by use of synchrotron radiation source

International Nuclear Information System (INIS)

Yoshioka, Yasuo; Matsui, Hisaaki; Moro-oka, Toshimasa; Hasegawa, Ken-ichi; Nakajima, Tetsuo.

1986-01-01

In the field of X-ray stress measurement of polycrystalline materials, a diffraction plane at higher Bragg angle has to be selected in order to obtain the precise value of stress. However, the stress measurement on an optional (hkl) plane desired is not always possible because the X-ray beam exited from a metal target has a dispersive wave length. Recently, we have been able to use the synchrotron radiation source (SR) as an excellent X-ray source. In Japan, the facility of synchrotron radiation (Photon Factory, PF) was constructed in the National Laboratory for High Energy Physics (KEK) at Tsukuba academic city. The use of this SR enables the stress measurements on many (hkl) planes with high accuracy in the higher Bragg angle region by providing an X-ray beam having an optional wave length. We have started the X-ray stress analysis by use of the synchrotron radiation source. This paper reports the system of measurement and some results of preliminaly experiments. Since a monochromatic X-ray beam is required for the stress measurement, we used a beam line which consists of a double crystal monochrometer and a focusing mirror. X-rays between 4 KeV (λ = 0.31 nm) and 10 KeV (λ = 0.12 nm) are available with this optical system. We adopted a constant Bragg angle of 2θ = 154 deg for all the diffraction planes. A PSPC having a carbon fiber anode is made and used as a detector with the use of a fast digital signal processor. We could observe the diffraction profiles from (200), (211), (220), (310) and (321) crystal plane of alpha iron, respectively, and the residual stresses in these planes except the (200) plane were measured with high accuracy in a short time. Such feature especially suits the stress analysis of the material which has preferred orientation or stress gradient. (author)

Internal stresses in α-plutonium during deformation

International Nuclear Information System (INIS)

Merz, M.D.

1976-01-01

Internal stresses were measured in fine grained (2 μm) and coarse grained (20 μm) α-plutonium. In the fine grained metal the internal stress sigmasub(i), which was interpreted as the stress driving recovery processes near grain boundaries, was weakly dependent on applied stress, sigmasub(a). The effective stress, sigmasub(e) = sigma sub(a) - sigmasub(i), which is the stress to move dislocations, increased nearly 1:1 with applied stress, especially at high applied stresses. The strain rate obeyed the relation epsilon=K(T)sigmasub(e)sup(n) where K(T) is a temperature dependent term and n approximately = 3. The recovery rate in fine grained α-plutonium during creep was concluded to be very sensitive to internal stress. The internal stress in α-plutonium with 20 μm grain size was much higher than in the finer grain metal. (Auth.)

Rock stress measurements. Preparatory stage of the equipment development project

International Nuclear Information System (INIS)

Mononen, S.; Hakala, M.; Mikkola, P.

2002-01-01

In recent years the rock stress measurement methods used in Finland have been overcoring and hydraulic fracturing. There have been mainly two companies involved in these measurements, namely Suomen Malmi Oy (Smoy) and SwedPower AB. Smoy has done measurements for mines and for rock engineering projects, whereas SwedPower AB has mainly been involved in nuclear waste disposal investigations and conducted hydraulic fracturing measurements in deep boreholes. Smoy together with its partners started in February 2001 a project named JTM, which was a preliminary stage for a future project, which aims to develop a device most suitable for rock stress measurements in Finland. The partners in the project were HUT Rock Engineering, Posiva Oy, Saanio and Riekkola Oy, Gridpoint Finland Oy and Geopros Oy. Tekes, the National Technology Agency, provided almost half of the project funding. In the management group of the project were Pekka Mikkola (chairman) and Tero Laurila from Smoy, Pekka Saerkkae and Sakari Mononen (full-time researcher) from HUT, Aimo Hautojaervi (Posiva Oy), Erik Johansson (Saanio and Riekkola Oy), Matti Hakala (Gridpoint Finland Oy) and Heikki Haemaelaeinen (Geopros Oy). The aim of the JTM-project was to find out the needs for the development of a device most suitable for rock stress measurements in Finnish mines and rock engineering projects. During the project work was done to find out the range of rock stress measurement devices available, to find out the needs for measurements, and to get acquainted to the measurements done in Scandinavia. Also a report of the most suitable methods for Finnish rock conditions was done based on literature and on interviews of rock stress experts. Based on all the information collected during the project a clear picture of the needs for rock stress measurements in Finland could be formed and a preliminary plan of a future project was done. The aim of the suggested project is to build a device based on hydraulic fracturing

Measuring the stress field around an evolving crack in tensile deformed Mg AZ31 using three-dimensional X-ray diffraction

International Nuclear Information System (INIS)

Oddershede, Jette; Camin, Bettina; Schmidt, Søren; Mikkelsen, Lars P.; Sørensen, Henning Osholm; Lienert, Ulrich; Poulsen, Henning Friis; Reimers, Walter

2012-01-01

The stress field around a notch in a coarse grained Mg AZ31 sample has been measured under tensile load using the individual grains as probes in an in situ high energy synchrotron diffraction experiment. The experimental set-up, a variant of three-dimensional X-ray diffraction microscopy, allows the position, orientation and full stress tensor of each illuminated grain to be determined and, hence, enables the study of evolving stress fields in coarse grained materials with a spatial resolution equal to the grain size. Grain resolved information like this is vital for understanding what happens when the traditional continuum mechanics approach breaks down and fracture is governed by local heterogeneities (e.g. phase or stress differences) between grains. As a first approximation the results obtained were averaged through the thickness of the sample and compared with an elastic–plastic continuum finite element simulation. It was found that a full three-dimensional simulation was required to account for the measured transition from the overall plane stress case away from the notch to the essentially plane strain case observed near the notch tip. The measured and simulated stress contours were shown to be in good agreement except at the highest applied load, at which stress relaxation at the notch tip was observed in the experimental data. This stress relaxation is attributed to the initiation and propagation of a crack. Finally, it was demonstrated that the measured lattice rotations could be used as a qualitative measure of the shape and extent of the plastic deformation zone.

Rock stress measurements using the LUT-Gauge overcoring method

International Nuclear Information System (INIS)

Leijon, B.

1988-04-01

With overcoring techniques, rock stresses are determined indirectly from measurements of the dimensional changes of a borehole, occurring when the rock volume surrounding the hole is isolated from the stresses in the host rock. This thesis describes the development and application of an overcoring technique. The key-component of the instrumentation that has been developed is a triaxial borehole strain cell, referred to as the LUT-Gauge. Laboratory tests were conducted to evaluate the performance of the instrumentation. Special emphasis was given to determining temperature sensitivity of the measuring system since this was identified as a potential source of measurement error. Results indicated good instrument reliability and that the measurement error due to temperature variations typically experienced under field conditions is ± 1 MPa or less. The technique was also evaluated by a series of field tests. Comparison of the results obtained by the different methods showed satisfactory agreement. Analysis of the comprehensive field data collected showed that the confidence that can be attached to an overcoring test is largely governed by the mechanical characteristics of the overcored specimen. Expressed as the standard deviation of the mean stress magnitude, the scatter obtained from repeated testing within a borehole section of about 10 m in length, is found to be ± 4 MPa or less. Rock engineering investigations typically refer to a scale of hundreds of metres or more. This study has demonstrated the existence of significant variations of the stress field on this scale. These variations thus impose difficulties in the application of stress data to the analysis of problems in rock engineering, since the pointwise results obtained from stress measurements cannot be extrapolated with good confidence. (30 refs.) (author)

In-situ stress measurements in the earth's crust in the eastern United States

International Nuclear Information System (INIS)

Rundle, T.A.; Singh, M.M.; Baker, C.H.

1987-04-01

The US Nuclear Regulatory Commission requires that the design basis for vibratory ground motion should be determined through correlation of seismicity with tectonic structures or provinces (10CFR100, Appendix A). Such criteria are difficult to apply in the eastern United States, which experiences persistent low level seismicity, with occasional moderate to large earthquakes. This report presents the results of in-situ stress measurements conducted towards reducing this uncertainty at three (3) seismically active sites in the region, namely, near Moodus, Connecticut, around the Ramapo fault zone in New York and New Jersey, and in central Virginia. As far as possible, at each location one bore hole was drilled close to the ''apparent'' epicenter of the seismic activity and one outside the ''known'' seismic zone, so that the data obtained could be compared. The results obtained were very consistent both as to magnitude and direction. No attempt was made to correlate the in-situ stress measurements with the tectonic setting or seismic activity, since this was beyond the scope of this project. Extensive appendices report experimental data. 35 refs

Method for measuring biaxial stress in a body subjected to stress inducing loads

Science.gov (United States)

Clotfelter, W. N. (Inventor)

1977-01-01

A method is described for measuring stress in test articles including the steps of obtaining for a calibrating specimen a series of transit time differentials between the second wave echo for a longitudinal wave and the first wave echo for each of a pair of shear waves propagated through the specimen as it is subjected to known stress load of a series of stress loads for thus establishing a series of indications of the magnitudes for stress loads induced in the specimen, and thereafter obtaining a transit time differential between the second wave echo for a longitudinal wave and the first wave echo for each of a pair of shear waves propagated in the planes of the stress axes of a test article and comparing the transit time differential thus obtained to the series of transit time differentials obtained for the specimen to determine the magnitude of biaxial stress in the test article.

Research Progress on Measurement Methods and Influence Factors of Thin-film Stress

Directory of Open Access Journals (Sweden)

MA Yibo

2018-02-01

Full Text Available With the size of thin-film electronic devices decreasing, the film stress became an important reason for the failure of thin film devices. Film stress not only affected the membrane structure, but also associated with film optics, electricity, mechanics and other properties, therefore film stress turned into one hot spot in the research field of thin-film materials. This paper reviewed the latest research progress of film stress, substrate curvature method, X-ray diffraction technique and Raman spectroscopy, several frequently used stress measuring techniques were compared and analyzed, and composition ratios of thin film, substrate types, magnetron sputtering process parameters (sputtering power, work pressure, substrate temperature and annealing etc. factors influencing thin film stress were summarized. It was found that substrate curvature method was suitable for measuring almost all kinds of thin film materials. X-ray diffraction and Raman spectroscopy were just fit for measuring materials with characteristic peaks. Nanoindentation method required extra stress-free samples as comparison experiments. During film fabrication and annealing process, film stress usually transited from compressive to tensile status, and several factors combined together could affect stress, so film stress could be reached the minimum value or even stress-free status through setting appropriate parameters. Finally, combined with film stress research status, accurate stress measurement methods for different materials as a thin-film stress research direction were introduced, and challenges in thin film detection range were pointed out.

Stress measurement in thin films by geometrical optics

Science.gov (United States)

Rossnagel, S. M.; Gilstrap, P.; Rujkorakarn, R.

1982-01-01

A variation of Newton's rings experiment is proposed for measuring film stress. The procedure described, the geometrical optics method, is used to measure radii of curvature for a series of film depositions with Ta, Al, and Mo films. The method has a sensitivity of 1 x 10 to the 9th dyn/sq cm, corresponding to the practical radius limit of about 50 m, and a repeatability usually within five percent. For the purposes of comparison, radii are also measured by Newton's rings method and the Talysurf method; all results are found to be in general agreement. Measurement times are also compared: the geometrical optics method requires only 1/2-1 minute. It is concluded that the geometrical optics method provides an inexpensive, fast, and a reasonably correct technique with which to measure stresses in film.

Modeling cell elongation during germ band retraction: cell autonomy versus applied anisotropic stress

International Nuclear Information System (INIS)

Lynch, Holley E; Shane Hutson, M; Veldhuis, Jim; Wayne Brodland, G

2014-01-01

The morphogenetic process of germ band retraction in Drosophila embryos involves coordinated movements of two epithelial tissues—germ band and amnioserosa. The germ band shortens along its rostral–caudal or head-to-tail axis, widens along its perpendicular dorsal-ventral axis, and uncurls from an initial ‘U’ shape. The amnioserosa mechanically assists this process by pulling on the crook of the U-shaped germ band. The amnioserosa may also provide biochemical signals that drive germ band cells to change shape in a mechanically autonomous fashion. Here, we use a finite-element model to investigate how these two contributions reshape the germ band. We do so by modeling the response to laser-induced wounds in each of the germ band’s spatially distinct segments (T1–T3, A1–A9) during the middle of retraction when segments T1–A3 form the ventral arm of the ‘U’, A4–A7 form its crook, and A8–A9 complete the dorsal arm. We explore these responses under a range of externally applied stresses and internal anisotropy of cell edge tensions—akin to a planar cell polarity that can drive elongation of cells in a direction parallel to the minimum edge tension—and identify regions of parameter space (edge-tension anisotropy versus stress anisotropy) that best match previous experiments for each germ band segment. All but three germ band segments are best fit when the applied stress anisotropy and the edge-tension anisotropy work against one another—i.e., when the isolated effects would elongate cells in perpendicular directions. Segments in the crook of the germ band (A4–A7) have cells that elongate in the direction of maximum external stress, i.e., external stress anisotropy is dominant. In most other segments, the dominant factor is internal edge-tension anisotropy. These results are consistent with models in which the amnioserosa pulls on the crook of the germ band to mechanically assist retraction. In addition, they suggest a mechanical cue for

Evaluation of Stress Loaded Steel Samples Using Selected Electromagnetic Methods

International Nuclear Information System (INIS)

Chady, T.

2004-01-01

In this paper the magnetic leakage flux and eddy current method were used to evaluate changes of materials' properties caused by stress. Seven samples made of ferromagnetic material with different level of applied stress were prepared. First, the leakage magnetic fields were measured by scanning the surface of the specimens with GMR gradiometer. Next, the same samples were evaluated using an eddy current sensor. A comparison between results obtained from both methods was carried out. Finally, selected parameters of the measured signal were calculated and utilized to evaluate level of the applied stress. A strong coincidence between amount of the applied stress and the maximum amplitude of the derivative was confirmed

Measurement of stress in vocal folds during phonation using spatiotemporal synchronization

Energy Technology Data Exchange (ETDEWEB)

Tao, Chao [Department of Surgery, Division of Otolaryngology Head and Neck Surgery, University of Wisconsin Medical School, Madison, WI 53792-7375 (United States); Jiang, Jack J. [Department of Surgery, Division of Otolaryngology Head and Neck Surgery, University of Wisconsin Medical School, Madison, WI 53792-7375 (United States)]. E-mail: jiang@surgery.wisc.edu; Zhang, Yu [Department of Surgery, Division of Otolaryngology Head and Neck Surgery, University of Wisconsin Medical School, Madison, WI 53792-7375 (United States)

2007-02-19

A method based on spatiotemporal synchronization is proposed to measure stress distribution in the vocal folds. It is theoretically proved that a measurement system can be synchronized with a vocal fold vibration system by coupling their surface dynamic variables. Therefore, the stress in the vocal folds is predicted by the synchronized continuous model. Numerical experiments are employed to verify this method. The influences of the different coupling variables and the parameter mismatches on stress measurement are also investigated.

Measurement of stress in vocal folds during phonation using spatiotemporal synchronization

International Nuclear Information System (INIS)

Tao, Chao; Jiang, Jack J.; Zhang, Yu

2007-01-01

A method based on spatiotemporal synchronization is proposed to measure stress distribution in the vocal folds. It is theoretically proved that a measurement system can be synchronized with a vocal fold vibration system by coupling their surface dynamic variables. Therefore, the stress in the vocal folds is predicted by the synchronized continuous model. Numerical experiments are employed to verify this method. The influences of the different coupling variables and the parameter mismatches on stress measurement are also investigated

Influence of applied compressive stress on the hysteresis curves and magnetic domain structure of grain-oriented transverse Fe-3%Si steel

International Nuclear Information System (INIS)

Perevertov, O; Schäfer, R

2012-01-01

The influence of an applied compressive stress on the hysteresis curve and domain structure in conventional (1 1 0) [0 0 1] Fe-3%Si steel cut transverse to the rolling direction is studied. Quasistatic hysteresis loops under compressive stress up to 75 MPa were measured. The magnetic domains and magnetization processes were observed by longitudinal Kerr microscopy at different levels of stress. It is shown that the bulk hysteresis loop can be described with a good accuracy by the action of an effective field, which is the product of the stress and a function of magnetization. Domain observations have shown that the reasons for the effective field are demagnetizing fields due to the disappearance of supplementary domains along [0 1 0] and [1 0 0] at low fields and different domain systems in different grains at moderate fields. The latter are caused by differences in grain sensitivity to stress depending on the degree of misorientation. A decrease in the effective field above 1 T is connected with a transformation of all grains into the same domain system—the column pattern. (paper)

Measurement of residual stresses in welded sample of dissimilar materials

International Nuclear Information System (INIS)

Mansur, Tanius Rodrigues; Gomes, Paulo de Tarso Vida; Scaldaferri, Denis Henrique Bianchi; Martins, Geraldo Antonio Scoralick; Atanazio Filho, Nelson do Nascimento

2008-01-01

The welding of dissimilar metals has several applications in the industry. Especially in the nuclear industry, this joint type, common between carbon steel and stainless steel, it is always reason of analysis and special cares tends in view the need to maintain the integrity of the equipment. Residual stresses are introduced in the material as a result of processes as welding, machining, sanding and polishing that can to produce deformation in the proximities of the surface of the material. Residual compressive stresses can be introduced in the material through the jetting process (bombardment of the surface for small glass spheres, dry sand or steel). That procedure allows a fine subsurface layer to suffer yielding, compressing the superficial layer and reducing the formation of areas of concentration of traction stresses, increasing the resistance of the material to the fatigue. The welding process introduces residual stresses due to the geometry resulting from the fusion of the material welded and of the heterogeneous cooling. Besides the microstructural alteration and chemical composition of the material in the affected area for the heat, introduced by the welding, it is also had the effect of the discontinuity of the passes and the formation of bubbles and emptiness that can contribute to the cracks nucleation, reducing the resistance to the fatigue. In the great majority of the times residual stresses are harmful and there are many documented cases which US these stresses went predominant factors for the failure for fatigue. A particularly dangerous aspect of the residual stresses is that their presence is not usually observed, what usually happens with an applied load to the structure. The knowledge of the surface residual stresses is important to predict the emergence of failure when the component or structure is requested. In nuclear power plants it is common to welding of piping of stainless steels with mouthpieces of carbon steel of pressure vases of

A strategy for accommodating residual stresses in the assessment of repair weldments based upon measurement of near surface stresses

International Nuclear Information System (INIS)

Mcdonald, E.J.; Hallam, K.R.; Flewitt, P.E.J.

2005-01-01

On many occasions repairs are undertaken to ferritic steel weldments on plant either during construction or to remove service induced defects. These repaired weldments are subsequently put into service with or without a post-weld heat treatment. In either case, but particularly for the latter, there is a need to accommodate the associated residual stresses in structural integrity assessments such as those based upon the R6 failure avoidance procedure. Although in some circumstances the residual macro-stresses developed within weldments of components and structures can be calculated this is not so readily achieved in the case of residual stresses introduced by repair welds. There is a range of physical and mechanical techniques available to undertake the measurement of macro-residual stresses. Of these X-ray diffraction has the advantage that it is essentially non-destructive and offers the potential for evaluating stresses, which exist in the near surface layer. Although for many structural integrity assessments both the magnitude and distribution of residual stresses have to be accommodated it is not practical to make destructive measurements on weld repaired components and structures to establish the through section distribution of stresses. An approach is to derive a description of the appropriate macro-stresses by a combination of measurement and calculation on trial ferritic steel repair weldments. Surface measurements on the plant can then be made to establish the relationship between the repaired component or structure and the trial weld and thereby improve confidence in predicted stresses and their distribution from the near-surface measured values. Hence X-ray diffraction measurements at the near-surface of the plant weldment can be used to underwrite the quality of the repair by confirming the magnitude and distribution of residual stresses used for the integrity assessment to demonstrate continued safe operation

Applicability of initial stress measurement methods to Horonobe Siliceous rocks and initial stress state around Horonobe Underground Research Laboratory

International Nuclear Information System (INIS)

Sanada, Hiroyuki; Niunoya, Sumio; Matsui, Hiroya; Fujii, Yoshiaki

2009-01-01

Understanding initial stress condition in deep underground is important for such construction as rock cavern for geological disposal of HLW and underground power plant. Neogene sedimentary rock is widely distributed in Japan. There are only a few studies of initial stress measurement in Neogene sedimentary rock mass in Japan due to difficulty of measurement. Evaluation of initial stress condition around Horonobe Underground Research Laboratory Project was carried out in order to understand initial stress condition and applicability of AE, DSCA and hydraulic fracturing (HF) methods to Neogene sedimentary rock. Initial stress values obtained from AE method is smaller than overburden pressure due to time dependency of Kaizer effect. It would be difficult to use AE method as initial stress measurement method for Horonobe Siliceous rocks. Principal stress values by DSCA are similar to those by HF tests. Directions of maximum horizontal principal stresses are approximately in E-W and corresponded to HF results. In HF, rod type and wire-line type systems were compared. Workability of rod type was much better than wire-line type. However, re-opening pressure were not able to be precisely measured in case of rod type system due to the large compliance of the packers and rods. Horizontal maximum and minimum principal stresses increase linearly in HF results. Deviatoric stress is acting at shallow depth. Initial stress condition approaches hydrostatic condition with depth. Direction of maximum horizontal principal stress was in E-W direction which was similar to tectonic movement around Horonobe URL by triangular surveying. (author)

Measuring Stress in Young Children Using Hair Cortisol: The State of the Science.

Science.gov (United States)

Bates, Randi; Salsberry, Pamela; Ford, Jodi

2017-10-01

Extensive literature suggests that adverse experiences in early childhood may deleteriously impact later health. These effects are thought to be related to the impact of persistent or chronic stress on various biological processes, mediated by dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, and ultimately irregularities in cortisol levels. Ameliorating persistent stress in young children requires accurately measuring the chronicity of physiologic stress, which is difficult in young children because of unreliable self-report and the burden and inaccuracy associated with using invasive acute-stress biomeasures. A better way to approximate persistent stress in young children is measuring hair cortisol concentration (HCC), as it only requires one noninvasive collection to measure months of HPA-axis activity or experienced stress. However, few studies measure HCC in young children despite wide use in adult stress research. This article reviews and synthesizes research that uses HCC to approximate persistent stress in healthy children, 12-60 months of age. Reviewed studies indicate that HCC is elevated in young children who are experiencing forms of persistent stress such as low socioeconomic status and maternal distress. Hair cortisol is thus a promising measure of early childhood persistent stress, but due to the limited use of HCC in this population, much research is still needed. Specifically, nurse researchers may need to measure several factors associated with early childhood persistent stress and HCC to identify which children are at risk for stress-related disease.

Residual stress distribution in carbon steel pipe welded joint measured by neutron diffraction

International Nuclear Information System (INIS)

Hayashi, Makoto; Ishiwata, Masayuki; Morii, Yukio; Minakawa, Nobuaki

2000-01-01

In order to estimate crack growth behavior of fatigue and stress corrosion cracking in pipes, the residual stress distribution near the pipe weld region has to be measured through the wall thickness. Since the penetration depth of neutron is deep enough to pass through the thick pipe wall, the neutron diffraction technique for the residual stress measurement is effective for this purpose. At the first step the residual stress distribution near the weld region in a butt-welded carbon steel pipe was measured by the neutron diffraction. Significant stresses extended only to a distance of 30 mm from the center of the weld. The major tensile stresses occurred in the hoop direction in the fusion and heat affected zones of the weldment, and they attained a level greater than 200 MPa through the thickness. While the axial residual stress at the inside surface was 50 MPa, the stress at the outside surface was -100 MPa. The comparison of residual stress distributions measured by the neutron diffraction, the X-ray diffraction and the strain gauge method reveals that the neutron diffraction is the most effective for measuring the residual stress inside the structural components. (author)

The measurement of in-situ stress in near surface environments

International Nuclear Information System (INIS)

Garritty, P.; Irvin, R.A.

1984-04-01

One of the major unknowns affecting aspects of underground construction and the geohydrology of rock masses is the magnitude and direction of the geostatic principal stresses in the earth's crust. This is particularly the case in near surface rocks where there are indications that high horizontal stresses may exist. The measurement of stress in near surface environments is particularly difficult. The techniques, experience and results of a geostatic stress measurement programme using four commercially available devices at shallow depth in the Carnmenellis Granite are critically discussed and compared. This report also brings together some of the conclusions of two previous reports in the series, Garritty (1983) and Garritty and Irvin (1983), and emphasises the fundamental relationship between the state of stress in the earth's crust and the geohydrology of rock masses. (author)

A methodology for interpretation of overcoring stress measurements in anisotropic rock

International Nuclear Information System (INIS)

Hakala, M.; Sjoeberg, J.

2006-11-01

The in situ state of stress is an important parameter for the design of a repository for final disposal of spent nuclear fuel. This report presents work conducted to improve the quality of overcoring stress measurements, focused on the interpretation of overcoring rock stress measurements when accounting for possible anisotropic behavior of the rock. The work comprised: (i) development/upgrading of a computer code for calculating stresses from overcoring strains for anisotropic materials and for a general overcoring probe configuration (up to six strain rosettes with six gauges each), (ii) development of a computer code for determining elastic constants for transversely isotropic rocks from biaxial testing, and (iii) analysis of case studies of selected overcoring measurements in both isotropic and anisotropic rocks from the Posiva and SKB sites in Finland and Sweden, respectively. The work was principally limited to transversely isotropic materials, although the stress calculation code is applicable also to orthotropic materials. The developed computer codes have been geared to work primarily with the Borre and CSIRO HI three-dimensional overcoring measurement probes. Application of the codes to selected case studies, showed that the developed tools were practical and useful for interpreting overcoring stress measurements conducted in anisotropic rock. A quantitative assessment of the effects of anisotropy may thus be obtained, which provides increased reliability in the stress data. Potential gaps in existing data and/or understanding can also be identified. (orig.)

Stress-free reference for neutron diffraction measurement of residual stress in butt-welded joints of austenitic stainless steel pipes

International Nuclear Information System (INIS)

Maekawa, Akira; Takahashi, Tsuneo; Tsuji, Takashi; Suzuki, Hiroshi; Moriai, Atsushi

2012-01-01

Stress-free lattice spacing d_0 has the most influence on reliability of neutron stress measurements made using an angle dispersive method. However, it is hard to evaluate the lattice spacing of welded structures and ductile materials such as stainless steel accurately. In this study, suitable measurement conditions for d_0 of welded pipe joints of austenitic stainless steel were discussed. The d_0 values derived from {311} and {111} reflections, which are often used in austenitic stainless steel for residual stress measurement, were examined. Comparison of the residual strains and stresses evaluated using the obtained d_0 and the finite element analysis showed that the way the d_0 values were chosen affected the measurement accuracy significantly. The stress measurement accuracy was remarkably improved when the {311} reflection was used and the proper d_0 value was chosen in the respective neutron diffraction measurements. For instance, for the axial diffraction measurements using the {311} reflection, it was recommended that only the axial d_0 value of the {311} reflection be used; the measurements using the {111} reflection were less accurate due to the large Young's modulus. Additionally, a lower diffraction angle was judged to be one of the factors leading to a decrease of the strain measurement accuracy. (author)

Measurement of fecal glucocorticoids in parrotfishes to assess stress

Science.gov (United States)

Turner, J.W.; Nemeth, R.; Rogers, C.

2003-01-01

Coral reefs are in decline worldwide from a combination of natural and human forces. The environmental compromises faced by coral reef habitats and their associated fishes are potentially stressful, and in this study we examined the potential for assessing stress levels in coral reef fish. We determined the feasibility of using fecal casts from parrotfishes for remote assessment of stress-related hormones (cortisol and corticosterone), and the response of these hormones to the stress of restraint and hypoxia. Measurement of these hormones in fecal extracts by high performance liquid chromatography (HPLC) was validated using mass spectrometry, chemical derivitization, and radioactive tracer methods. In aquarium-adapted parrotfish, baseline levels of cortisol and corticosterone averaged 3.4??1.1 and 14.8??2.8ng/g feces, respectively, across 32 days. During 13 days of periodic stress these hormones, respectively, average 10.8-fold and 3.2-fold greater than baseline, with a return to near baseline during a 23-day follow-up. Testosterone was also measured as a reference hormone which is not part of the stress-response axis. Levels of this hormone were similar across the study. These fecal hormones were also measured in a field study of parrotfish in 10 fringing coral reef areas around the Caribbean Island of St. John, US Virgin Islands. Extracts of remotely collected fecal casts of three parrotfish species revealed no difference in respective average hormone levels among these species. Also, there was no difference in respective hormone levels between aquarium and field environments. However, levels of both cortisol and corticosterone, but not testosterone, were elevated in two of the 10 reef sites surveyed. This study demonstrates that parrotfish fecals can be collected in aquarium and field conditions and that steroid hormones in these fecals can be extracted and reliably measured. The study also demonstrates that cortisol and corticosterone in parrotfish fecals can

Measurement and interpretation of threshold stress intensity factors for steels in high-pressure hydrogen gas.

Energy Technology Data Exchange (ETDEWEB)

Dadfarnia, Mohsen (University of Illinois at Urbana-Champaign, Urbana, IL); Nibur, Kevin A.; San Marchi, Christopher W.; Sofronis, Petros (University of Illinois at Urbana-Champaign, Urbana, IL); Somerday, Brian P.; Foulk, James W., III; Hayden, Gary A. (CP Industries, McKeesport, PA)

2010-07-01

Threshold stress intensity factors were measured in high-pressure hydrogen gas for a variety of low alloy ferritic steels using both constant crack opening displacement and rising crack opening displacement procedures. The sustained load cracking procedures are generally consistent with those in ASME Article KD-10 of Section VIII Division 3 of the Boiler and Pressure Vessel Code, which was recently published to guide design of high-pressure hydrogen vessels. Three definitions of threshold were established for the two test methods: K{sub THi}* is the maximum applied stress intensity factor for which no crack extension was observed under constant displacement; K{sub THa} is the stress intensity factor at the arrest position for a crack that extended under constant displacement; and K{sub JH} is the stress intensity factor at the onset of crack extension under rising displacement. The apparent crack initiation threshold under constant displacement, K{sub THi}*, and the crack arrest threshold, K{sub THa}, were both found to be non-conservative due to the hydrogen exposure and crack-tip deformation histories associated with typical procedures for sustained-load cracking tests under constant displacement. In contrast, K{sub JH}, which is measured under concurrent rising displacement and hydrogen gas exposure, provides a more conservative hydrogen-assisted fracture threshold that is relevant to structural components in which sub-critical crack extension is driven by internal hydrogen gas pressure.

Applying the Stress and ‘Strength’ Hypothesis to Black Women’s Breast Cancer Screening Delays

Science.gov (United States)

Black, Angela Rose; Woods-Giscombé, Cheryl

2013-01-01

Associations between stress and breast cancer highlight stressful life events as barriers to breast cancer screening, increased stress due to a breast cancer scare or diagnosis, or the immunosuppressive properties of stress as a risk factor for breast cancer occurrence. Little is known, however, about how women’s reactions to stressful life events impact their breast health trajectory. In this study, we explore how reactions to stressors serve as a potential barrier to breast cancer screening among Black women. We apply a gender-specific, culturally responsive stress-process framework, the Stress and ‘Strength’ Hypothesis (“strength hypothesis”), to understand links between the ‘Strong Black Woman role’ role, Black women’s stress reactions and their observed screening delays. We conceptualize strength as a culturally prescribed coping style that conditions resilience, self-reliance and psychological hardiness as a survival response to race-related and gender-related stressors. Using qualitative methods, we investigate the potential for this coping mechanism to manifest as extraordinary caregiving, emotional suppression and self-care postponement. These manifestations may result in limited time for scheduling and attending screening appointments, lack of or delay in acknowledgement of breast health symptoms and low prioritization of breast care. Limitations and future directions are discussed. PMID:23129558

A Piezoelectric Shear Stress Sensor

Science.gov (United States)

Kim, Taeyang; Saini, Aditya; Kim, Jinwook; Gopalarathnam, Ashok; Zhu, Yong; Palmieri, Frank L.; Wohl, Christopher J.; Jiang, Xiaoning

2016-01-01

In this paper, a piezoelectric sensor with a floating element was developed for shear stress measurement. The piezoelectric sensor was designed to detect the pure shear stress suppressing effects of normal stress generated from the vortex lift-up by applying opposite poling vectors to the: piezoelectric elements. The sensor was first calibrated in the lab by applying shear forces and it showed high sensitivity to shear stress (=91.3 +/- 2.1 pC/Pa) due to the high piezoelectric coefficients of PMN-33%PT (d31=-1330 pC/N). The sensor also showed almost no sensitivity to normal stress (less than 1.2 pC/Pa) because of the electromechanical symmetry of the device. The usable frequency range of the sensor is 0-800 Hz. Keywords: Piezoelectric sensor, shear stress, floating element, electromechanical symmetry

Measurement of the uniaxial mechanical properties of rat skin using different stress-strain definitions.

Science.gov (United States)

Karimi, A; Navidbakhsh, M

2015-05-01

The mechanical properties of skin tissue may vary according to the anatomical locations of a body. There are different stress-strain definitions to measure the mechanical properties of skin tissue. However, there is no agreement as to which stress-strain definition should be implemented to measure the mechanical properties of skin at different anatomical locations. Three stress definitions (second Piola-Kichhoff stress, engineering stress, and true stress) and four strain definitions (Almansi-Hamel strain, Green-St. Venant strain, engineering strain, and true strain) are employed to determine the mechanical properties of skin tissue at back and abdomen locations of a rat body. The back and abdomen skins of eight rats are excised and subjected to a series of tensile tests. The elastic modulus, maximum stress, and strain of skin tissues are measured using three stress definitions and four strain definitions. The results show that the effect of varying the stress definition on the maximum stress measurements of the back skin is significant but not when calculating the elastic modulus and maximum strain. No significant effects are observed on the elastic modulus, maximum stress, and strain measurements of abdomen skin by varying the stress definition. In the true stress-strain diagram, the maximum stress (20%), and elastic modulus (35%) of back skin are significantly higher than that of abdomen skin. The true stress-strain definition is favored to measure the mechanical properties of skin tissue since it gives more accurate measurements of the skin's response using the instantaneous values. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Residual stress measurements by means of neutron diffraction

International Nuclear Information System (INIS)

Pintschovius, L.; Jung, V.; Macherauch, E.; Voehringer, O.

1983-01-01

A new method for the analysis of multiaxial residual stress states is presented, which is based on high resolution neutron diffraction. It is analogous to X-ray stress analysis, but the use of neutrons instead of X-rays allows the analysis of the stress distributions also in the interior of technical components in a non-destructive way. To prove the feasibility of the method, investigations of the loading stress distributions of an aluminium bar subjected to purely elastic bending were performed. Limiting factors due to the volume of the internal probe region and the sample thickness are discussed. Complete neutron residual stress analyses were carried out for a plastically deformed bending bar and a transformation-free water-quenched steel cylinder. The results are in fairly good agreement with theoretical expectations and with X-ray control measurements at the surface of the objects. (Auth.)

Detection of Stress Levels from Biosignals Measured in Virtual Reality Environments Using a Kernel-Based Extreme Learning Machine.

Science.gov (United States)

Cho, Dongrae; Ham, Jinsil; Oh, Jooyoung; Park, Jeanho; Kim, Sayup; Lee, Nak-Kyu; Lee, Boreom

2017-10-24

Virtual reality (VR) is a computer technique that creates an artificial environment composed of realistic images, sounds, and other sensations. Many researchers have used VR devices to generate various stimuli, and have utilized them to perform experiments or to provide treatment. In this study, the participants performed mental tasks using a VR device while physiological signals were measured: a photoplethysmogram (PPG), electrodermal activity (EDA), and skin temperature (SKT). In general, stress is an important factor that can influence the autonomic nervous system (ANS). Heart-rate variability (HRV) is known to be related to ANS activity, so we used an HRV derived from the PPG peak interval. In addition, the peak characteristics of the skin conductance (SC) from EDA and SKT variation can also reflect ANS activity; we utilized them as well. Then, we applied a kernel-based extreme-learning machine (K-ELM) to correctly classify the stress levels induced by the VR task to reflect five different levels of stress situations: baseline, mild stress, moderate stress, severe stress, and recovery. Twelve healthy subjects voluntarily participated in the study. Three physiological signals were measured in stress environment generated by VR device. As a result, the average classification accuracy was over 95% using K-ELM and the integrated feature (IT = HRV + SC + SKT). In addition, the proposed algorithm can embed a microcontroller chip since K-ELM algorithm have very short computation time. Therefore, a compact wearable device classifying stress levels using physiological signals can be developed.

Residual stress analysis in thick uranium films

International Nuclear Information System (INIS)

Hodge, A.M.; Foreman, R.J.; Gallegos, G.F.

2005-01-01

Residual stress analysis was performed on thick, 1-25 μm, depleted uranium (DU) films deposited on an Al substrate by magnetron sputtering. Two distinct characterization techniques were used to measure substrate curvature before and after deposition. Stress evaluation was performed using the Benabdi/Roche equation, which is based on beam theory of a bi-layer material. The residual stress evolution was studied as a function of coating thickness and applied negative bias voltage (0, -200, -300 V). The stresses developed were always compressive; however, increasing the coating thickness and applying a bias voltage presented a trend towards more tensile stresses and thus an overall reduction of residual stresses

Modeling and Measurement of Stress and Strain Evolution in Cu Interconnects

International Nuclear Information System (INIS)

Besser, Paul R.; Zhai, Charlie Jun

2004-01-01

The damascene fabrication method and the introduction of low-K dielectrics present a host of reliability challenges to Cu interconnects and fundamentally change the mechanical stress state of Cu lines used as interconnects for integrated circuits. In order to capture the effect of individual process steps on the stress evolution in the BEoL (Back End of Line), a process-oriented finite element modeling (FEM) approach was developed. In this model, the complete stress history at any step of BEoL can be simulated as a dual damascene Cu structure is fabricated. The model was calibrated with both wafer-curvature blanket film measurements and X-Ray diffraction (XRD) measurement of metal line stress. The Cu line stress evolution was simulated during the process of multi-step processing for dual damascene Cu/TEOS and Cu/low-k structures. The in-plane stress of Cu lines is nearly independent of subsequent processes, while the out-of-plane stress increases considerably with the subsequent process steps. The modeling results will be compared with recent XRD measurements and extended generically to illustrate the relative influence of the dielectric (ILD) modulus (E) and coefficient of thermal expansion (CTE) on strain/stress in the Cu lines. It will be shown that the stress magnitude and state (hydrostatic, deviatoric) depend on ILD properties. The stress along the line length (longitudinal) is substrate-dominated, while the transverse and normal stresses vary with both CTE and modulus of the dielectric. The hydrostatic stress is primarily determined by ILD modulus and is nearly independent of the ILD CTE, while the Von Mises stress depends on both CTE and E of the ILD. The stress of the Cu line tends to be more deviatoric with spin-on low K ILDs, and more hydrostatic with oxide encapsulation

X-ray residual stress measurement and its variation during plane bending fatigue and sliding wear processes in TiC, TiN, TiB2 and Al2O3 coated carbon steels

International Nuclear Information System (INIS)

Endoh, Takashi; Idemitsu, Kohji; Kawakami, Mamoru

1993-01-01

The development of ceramic coating to metals was stimulated by the need for high temperature, wear and corrosion resistant materials. Recently TiC, TiN, TiB 2 and Al 2 O 3 are used as ceramic coating materials. In the present study, the X-ray method was successfully applied to measure the residual stress distribution in their ceramics coated steels. The X-ray elastic constants were determined and compared with the mechanically measured values. And plane bending and sliding wear tests were carried out. The X-ray method was successfully applied to measure the residual stress changes during fatigue and wear processes. The relationship between the change of residual stress and damage accumulation was investigated. (author)

Measurement of residual stress in quenched 1045 steel by the nanoindentation method

International Nuclear Information System (INIS)

Zhu Lina; Xu Binshi; Wang Haidou; Wang Chengbiao

2010-01-01

In this paper, the residual stress in quenched AISI 1045 steel was measured by a recently developed nanoindentation technique. Depth control mode was adopted to measure the residual stress. It was found that residual compressive stress was generated in the quenched steel. The material around nanoindents exhibits significant pile-up deformation. A new method was proposed to determine the real contact area for pile-up material on the basis of invariant pile-up morphology of the loaded or unloaded states. The results obtained by the new method were in good agreement with the residual stresses measured by the classical X-ray diffraction (XRD) method. - Research Highlights: → A new method was proposed to measure the real contact area for pile-up materials. → The real contact depth is defined as the sum of h max and the pile-up height h p . → The value of residual stress measured by the nanoindentation method was in good agreement with that by the XRD method.

A new sensor for stress measurement based on blood flow fluctuations

Science.gov (United States)

Fine, I.; Kaminsky, A. V.; Shenkman, L.

2016-03-01

It is widely recognized that effective stress management could have a dramatic impact on health care and preventive medicine. In order to meet this need, efficient and seamless sensing and analytic tools for the non-invasive stress monitoring during daily life are required. The existing sensors still do not meet the needs in terms of specificity and robustness. We utilized a miniaturized dynamic light scattering sensor (mDLS) which is specially adjusted to measure skin blood flow fluctuations and provides multi- parametric capabilities. Based on the measured dynamic light scattering signal from the red blood cells flowing in skin, a new concept of hemodynamic indexes (HI) and oscillatory hemodynamic indexes (OHI) have been developed. This approach was utilized for stress level assessment for a few usecase scenario. The new stress index was generated through the HI and OHI parameters. In order to validate this new non-invasive stress index, a group of 19 healthy volunteers was studied by measuring the mDLS sensor located on the wrist. Mental stress was induced by using the cognitive dissonance test of Stroop. We found that OHIs indexes have high sensitivity to the mental stress response for most of the tested subjects. In addition, we examined the capability of using this new stress index for the individual monitoring of the diurnal stress level. We found that the new stress index exhibits similar trends as reported for to the well-known diurnal behavior of cortisol levels. Finally, we demonstrated that this new marker provides good sensitivity and specificity to the stress response to sound and musical emotional arousal.

Measurement of residual stress in materials using neutrons. Proceedings of a technical meeting

International Nuclear Information System (INIS)

2005-06-01

One of the objectives of the IAEA's project on effective utilization of research reactors is to promote the use of the existing research reactors based on their capabilities and is implemented through workshops and technical meetings. Measurement of residual stress is one of the techniques that find wide applications in materials development and testing. The Technical Meeting on Measurement of Residual Stress Using Neutrons was organized to meet this objective. This publication is the outcome of the deliberations during the meeting and the presentations by the participants and is addressed to the research reactor managers, users and designers of facilities for reactor utilization. It will especially benefit those seeking to develop new facilities or upgrade the existing ones to enhance the utilization of their research reactors. Experts with a long experience in developing and using neutron beam instruments in high flux and medium flux research reactors participated in this technical meeting. They presented the design, development and utilization of the facilities at their respective centres and reviewed the current status of the residual stress measurements using neutron beams from research reactors. The sessions included brainstorming on the methodology and data analysis, characterization and standardization of the equipment and identifying the scope for further development. This publication refers to the determination of residual and/or applied stresses in polycrystalline materials using neutron diffraction technique. Stress is developed during the synthesis and use of materials such as alloys and compounds. Measurement of residual stress is essential to improve the quality of synthesized materials and diagnosis of failure and/or reliability of fabricated components. Neutron scattering has played an important role in studying structure and dynamics of condensed matter. Neutron scattering is a non-destructive technique and is useful for testing large samples. The

Measurements of three dimensional residual stress distribution on laser irradiated spot

International Nuclear Information System (INIS)

Tanaka, Hirotomo; Akita, Koichi; Ohya, Shin-ichi; Sano, Yuji; Naito, Hideki

2004-01-01

Three dimensional residual stress distributions on laser irradiated spots were measured using synchrotron radiation to study the basic mechanism of laser peening. A water-immersed sample of high tensile strength steel was irradiated with Q-switched and frequency-doubled Nd:YAG laser. The residual stress depth profile of the sample was obtained by alternately repeating the measurement and surface layer removal by electrolytic polishing. Tensile residual stresses were observed on the surface of all irradiated spots, whereas residual stress changed to compressive just beneath the surface. The depth of compressive residual stress imparted by laser irradiation and plastic deformation zone increased with increasing the number of laser pulses irradiated on the same spot. (author)

In situ subsoil stress-strain behaviour in relation to soil precompression stress

DEFF Research Database (Denmark)

Keller, T; Arvidsson, J; Schjønning, Per

2012-01-01

is assumed to be elastic and reversible as long as [sigma] work examined soil stress-strain behavior as measured in situ during wheeling experiments and related it to the stress-strain behavior and [sigma]pc measured on soil cores in uniaxial compression tests in the laboratory. The data......Soil compaction negatively influences many important soil functions, including crop growth. Compaction occurs when the applied stress, [sigma], overcomes the soil strength. Soil strength in relation to compaction is typically expressed by the soil precompression stress, [sigma]pc. Deformation...... analyzed were from a large number of wheeling experiments carried out in Sweden and Denmark on soils with a wide range of texture. Contradicting the concept of precompression stress, we observed residual strain, [Latin Small Letter Open E]res, at [sigma

Evaluation of stress gradient by x-ray stress measurement based on change in angle phi

International Nuclear Information System (INIS)

Sasaki, Toshihiko; Kuramoto, Makoto; Yoshioka, Yasuo.

1985-01-01

A new principle of X-ray stress evaluation for a sample with steep stress gradient has been prosed. The feature of this method is that the stress is determined by using so-called phi-method based on the change of phi-angle and thus has no effect on the penetration depth of X-rays. The procedure is as follows; firstly, an average stress within the penetration depth of X-rays is determined by changing only phi-angle under a fixed psi-angle, and then a distribution of the average stress vs. the penetration depth of X-rays is detected by repeating the similar procedure at different psi-angles. The following conclusions were found out as the result of residual stress measurements on a carbon steel of type S 55 C polished by emery paper. This method is practical enough to use for a plane stress problem. And the assumption of a linear stress gradient adopted in the authors' previous investigations is valid. In case of a triaxial stress analysis, this method is effective for the solution of three shearing stresses. However, three normal stresses can not be solved perfectly except particular psi-angles. (author)

Measuring general and specific stress causes and stress responses among beginning secondary school teachers in the Netherlands

NARCIS (Netherlands)

Harmsen, R; Helms-Lorenz, M.; Maulana, R; van Veen, K; van Veldhoven, M.J.P.M.

2018-01-01

The main aim of this study was to adjust the Questionnaire on the Experience and Evaluation of Work (QEEW) in order to measure stress causes and stress responses of beginning secondary school teachers in the Netherlands. First, the suitability of the original QEEW stress scales for use in the

Residual stress measurement using the pulsed neutron source at LANSCE

International Nuclear Information System (INIS)

Bourke, M.A.M.; Goldstone, J.A.; Holden, T.M.

1991-01-01

The presence of residual stress in engineering components can effect their mechanical properties and structural integrity. Neutron diffraction is the only measuring technique which can make spatially resolved non-destructive strain measurements in the interior of components. By recording the change in the crystalline interplanar spacing, elastic strains can be measured for individual lattice reflections. Using a pulsed neutron source, all the lattice reflections are recorded in each measurement which allows anisotropic effects to be studied. Measurements made at the Manuel Lujan Jr Neutron Scattering Centre (LANSCE) demonstrate the potential for stress measurements on a pulsed source and indicate the advantages and disadvantages over measurements made on a reactor. 15 refs., 7 figs

Evaluation of cladding residual stresses in clad blocks by measurements and numerical simulations

International Nuclear Information System (INIS)

Dupas, P.; Moinereau, D.

1996-01-01

Reactor pressure vessels are internally clad with austenitic stainless steel. This welding operation generates residual stresses which can have an important role in integrity assessments. In order to evaluate these stresses, an experimental and numerical programme has been conducted. The experiments includes cladding operations, macrographic analyses, temperature and residual stresses measurements with different methods. According to these measurements, transversal stresses (perpendicular to the welding direction) and longitudinal stresses (parallel to the welding direction) are highly tensile in stainless steel and they are compressive in the HAZ. Finite element calculations were used to simulate both welding operations and post weld heat treatment. These calculations coupled the thermal, metallurgical and mechanical aspects in a 2D representation. Different models were studied including effect of generalised plane strain, transformation plasticity, creep and tempering. The transversal stresses calculated are similar to the measured ones, but the longitudinal stresses showed to be very sensitive to the model used. As expected because of the two-dimension model, the longitudinal stresses can't be well estimated. More work is needed to improve measurements of stresses in depth (important differences appeared between the different methods). A predictive model would be also very useful to determine the thermal loading which is at present dependant on measurements. A 3D calculation appears to be necessary to evaluate longitudinal stresses. (orig.)

Survey of horizontal stresses in coal mines from available measurements and mapping.

CSIR Research Space (South Africa)

Frith, R

2002-09-01

Full Text Available of work for the project was outlined in the proposal submitted to SIMRAC in mid-2000 and is summarised as follows: (i) to undertake a peer review of available in-situ stress measurements relating to the Witbank and Highveld coalfields in South Africa... OF HORIZONTAL STRESS IN THE WITBANK AND HIGHVELD COALFIELDS 21 4.1 Is Horizontal Stress at Work in Roadway Roof Behaviour? 21 4.2 Summary of Measured Horizontal Stresses 24 4.3 Proposed Model for the Origin of Horizontal Stress Within the Coalfields 27 4...

Rock stress investigations

International Nuclear Information System (INIS)

Pahl, A.; Heusermann, St.; Braeuer, V.; Gloeggler, W.

1989-04-01

On the research project 'Rock Stress Mesurements' the BGR has developed and tested several methods for use in boreholes at a depth of 200 m. Indirect stress measurements using overcoring methods with BGR-probes and CSIR-triaxial cells as well as direct stress measurements using the hydraulic-fracturing method were made. To determine in-situ rock deformation behavior borehole deformation tests, using a BGR-dilatometer, were performed. Two types of the BGR-probe were applied: a four-component-probe to determine horizontal stresses and a five-component-probe to determine a quasi three-dimensional stress field. The first time a computer for data processing was installed in the borehole together with the BGR-probe. Laboratory tests on low cylinders were made to study the stress-deformation behavior. To validate and to interprete the measurement results some test methods were modelled using the finite-element method. The dilatometer-tests yielded high values of Young's modulus, whereas laboratory tests showed lower values with a distinct deformation anisotropy. Stress measurements with the BGR-probe yielded horizontal stresses being higher than the theoretical overburden pressure. These results are comparable to the results of the hydraulic fracturing tests, whereas stresses obtained with CSIR-triaxial cells are lower. The detailed geological mapping of the borehole indicated relationships between stress and geology. With regard to borehole depth different zones of rock structure joint frequency, joint orientation, and orientation of microfissures as well as stress magnitude, stress direction, and degree of deformation anisotropy could be distinguished. (author) 4 tabs., 76 figs., 31 refs

Measured residual stresses in overlay pipe weldments removed from service

International Nuclear Information System (INIS)

Shack, W.J.

1985-02-01

Surface and throughwall residual stresses were measured on an elbow-to-pipe weldment that had been removed from the Hatch-2 reactor about a year after the application of a weld overlay. The results were compared with experimental measurements on three mock-up weldments and with finite-element calculations. The comparison shows that there are significant differences in the form and magnitude of the residual stress distributions. However, even after more than a year of service, the residual stresses over most of the inner surface of the actual plant weldment with an overlay were strongly compressive. 3 refs., 7 figs

Quantifying Stress in Marine Mammals: Measuring Biologically Active Cortisol in Cetaceans and Pinnipeds

Science.gov (United States)

2015-09-30

boonstra/ LONG-TERM GOALS This research will improve our ability to measure stress in marine mammals. Stress hormones ( glucocorticoids ...either cortisol or corticosterone) are easily measured in blood and are an important measure of stress. However, a large proportion of glucocorticoids ...are best estimated by measuring “free glucocorticoid ” levels (i.e. that hormone not bound by CBG). This project will improve the capacity of marine

Using multiple biomarkers and determinants to obtain a better measurement of oxidative stress: a latent variable structural equation model approach.

Science.gov (United States)

Eldridge, Ronald C; Flanders, W Dana; Bostick, Roberd M; Fedirko, Veronika; Gross, Myron; Thyagarajan, Bharat; Goodman, Michael

2017-09-01

Since oxidative stress involves a variety of cellular changes, no single biomarker can serve as a complete measure of this complex biological process. The analytic technique of structural equation modeling (SEM) provides a possible solution to this problem by modelling a latent (unobserved) variable constructed from the covariance of multiple biomarkers. Using three pooled datasets, we modelled a latent oxidative stress variable from five biomarkers related to oxidative stress: F 2 -isoprostanes (FIP), fluorescent oxidation products, mitochondrial DNA copy number, γ-tocopherol (Gtoc) and C-reactive protein (CRP, an inflammation marker closely linked to oxidative stress). We validated the latent variable by assessing its relation to pro- and anti-oxidant exposures. FIP, Gtoc and CRP characterized the latent oxidative stress variable. Obesity, smoking, aspirin use and β-carotene were statistically significantly associated with oxidative stress in the theorized directions; the same exposures were weakly and inconsistently associated with the individual biomarkers. Our results suggest that using SEM with latent variables decreases the biomarker-specific variability, and may produce a better measure of oxidative stress than do single variables. This methodology can be applied to similar areas of research in which a single biomarker is not sufficient to fully describe a complex biological phenomenon.

Measurement of residual stress in plasma-sprayed metallic, ceramic and composite coatings

Energy Technology Data Exchange (ETDEWEB)

Kesler, O.; Suresh, S. [Massachusetts Inst. of Tech., Cambridge, MA (United States); Matejicek, J.; Sampath, S. [State Univ. of New York, Stony Brook, NY (United States). Inst. for Mathematical Sciences; Gnaeupel-Herold, T.; Brand, P.C.; Prask, H.J. [National Institute of Standards and Technology, Gaithersburg, MD (United States)

1998-12-15

Residual stresses in plasma-sprayed coatings were studied by three experimental techniques: curvature measurements, neutron diffraction and X-ray diffraction. Two distinct material classes were investigated: (1) single-material coatings (molybdenum) and (2) bi-material composites (nickel+alumina and NiCrAlY+yttria-stabilized zirconia), with and without graded layers. This paper deals with the effects of coating thickness and material properties on the evolution of residual stresses as a function of composition and thickness in both homogeneous and graded coatings. Mathematical analysis of the results allowed in some cases the separation of the quenching stress and thermal stress contributions to the final residual stress, as well as the determination of the through-thickness stress profile from measurements of different thickness specimens. In the ceramic-metal composites, it was found that the quenching stress plays a dominant role in the metallic phase, whereas the stress in the ceramic phase is mostly dominated by thermal mismatch. The respective thermal expansion coefficients and mechanical properties are the most important factors determining the stress sign and magnitude. The three residual stress measurement methods employed here were found to be complementary, in that each can provide unique information about the stress state. The most noteworthy outcomes are the determination of the through-thickness stress profile in graded coatings with high spatial resolution (curvature method) and determination of stress in each phase of a composite separately (neutron diffraction). (orig.) 25 refs.

Time-Resolved Particle Image Velocimetry Measurements with Wall Shear Stress and Uncertainty Quantification for the FDA Nozzle Model.

Science.gov (United States)

Raben, Jaime S; Hariharan, Prasanna; Robinson, Ronald; Malinauskas, Richard; Vlachos, Pavlos P

2016-03-01

We present advanced particle image velocimetry (PIV) processing, post-processing, and uncertainty estimation techniques to support the validation of computational fluid dynamics analyses of medical devices. This work is an extension of a previous FDA-sponsored multi-laboratory study, which used a medical device mimicking geometry referred to as the FDA benchmark nozzle model. Experimental measurements were performed using time-resolved PIV at five overlapping regions of the model for Reynolds numbers in the nozzle throat of 500, 2000, 5000, and 8000. Images included a twofold increase in spatial resolution in comparison to the previous study. Data was processed using ensemble correlation, dynamic range enhancement, and phase correlations to increase signal-to-noise ratios and measurement accuracy, and to resolve flow regions with large velocity ranges and gradients, which is typical of many blood-contacting medical devices. Parameters relevant to device safety, including shear stress at the wall and in bulk flow, were computed using radial basis functions. In addition, in-field spatially resolved pressure distributions, Reynolds stresses, and energy dissipation rates were computed from PIV measurements. Velocity measurement uncertainty was estimated directly from the PIV correlation plane, and uncertainty analysis for wall shear stress at each measurement location was performed using a Monte Carlo model. Local velocity uncertainty varied greatly and depended largely on local conditions such as particle seeding, velocity gradients, and particle displacements. Uncertainty in low velocity regions in the sudden expansion section of the nozzle was greatly reduced by over an order of magnitude when dynamic range enhancement was applied. Wall shear stress uncertainty was dominated by uncertainty contributions from velocity estimations, which were shown to account for 90-99% of the total uncertainty. This study provides advancements in the PIV processing methodologies over

Final Report: Geothermal dual acoustic tool for measurement of rock stress

Energy Technology Data Exchange (ETDEWEB)

Normann, Randy A. [Perma Works LLC, Pattonville, TX (United States)

2014-12-01

This paper outlines the technology need for a rock formation stress measurement in future EGS wells. This paper reports on the results of work undertaken under a Phase I, DOE/SBIR on the feasibility to build an acoustic well logging tool for measuring rock formation stress.

Final Report. Geothermal Dual Acoustic Tool for Measurement of Rock Stress

Energy Technology Data Exchange (ETDEWEB)

Normann, Randy A [Perma Works LLC, Pattonville, TX (United States)

2014-12-01

This paper outlines the technology need for a rock formation stress measurement in future EGS wells. This paper reports on the results of work undertaken under a Phase I, DOE/SBIR on the feasibility to build an acoustic well logging tool for measuring rock formation stress.

Micromachined sensor for stress measurement and micromechanical study of free-standing thin films for MEMS applications

Science.gov (United States)

Zhang, Ping

Microelectromechanical systems (MEMS) have a wide range of applications. In the field of wireless and microwave technology, considerable attention has been given to the development and integration of MEMS-based RF (radio frequency) components. An RF MEMS switch requires low insertion loss, high isolation, and low actuation voltage - electrical aspects that have been extensively studied. The mechanical requirements of the switch, such as low sensitivity to built-in stress and high reliability, greatly depend on the micromechanical properties of the switch materials, and have not been thoroughly explored. RF MEMS switches are typically in the form of a free-standing thin film structure. Large stress gradients and across-wafer stress variations developed during fabrication severely degrade their electrical performance. A micromachined stress measurement sensor has been developed that can potentially be employed for in-situ monitoring of stress evolution and stress variation. The sensors were micromachined using five masks on two wafer levels, each measuring 5x3x1 mm. They function by means of an electron tunneling mechanism, where a 2x2 mm silicon nitride membrane elastically deflects under an applied deflection voltage via an external feedback circuitry. For the current design, the sensors are capable of measuring tensile stresses up to the GPa range under deflection voltages of 50--100 V. Sensor functionality was studied by finite element modeling and a theoretical analysis of square membrane deflection. While the mechanical properties of thin films on substrates have been extensively studied, studies of free-standing thin films have been limited due to the practical difficulties in sample handling and testing. Free-standing Al and Al-Ti thin films specimens have been successfully fabricated and microtensile and stress relaxation tests have been performed using a custom-designed micromechanical testing apparatus. A dedicated TEM (transmission electron microscopy

Measurement of exercise-induced oxidative stress in lymphocytes.

Science.gov (United States)

Turner, James E; Bosch, Jos A; Aldred, Sarah

2011-10-01

Vigorous exercise is associated with oxidative stress, a state that involves modifications to bodily molecules due to release of pro-oxidant species. Assessment of such modifications provides non-specific measures of oxidative stress in human tissues and blood, including circulating lymphocytes. Lymphocytes are a very heterogeneous group of white blood cells, consisting of subtypes that have different functions in immunity. Importantly, exercise drastically changes the lymphocyte composition in blood by increasing the numbers of some subsets, while leaving other cells unaffected. This fact may imply that observed changes in oxidative stress markers are confounded by changes in lymphocyte composition. For example, lymphocyte subsets may differ in exposure to oxidative stress because of subset differences in cell division and the acquisition of cytotoxic effector functions. The aim of the present review is to raise awareness of interpretational issues related to the assessment of oxidative stress in lymphocytes with exercise and to address the relevance of lymphocyte subset phenotyping in these contexts.

On fully stressed design and p-norm measures in structural optimization

DEFF Research Database (Denmark)

Zhou, Mingdong; Sigmund, Ole

2017-01-01

This brief note revisits the fully stressed design schemes and p-norm measures used in stress-based structural optimization. Two simple shape optimization cases are used to remind the reader that fully stressed designs only are optimal when unimpeded by geometrical restrictions and that high valu...... of the stress norm are needed in order to achieve satisfactory designs....

Stress-affected microstructural development and creep-swelling interrelationship

International Nuclear Information System (INIS)

Brager, H.R.; Garner, F.A.; Gilbert, E.R.; Flinn, J.E.; Wolfer, W.G.

1977-05-01

Macroscopic measurement of the deformations arising from swelling and creep during neutron irradiation indicate that both processes are dependent on the magnitude and possibly the sign of the applied stress state. Current modeling efforts also indicate that a strong interaction exists between swelling and creep through the stress state. Because the macroscopic distortions arise from the integrated microscopic strains associated with specific microstructural elements, the effect of applied stress on microstructural development has been studied

Process for measuring residual stresses

International Nuclear Information System (INIS)

Elfinger, F.X.; Peiter, A.; Theiner, W.A.; Stuecker, E.

1982-01-01

No single process can at present solve all problems. The complete destructive processes only have a limited field of application, as the component cannot be reused. However, they are essential for the basic determination of stress distributions in the field of research and development. Destructive and non-destructive processes are mainly used if investigations have to be carried out on original components. With increasing component size, the part of destructive tests becomes smaller. The main applications are: quality assurance, testing of manufactured parts and characteristics of components. Among the non-destructive test procedures, X-raying has been developed most. It gives residual stresses on the surface and on surface layers near the edges. Further development is desirable - in assessment - in measuring techniques. Ultrasonic and magnetic crack detection processes are at present mainly used in research and development, and also in quality assurance. Because of the variable depth of penetration and the possibility of automation they are gaining in importance. (orig./RW) [de

Workshop on industrial application of neutron diffraction. Stress measurement by neutron diffraction

CERN Document Server

Minakawa, N; Morii, Y; Oyama, Y

2002-01-01

This workshop was planned to make use of the neutron from the reactor and the pulse neutron source JSNS for the industrial world. Especially, this workshop focused on the stress measurement by the neutron diffraction and it was held on the Tokai JAERI from October 15 to 16, 2001. The participant total was 93 and 40 participated from the industrial world. The introduction of the residual stress development of measurement technique by the neutron diffraction method and a research of the measurement of the residual stress such as the nuclear reactor material, the ordinary structure material, the composite material, the quenching steel, the high strength material were presented and discussed in this workshop. Moreover, it was introduced for the industrial world that an internal stress measurement is important for development of new product or an improvement of a manufacturing process. The question from the industrial world about which can be measured the product form, the size, the measurement precision, the reso...

Self-contained in-vacuum in situ thin film stress measurement tool

Science.gov (United States)

Reinink, J.; van de Kruijs, R. W. E.; Bijkerk, F.

2018-05-01

A fully self-contained in-vacuum device for measuring thin film stress in situ is presented. The stress was measured by measuring the curvature of a cantilever on which the thin film was deposited. For this, a dual beam laser deflectometer was used. All optics and electronics needed to perform the measurement are placed inside a vacuum-compatible vessel with the form factor of the substrate holders of the deposition system used. The stand-alone nature of the setup allows the vessel to be moved inside a deposition system independently of optical or electronic feedthroughs while measuring continuously. A Mo/Si multilayer structure was analyzed to evaluate the performance of the setup. A radius of curvature resolution of 270 km was achieved. This allows small details of the stress development to be resolved, such as the interlayer formation between the layers and the amorphous-to-crystalline transition of the molybdenum which occurs at around 2 nm. The setup communicates with an external computer via a Wi-Fi connection. This wireless connection allows remote control over the acquisition and the live feedback of the measured stress. In principle, the vessel can act as a general metrology platform and add measurement capabilities to deposition setups with no modification to the deposition system.

State of charge estimation for lithium-ion pouch batteries based on stress measurement

International Nuclear Information System (INIS)

Dai, Haifeng; Yu, Chenchen; Wei, Xuezhe; Sun, Zechang

2017-01-01

State of charge (SOC) estimation is one of the important tasks of battery management system (BMS). Being different from other researches, a novel method of SOC estimation for pouch lithium-ion battery cells based on stress measurement is proposed. With a comprehensive experimental study, we find that, the stress of the battery during charge/discharge is composed of the static stress and the dynamic stress. The static stress, which is the measured stress in equilibrium state, corresponds to SOC, this phenomenon facilitates the design of our stress-based SOC estimation. The dynamic stress, on the other hand, is influenced by multiple factors including charge accumulation or depletion, current and historical operation, thus a multiple regression model of the dynamic stress is established. Based on the relationship between static stress and SOC, as well as the dynamic stress modeling, the SOC estimation method is founded. Experimental results show that the stress-based method performs well with a good accuracy, and this method offers a novel perspective for SOC estimation. - Highlights: • A State of Charge estimator based on stress measurement is proposed. • The stress during charge and discharge is investigated with comprehensive experiments. • Effects of SOC, current, and operation history on battery stress are well studied. • A multiple regression model of the dynamic stress is established.

Turbulent stress measurements with phase-contrast magnetic resonance through tilted slices

Energy Technology Data Exchange (ETDEWEB)

MacKenzie, Jordan; Soederberg, Daniel; Lundell, Fredrik [Linne FLOW Centre, KTH Mechanics, Stockholm (Sweden); Swerin, Agne [SP Technical Research Institute of Sweden-Chemistry, Materials and Surfaces, Stockholm (Sweden); KTH Royal Institute of Technology, Surface and Corrosion Science, Stockholm (Sweden)

2017-05-15

Aiming at turbulent measurements in opaque suspensions, a simplistic methodology for measuring the turbulent stresses with phase-contrast magnetic resonance velocimetry is described. The method relies on flow-compensated and flow-encoding protocols with the flow encoding gradient normal to the slice. The experimental data is compared with direct numerical simulations (DNS), both directly but also, more importantly, after spatial averaging of the DNS data that resembles the measurement and data treatment of the experimental data. The results show that the most important MRI data (streamwise velocity, streamwise variance and Reynolds shear stress) is reliable up to at least anti r = 0.75 without any correction, paving the way for dearly needed turbulence and stress measurements in opaque suspensions. (orig.)

Automatic Earthquake Shear Stress Measurement Method Developed for Accurate Time- Prediction Analysis of Forthcoming Major Earthquakes Along Shallow Active Faults

Science.gov (United States)

Serata, S.

2006-12-01

basis to disclose an acting earthquake shear stress S at top of the tectonic plate is established at the depth of 600-800m (Window). This concept is supported by outcome of the Japanese government stress measurement made at the epicenter of the Kobe earthquake of 1995, where S is found to be less than 5 MPa. At the same time S at the earthquake active Ashio mining district was found to be 36 MPa (90 percent of maximum S) at Window. These findings led to formulation of a quantitative method proposed to monitor earthquake triggering potential in and around any growing earthquake stress nucleus along shallow active faults. For future earthquake time prediction, the Stressmeter can be applied first to survey general distribution of earthquake shear stress S along major active faults. A site with its shear stress greater than 30 MPa may be identified as a site of growing stress nucleus. A Stressmeter must be permanently buried at the site to monitor future stress growth toward a possible triggering by mathematical analysis of the stress excursion dynamics. This is made possible by the automatic stress measurement capability of the Stressmeter at a frequency up to 100 times per day. The significance of this approach is a possibility to save lives by time-prediction of a forthcoming major earthquake with accuracy in hours and minutes.

Measures against heat stress in the city of Gelsenkirchen, Germany

Directory of Open Access Journals (Sweden)

Dütemeyer, Dirk

2014-04-01

Full Text Available In the near-surface atmosphere, heat waves during the summer cause situations that may lead to human-biometeorological impairment. Because of their high population density, overheated cities are particularly strongly affected by heat stress. In the future, due to the effects of climate change, heat stress will increase in terms of its intensity and spatial expansion in the areas of concern. Taking the example of the city of Gelsenkirchen, Germany, this article presents a method for the identification of areas requiring adaptation or protection. A scenario of the future increase of heat stress events is presented, based on data of the German climate change model STAR II. For the identification of areas requiring adaptation and protection, spatial analyses of the urban heat island, land use and demographic aspects were performed using GIS tools. The application and assessment of adaptation measures is investigated for an urban quarter using the microscale numerical model ENVI-met. Finally adaptation measures in urban planning against heat stress are discussed. The relevant urban planning adaptation measures, which are also important in view of climate change, not only involve heat stress reduction in the residential areas already affected, but also involve the protection and optimisation of existing favourable and compensation areas.

Principles of the measurement of residual stress by neutron diffraction

Energy Technology Data Exchange (ETDEWEB)

Webster, G A; Ezeilo, A N [Imperial Coll. of Science and Technology, London (United Kingdom). Dept. of Mechanical Engineering

1996-11-01

The presence of residual stresses in engineering components can significantly affect their load carrying capacity and resistance to fracture. In order to quantify their effect it is necessary to know their magnitude and distribution. Neutron diffraction is the most suitable method of obtaining these stresses non-destructively in the interior of components. In this paper the principles of the technique are described. A monochromatic beam of neutrons, or time of flight measurements, can be employed. In each case, components of strain are determined directly from changes in the lattice spacings between crystals. Residual stresses can then be calculated from these strains. The experimental procedures for making the measurements are described and precautions for achieving reliable results discussed. These include choice of crystal planes on which to make measurements, extent of masking needed to identify a suitable sampling volume, type of detector and alignment procedure. Methods of achieving a stress free reference are also considered. A selection of practical examples is included to demonstrate the success of the technique. (author) 14 figs., 1 tab., 18 refs.

Principles of the measurement of residual stress by neutron diffraction

International Nuclear Information System (INIS)

Webster, G.A.; Ezeilo, A.N.

1996-01-01

The presence of residual stresses in engineering components can significantly affect their load carrying capacity and resistance to fracture. In order to quantify their effect it is necessary to know their magnitude and distribution. Neutron diffraction is the most suitable method of obtaining these stresses non-destructively in the interior of components. In this paper the principles of the technique are described. A monochromatic beam of neutrons, or time of flight measurements, can be employed. In each case, components of strain are determined directly from changes in the lattice spacings between crystals. Residual stresses can then be calculated from these strains. The experimental procedures for making the measurements are described and precautions for achieving reliable results discussed. These include choice of crystal planes on which to make measurements, extent of masking needed to identify a suitable sampling volume, type of detector and alignment procedure. Methods of achieving a stress free reference are also considered. A selection of practical examples is included to demonstrate the success of the technique. (author) 14 figs., 1 tab., 18 refs

Measurement of stress-induced birefringence in glasses based on reflective laser feedback effect

Science.gov (United States)

Haisha, Niu; YanXiong, Niu; Jiyang, Li

2017-02-01

A glass birefringence measurement system utilizing the reflective laser feedback (RLF) effect is presented. The measurement principle is analyzed based on the equivalent cavity of a Fabry-Perot interferometer, and the experiments are conducted with a piece of quartz glass with applied extrusion force. In the feedback system, aluminum film used as a feedback mirror is affixed to the back of the sample. When the light is reflected back into the cavity, as the reinjected light is imprinted with the birefringence information in the sample, the gain and polarization states of the laser are modulated. The variation of optical power and polarization states hopping is monitored to obtain the magnitude of the stress. The system has advantages such as simplicity and low-cost with a precision of 1.9 nm. Moreover, by adjusting the position of the aluminum, large-area samples can be measured anywhere at any place.

Differentiation of molecular chain entanglement structure through laser Raman spectrum measurement of High strength PET fibers under stress

Science.gov (United States)

Go, D.; Takarada, W.; Kikutani, T.

2017-10-01

The aim of this study was to investigate the mechanism for the improvement of mechanical properties of poly(ethylene terephthalate) (PET) fibers based on the concept of controlling the state of molecular entanglement. For this purpose, five different PET fibers were prepared through either the conventional melt spinning and drawing/annealing process or the high-speed melt spinning process. In both cases, the melt spinning process was designed so as to realize different Deborah number conditions. The prepared fibers were subjected to the laser Raman spectroscopy measurement and the characteristics of the scattering peak at around 1616 cm-1, which corresponds to the C-C/C=C stretching mode of the aromatic ring in the main chain, were investigated in detail. It was revealed that the fibers drawn and annealed after the melt spinning process of lower Deborah number showed higher tensile strength as well as lower value of full width at half maximum (FWHM) in the laser Raman spectrum. Narrow FWHM was considered to represent the homogeneous state of entanglement structure, which may lead to the higher strength and toughness of fibers because individual molecular chains tend to bare similar level of tensile stress when the fiber is stretched. In case of high-speed spun fibers prepared with a high Deborah number condition, the FWHM was narrow presumably because much lower tensile stress in comparison with the drawing/annealing process was applied when the fiber structure was developed, however the value increased significantly upon applying tensile load to the fibers during the laser Raman spectrum measurement. From these results, it was concluded that the Laser Raman spectroscopy could differentiate molecular chain entanglement structure of various fiber samples, in that low FWHM, which corresponds to either homogeneous state of molecular entanglement or lower level of mean residual stress, and small increase of FWTH upon applying tensile stress are considered to be the key

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

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

Calibration of Heat Stress Monitor and its Measurement Uncertainty

Science.gov (United States)

Ekici, Can

2017-07-01

Wet-bulb globe temperature (WBGT) equation is a heat stress index that gives information for the workers in the industrial areas. WBGT equation is described in ISO Standard 7243 (ISO 7243 in Hot environments—estimation of the heat stress on working man, based on the WBGT index, ISO, Geneva, 1982). WBGT is the result of the combined quantitative effects of the natural wet-bulb temperature, dry-bulb temperature, and air temperature. WBGT is a calculated parameter. WBGT uses input estimates, and heat stress monitor measures these quantities. In this study, the calibration method of a heat stress monitor is described, and the model function for measurement uncertainty is given. Sensitivity coefficients were derived according to GUM. Two-pressure humidity generators were used to generate a controlled environment. Heat stress monitor was calibrated inside of the generator. Two-pressure humidity generator, which is located in Turkish Standard Institution, was used as the reference device. This device is traceable to national standards. Two-pressure humidity generator includes reference temperature Pt-100 sensors. The reference sensor was sheltered with a wet wick for the calibration of natural wet-bulb thermometer. The reference sensor was centred into a black globe that has got 150 mm diameter for the calibration of the black globe thermometer.

FIB-based measurement of local residual stresses on microsystems

Science.gov (United States)

Vogel, Dietmar; Sabate, Neus; Gollhardt, Astrid; Keller, Juergen; Auersperg, Juergen; Michel, Bernd

2006-03-01

The paper comprises research results obtained for stress determination on micro and nanotechnology components. It meets the concern of controlling stresses introduced to sensors, MEMS and electronics devices during different micromachining processes. The method bases on deformation measurement options made available inside focused ion beam equipment. Removing locally material by ion beam milling existing stresses / residual stresses lead to deformation fields around the milled feature. Digital image correlation techniques are used to extract deformation values from micrographs captured before and after milling. In the paper, two main milling features have been analyzed - through hole and through slit milling. Analytical solutions for stress release fields of in-plane stresses have been derived and compared to respective experimental findings. Their good agreement allows to settle a method for determination of residual stress values, which is demonstrated for thin membranes manufactured by silicon micro technology. Some emphasis is made on the elimination of main error sources for stress determination, like rigid body object displacements and rotations due to drifts of experimental conditions under FIB imaging. In order to illustrate potential application areas of the method residual stress suppression by ion implantation is evaluated by the method and reported here.

High-resolution stress measurements for microsystem and semiconductor applications

Science.gov (United States)

Vogel, Dietmar; Keller, Juergen; Michel, Bernd

2006-04-01

Research results obtained for local stress determination on micro and nanotechnology components are summarized. It meets the concern of controlling stresses introduced to sensors, MEMS and electronics devices during different micromachining processes. The method bases on deformation measurement options made available inside focused ion beam equipment. Removing locally material by ion beam milling existing stresses / residual stresses lead to deformation fields around the milled feature. Digital image correlation techniques are used to extract deformation values from micrographs captured before and after milling. In the paper, two main milling features have been analyzed - through hole and through slit milling. Analytical solutions for stress release fields of in-plane stresses have been derived and compared to respective experimental findings. Their good agreement allows to settle a method for determination of residual stress values, which is demonstrated for thin membranes manufactured by silicon micro technology. Some emphasis is made on the elimination of main error sources for stress determination, like rigid body object displacements and rotations due to drifts of experimental conditions under FIB imaging. In order to illustrate potential application areas of the method residual stress suppression by ion implantation is evaluated by the method and reported here.

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.

Residual stress measurement by x-ray under the consideration of its penetration depth

International Nuclear Information System (INIS)

Doi, Osamu; Ukai, Takayoshi

1983-01-01

The authors derived the fundamental relations between the measured stress by X-ray and the residual stress distribution from the consideration of the contribution of internal stress in definite subsurface layer of metal to X-ray diffraction and proposed the exact formulas and their applications of residual stress measurements by successive thin layer removal in a plate, a hollow cylinder and a hollow sphere. (author)

Interactions between the phase stress and the grain-orientation-dependent stress in duplex stainless steel during deformation

International Nuclear Information System (INIS)

Jia, N.; Peng, R. Lin; Wang, Y.D.; Chai, G.C.; Johansson, S.; Wang, G.; Liaw, P.K.

2006-01-01

The development of phase stress and grain-orientation-dependent stress under uniaxial compression was investigated in a duplex stainless steel consisting of austenite and ferrite. Using in situ neutron diffraction measurements, the strain response of several h k l planes to the applied compressive stress was mapped as a function of applied stress and sample direction. Analysis based on the experimental results and elastoplastic self-consistent simulations shows that phase stresses of thermal origin further increase during elastic loading but decrease with increased plastic deformation. Grain-orientation-dependent stresses become significant in both austenite and ferrite after loading into the plastic region. After unloading from the plastic regime, a considerable intergranular stress remains in the austenitic phase and dominates over the phase stress. This study provides fundamental experimental inputs for future micromechanical modeling aiming at the evaluation and prediction of the mechanical performance of multiphase materials

Residual stress measurements in thick structural weldments by means of neutron diffraction

International Nuclear Information System (INIS)

Ohms, C.; Youtsos, A.G.; Idsert, P. v.d.; Timke, T.

2000-01-01

Welding residual stresses in large structural components are a major concern with respect to their performance and lifetime. In large structures reasonable thermal stress relief treatment is usually impossible due to the component size. On the other hand, prediction of welding stresses by numerical modelling has not yet proven to be generally reliable, while the experimental determination of such stresses remains a demanding task. At the high flux reactor (HFR), Petten, a new residual stress diffractometer has been installed recently capable of handling of components up to 1000 kg - the large component neutron diffraction facility (LCNDF). It has facilitated residual stress measurements in two large welded components, of which results are presented here. The first component represents a bi-metallic weld in form of a pipe of 25 mm wall thickness. Three dimensional measurements of residual stress are discussed in detail. The second specimen is a 66 mm wall thickness austenitic steel nuclear piping weld. Results on relief of strain within the weld through post weld heat treatment (PWHT) are presented. Additionally results obtained earlier at former CRNL (CAN) on a section of a thick nuclear piping weld are presented in order to illustrate the variation in the reference lattice parameter trough the weld and the heat affected zone (HAZ). These results clearly show the necessity to determine the reference parameters for each location in all measurement directions by means of measurements in small coupons free of macro-stresses. (orig.)

Effect of residual stress on the nanoindentation response of (100) copper single crystal

International Nuclear Information System (INIS)

Zhu, Li-na; Xu, Bin-shi; Wang, Hai-dou; Wang, Cheng-biao

2012-01-01

Experimental measurements were used to investigate the effect of residual stress on the nanoindentation of (100) copper single crystal. Equi-biaxial tensile and compressive stresses were applied to the copper single crystal using a special designed apparatus. It was found that residual stresses greatly affected peak load, curvature of the loading curve, elastically recovered depth, residual depth, indentation work, pile-up amount and contact area. The Suresh and Giannakopoulos and Lee and Kwon methods were used to calculate the residual stresses from load-depth data and morphology observation of nanoindents using atomic force microscopy. Comparison of the obtained results with stress values from strain gage showed that the residual stresses analyzed from the Suresh and Giannakopoulos model agreed well with the applied stresses. -- Highlights: ► Residual stresses greatly affected various nanoindentation parameters. ► The contact area can be accurately measured from AFM observation. ► The residual stresses analyzed from the S and G model agreed well with applied stresses.

Residual stress analysis in carbon fiber-reinforced SiC ceramics

International Nuclear Information System (INIS)

Broda, M.

1998-01-01

Systematic residual stress analyses are reported, carried out in long-fiber reinforced SiC ceramics. The laminated C fiber /SiC matrix specimens used were prepared by polymer pyrolysis, and the structural component specimens used are industrial products. Various diffraction methods have been applied for non-destructive evaluation of residual stress fields, so as to completely detect the residual stresses and their distribution in the specimens. The residual stress fields at the surface (μm) have been measured using characteristic X-radiation and applying the sin 2 ψ method as well as the scatter vector method. For residual stress field analysis in the mass volume (cm), neutron diffraction has been applied. The stress fields in the fiber layers (approx. 250μm) have been measured as a function of their location within the laminated composite by using an energy-dispersive method and synchrotron radiation. By means of the systematic, process-accompanying residual stress and phase analyses, conclusions can be drawn as to possible approaches for optimization of fabrication parameters. (orig./CB) [de

Residual Stress Measurement of Coarse Crystal Grain in Aluminium Casting Alloy by Neutron Diffraction

International Nuclear Information System (INIS)

Nishida, Masayuki; Watanabe, Yoshitaka; Hanabusa, Takao

2009-01-01

Full text: Neutron stress measurement can detect strain and stress information in deep region because of large penetration ability of neutron beams. The present paper describes procedure and results in the residual stress measurement of aluminium casting alloy by neutron diffraction. Usually, the aluminium casting alloy includes the large crystal grains. The existence of large crystal grains makes it difficult to estimate the residual stresses in highly accuracy. In this study, the modified three axial method using Hook's equation was employed for neutron stress measurement. These stress measurements were performed under the two kinds of new techniques. One is a rocking curve method to calculate the principal strains in three directions. The peak profiles which appear discretely on rocking curves were translated to principle stresses by the Bragg law and the basic elastic theory. Another is the consideration of measurement positions and the edge effect in the neutron irradiated area (volume gage). The edge effect generates the errors of 2θ-peak position in the neutron stress measurement. In this study, the edge effect was investigated in detail by a small bit of copper single crystal. The copper bit was moved and scanned on three dimensionally within the gage volume. Furthermore, the average strains of symmetrical positions are measure by the sample turning at 180 degrees, because the error distributions of the 2θ-peak position followed to positions inside the gage volume. Form these results of this study, the residual stresses in aluminium casting alloy which includes the large crystal grains were possible to estimate by neutron stress measurement with the rocking curve method and the correction of the edge effect. (author)

Assessment on the methods of measuring the tyre-road contact patch stresses

Science.gov (United States)

Anghelache, G.; Moisescu, A.-R.; Buretea, D.

2017-08-01

The paper reviews established and modern methods for investigating tri-axial stress distributions in the tyre-road contact patch. The authors used three methods of measuring stress distributions: strain gauge method; force sensing technique; acceleration measurements. Four prototypes of instrumented pins transducers involving mentioned measuring methods were developed. Data acquisitions of the contact patch stresses distributions were performed using each transducer with instrumented pin. The results are analysed and compared, underlining the advantages and drawbacks of each method. The experimental results indicate that the three methods are valuable.

Stresses and residual stresses optical measurements systems evaluation; Avaliacao de sistemas opticos de medicao de tensoes e tensoes residuais em dutos

Energy Technology Data Exchange (ETDEWEB)

Peixoto Filho, Flavio Tito; Goncalves Junior, Armando Albertazzi [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Lab. de Metrologia e Automatizacao (LABMETRO)

2004-07-01

There is always a constant concern about the pipelines' integrity. An important control parameter is the level of total mechanical stresses acting over the pipeline. However, the loading and residual stresses acting on a pipeline are not measured in the field as much as necessary. Technical difficulties and the high cost of the nowadays techniques and the hostile measurement conditions are the main reason for that. An alternative method has been developed at the Universidade Federal de Santa Catarina (UFSC) since 1992. A new optical measurement device is used to measure strains, mechanical stresses and residual stresses acting over the structure. A metrological and functional evaluation of this system is the main focus of this paper. (author)

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

Measurement of in-situ stress in salt and rock using NQR techniques

International Nuclear Information System (INIS)

Schempp, E.; Hirschfeld, T.; Klainer, S.

1980-01-01

A discussion of how stress and strain affect the quantities which can be measured in an NQR experiment shows that, for stresses of the magnitude to be expected at depths up to about 10,000 feet, quadrupole coupling constants will fall in the range of 1 to 10 kHz for both the sodium and chloride ions in NaCl. The most promising system involves pulsed nuclear double resonance detection; and alterative is to observe the quadrupolar splitting of the NMR signal. Choices to be made in the measurement and mapping techniques are discussed. The well-known perturbation of the homogenous stress field in the neighborhood of a borehole is shown to be advantageous from the point of view of obtaining directional information on the stress. Construction and operation of a borehole stress sensor are considered. The NQR technique seems feasible for measuring the magnitude and direction of underground stress with a resolution of about 25 psi, or 2.5% at 1000 psi. Downhole instrumentation suitable for in-situ determinations of stress appears within the state of the art. Additional tasks required on the project are identified

Residual stress measurement in socket welded joints by neutron diffraction

International Nuclear Information System (INIS)

Hayashi, Makoto; Ishiwata, Masayuki; Minakawa, Noriaki; Funahashi, Satoru.

1995-01-01

Neutron diffraction measurements of lattice spacings provide the spatial map of residual stress near welds in ferritic steel socket joints. The high tensile stress greater than 200 MPa was found in the fusion and heat-affected zones in the hoop direction. However, the highest tensile stress in the axial direction at the weld root was about 110 MPa relatively lower than the expected value from the fatigue test results. The balancing compressive stress was found near the surface of the socket weld fusion zone. Heat treatment at 625degC for 2 hours was sufficient for the relief of residual stress in socket welds. (author)

Magnitude of shear stress on the san andreas fault: implications of a stress measurement profile at shallow depth.

Science.gov (United States)

Zoback, M D; Roller, J C

1979-10-26

A profile of measurements of shear stress perpendicular to the San Andreas fault near Palmdale, California, shows a marked increase in stress with distance from the fault. The pattern suggests that shear stress on the fault increases slowly with depth and reaches a value on the order of the average stress released during earthquakes. This result has important implications for both long- and shortterm prediction of large earthquakes.

Neutron diffraction measurements of residual stress in a powder metallurgy component

International Nuclear Information System (INIS)

Schneider, L.C.R.; Hainsworth, S.V.; Cocks, A.C.F.; Fitzpatrick, M.E.

2005-01-01

Residual stresses in a typical industrial green component were determined using neutron diffraction. The measured residual stresses were found to correlate with cross-sectional variations. Residual stress at the edge of the compact in contact with the die wall during compaction reached up to +80 MPa (tension) and -100 MPa (compression)

Child Autism Spectrum Disorder Traits and Parenting Stress: The Utility of Using a Physiological Measure of Parental Stress

Science.gov (United States)

Factor, Reina S.; Swain, Deanna M.; Scarpa, Angela

2018-01-01

Caregivers of children with autism spectrum disorder (ASD) report greater stress due to unique parenting demands (e.g.; Estes et al. in "Brain Dev" 35(2):133-138, 2013). Stress is often studied through self-report and has not been extensively studied using physiological measures. This study compared parenting stress in mothers of…

A Hydraulic Stress Measurement System for Deep Borehole Investigations

Science.gov (United States)

Ask, Maria; Ask, Daniel; Cornet, Francois; Nilsson, Tommy

2017-04-01

Luleå University of Technology (LTU) is developing and building a wire-line system for hydraulic rock stress measurements, with funding from the Swedish Research Council and Luleå University of Technology. In this project, LTU is collaborating with University of Strasbourg and Geosigma AB. The stress state influences drilling and drillability, as well as rock mass stability and permeability. Therefore, knowledge about the state of in-situ stress (stress magnitudes, and orientations) and its spatial variation with depth is essential for many underground rock engineering projects, for example for underground storage of hazardous material (e.g. nuclear waste, carbon dioxide), deep geothermal exploration, and underground infrastructure (e.g. tunneling, hydropower dams). The system is designed to conduct hydraulic stress testing in slim boreholes. There are three types of test methods: (1) hydraulic fracturing, (2) sleeve fracturing and (3) hydraulic testing of pre-existing fractures. These are robust methods for determining in situ stresses from boreholes. Integration of the three methods allows determination of the three-dimensional stress tensor and its spatial variation with depth in a scientific unambiguously way. The stress system is composed of a downhole and a surface unit. The downhole unit consists of hydraulic fracturing equipment (straddle packers and downhole imaging tool) and their associated data acquisition systems. The testing system is state of the art in several aspects including: (1) Large depth range (3 km), (2) Ability to test three borehole dimensions (N=76 mm, H=96 mm, and P=122 mm), (3) Resistivity imager maps the orientation of tested fracture; (4) Highly stiff and resistive to corrosion downhole testing equipment; and (5) Very detailed control on the injection flow rate and cumulative volume is obtained by a hydraulic injection pump with variable piston rate, and a highly sensitive flow-meter. At EGU General Assembly 2017, we would like to

Ground Motion Prediction Equations Empowered by Stress Drop Measurement

Science.gov (United States)

Miyake, H.; Oth, A.

2015-12-01

Significant variation of stress drop is a crucial issue for ground motion prediction equations and probabilistic seismic hazard assessment, since only a few ground motion prediction equations take into account stress drop. In addition to average and sigma studies of stress drop and ground motion prediction equations (e.g., Cotton et al., 2013; Baltay and Hanks, 2014), we explore 1-to-1 relationship for each earthquake between stress drop and between-event residual of a ground motion prediction equation. We used the stress drop dataset of Oth (2013) for Japanese crustal earthquakes ranging 0.1 to 100 MPa and K-NET/KiK-net ground motion dataset against for several ground motion prediction equations with volcanic front treatment. Between-event residuals for ground accelerations and velocities are generally coincident with stress drop, as investigated by seismic intensity measures of Oth et al. (2015). Moreover, we found faster attenuation of ground acceleration and velocities for large stress drop events for the similar fault distance range and focal depth. It may suggest an alternative parameterization of stress drop to control attenuation distance rate for ground motion prediction equations. We also investigate 1-to-1 relationship and sigma for regional/national-scale stress drop variation and current national-scale ground motion equations.

Estimation of stress distribution in ferromagnetic tensile specimens using low cost eddy current stress measurement system and BP neural network.

Science.gov (United States)

Li, Jianwei; Zhang, Weimin; Zeng, Weiqin; Chen, Guolong; Qiu, Zhongchao; Cao, Xinyuan; Gao, Xuanyi

2017-01-01

Estimation of the stress distribution in ferromagnetic components is very important for evaluating the working status of mechanical equipment and implementing preventive maintenance. Eddy current testing technology is a promising method in this field because of its advantages of safety, no need of coupling agent, etc. In order to reduce the cost of eddy current stress measurement system, and obtain the stress distribution in ferromagnetic materials without scanning, a low cost eddy current stress measurement system based on Archimedes spiral planar coil was established, and a method based on BP neural network to obtain the stress distribution using the stress of several discrete test points was proposed. To verify the performance of the developed test system and the validity of the proposed method, experiment was implemented using structural steel (Q235) specimens. Standard curves of sensors at each test point were achieved, the calibrated data were used to establish the BP neural network model for approximating the stress variation on the specimen surface, and the stress distribution curve of the specimen was obtained by interpolating with the established model. The results show that there is a good linear relationship between the change of signal modulus and the stress in most elastic range of the specimen, and the established system can detect the change in stress with a theoretical average sensitivity of -0.4228 mV/MPa. The obtained stress distribution curve is well consonant with the theoretical analysis result. At last, possible causes and improving methods of problems appeared in the results were discussed. This research has important significance for reducing the cost of eddy current stress measurement system, and advancing the engineering application of eddy current stress testing.

Assessing College Student-Athletes' Life Stress: Initial Measurement Development and Validation

Science.gov (United States)

Lu, Frank Jing-Horng; Hsu, Ya-Wen; Chan, Yuan-Shuo; Cheen, Jang-Rong; Kao, Kuei-Tsu

2012-01-01

College student-athletes have unique life stress that warrants close attention. The purpose of this study was to develop a reliable and valid measurement assessing college student-athletes' life stress. In Study 1, a focus group discussion and Delphi method produced a questionnaire draft, termed the College Student-Athletes' Life Stress Scale. In…

Measurement of residual stress in plasma-sprayed composite coatings with graded and uniform compositions

Energy Technology Data Exchange (ETDEWEB)

Kesler, O.; Suresh, S. [Massachusetts Inst. of Tech., Cambridge, MA (United States); Matejicek, J.; Sampath, S.

1999-10-01

Residual stresses in plasma sprayed composite coatings were studied experimentally by both curvature and neutron diffraction measurements. Graded and uniform composite coatings, consisting of nickel + alumina and NiCrAlY + yttria-stabilized zirconia, were investigated. This paper briefly summarizes our recent work dealing with the effects of coating thickness, composition, and material properties on the evolution of residual stresses in coatings. Analysis of the results allowed in some cases the separation of the quenching stress and thermal stress contributions to the final residual stress, as well as the determination of the through-thickness stress profile from measurements of different thickness specimens. In the ceramic-metal composites, it was found that the thermal mismatch stress plays a dominant role in the ceramic phase, whereas the stress in the metallic phase is mostly dominated by quenching stress. The residual stress measurement methods employed here were found to be complementary, in that each can provide unique information about the stress state. Through-thickness stress profiles in graded coatings were determined with high spatial resolution by the curvature method, and determination of the stress in each separate phase of a composite was made by neutron diffraction. (orig.) 14 refs.

Measurement of stress distributions in truck tyre contact patch in real rolling conditions

Science.gov (United States)

Anghelache, Gabriel; Moisescu, Raluca

2012-12-01

Stress distributions on three orthogonal directions have been measured across the contact patch of truck tyres using the complex measuring system that contains a transducer assembly with 30 sensing elements placed in the road surface. The measurements have been performed in straight line, in real rolling conditions. Software applications for calibration, data acquisition, and data processing were developed. The influence of changes in inflation pressure and rolling speed on the shapes and sizes of truck tyre contact patch has been shown. The shapes and magnitudes of normal, longitudinal, and lateral stress distributions, measured at low speed, have been presented and commented. The effect of wheel toe-in and camber on the stress distribution results was observed. The paper highlights the impact of the longitudinal tread ribs on the shear stress distributions. The ratios of stress distributions in the truck tyre contact patch have been computed and discussed.

Remarks on residual stress measurement by hole-drilling and electronic speckle pattern interferometry.

Science.gov (United States)

Barile, Claudia; Casavola, Caterina; Pappalettera, Giovanni; Pappalettere, Carmine

2014-01-01

Hole drilling is the most widespread method for measuring residual stress. It is based on the principle that drilling a hole in the material causes a local stress relaxation; the initial residual stress can be calculated by measuring strain in correspondence with each drill depth. Recently optical techniques were introduced to measure strain; in this case, the accuracy of the final results depends, among other factors, on the proper choice of the area of analysis. Deformations are in fact analyzed within an annulus determined by two parameters: the internal and the external radius. In this paper, the influence of the choice of the area of analysis was analysed. A known stress field was introduced on a Ti grade 5 sample and then the stress was measured in correspondence with different values of the internal and the external radius of analysis; results were finally compared with the expected theoretical value.

Instruction manual for the use of CSIR triaxial rock stress measuring equipment

CSIR Research Space (South Africa)

Coetzer, SJ

1998-08-01

Full Text Available This is an updated version of CSIR Report no ME 1763 entitled "Instruction manual for the use for the CSIR triaxial rock stress measuring equipment" by F A Vreede. The manual contains a detailed description of CSIR Triaxial rock stress measuring...

Comparing measured with simulated vertical soil stress under vehicle load

DEFF Research Database (Denmark)

Keller, Thomas; Lamandé, Mathieu; Arvidsson, Johan

The load transfer within agricultural soil is typically modelled on the basis of the theory of stress transmission in elastic media, usually in the semi-empirical form that includes the “concentration factor” (v). Measurements of stress in soil are needed to evaluate model calculations, but may...

Residual stress measurements with barkhausen noise in power plant creep failure analysis

Energy Technology Data Exchange (ETDEWEB)

Karvonen, I. [CoMoTest Oy, Maentsaelae (Finland)] Suominen, L. [Stresstech Oy, Jyvaeskylae (Finland)

1998-12-31

Continuously developing power and process industry needs predictive maintenance inspection methods in order to prevent failures with correctly timed and properly specified measures. Materials` monitoring has traditionally been non-destructive inspection to detect growing cracks or other deficiencies. Recently, after the development of portable stress measurement systems, some advances has been reached. Based on stress anomalies due to creep, fatigue or corrosion, new applications have been found in the use of Barkhausen noise inspection. When the Barkhausen noise findings have been simultaneously confirmed with other stress measuring methods, a wider acceptance of the application of the method can be proposed. (orig.) 7 refs.

Residual stress measurements with barkhausen noise in power plant creep failure analysis

Energy Technology Data Exchange (ETDEWEB)

Karvonen, I. [CoMoTest Oy, Maentsaelae (Finland)] Suominen, L. [Stresstech Oy, Jyvaeskylae (Finland)

1997-12-31

Continuously developing power and process industry needs predictive maintenance inspection methods in order to prevent failures with correctly timed and properly specified measures. Materials` monitoring has traditionally been non-destructive inspection to detect growing cracks or other deficiencies. Recently, after the development of portable stress measurement systems, some advances has been reached. Based on stress anomalies due to creep, fatigue or corrosion, new applications have been found in the use of Barkhausen noise inspection. When the Barkhausen noise findings have been simultaneously confirmed with other stress measuring methods, a wider acceptance of the application of the method can be proposed. (orig.) 7 refs.

Overcoring rock stress measurements in drillholes ONK-PP169 and ONK-PP170 Olkiluoto

International Nuclear Information System (INIS)

Berg, S.; Sjoeberg, J.

2009-03-01

Three-dimensional overcoring rock stress measurements were conducted in drillholes ONK-PP169 and ONK-PP170 at the 230 m depth level in the ONKALO site ramp. The measurements were performed during the spring of 2008. The objective of the measurements was to obtain better understanding of the in situ stress field for the measured depth levels. Another objective was to increase the confidence and reliability and to diminish the uncertainties concerning the state of stress at shallow depth of ONKALO. Due to problems with bonding of strain gauges, which may have been caused by a thin layer/coating of unknown material on the pilot hole wall, stress measurements results were only achieved in drillhole ONK-PP170 at -230 m level. The initial plan was to conduct measurements at three depth levels, -120 m, -180 m and -220 m levels, in the ONKALO ramp. Two (2) of the conducted measurements could be rated as successful (rating a) two (2) measurement were partly successful (rating b). The results from the measurements assuming isotropic condition, the major principal stress is plunging between 18deg and 35deg and trending between S and WSW. Stress magnitudes (for σ 1 ) varied between 12 and 16 MPa except for test 2:3:3 where a much higher value (47 MPa) was obtained. The orientation of the major principal stress are similar for test 2:3:3 and 2:4:3 (WSW), but are different from the orientation of the major principal stress for test 2:5:1 and 2:6:1 (S). Likewise, the horizontal stresses have the highest values for test 2:3:3 but in this case the orientation is similar to test 2:5:1 and 2:4:3. The horizontal stress magnitudes of test 2:4:3, 2:5:1 and 2:6:1 are similar but the orientation for test 2:6:1 are different from the other three tests. The results from two of the measurements assuming transversely isotropic conditions, the major principal stress is 12.3 MPa and 12.7 MPa, trending WSW and S, plunging 30 deg. (orig.)

Stress measurement and bolt tensioning by ultrasonic methods

International Nuclear Information System (INIS)

Smith, J.F.; Greiner, J.D.

1980-01-01

In the past decade, a new technique has been developed for measuring tensile stresses in solids. This ultrasonic technique has been used thus far primarily for measuring fastener tension. The precision of measurement is routinely to 2-3% and, with special care, to approx. 1%. The method is insensitive to the frictional losses which plague tensioning by torque wrench. Though the approach is relatively new, it promises a wide range of applicability

Stress Measurement and Bolt Tensioning by Ultrasonic Methods

Science.gov (United States)

Smith, J. F.; Greiner, John D.

1980-07-01

In the past decade, a new technique has been developed for measuring tensile stresses in solids. This ultrasonic technique has been used thus far primarily for measuring fastener tension. The precision of measurement is routinely to 2-3% and, with special care, to ˜1%. The method is insensitive to the frictional losses which plague tensioning by torque wrench. Though the approach is relatively new, it promises a wide range of applicability.

Bolt Stress Monitor

Science.gov (United States)

1978-01-01

In photo, an engineer is using a new Ultrasonic Bolt Stress Monitor developed by NASA's Langley Research Center to determine whether a bolt is properly tightened. A highly accurate device, the monitor is an important tool in construction of such structures as pressure vessels, bridges and power plants, wherein precise measurement of the stress on a tightened bolt is critical. Overtightened or undertightened bolts can fail and cause serious industrial accidents or costly equipment break-downs. There are a number of methods for measuring bolt stress. Most widely used and least costly is the torque wrench, which is inherently inaccurate; it does not take into account the friction between nut and bolt, which has an influence on stress. At the other end of the spectrum, there are accurate stress-measuring systems, but they are expensive and not portable. The battery-powered Langley monitor fills a need; it is inexpensive, lightweight, portable and extremely accurate because it is not subject to friction error. Sound waves are transmitted to the bolt and a return signal is received. As the bolt is tightened, it undergoes changes in resonance due to stress, in the manner that a violin string changes tone when it is tightened. The monitor measures the changes in resonance and provides a reading of real stress on the bolt. The device, patented by NASA, has aroused wide interest and a number of firms have applied for licenses to produce it for the commercial market.

Failure prevention with stress measurement for dismantling of nuclear facilities. Final report

International Nuclear Information System (INIS)

Komber, T.; Reimche, W.; Bach, F.W.

2003-07-01

The dismantling of nuclear facilities is in progress since 20 years in Germany. Practical experiences in decommissioning have shown, that problem can occur during dismantling operations caused by release of residual stresses. In this case cutting parts or cutting tools get jammed if mechanical cutting techniques are used. The aim of this research work was to develop measuring techniques for the determination of the stress state in RPV, to predict the deformation during dismantling operations. This can serve as additional base for improved decommissioning planning and for time optimised dismantling. For determination of the stress state in components two small and inexpensive measuring techniques were new designed, for remote-controlled on-site use in atmosphere and under water. For the nondestructive determination of the directional stress state, based on the magnetostriction and the Harmonic-Analysis of alternating magnetic fields, a new developed rotating sensor is in use with a principal magnetisation direction. Because of the mainly isotropic material properties and the directional stresses, measured Harmonic values are influenced mainly by the stress state in the surface areas. In this way it is possible to determine the stress state qualitatively and the direction of principal stresses in the surface areas of the component. As an alternative to the established wire strain gauge, which remote-controlled application is still not possible under water, a new slot jet cutting strain control technique was designed. This technique detects the deformation in the surface after stresses are cut free by a water jet. So the stress state could be determined quantitatively in the surface and assessed in the depth. With the help of these two measuring techniques it is possible to characterize the stress state along a planned cutting line. The use of an adapted FEM simulation enables to calculate and determine the deformation of the cutting gap beforehand. These information

Does the stress generation hypothesis apply to eating disorders?: an examination of stress generation in eating, depressive, and anxiety symptoms.

Science.gov (United States)

Bodell, Lindsay P; Hames, Jennifer L; Holm-Denoma, Jill M; Smith, April R; Gordon, Kathryn H; Joiner, Thomas E

2012-12-15

The stress generation hypothesis posits that individuals actively contribute to stress in their lives. Although stress generation has been studied frequently in the context of depression, few studies have examined whether this stress generation process is unique to depression or whether it occurs in other disorders. Although evidence suggests that stress contributes to the development of eating disorders, it is unclear whether eating disorders contribute to subsequent stress. A prospective design was used to examine the influence of eating disorder symptoms on negative life stressors. Two hundred and ninety female undergraduates completed questionnaires at two time points that examined eating disorder, depressive and anxiety symptoms and the presence of negative life events. Regression analyses found that while eating disorder symptoms (i.e. bulimic symptoms and drive for thinness) were independent, significant predictors of negative life events, they did not predict negative life events above and beyond symptoms of depression. Limitations include the use of self-report measures and a college-based sample, which may limit generalizability of the results. Findings suggest that if stress generation is present in individuals with symptoms of eating disorders, it is likely attributable to symptoms of depression. Thus, it may be important for clinicians to target depressive symptoms in order to reduce the frequency of negative life stressors among individuals with eating disorders. Copyright © 2012 Elsevier B.V. All rights reserved.

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

Stress responses of Calluna vulgaris to reduced and oxidised N applied under 'real world conditions'

International Nuclear Information System (INIS)

Sheppard, Lucy J.; Leith, Ian D.; Crossley, A.; Van Dijk, N.; Fowler, D.; Sutton, M.A.; Woods, C.

2008-01-01

Effects and implications of reduced and oxidised N, applied under 'real world' conditions, since May 2002, are reported for Calluna growing on an ombrotrophic bog. Ammonia has been released from a 10 m line source generating monthly concentrations of 180-6 μg m -3 , while ammonium chloride and sodium nitrate are applied in rainwater at nitrate and ammonium concentrations below 4 mM and providing up to 56 kg N ha -1 year -1 above a background deposition of 10 kg N ha -1 year -1 . Ammonia concentrations, >8 μg m -3 have significantly enhanced foliar N concentrations, increased sensitivity to drought, frost and winter desiccation, spring frost damage and increased the incidence of pathogen outbreaks. The mature Calluna bushes nearest the NH 3 source have turned bleached and moribund. By comparison the Calluna receiving reduced and oxidised N in rain has shown no significant visible or stress related effects with no significant increase in N status. - Exposure to NH 3 reduces stress resistance and increases visible damage in mature Calluna

Residual stress measurement of large scaled welded pipe using neutron diffraction method. Effect of SCC crack propagation and repair weld on residual stress distribution

International Nuclear Information System (INIS)

Suzuki, Hiroshi; Katsuyama, Jinya; Tobita, Tohru; Morii, Yukio

2011-01-01

The RESA-1 neutron engineering diffractometer in the JRR-3 (Japan Research Reactor No.3) at the Japan Atomic Energy Agency, which is used for stress measurements, was upgraded to realize residual stress measurements of large scaled mechanical components. A series of residual stress measurements was made to obtain through-thickness residual stress distributions in a Type 304 stainless steel butt-welded pipe of 500A-sch.80 using the upgraded RESA-1 diffractometer. We evaluated effects of crack propagation such as stress corrosion cracking (SCC) and a part-circumference repair weld on the residual stress distributions induced by girth welding. Measured residual stress distributions near original girth weld revealed good agreement with typical results shown in some previous works using finite element method, deep hole drilling as well as neutron diffraction. After introducing a mock crack with 10 mm depth in the heat affected zone on the inside wall of the pipe by electro discharge machining, the axial residual stresses were found to be released in the part of the mock crack. However, changes in the through-wall bending stress component and the self-equilibrated stress component were negligible and hence the axial residual stress distribution in the ligament was remained in the original residual stresses near girth weld without the mock crack. Furthermore, changes in hoop and radial residual stress were also small. The residual stress distributions after a part repair welding on the outer circumference of the girth weld were significantly different from residual stress distributions near the original girth weld. The through-thickness average axial residual stress was increased due to increase of the tensile membrane stress and mitigation of the bending stress after repair welding. Throughout above studies, we evidenced that the neutron diffraction technique is useful and powerful tool for measuring residual stress distributions in large as well as thick mechanical

Stress measurements in the Stripa granite. Technical project report No. 4

International Nuclear Information System (INIS)

Carlsson, H.

1978-08-01

Rock stress measurements at the 348 m level of the Stripa Mine have been carried out with the Leeman tri-axial equipment. The largest principal stress is found to be 20.0 MPa and directed parallel with the strike of the contact between the granite and the orebody. The intermediate principal stress is 11.4 MPa and directed almost horizontal and perpendicular to the contact. The minor principal stress has a magnitude of 5.4 MPa. The deduced vertical stress is approximately of the same value as can be theoretically calculated

Report on achievements of research and development of a technology to apply human senses to measurements in fiscal 1995. 2. Main subject (Part 1. Physiologic indexing technology); 1995 nendo ningen kankaku kesoku oyo gijutsu no kenkyu kaihatsu. 2. Honronhen (Seiri shihyoka gijutsu no kenkyu kaihatsu)

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-03-01

This paper describes the physiological indexing technology, extracted from the achievements in the development of a technology to apply human senses to measurements in fiscal 1995. In work stress evaluation using mainly autonomic nervous system indexes, factors for the work stresses were extracted and experimental environments were put in order in applying the technology to the indexing at higher levels and the coordinative works. Use of common primary indexes was introduced for transitory stress, and the common primary indexes were introduced also for chronic stress. In the stress evaluation using composite physiological function measurement, data analyses were made, and discussions were given on the time series basis on the action indexes and the physiological indexes as the work performance of a work load assigning work to elucidate points of the problems. In stress indexing using skin temperatures, a possibility was obtained in indexing by using the skin temperatures on transitory stresses during tension and monotonous work. Measurement of stresses with hormone placed as the main subject tries to apply to human being the changes in hormones which have been verified since quite some time ago by animal experiments. However, it is difficult to find a definite trend because of complexity of stresses in the human society. For the basic arousal indexing, studies were made on improvement of accuracy of the monitor and quantification of actions of physical stimulation. (NEDO)

Estimation of stress distribution in ferromagnetic tensile specimens using low cost eddy current stress measurement system and BP neural network.

Directory of Open Access Journals (Sweden)

Jianwei Li

Full Text Available Estimation of the stress distribution in ferromagnetic components is very important for evaluating the working status of mechanical equipment and implementing preventive maintenance. Eddy current testing technology is a promising method in this field because of its advantages of safety, no need of coupling agent, etc. In order to reduce the cost of eddy current stress measurement system, and obtain the stress distribution in ferromagnetic materials without scanning, a low cost eddy current stress measurement system based on Archimedes spiral planar coil was established, and a method based on BP neural network to obtain the stress distribution using the stress of several discrete test points was proposed. To verify the performance of the developed test system and the validity of the proposed method, experiment was implemented using structural steel (Q235 specimens. Standard curves of sensors at each test point were achieved, the calibrated data were used to establish the BP neural network model for approximating the stress variation on the specimen surface, and the stress distribution curve of the specimen was obtained by interpolating with the established model. The results show that there is a good linear relationship between the change of signal modulus and the stress in most elastic range of the specimen, and the established system can detect the change in stress with a theoretical average sensitivity of -0.4228 mV/MPa. The obtained stress distribution curve is well consonant with the theoretical analysis result. At last, possible causes and improving methods of problems appeared in the results were discussed. This research has important significance for reducing the cost of eddy current stress measurement system, and advancing the engineering application of eddy current stress testing.

Statistical analysis of x-ray stress measurement by centroid method

International Nuclear Information System (INIS)

Kurita, Masanori; Amano, Jun; Sakamoto, Isao

1982-01-01

The X-ray technique allows a nondestructive and rapid measurement of residual stresses in metallic materials. The centroid method has an advantage over other X-ray methods in that it can determine the angular position of a diffraction line, from which the stress is calculated, even with an asymmetrical line profile. An equation for the standard deviation of the angular position of a diffraction line, σsub(p), caused by statistical fluctuation was derived, which is a fundamental source of scatter in X-ray stress measurements. This equation shows that an increase of X-ray counts by a factor of k results in a decrease of σsub(p) by a factor of 1/√k. It also shows that σsub(p) increases rapidly as the angular range used in calculating the centroid increases. It is therefore important to calculate the centroid using the narrow angular range between the two ends of the diffraction line where it starts to deviate from the straight background line. By using quenched structural steels JIS S35C and S45C, the residual stresses and their standard deviations were calculated by the centroid, parabola, Gaussian curve, and half-width methods, and the results were compared. The centroid of a diffraction line was affected greatly by the background line used. The standard deviation of the stress measured by the centroid method was found to be the largest among the four methods. (author)

Measurement techniques for in situ stresses around underground constructions in a deep clay formation

Directory of Open Access Journals (Sweden)

Li X.L.

2010-06-01

Full Text Available Disposal in deep underground geological formations is internationally recognized as the most viable option for the long-term management of high-level radioactive waste. In Belgium, the Boom clay formation is extensively studied in this context, in particular at the 225 m deep HADES Underground Research Facility in Mol. A cost-effective design of deep underground structures requires an accurate assessment of the in situ stresses; a good estimation of these stresses is also essential when interpreting in situ experiments regarding the hydro-mechanical behaviour of the host formation. Different measurement techniques are available to provide data on the stress evolution and other mechanical properties of the geological formation. The measurement can be direct (measurement of total pressure, or it can be an indirect technique, deriving the stress from related quantities such as strain (changes in structural members. Most total stress measurements are performed through permanently installed sensors; also once-only measurements are performed through specific methods (e.g. pressuremeter. Direct measurement of the stress state is challenging due to the complex mechanical behaviour of the clay, and the fact that the sensor installation inevitably disturbs the original stress field. This paper describes ways to deal with these problems and presents the results obtained using different techniques at HADES.

Remarks on Residual Stress Measurement by Hole-Drilling and Electronic Speckle Pattern Interferometry

Directory of Open Access Journals (Sweden)

Claudia Barile

2014-01-01

Full Text Available Hole drilling is the most widespread method for measuring residual stress. It is based on the principle that drilling a hole in the material causes a local stress relaxation; the initial residual stress can be calculated by measuring strain in correspondence with each drill depth. Recently optical techniques were introduced to measure strain; in this case, the accuracy of the final results depends, among other factors, on the proper choice of the area of analysis. Deformations are in fact analyzed within an annulus determined by two parameters: the internal and the external radius. In this paper, the influence of the choice of the area of analysis was analysed. A known stress field was introduced on a Ti grade 5 sample and then the stress was measured in correspondence with different values of the internal and the external radius of analysis; results were finally compared with the expected theoretical value.

The Fertility Problem Inventory: measuring perceived infertility-related stress.

Science.gov (United States)

Newton, C R; Sherrard, W; Glavac, I

1999-07-01

To develop a reliable, valid instrument to evaluate perceived infertility-related stress. Prospective study. University-affiliated teaching hospital. Consecutively referred patients (1,153 women and 1,149 men) seen for infertility treatment. None. Participants' infertility-related stress was assessed by written questionnaire using the Fertility Problem Inventory. Current levels of anxiety, depression, and marital satisfaction also were determined. Women described greater global stress than men and higher specific stress in terms of social concerns, sexual concerns, and need for parenthood. Both men and women facing male infertility reported higher global stress and more social and sexual concerns than men and women experiencing female infertility. Social, sexual, and relationship concerns related to infertility were more effective predictors of depression and marital dissatisfaction than expressed needs for parenthood or attitudes toward child-free living. The Fertility Problem Inventory provides a reliable measure of perceived infertility-related stress and specific information on five separate domains of patient concern. Patterns of infertility-related stress differed depending on gender, fertility history, and infertility diagnosis. Among patients receiving treatment, social, sexual, and relationship concerns appear central to current distress. Counseling interventions that target these domains appear likely to offer maximal therapeutic benefit.

Comparison of Some Mechanical and Physical Methods for Measurement of Residual Stresses in Brush-Plated Nickel Hardened Gold and Silver Coatings

Directory of Open Access Journals (Sweden)

Harri LILLE

2016-05-01

Full Text Available Hard gold and silver are applied in coating owing to their high hardness, good wear and corrosion resistance for engineering application (e.g. on generators slip rings, sliding contacts and small machine parts and are typically plated on copper (mostly, brass and bronze. The studied nickel-hardened gold and silver coatings were brush plated on open thin-walled copper ring substrates. Residual stresses in the coatings were calculated from the curvature changes of the substrates. Biaxial intrinsic residual stresses were also determined by nanoindentation testing and by the X-ray technique. The values of the residual stresses represented tensile stresses and when determined by the techniques used they were comparable within a maximum limit of measurement uncertainty. These stresses relax; the dependence of relaxation time was approximated by a linear-fractional function.DOI: http://dx.doi.org/10.5755/j01.ms.22.1.7439

Applied photometry, radiometry, and measurements of optical losses

CERN Document Server

Bukshtab, Michael

2012-01-01

Applied Photometry, Radiometry, and Measurements of Optical Losses reviews and analyzes physical concepts of radiation transfer, providing quantitative foundation for the means of measurements of optical losses, which affect propagation and distribution of light waves in various media and in diverse optical systems and components. The comprehensive analysis of advanced methodologies for low-loss detection is outlined in comparison with the classic photometric and radiometric observations, having a broad range of techniques examined and summarized: from interferometric and calorimetric, resonator and polarization, phase-shift and ring-down decay, wavelength and frequency modulation to pulse separation and resonant, acousto-optic and emissive - subsequently compared to direct and balancing methods for studying free-space and polarization optics, fibers and waveguides. The material is focused on applying optical methods and procedures for evaluation of transparent, reflecting, scattering, absorbing, and aggregat...

Developments in wireline in-situ rock stress measurement

Energy Technology Data Exchange (ETDEWEB)

Pedroso, Carlos [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil); Canas, Jesus A.; Holzberg, Bruno; Gmach, Helmut [Schlumberger Servicos de Petroleo Ltda., Rio de Janeiro, RJ (Brazil)

2008-07-01

This paper presents recent developments of in-situ stress measurements with wireline tools. The stress measurements are based on the micro hydraulic techniques that can be initialized when an interval is pressurized by pumping fluid until a tensile fracture begins or by packers fracturing (sleeve fracturing). Ultrasonic and Micro-resistivity borehole image logs (before and after the testes) are used as a complement, in order to observe the fractures created by the tests, evaluating the mechanical behavior of the formation. An offshore case study is presented, where shales and tight sandstones at depths deeper than 4500 meters depth were successfully evaluated. A workflow to succeed on stress measurements on such environments is proposed, what includes a planning phase: where breakdown pressures ranges are estimated and compared with the capacity of the tools, a Real Time Monitoring phase, where a decision tree is proposed to help on quick decisions while testing, and an interpretation phase, where appropriate techniques are indicated to evaluate the results. Also, the paper presents the main operational needs to succeed on such environments. Basically, such tests require an entirely software controlled, motorized and modular design tool consisting of dual packer (DP), pump out and flow control modules (Figure 1). These modules were upgraded for the present environment: conditions such as temperatures above 300 deg F, formation pressures above 10,000 psia, very low formation permeability, high pressure differential need and oil based mud (OBM) environment. (author)

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...

A Steel Wire Stress Measuring Sensor Based on the Static Magnetization by Permanent Magnets

Directory of Open Access Journals (Sweden)

Dongge Deng

2016-10-01

Full Text Available A new stress measuring sensor is proposed to evaluate the axial stress in steel wires. Without using excitation and induction coils, the sensor mainly consists of a static magnetization unit made of permanent magnets and a magnetic field measurement unit containing Hall element arrays. Firstly, the principle is illustrated in detail. Under the excitation of the magnetization unit, a spatially varying magnetized region in the steel wire is utilized as the measurement region. Radial and axial magnetic flux densities at different lift-offs in this region are measured by the measurement unit to calculate the differential permeability curve and magnetization curve. Feature parameters extracted from the curves are used to evaluate the axial stress. Secondly, the special stress sensor for Φ5 and Φ7 steel wires is developed accordingly. At last, the performance of the sensor is tested experimentally. Experimental results show that the sensor can measure the magnetization curve accurately with the error in the range of ±6%. Furthermore, the obtained differential permeability at working points 1200 A/m and 10000 A/m change almost linearly with the stress in steel wires, the goodness of linear fits are all higher than 0.987. Thus, the proposed steel wire stress measuring sensor is feasible.

Review of Stress and the Measurement of Stress in Marine Mammals

Science.gov (United States)

2013-09-30

the hypothalamic- pituitary -adrenal (HPA) and hypothalamic- pituitary -thyroid (HPT) axes across multiple matrices. APPROACH Task 1 – Natural...performance. Hair samples will be collected from the anterior back region of seals for determination of cortisol as a measure of chronic stress (Davenport...and 5 juveniles. Task 3 – TSH challenges Thyroid hormones (thyroxin, T4 and triiodothyronine, T3) are released from the thyroid gland and are

Residual stress measurement by X-ray diffraction with the Gaussian curve method and its automation

International Nuclear Information System (INIS)

Kurita, M.

1987-01-01

X-ray technique with the Gaussian curve method and its automation are described for rapid and nondestructive measurement of residual stress. A simplified equation for measuring the stress by the Gaussian curve method is derived because in its previous form this method required laborious calculation. The residual stress can be measured in a few minutes, depending on materials, using an automated X-ray stress analyzer with a microcomputer which was developed in the laboratory. The residual stress distribution of a partially induction hardened and tempered (at 280 0 C) steel bar was measured with the Gaussian curve method. A sharp residual tensile stress peak of 182 MPa appeared right outside the hardened region at which fatigue failure is liable to occur

Perceived stress, recurrent pain, and aggregate salivary cortisol measures in mid-adolescent girls and boys.

Science.gov (United States)

Lindfors, Petra; Folkesson Hellstadius, Lisa; Östberg, Viveca

2017-02-01

Measures of perceived stress have been criticized for theoretical inconsistency. However, the validated pressure activation stress scale has been suggested as a theoretically sound alternative. But it is unclear how pressure and activation stress relate to objective and subjective measures including commonly used aggregate cortisol measures and health complaints respectively. Specifically, this study aimed at investigating how pressure and activation stress were related to aggregate salivary cortisol measures and recurrent pain in mid-adolescent girls and boys. Mid-adolescents (119 girls and 56 boys) provided self-reports in questionnaires on activation and pressure stress and recurrent pain (headache, stomach ache, neck/shoulder and back pain). Additionally, adolescents sampled saliva during an ordinary school day: (1) immediately at awakening; (2) 30 minutes after waking up; (3) 60 minutes after waking up, and (4) at 8 p.m. These samples were analyzed for cortisol. Hierarchical regressions showed no statistically significant associations between activation and pressure stress and cortisol, neither for girls nor for boys. However, activation and pressure stress were significantly associated with recurrent pain but only for girls. The findings may relate to subjective and objective measures reflecting distinct aspects of stress-related functioning. However, the study participants included mid-adolescents whose bodily systems are flexible and still relatively unaffected by the strain of their daily stress perceptions. To conclude, the non-significant relationships between activation and pressure stress and commonly used aggregate measures of cortisol adds to the understanding of how perceived stress may relate to physiological functioning in the daily life of adolescents when using such aggregate measures. © 2017 Scandinavian Psychological Associations and John Wiley & Sons Ltd.

Prediction of residual stress distribution in multi-stacked thin film by curvature measurement and iterative FEA

International Nuclear Information System (INIS)

Choi, Hyeon Chang; Park, Jun Hyub

2005-01-01

In this study, residual stress distribution in multi-stacked film by MEMS (Micro-Electro Mechanical System) process is predicted using Finite Element Method (FEM). We develop a finite element program for REsidual Stress Analysis (RESA) in multi-stacked film. The RESA predicts the distribution of residual stress field in multi-stacked film. Curvatures of multi-stacked film and single layers which consist of the multi-stacked film are used as the input to the RESA. To measure those curvatures is easier than to measure a distribution of residual stress. To verify the RESA, mean stresses and stress gradients of single and multilayers are measured. The mean stresses are calculated from curvatures of deposited wafer by using Stoney's equation. The stress gradients are calculated from the vertical deflection at the end of cantilever beam. To measure the mean stress of each layer in multi-stacked film, we measure the curvature of wafer with the film after etching layer by layer in multi-stacked film

Interpretation of stress measurements around mining cavities in rock salt - a finite-element study

International Nuclear Information System (INIS)

Heusermann, S.

1986-01-01

Finite-element studies of stress measurements using the overcoring method and of large drift fields in rock salt show that the measurements are affected by local stress relaxation occurring near the test borehole and by general time-dependent stress redistribution in the marginal zones of adjacent drifts. Analysis of the overcoring method indicates that the following local effects have to be considered in the interpretation of the test results as opposed to measurements in elastic rock: The inelastic deformation behaviour of rock salt causes stress relaxation at the pilot borehole which can lead to an underestimation of the actual stress state in rock. During overcoring considerable inelastic deformations occur in rock salt which demand a modified interpretation of the measurements and as a result of stress relaxation at the borehole various tests conditions, such as overcoring diameter, pilot borehole diameter and time between drilling and overcoring, have an effect on the test results. (orig./PW)

Measuring general and specific stress causes and stress responses among beginning secondary school teachers in the Netherlands

OpenAIRE

Harmsen, R; Helms-Lorenz, M.; Maulana, R; van Veen, K; van Veldhoven, M.J.P.M.

2018-01-01

The main aim of this study was to adjust the Questionnaire on the Experience and Evaluation of Work (QEEW) in order to measure stress causes and stress responses of beginning secondary school teachers in the Netherlands. First, the suitability of the original QEEW stress scales for use in the beginning teachers (BTs) context was investigated using a sample of 356 beginning teachers from 52 different secondary school locations in the Netherlands. Confirmatory Factor Analyses, Principal Compone...

Measuring general and specific stress causes and stress responses among beginning secondary school teachers in the Netherlands.

OpenAIRE

Harmsen, Ruth; Helms-Lorenz, Michelle; Maulana, Ridwan; van Veen, Klaas; van Veldhoven, M.J.P.M.

2018-01-01

The main aim of this study was to adjust the Questionnaire on the Experience and Evaluation of Work (QEEW) in order to measure stress causes and stress responses of beginning secondary school teachers in the Netherlands. First, the suitability of the original QEEW stress scales for use in the beginning teachers (BTs) context was investigated using a sample of 356 beginning teachers from 52 different secondary school locations in the Netherlands. Confirmatory Factor Analyses, Principal Compone...

Using the analysis of stress waves to build research for experimentation on ultrasonic film measurement

Science.gov (United States)

Chang, Shi-Shing; Wu, John H.

1993-09-01

After the 2th world war, although the application of ultrasonic wave in industries is becoming more and more popular. But due to the restriction of the precise equivelent , experimental method and the support of the basic theoremsetc. Ultrasonic wave is not applied in precise measurement. Nowadays due to many conditions - the improvement in the production technic, the precise of the equivelent, causes to increase the application of ultrasonic wave. But it's still limited due to the lack of measurement and analysis theorem. In this paper, first we caculate translation of the stress wave (elastic wave) in material for the free surface of material by a normal impulse load. as the theorem analysis base in real application. It is applied to an experiment of film measurement. We can find the partical motion in material and the arriving time of wave front. Then we can estimate the thickness of layers and can prove the actual condition with the result of experiment. This resarch is not only in the theoretical investigation but also in setting overall the measurement system, and excutes the following three experiments: the thickness measurement of two layers, the thickness measurement of film material. the thickness measurement of air propagation. About the data processing, we relied on the frequency analysis to evalute the time difference of two overlapped ultrasonic wave signal. in the meanwhile. we also designed several computer programs to assist the sonic wave identification and signal analysis.

In situ stress measurements at 250m gallery off the ventilation shaft

International Nuclear Information System (INIS)

Nakamura, Takahiro; Sanada, Hiroyuki; Sugita, Yutaka; Kato, Harumi

2011-06-01

From FY2000 to FY2005, JAEA had been making research at ground surface of Horonobe town for repository of high-level radioactive waste. During this period, geological investigation, hydrogeology investigation, rock mechanics investigation, geochemical investigation using boreholes were carried out in Hokushin area which is about 3kmx3km in surface area of Horonobe town in order to construct a geological environment model and to confirm the methodology for safety assessment. Now the research program proceeds to the next stage where the underground drifts and shafts are under construction. In the underground rock mass, in situ stress is the sum of tectonic stress as well as overlying stress due to gravity. In situ stresses enter into excavation design and are required in order to predict the response of rock masses to the disturbance associated with those structures. For these reasons, JAEA has carried out in situ stress measurements using vertical boreholes drilled from ground surface to evaluate the state of horizontal stress in the area. In the research during the underground construction, comparison between the stress measurements carried out at surface and at underground is conducted. And if inconsistency between these two measurements is found, the state of stress will be updated based on more reliable information. In order to study the 3D in situ state of stress around Horonobe Underground Research Laboratory, hydraulic fracturing tests and stress relief method (Conical-ended borehole method) were conducted at the 250m gallery located near the bottom of the ventilation shaft. Three 20.0m long boreholes, 09-V250-M01(slightly upwards), 09-V250-M02(slightly upwards) and 09-V250-M03(vertical), were drilled from the gallery using 76mm diameter bit. The results of the measurements are summarized as follows: (1) Hydraulic fracturing technique. Hydraulic fracturing technique using the test equipment with sufficiently small compliance was carried out in the three

Stress Prediction for Distributed Structural Health Monitoring Using Existing Measurements and Pattern Recognition.

Science.gov (United States)

Lu, Wei; Teng, Jun; Zhou, Qiushi; Peng, Qiexin

2018-02-01

The stress in structural steel members is the most useful and directly measurable physical quantity to evaluate the structural safety in structural health monitoring, which is also an important index to evaluate the stress distribution and force condition of structures during structural construction and service phases. Thus, it is common to set stress as a measure in steel structural monitoring. Considering the economy and the importance of the structural members, there are only a limited number of sensors that can be placed, which means that it is impossible to obtain the stresses of all members directly using sensors. This study aims to develop a stress response prediction method for locations where there are insufficent sensors, using measurements from a limited number of sensors and pattern recognition. The detailed improved aspects are: (1) a distributed computing process is proposed, where the same pattern is recognized by several subsets of measurements; and (2) the pattern recognition using the subset of measurements is carried out by considering the optimal number of sensors and number of fusion patterns. The validity and feasibility of the proposed method are verified using two examples: the finite-element simulation of a single-layer shell-like steel structure, and the structural health monitoring of the space steel roof of Shenzhen Bay Stadium; for the latter, the anti-noise performance of this method is verified by the stress measurements from a real-world project.

Enhancement to Non-Contacting Stress Measurement of Blade Vibration Frequency

Science.gov (United States)

Platt, Michael; Jagodnik, John

2011-01-01

A system for turbo machinery blade vibration has been developed that combines time-of-arrival sensors for blade vibration amplitude measurement and radar sensors for vibration frequency and mode identification. The enabling technology for this continuous blade monitoring system is the radar sensor, which provides a continuous time series of blade displacement over a portion of a revolution. This allows the data reduction algorithms to directly calculate the blade vibration frequency and to correctly identify the active modes of vibration. The work in this project represents a significant enhancement in the mode identification and stress calculation accuracy in non-contacting stress measurement system (NSMS) technology when compared to time-of-arrival measurements alone.

Stress measurements by multi-reflection grazing-incidence X-ray diffraction method (MGIXD) using different radiation wavelengths and different incident angles

International Nuclear Information System (INIS)

Marciszko, Marianna; Baczmański, Andrzej; Braham, Chedly; Wróbel, Mirosław; Wroński, Sebastian; Cios, Grzegorz

2017-01-01

The presented study introduces the development of the multi-reflection grazing-incidence X-ray diffraction method (MGIXD) for residual stress determination. The proposed new methodology is aimed at obtaining more reliable experimental data and increasing the depth of non-destructive stress determination below the sample surface. To verify proposed method measurements were performed on a classical X-ray diffractometer (Cu Kα radiation) and using synchrotron radiation (three different wavelengths: λ = 1.2527 Å, λ = 1.5419 Å and λ = 1.7512 Å). The Al2017 alloy subjected to three different surface treatments was investigated in this study. The obtained results showed that the proposed development of MGIXD method, in which not only different incident angles but also different wavelengths of X-ray are used, can be successfully applied for residual stress determination, especially when stress gradients are present in the sample.

X-Ray diffraction technique applied to study of residual stresses after welding of duplex stainless steel plates

International Nuclear Information System (INIS)

Monin, Vladimir Ivanovitch; Assis, Joaquim Teixeira de; Lopes, Ricardo Tadeu; Turibus, Sergio Noleto; Payao Filho, Joao C.

2014-01-01

Duplex stainless steel is an example of composite material with approximately equal amounts of austenite and ferrite phases. Difference of physical and mechanical properties of component is additional factor that contributes appearance of residual stresses after welding of duplex steel plates. Measurements of stress distributions in weld region were made by X-ray diffraction method both in ferrite and austenite phases. Duplex Steel plates were joined by GTAW (Gas Tungsten Arc Welding) technology. There were studied longitudinal and transverse stress components in welded butt joint, in heat affected zone (HAZ) and in points of base metal 10 mm from the weld. Residual stresses measured in duplex steel plates jointed by welding are caused by temperature gradients between weld zone and base metal and by difference of thermal expansion coefficients of ferrite and austenite phases. Proposed analytical model allows evaluating of residual stress distribution over the cross section in the weld region. (author)

Residual stress measurement in 304 stainless steel weld overlay pipes

International Nuclear Information System (INIS)

Yen, H.J.; Lin, M.C.C.; Chen, L.J.

1996-01-01

Welding overlay repair (WOR) is commonly employed to rebuild piping systems suffering from intergranular stress corrosion cracking (IGSCC). To understand the effects of this repair, it is necessary to investigate the distribution of residual stresses in the welding pipe. The overlay welding technique must induce compressive residual stress at the inner surface of the welded pipe to prevent IGSCC. To understand the bulk residual stress distribution, the stress profile as a function of location within wall is examined. In this study the full destructive residual stress measurement technique -- a cutting and sectioning method -- is used to determine the residual stress distribution. The sample is type 304 stainless steel weld overlay pipe with an outside diameter of 267 mm. A pipe segment is cut from the circular pipe; then a thin layer is removed axially from the inner to the outer surfaces until further sectioning is impractical. The total residual stress is calculated by adding the stress relieved by cutting the section away to the stress relieved by axially sectioning. The axial and hoop residual stresses are compressive at the inner surface of the weld overlay pipe. Compressive stress exists not only at the surface but is also distributed over most of the pipe's cross section. On the one hand, the maximum compressive hoop residual stress appears at the pipe's inner surface. The thermal-mechanical induced crack closure from significant compressive residual stress is discussed. This crack closure can thus prevent IGSCC very effectively

Transient water stress in a vegetation canopy - Simulations and measurements

Science.gov (United States)

Carlson, Toby N.; Belles, James E.; Gillies, Robert R.

1991-01-01

Consideration is given to observational and modeling evidence of transient water stress, the effects of the transpiration plateau on the canopy radiometric temperature, and the factors responsible for the onset of the transpiration plateau, such as soil moisture. Attention is also given to the point at which the transient stress can be detected by remote measurement of surface temperature.

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

X-ray stress measurement of ferritic steel using fourier analysis of Debye-Scherrer ring

International Nuclear Information System (INIS)

Fujimoto, Yohei; Sasaki, Toshihiko; Miyazaki, Toshiyuki

2015-01-01

In this study, X-ray stress measurements of ferritic steel based on Fourier analysis are conducted. Taira et al. developed the cosα method for X-ray stress measurements using a two-dimensional X-ray detector. Miyazaki et al. reported that the cosα method can be described more concisely by developing the Fourier series (the Fourier analysis method). The Fourier analysis method is expected to yield the stress measurement with an imperfect Debye-Scherrer ring and there is a possibility that the materials evaluation is different compared with the conventional method, that is, the sin 2 ψ method. In the Fourier analysis method, the strain measured by X-rays is developed as a Fourier series, and all the plane-stress components can be calculated from the Fourier series. In this study, the normal stress calculation was confirmed. In addition, the Fourier-analysis and cosα methods were used for X-ray stress measurements during a four-point bending test on a S45C test piece, and the effectiveness of the Fourier analysis method was confirmed. It was found that the experimental results from the Fourier analysis and cosα methods were nearly identical. In addition, the measurement accuracies of both the methods were equivalent. (author)

One- and multistage total strain and stress-controlled fatigue tests with a steel of type 42 CrMo 4 subject to varied residual and mean stress loading. Final report

International Nuclear Information System (INIS)

Macherauch, E.; Schulze, V.

1995-01-01

Work under this research project covered tests with the quenched and tempered steel 42 CrMo 4 to which one- and two-stage tension-compression fatigue stresses were applied with varying mean loads, under conditions of nominal stress and total strain control. Shot peening was used to induce various microstructural conditions in the material at the surface and near below. Softening in the material was observed to be a continuous process, and the steel showed no stabilised, cyclic deformation behaviour. The cyclic stress-strain curve measured with equal stress amplitudes and total strain control applied shows higher plastic strain amplitudes than that measured with nominal stresses. The fatigue behaviour under two-stage loading depends on the chosen sequence of loads applied, the testing periods, and the overall testing procedure, so that there is no way of deriving data for two-stage testing procedures from single-stage test results. (orig.) [de

The effect of compressive stress on the Young's modulus of unirradiated and irradiated nuclear graphites

International Nuclear Information System (INIS)

Oku, T.; Usui, T.; Ero, M.; Fukuda, Y.

1977-01-01

The Young's moduli of unirradiated and high temperature (800 to 1000 0 C) irradiated graphites for HTGR were measured by the ultrasonic method in the direction of applied compressive stress during and after stressing. The Young's moduli of all the tested graphites decreased with increasing compressive stress both during and after stressing. In order to investigate the reason for the decrease in Young's modulus by applying compressive stress, the mercury pore diameter distributions of a part of the unirradiated and irradiated specimens were measured. The change in pore distribution is believed to be associated with structural changes produced by irradiation and compressive stressing. The residual strain, after removing the compressive stress, showed a good correlation with the decrease in Young's modulus caused by the compressive stress. The decrease in Young's modulus by applying compressive stress was considered to be due to the increase in the mobile dislocation density and the growth or formation of cracks. The results suggest, however, that the mechanism giving the larger contribution depends on the brand of graphite, and in anisotropic graphite it depends on the direction of applied stress and the irradiation conditions. (author)

Single-cell analysis of S. cerevisiae growth recovery after a sublethal heat-stress applied during an alcoholic fermentation.

Science.gov (United States)

Tibayrenc, Pierre; Preziosi-Belloy, Laurence; Ghommidh, Charles

2011-06-01

Interest in bioethanol production has experienced a resurgence in the last few years. Poor temperature control in industrial fermentation tanks exposes the yeast cells used for this production to intermittent heat stress which impairs fermentation efficiency. Therefore, there is a need for yeast strains with improved tolerance, able to recover from such temperature variations. Accordingly, this paper reports the development of methods for the characterization of Saccharomyces cerevisiae growth recovery after a sublethal heat stress. Single-cell measurements were carried out in order to detect cell-to-cell variability. Alcoholic batch fermentations were performed on a defined medium in a 2 l instrumented bioreactor. A rapid temperature shift from 33 to 43 °C was applied when ethanol concentration reached 50 g l⁻¹. Samples were collected at different times after the temperature shift. Single cell growth capability, lag-time and initial growth rate were determined by monitoring the growth of a statistically significant number of cells after agar medium plating. The rapid temperature shift resulted in an immediate arrest of growth and triggered a progressive loss of cultivability from 100 to 0.0001% within 8 h. Heat-injured cells were able to recover their growth capability on agar medium after a lag phase. Lag-time was longer and more widely distributed as the time of heat exposure increased. Thus, lag-time distribution gives an insight into strain sensitivity to heat-stress, and could be helpful for the selection of yeast strains of technological interest.

Stress studies in EFG

Science.gov (United States)

1983-01-01

Stress distributions were calculated for a creep law to predict a rate of plastic deformation. The expected reduction in stresses is obtained. Improved schemes for calculating growth system temperature distributions were evaluated. Temperature field modeling examined the possibility of using horizontal temperature gradients to influence stress distribution in ribbon. The defect structure of 10 cm wide ribbon grown in the cartridge system was examined. A new feature is identified from an examination of cross sectional micrographs. It consists of high density dislocation bands extending through the ribbon thickness. A four point bending apparatus was constructed for high temperature study of the creep response of silicon, to be used to generate defects for comparison with as grown defects in ribbon. The feasibility of laser interferometric techniques for sheet residual stress distribution measurement is examined. The mathematical formalism for calculating residual stress from changes in surface topology caused by an applied stress in a rectangular specimen was developed, and the system for laser interferometric measurement to obtain surface topology data was tested on CZ silicon.

Measurement of the temperature-dependent threshold shear-stress of red blood cell aggregation.

Science.gov (United States)

Lim, Hyun-Jung; Nam, Jeong-Hun; Lee, Yong-Jin; Shin, Sehyun

2009-09-01

Red blood cell (RBC) aggregation is becoming an important hemorheological parameter, which typically exhibits temperature dependence. Quite recently, a critical shear-stress was proposed as a new dimensional index to represent the aggregative and disaggregative behaviors of RBCs. The present study investigated the effect of the temperature on the critical shear-stress that is required to keep RBC aggregates dispersed. The critical shear-stress was measured at various temperatures (4, 10, 20, 30, and 37 degrees C) through the use of a transient microfluidic aggregometry. The critical shear-stress significantly increased as the blood temperature lowered, which accorded with the increase in the low-shear blood viscosity with the lowering of the temperature. Furthermore, the critical shear-stress also showed good agreement with the threshold shear-stress, as measured in a rotational Couette flow. These findings assist in rheologically validating the critical shear-stress, as defined in the microfluidic aggregometry.

Neutron diffraction measurement of residual stress in NPP construction materials

International Nuclear Information System (INIS)

Hinca, R.; Bokuchava, G.

2000-01-01

The aim of the investigation is to study the level of residual stresses induced by the surfacing in the weld deposit zone and in the base metal, where considerable thermal gradients are present. Surfacing high-nickel filler on an austenitic base metal is one of techniques in repair of primary collector the primary circuit of nuclear power plant type VVER. The repair technology was developed at Welding Research Institute Bratislava. Measurements of residual stresses in the weld overlay and the base metal are necessary for approving the mechanical analysis and verifying of residual stresses determination on welded material by numerical weld g computer simulation. Investigations of residual stresses are important for developing optimal welding techniques. (authors)

Tomographic measurement of femtosecond-laser induced stress changes in optical fibers

International Nuclear Information System (INIS)

Duerr, F.; Limberger, H.G.; Salathe, R.P.; Hindle, F.; Douay, M.; Fertein, E.; Przygodzki, C.

2004-01-01

The tomographic measurement of the residual stress profile in femtosecond-laser irradiated standard SMF-28 germanium-doped telecommunication fiber is demonstrated. The fiber is irradiated with weakly focused pulses to realize long-period fiber gratings. In the irradiated grating regions, an asymmetrical increase in axial core stress up to 6.2 kg/mm2 is found. The increase in stress is attributed to a densification of the irradiated glass matrix. The stress-induced anisotropic index distribution is calculated and related to the absolute index change in the irradiated regions

In situ stress measurement with the new LVDT - Cell - method description and verification

International Nuclear Information System (INIS)

Hakala, M.; Christiansson, R.; Martin, D.; Siren, T.; Kemppainen, K.

2013-11-01

Posiva Oy and SKB (Svensk Kaernbraenslehantering AB) tested the suitability a new LVDT-cell (Linear Variable Differential Transducer cell) to measure the induced stresses in the vicinity of an excavated surface and further to use these results to interpret the in situ state of stress. It utilises the overcoring methodology, measuring the radial convergence of four diameters using eight LVDTs, and is similar in concept to the USBM-gauge. A 127 mm diameter pilot-hole is required and the overcore diameter is 200 mm. The minimum overcoring length is 350 mm, and hence a compact drill can be utilised. Extensive testing of the LVDT-cell shows it to be robust and suitable for use in an underground environment. Sensitivity tests also show that the cell can withstand a range of operating conditions and still provide acceptable results. The in situ stress at the measurement location can be solved by numerical inversion using the results of at least three overcoring measurements around the three-dimensional tunnel section. The large dimensions of the measurement tool and the ability to utilise multiple measurements at various locations in a tunnel section, provides flexibility in selecting an appropriate rock mass volume. Because the inversion technique relies on knowing the exact location of the measurements and the geometry profile of the tunnel, modern survey techniques such as Lidar or photogrammetric technology should be used. Checks using traditional surveying techniques should also be used to ensure adequate survey resolution, specially in case of sidecoring measurements. To evaluate the suitability of the LVDT-cell to provide the in situ state of stress, tests were carried out in the drill-and-blast TASS tunnel and TBM tunnel at the Aespoe Hard Rock Laboratory in Sweden. The state of stress established using the LVDT-cell was in agreement with the state of stress established previously using traditional overcoring and hydraulic fracturing methods. In this study, the

In situ stress measurement with the new LVDT - Cell - method description and verification

Energy Technology Data Exchange (ETDEWEB)

Hakala, M. [KMS Hakala Oy, Nokia (Finland); Christiansson, R. [Svensk Kaernbraenslehantering AB, Stockholm (Sweden); Martin, D. [Univ. of Alberta, Edmonton (Canada); Siren, T.; Kemppainen, K.

2013-11-15

Posiva Oy and SKB (Svensk Kaernbraenslehantering AB) tested the suitability a new LVDT-cell (Linear Variable Differential Transducer cell) to measure the induced stresses in the vicinity of an excavated surface and further to use these results to interpret the in situ state of stress. It utilises the overcoring methodology, measuring the radial convergence of four diameters using eight LVDTs, and is similar in concept to the USBM-gauge. A 127 mm diameter pilot-hole is required and the overcore diameter is 200 mm. The minimum overcoring length is 350 mm, and hence a compact drill can be utilised. Extensive testing of the LVDT-cell shows it to be robust and suitable for use in an underground environment. Sensitivity tests also show that the cell can withstand a range of operating conditions and still provide acceptable results. The in situ stress at the measurement location can be solved by numerical inversion using the results of at least three overcoring measurements around the three-dimensional tunnel section. The large dimensions of the measurement tool and the ability to utilise multiple measurements at various locations in a tunnel section, provides flexibility in selecting an appropriate rock mass volume. Because the inversion technique relies on knowing the exact location of the measurements and the geometry profile of the tunnel, modern survey techniques such as Lidar or photogrammetric technology should be used. Checks using traditional surveying techniques should also be used to ensure adequate survey resolution, specially in case of sidecoring measurements. To evaluate the suitability of the LVDT-cell to provide the in situ state of stress, tests were carried out in the drill-and-blast TASS tunnel and TBM tunnel at the Aespoe Hard Rock Laboratory in Sweden. The state of stress established using the LVDT-cell was in agreement with the state of stress established previously using traditional overcoring and hydraulic fracturing methods. In this study, the

Study of the effect of the stress on CdTe nuclear detectors

International Nuclear Information System (INIS)

Ayoub, M.; Radley, I.; Mullins, J. T.; Hage-Ali, M.

2013-01-01

CdTe detectors are commonly used for X and γ ray applications. The performance of these detectors is strongly affected by different types of mechanical stress; such as that caused by differential expansion between the semiconductor and its intimate metallic contacts and that caused by applied pressure during the bonding process. The aim of this work was to study the effects of stress on the performance of CdTe detectors. A difference in expansion coefficients induces transverse stress under the metallic contact, while contact pressure induces longitudinal stress. These stresses have been simulated by applying known static pressures. For the longitudinal case, the pressure was applied directly to the metallic contact; while in the transverse case, it was applied to the side. We have studied the effect of longitudinal and transverse stresses on the electrical characteristics including leakage current measurements and γ-ray detection performance. We have also investigated induced defects, their nature, activation energies, cross sections, and concentrations under the applied stress by using photo-induced current transient spectroscopy and thermoelectric effect spectroscopy techniques. The operational stress limit is also given

Study of the effect of the stress on CdTe nuclear detectors

Energy Technology Data Exchange (ETDEWEB)

Ayoub, M.; Radley, I.; Mullins, J. T. [Kromek, Thomas Wright way, TS21 3FD, Sedgefield, County Durham (United Kingdom); Hage-Ali, M. [CLEA, Airport road, Beirut (Lebanon)

2013-09-14

CdTe detectors are commonly used for X and γ ray applications. The performance of these detectors is strongly affected by different types of mechanical stress; such as that caused by differential expansion between the semiconductor and its intimate metallic contacts and that caused by applied pressure during the bonding process. The aim of this work was to study the effects of stress on the performance of CdTe detectors. A difference in expansion coefficients induces transverse stress under the metallic contact, while contact pressure induces longitudinal stress. These stresses have been simulated by applying known static pressures. For the longitudinal case, the pressure was applied directly to the metallic contact; while in the transverse case, it was applied to the side. We have studied the effect of longitudinal and transverse stresses on the electrical characteristics including leakage current measurements and γ-ray detection performance. We have also investigated induced defects, their nature, activation energies, cross sections, and concentrations under the applied stress by using photo-induced current transient spectroscopy and thermoelectric effect spectroscopy techniques. The operational stress limit is also given.

Residual stresses in non-symmetrical carbon-epoxy laminates

NARCIS (Netherlands)

Wijskamp, Sebastiaan; Akkerman, Remko; Lamers, E.A.D.; Martin, M.J.; Hahn, H.T.

2003-01-01

The curvature of unsymmetrical [0/90] laminates moulded from AS4/8552 uni-directional tape has been measured. A linear thermoelastic approach has been applied to predict the related residual stress state before demoulding, giving an estimate of the stress induced by polymerisation strain. The

Residual stress measurement of the jacket material for ITER coil by neutron diffraction

Energy Technology Data Exchange (ETDEWEB)

Tsuchiya, Yoshinori [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

1998-03-01

Nickel-Iron based super alloy INCOLOY 908 is used for the jacket of a central solenoid coil (CS coil) of the International Thermonuclear Experimental Reactor (ITER). INCOLOY 908, however, has a possibility of fracture due to Stress Accelerated Grain Boundary Oxidation (SAGBO) under a tensile residual stress beyond 200MPa. Therefore it is necessary to measure the residual stress of the jacket to avoid SAGBO. We performed residual stress measurement of the jacket by neutron diffraction using the neutron diffractometer for residual stress analysis (RESA) installed at JRR-3M in JAERI. A sample depth dependence of internal strain was obtained from the (111) plane spacing. A residual stress distribution was calculated from the strain using Young`s modulus and Poisson`s ratio that were evaluated by a tensile test with neutron diffraction. The result shows that the tensile residual stress exceeds 200MPa of the SAGBO condition in some regions inside the jacket. (author)

Applied use of cardiac and respiration measures: practical considerations and precautions.

Science.gov (United States)

Wilson, G F

1992-11-01

Cardiac and respiratory measures can be successfully applied to "real world" environments and these measures have certain advantages over both performance and subjective measures that are typically used to monitor operator state and workload. However, because of large differences between laboratory and "real world" environments one must utilize caution in directly applying laboratory data and theories to the day-to-day world environment. While most workers are highly over-trained in their jobs, laboratory subjects are often under-trained in the cognitive tasks that are used to study cognitive activity. It is possible that a substantial portion of experimental effects reported in laboratory studies is due to learning effects. In addition, relatively small changes in cardiac and respiration measures are reported to experimental manipulations in the laboratory while a much larger range of changes are reported in "real world" environments. These differences highlight questions about laboratory/real world similarities and the need to develop a database of actual work environment data. A third area of concern is the relative lack of control over the experimental situation that is the case with most applied research. The possible confounding of changes due to cognitive and physical activity levels is a major concern and strategies for overcoming these problems are suggested. The potential for valuable contributions by cardiac and respiratory measures to applied research make overcoming these difficulties worthwhile.

Neutron diffraction measurements of microstress and macrostress in composites

International Nuclear Information System (INIS)

Tanaka, Keisuke; Akiniwa, Yoshiaki

2001-01-01

For accurate stress measurements, precise values of the diffraction elastic constant (DEC) is required. The theoretical prediction of DEC of engineering materials on the basis of the self-consistent model agreed well with the experimental results of sintered alumina with various porosities. From the experimental results of DEC of sintered silicon nitride, the elastic anisotropy of single crystals of β-silicon nitride was estimated with the simplex method. The phase stress measured in the matrix and SiC particles of composite subjected to the applied stress agreed well with the theoretical prediction. The macrostress calculated from the phase stress by using the rule of mixture was equal to the applied stress. The measured values of the thermal residual stress in ceramic composites of alumina mixed with various volume fractions of zirconia agreed well with the theoretical prediction based on Eshelby's inclusion model. (author)

Flexural Capability of Patterned Transparent Conductive Substrate by Performing Electrical Measurements and Stress Simulations

Directory of Open Access Journals (Sweden)

Chang-Chun Lee

2016-10-01

Full Text Available The suitability of stacked thin films for next-generation display technology was analyzed based on their properties and geometrical designs to evaluate the mechanical reliability of transparent conducting thin films utilized in flexural displays. In general, the high bending stress induced by various operation conditions is a major concern regarding the mechanical reliability of indium–tin–oxide (ITO films deposited on polyethylene terephthalate (PET substrates; mechanical reliability is commonly used to estimate the flexibility of displays. However, the pattern effect is rarely investigated to estimate the mechanical reliability of ITO/PET films. Thus, this study examined the flexible content of patterned ITO/PET films with two different line widths by conducting bending tests and sheet resistance measurements. Moreover, a stress–strain simulation enabled by finite element analysis was performed on the patterned ITO/PET to explore the stress impact of stacked film structures under various levels of flexural load. Results show that the design of the ITO/PET film can be applied in developing mechanically reliable flexible electronics.

Predictions and measurements of residual stress in repair welds in plates

Energy Technology Data Exchange (ETDEWEB)

Brown, T.B. [Mitsui Babcock Energy Limited, Technology and Engineering, Porterfield Road, Renfrew, PA4 8DJ, Scotland (United Kingdom)]. E-mail: bbrown@mitsuibabcock.com; Dauda, T.A. [Mitsui Babcock Energy Limited, Technology and Engineering, Porterfield Road, Renfrew, PA4 8DJ, Scotland (United Kingdom); Truman, C.E. [Department of Mechanical Engineering, University of Bristol, Bristol BS8 1TR, England (United Kingdom); Smith, D.J. [Department of Mechanical Engineering, University of Bristol, Bristol BS8 1TR (United Kingdom); Memhard, D. [Fraunhofer-Institut fuer Werkstoffmechanik, Freiburg (Germany); Pfeiffer, W. [Fraunhofer-Institut fuer Werkstoffmechanik, Freiburg (Germany)

2006-11-15

This paper presents the work, from the European Union FP-5 project ELIXIR, on a series of rectangular repair welds in P275 and S690 steels to validate the numerical modelling techniques used in the determination of the residual stresses generated during the repair process. The plates were 1,000 mm by 800 mm with thicknesses of 50 and 100 mm. The repair welds were 50%, 75% and 100% through the plate thickness. The repair welds were modelled using the finite element method to make predictions of the as-welded residual stress distributions. These predictions were compared with surface-strain measurements made on the parent plates during welding and found to be in good agreement. Through-thickness residual stress measurements were obtained from the test plates through, and local to, the weld repairs using the deep hole drilling technique. Comparisons between the measurements and the finite element predictions generally showed good agreement, thus providing confidence in the method.

Predictions and measurements of residual stress in repair welds in plates

International Nuclear Information System (INIS)

Brown, T.B.; Dauda, T.A.; Truman, C.E.; Smith, D.J.; Memhard, D.; Pfeiffer, W.

2006-01-01

This paper presents the work, from the European Union FP-5 project ELIXIR, on a series of rectangular repair welds in P275 and S690 steels to validate the numerical modelling techniques used in the determination of the residual stresses generated during the repair process. The plates were 1,000 mm by 800 mm with thicknesses of 50 and 100 mm. The repair welds were 50%, 75% and 100% through the plate thickness. The repair welds were modelled using the finite element method to make predictions of the as-welded residual stress distributions. These predictions were compared with surface-strain measurements made on the parent plates during welding and found to be in good agreement. Through-thickness residual stress measurements were obtained from the test plates through, and local to, the weld repairs using the deep hole drilling technique. Comparisons between the measurements and the finite element predictions generally showed good agreement, thus providing confidence in the method

Design of specimen for weld residual stress simulation

International Nuclear Information System (INIS)

Kim, Jin Weon; Park, Jong Sun; Lee, Kyung Soo

2008-01-01

The objective of this study is to design a laboratory specimen for simulating residual stress of circumferential butt welding of pipe. Specimen type and method for residual stress generation were proposed based on the review of prior studies and parametric finite element simulation. To prove the proposed specimen type and loading method, the residual stress was generated using the designed specimen by applying proposed method and was measured. The measured residual stress using X-ray diffraction reasonably agreed with the results of finite element simulation considered in the specimen design. Comparison of residual strains measured at several locations of specimen and given by finite element simulation also showed good agreement. Therefore, it is indicated that the designed specimen can reasonably simulate the residual stress of circumferential butt welding of pipe

Measurement of Young’s modulus and residual stress of atomic layer deposited Al2O3 and Pt thin films

Science.gov (United States)

Purkl, Fabian; Daus, Alwin; English, Timothy S.; Provine, J.; Feyh, Ando; Urban, Gerald; Kenny, Thomas W.

2017-08-01

The accurate measurement of mechanical properties of thin films is required for the design of reliable nano/micro-electromechanical devices but is increasingly challenging for thicknesses approaching a few nanometers. We apply a combination of resonant and static mechanical test structures to measure elastic constants and residual stresses of 8-27 nm thick Al2O3 and Pt layers which have been fabricated through atomic layer deposition. Young’s modulus of poly-crystalline Pt films was found to be reduced by less than 15% compared to the bulk value, whereas for amorphous Al2O3 it was reduced to about half of its bulk value. We observed no discernible dependence of the elastic constant on thickness or deposition method for Pt, but the use of plasma-enhanced atomic layer deposition was found to increase Young’s modulus of Al2O3 by 10% compared to a thermal atomic layer deposition. As deposited, the Al2O3 layers had an average tensile residual stress of 131 MPa. The stress was found to be higher for thinner layers and layers deposited without the help of a remote plasma. No residual stress values could be extracted for Pt due to insufficient adhesion of the film without an underlying layer to promote nucleation.

Rock stress measurements in the Grimsel Underground Rock Laboratory and their geological interpretation

International Nuclear Information System (INIS)

Braeuer, V.; Heusermann, S.; Pahl, A.

1989-01-01

Rock stress is being studied as part of the Swiss-German cooperation between the National Cooperative for the Storage of Radioactive Waste (NAGRA), the Research Centre for Environmental Sciences (GSF), and the Federal Institute for Geosciences and Natural Resources (BGR) in the Grimsel Rock Laboratory in Switzerland. Several methods and various equipment for measuring rock stress have been developed and tested in an approximately 200-m borehole drilled from a gallery at a depth of 450 m. The measurements were made continually during overcoring; the data were recorded and processed in a computer located downhole or outside the borehole. The results of the overcoring tests and of frac tests indicate a principle horizontal stress of 25-40 MPa, directed mainly NW-SE. Detailed geological mapping shows relationships between stress and rock structure. A zone of nearly unfractured rock exhibits an increase in stress and a change in stress direction. (orig.)

Transactional stress and coping theory in accounting for psychological states measures

Directory of Open Access Journals (Sweden)

V. Buško

2007-08-01

Full Text Available The paper examines a relative predictive value of some stable individual attributes and the processes of cognitive appraisals and coping with stress in accounting for specific components of anxiety state measures. Self-report instruments for the measurement of selected psychological constructs, i.e. perceived incompetence, externality, stress intensity and duration, situation-specific coping strategies, and the two anxiety state components, were taken in a sample of 449 male military basics trainees, ranging in age from 18-27. Hierarchical multiple regression analyses showed that the set of predictors employed could account for statistically, as well as theoretically and practically a significant part of variance in cognitive anxiety component (45,5%, and in visceral-emotional component (32,2% of the anxiety state. The extent of anxiety reactions assessed by both scales could primarily be explained by general perception of personal incompetence, as a relatively stable dimension of general self-concept. Of the ways of coping examined, reinterpretation of stressful events was the only strategy contributing to low level, whereas passivization, wishful thinking, and seeking social support contributed to higher levels of anxiety measured by both scales. The results give partial support to the basic hypotheses on the mediating role of coping in the relationships among particular components of the stress and coping models.

Four-point bend apparatus for in situ micro-Raman stress measurements

Science.gov (United States)

Ward, Shawn H.; Mann, Adrian B.

2018-06-01

A device for in situ use with a micro-Raman microscope to determine stress from the Raman peak position was designed and validated. The device is a four-point bend machine with a micro-stepping motor and load cell, allowing for fine movement and accurate readings of the applied force. The machine has a small footprint and easily fits on most optical microscope stages. The results obtained from silicon are in good agreement with published literature values for the linear relationship between stress and peak position for the 520.8 cm‑1 Raman peak. The device was used to examine 4H–SiC and a good linear relationship was found between the 798 cm‑1 Raman peak position and stress, with the proportionality coefficient being close to the theoretical value of 0.0025. The 777 cm‑1 Raman peak also showed a linear dependence on stress, but the dependence was not as strong. The device examines both the tensile and compressive sides of the beam in bending, granting the potential for many materials and crystal orientations to be examined.

Residual stress improvement in multi-layer welded plates using water-shower cooling during welding process

International Nuclear Information System (INIS)

Yanagida, Nobuyoshi; Koide, Hiroo

2006-01-01

To reduce tensile residual stress in a welded region, we developed a new welding method that applies a water-shower behind the welding torch. When this method is applied to welding of austenitic stainless steel plates, cooling conditions mainly determine how much the residual stress can be reduced. To determine the conditions, we first used FEM to evaluate the effects of interpass temperature on the residual stress. And we found effective conditions for reducing tensile residual stress. To verify the validity of the conditions, specimens welded with or without water shower cooling were manufactured. Residual stresses of the specimens were experimentally measured. It was found that tensile residual stresses were generated on the surface of the welds and those were reduced in the case that the water-shower was applied. These measurement results agree well with the FEM analyses. It can therefore be concluded that the water-shower cooling during welding is appropriate for reducing tensile residual stress in austenitic stainless steel welding. (author)

An in-fiber Bragg grating sensor for contact force and stress measurements in articular joints

International Nuclear Information System (INIS)

Dennison, Christopher R; Wild, Peter M; Wilson, David R; Gilbart, Michael K

2010-01-01

We present an in-fiber Bragg grating-based sensor (240 µm diameter) for contact force/stress measurements in articular joints. The contact force sensor and another Bragg grating-based pressure sensor (400 µm diameter) are used to conduct the first simultaneous measurements of contact force/stress and fluid pressure in intact cadaveric human hips. The contact force/stress sensor addresses limitations associated with stress-sensitive films, the current standard tools for contact measurements in joints, including cartilage modulus-dependent sensitivity of films and the necessity to remove biomechanically relevant anatomy to implant the films. Because stress-sensitive films require removal of anatomy, it has been impossible to validate the mechanical rationale underlying preventive or corrective surgeries, which repair these anatomies, by conducting simultaneous stress and pressure measurements in intact hips. Methods are presented to insert the Bragg grating-based sensors into the joint, while relevant anatomy is left largely intact. Sensor performance is predicted using numerical models and the predicted sensitivity is verified through experimental calibrations. Contact force/stress and pressure measurements in cadaveric joints exhibited repeatability. With further validation, the Bragg grating-based sensors could be used to study the currently unknown relationships between contact forces and pressures in both healthy and degenerated joints

Raman microprobe measurements of stress in ion implanted materials

Energy Technology Data Exchange (ETDEWEB)

Nugent, K.W.; Prawer, S.; Weiser, P.S.; Dooley, S.P. [Melbourne Univ., Parkville, VIC (Australia). School of Physics

1993-12-31

Raman microprobe measurements of ion implanted diamond and silicon have shown significant shifts in the Raman line due to stresses in the materials. The Raman line shifts to higher energy if the stress is compressive and to lower energy for tensile stress{sup 1}. The silicon sample was implanted in a 60 {mu}m square with 2.56 x 10{sup 17} ions per square centimeter of 2 MeV Helium. This led to the formation of raised squares with the top 370mm above the original surface. In Raman studies of silicon using visible light, the depth of penetration of the laser beam into the sample is much less than one micron. It was found that the Raman line is due to the silicon overlying the damage region. The diamond sample was implanted with 2 x 10{sup 15} ions per square centimeter of 2.8 MeV carbon. It was concluded that the Raman spectrum could provide information concerning both the magnitude and the direction of stress in an ion implanted sample. It was possible in some cases to determine whether the stress direction is parallel or perpendicular to the sample surface. 1 refs., 2 figs.

Raman microprobe measurements of stress in ion implanted materials

Energy Technology Data Exchange (ETDEWEB)

Nugent, K W; Prawer, S; Weiser, P S; Dooley, S P [Melbourne Univ., Parkville, VIC (Australia). School of Physics

1994-12-31

Raman microprobe measurements of ion implanted diamond and silicon have shown significant shifts in the Raman line due to stresses in the materials. The Raman line shifts to higher energy if the stress is compressive and to lower energy for tensile stress{sup 1}. The silicon sample was implanted in a 60 {mu}m square with 2.56 x 10{sup 17} ions per square centimeter of 2 MeV Helium. This led to the formation of raised squares with the top 370mm above the original surface. In Raman studies of silicon using visible light, the depth of penetration of the laser beam into the sample is much less than one micron. It was found that the Raman line is due to the silicon overlying the damage region. The diamond sample was implanted with 2 x 10{sup 15} ions per square centimeter of 2.8 MeV carbon. It was concluded that the Raman spectrum could provide information concerning both the magnitude and the direction of stress in an ion implanted sample. It was possible in some cases to determine whether the stress direction is parallel or perpendicular to the sample surface. 1 refs., 2 figs.

Direct measurement of wall shear stress in a reattaching flow with a photonic sensor

International Nuclear Information System (INIS)

Ayaz, U K; Ioppolo, T; Ötügen, M V

2013-01-01

Wall shear stress measurements are carried out in a planar backward-facing step flow using a micro-optical sensor. The sensor is essentially a floating element system and measures the shear stress directly. The transduction method to measure the floating element deflection is based on the whispering gallery optical mode (WGM) shifts of a dielectric microsphere. This method is capable of measuring floating element displacements of the order of a nanometer. The floating element surface is circular with a diameter of ∼960 µm, which is part of a beam that is in contact with the dielectric microsphere. The sensor is calibrated for shear stress as well as pressure sensitivity yielding 7.3 pm Pa −1 and 0.0236 pm Pa −1 for shear stress and pressure sensitivity, respectively. Hence, the contribution by the wall pressure is less than two orders of magnitude smaller than that of shear stress. Measurements are made for a Reynolds number range of 2000–5000 extending to 18 step heights from the step face. The results are in good agreement with those of earlier reports. An analysis is also carried out to evaluate the performance of the WGM sensor including measurement sensitivity and bandwidth. (paper)

Evaluation and upgrading of records of stress measurement data in the mining industry.

CSIR Research Space (South Africa)

Stacey, TR

1998-06-01

Full Text Available to tectonic inversion, Proc. Centennial Geocongress (1995), ed J.M.Barton Jnr and Y.E.Copperthwaite, Geological Society of South Africa, pp 452- 455. Gay, N.C. 1972. Virgin rock stresses at Doornfontein Gold Mine, Carletonville, South Africa, Journal... of Geology, Vol 80, pp 61-80. Gay, N.C. 1975. In-situ stress measurements in Southern Africa, Tectonophysics, Vol 29, pp 447-459. Handley, M.F. 1996. In-situ stress measurements taken near SVC raisebore on 109 level at Western Deep Levels Limited South...

2D magnetization of grain-oriented 3%-Si steel under uniaxial stress

International Nuclear Information System (INIS)

Permiakov, V.; Dupre, L.; Pulnikov, A.; Melkebeek, J.

2005-01-01

Magnetization in electrical steels is strongly affected by mechanical stress. The stress dependence of magnetic properties of non-oriented steels has been studied at one- and two-dimensional magnetization. This paper deals with the stress effect on one- and two-dimensional magnetization in grain-oriented 3%-Si steel. The special magnetic measurements system is applied to combine uniaxial stress and 2D magnetic measurements. The uniaxial stress ranges from 10 MPa compressive stress to 100 MPa tensile stress. A domain theory is a suitable tool for prediction and a physical explanation of stress dependency in grain-oriented steel

Internal Stress Distribution Measurement of TIG Welded SUS304 Samples Using Neutron Diffraction Technique

Science.gov (United States)

Muslih, M. Refai; Sumirat, I.; Sairun; Purwanta

2008-03-01

The distribution of residual stress of SUS304 samples that were undergone TIG welding process with four different electric currents has been measured. The welding has been done in the middle part of the samples that was previously grooved by milling machine. Before they were welded the samples were annealed at 650 degree Celsius for one hour. The annealing process was done to eliminate residual stress generated by grooving process so that the residual stress within the samples was merely produced from welding process. The calculation of distribution of residual stress was carried out by measuring the strains within crystal planes of Fe(220) SUS304. Strain, Young modulus, and Poisson ratio of Fe(220) SUS304 were measured using DN1-M neutron diffractometer. Young modulus and Poisson ratio of Fe(220) SUS304 sample were measured in-situ. The result of calculations showed that distribution of residual stress of SUS304 in the vicinity of welded area is influenced both by treatments given at the samples-making process and by the electric current used during welding process.

Association between objectively measured physical activity, chronic stress and leukocyte telomere length.

Science.gov (United States)

von Känel, Roland; Bruwer, Erna J; Hamer, Mark; de Ridder, J Hans; Malan, Leoné

2017-10-01

Physical activity (PA) attenuates chronic stress and age-related and cardiovascular disease risks, whereby potentially slowing telomere shortening. We aimed to study the association between seven-day objectively measured habitual PA, chronic stress and leukocyte telomere length. Study participants were African (N.=96) and Caucasian (N.=107) school teachers of the Sympathetic activity and Ambulatory Blood Pressure in Africans study. All lifestyle characteristics (including PA) were objectively measured. The general health questionnaire and serum cortisol were assessed as psychological and physical measures of chronic stress. Leukocyte telomere length was measured using the quantitative real-time polymerase chain reaction. Africans had significantly shorter telomeres (Pstress or telomere length. However, more time spent with light intensity PA time was significantly and independently correlated with lower waist circumference (r=-0.21, P=0.004); in turn, greater waist circumference was significantly associated shorter telomeres (β=-0.17 [-0.30, -0.03], P=0.017). Habitual PA of different intensity was not directly associated with markers of chronic stress and leukocyte telomere length in this biethnic cohort. However, our findings suggest that light intensity PA could contribute to lowered age-related disease risk and healthy ageing by facilitating maintenance of a normal waist circumference.

Comparison of neutron and synchrotron diffraction measurements of residual stress in bead-on-plate weldments

International Nuclear Information System (INIS)

Paradowska, A.M.; Price, J.W.; Finlayson, T.R.; Lienert, U.; Ibrahim, R.

2010-01-01

This paper explores the use of neutron and synchrotron diffractions for the evaluation of residual stresses in welded components. It has been shown that it is possible to achieve very good agreement between the two independent diffraction techniques. This study shows the significance of the weld start and end sites on the residual strain/stress distribution. Quantitative evaluation of the residual stress development process for multibead weldments has been presented. Some measurements were also taken before and after postweld stress relieving to establish the reduction and redistribution of the residual stress. The detailed measurements of residual stress around the weld achieved in this work significantly improve the knowledge and understanding of residual stress in welded components.

Stress testing of electrically active FlexMEAs with simultaneous electrical recording in fluidic environment: Introduction of a new measurement setup

Science.gov (United States)

Westerhausen, Markus; Martin, Tanja; Kappel, Marcel; Hofmann, Boris

2018-02-01

We present a measurement setup consisting of two fluid-filled pressure chambers to mimic the mechanical stress likely to that of small body movements on biomedical flexible micro-electrode arrays for the analysis of various degradation mechanisms. Our main goal was the simulation of micro-motions in fluid conditions, while maintaining an electric access to the device. These micro-motions would be likely to those occurring in the human body caused by the intracranial pressure in magnitudes of 7-25 mmHg, which translates to a fluid pressure of 9-33 mbar. Furthermore, severe mechanical stress can be administered to the samples under the previously mentioned environment. Therefore, a flexible, polyimide-based sample with various metal test structures was fabricated and analyzed in the presented measurement setup. A comparison of the elongation of the sample's surface as a function of the applied hydrostatic pressure is given with computer simulations.

Application of x-ray method for measuring internal stress in the gear teeth surface layer

International Nuclear Information System (INIS)

Zaborowski, T.

1996-01-01

This paper presents the methodics of the internal stress measurements concerning cylindrical gear teeth of involute profile. There are the method selected, relation between stress and strain presented and conditions of investigation discussed in the study, including preparation of samples for investigation and conditions of the strain measurement. Exemplifying results of stress measurements for teeth of gears made of 4OH steel are shown. Suitability of the developed investigation method is indicated

Applied potential tomography. A new noninvasive technique for measuring gastric emptying

International Nuclear Information System (INIS)

Avill, R.; Mangnall, Y.F.; Bird, N.C.; Brown, B.H.; Barber, D.C.; Seagar, A.D.; Johnson, A.G.; Read, N.W.

1987-01-01

Applied potential tomography is a new, noninvasive technique that yields sequential images of the resistivity of gastric contents after subjects have ingested a liquid or semisolid meal. This study validates the technique as a means of measuring gastric emptying. Experiments in vitro showed an excellent correlation between measurements of resistivity and either the square of the radius of a glass rod or the volume of water in a spherical balloon when both were placed in an oval tank containing saline. Altering the lateral position of the rod in the tank did not alter the values obtained. Images of abdominal resistivity were also directly correlated with the volume of air in a gastric balloon. Profiles of gastric emptying of liquid meals obtained using applied potential tomography were very similar to those obtained using scintigraphy or dye dilution techniques, provided that acid secretion was inhibited by cimetidine. Profiles of emptying of a mashed potato meal using applied potential tomography were also very similar to those obtained by scintigraphy. Measurements of the emptying of a liquid meal from the stomach were reproducible if acid secretion was inhibited by cimetidine. Thus, applied potential tomography is an accurate and reproducible method of measuring gastric emptying of liquids and particulate food. It is inexpensive, well tolerated, easy to use, and ideally suited for multiple studies in patients, even those who are pregnant

Applied potential tomography. A new noninvasive technique for measuring gastric emptying

Energy Technology Data Exchange (ETDEWEB)

Avill, R.; Mangnall, Y.F.; Bird, N.C.; Brown, B.H.; Barber, D.C.; Seagar, A.D.; Johnson, A.G.; Read, N.W.

1987-04-01

Applied potential tomography is a new, noninvasive technique that yields sequential images of the resistivity of gastric contents after subjects have ingested a liquid or semisolid meal. This study validates the technique as a means of measuring gastric emptying. Experiments in vitro showed an excellent correlation between measurements of resistivity and either the square of the radius of a glass rod or the volume of water in a spherical balloon when both were placed in an oval tank containing saline. Altering the lateral position of the rod in the tank did not alter the values obtained. Images of abdominal resistivity were also directly correlated with the volume of air in a gastric balloon. Profiles of gastric emptying of liquid meals obtained using applied potential tomography were very similar to those obtained using scintigraphy or dye dilution techniques, provided that acid secretion was inhibited by cimetidine. Profiles of emptying of a mashed potato meal using applied potential tomography were also very similar to those obtained by scintigraphy. Measurements of the emptying of a liquid meal from the stomach were reproducible if acid secretion was inhibited by cimetidine. Thus, applied potential tomography is an accurate and reproducible method of measuring gastric emptying of liquids and particulate food. It is inexpensive, well tolerated, easy to use, and ideally suited for multiple studies in patients, even those who are pregnant.

Children of Trauma: Stressful Life Events and Their Effects on Children and Adolescents. International Universities Press Stress and Health Series. Monograph 8.

Science.gov (United States)

Miller, Thomas W., Ed.

Clinical theory and practice models are provided along with current concepts in diagnosis and treatment. Theoretical formulations, hypotheses, issues, and implications related to life stress measurement are addressed and applied to medical and mental health concerns. Contributions include: (1) "Stress Response and Adaptation in Children:…

Measurements of skin friction in water using surface stress sensitive films

International Nuclear Information System (INIS)

Crafton, J W; Fonov, S D; Jones, E G; Goss, L P; Forlines, R A; Fontaine, A

2008-01-01

The measurement of skin friction on hydrodynamic surfaces is of significant value for the design of advanced naval technology, particularly at high Reynolds numbers. Here we report on the development of a new sensor for measurement of skin friction and pressure that operates in both air and water. This sensor is based on an elastic polymer film that deforms under the action of applied normal and tangential loads. Skin friction and pressure gradients are determined by monitoring these deformations and then solving an inverse problem using a finite element model of the elastic film. This technique is known as surface stress sensitive films. In this paper, we describe the development of a sensor package specifically designed for two-dimensional skin friction measurements at a single point. The package has been developed with the goal of making two-dimensional measurements of skin friction in water. Quantitative measurements of skin friction are performed on a high Reynolds number turbulent boundary layer in the 12 inch water tunnel at Penn State University. These skin friction measurements are verified by comparing them to measurements obtained with a drag plate as well as by performing two-dimensional velocity measurements above the sensor using a laser Doppler velocimetry system. The results indicate that the sensor skin friction measurements are accurate to better than 5% and repeatable to better than 2%. The directional sensitivity of the sensor is demonstrated by positioning the sensor at several orientations to the flow. A final interesting feature of this sensor is that it is sensitive to pressure gradients, not to static pressure changes. This feature should prove useful for monitoring the skin friction on a seafaring vessel as the operating depth is changed

Numerical analysis of residual stresses in preforms of stress applying part for PANDA-type polarization maintaining optical fibers in view of technological imperfections of the doped zone geometry

Science.gov (United States)

Trufanov, Aleksandr N.; Trufanov, Nikolay A.; Semenov, Nikita V.

2016-09-01

The experimental data analysis of the stress applying rod section geometry for the PANDA-type polarization maintaining optical fiber has been performed. The dependencies of the change in the radial dimensions of the preform and the doping boundary on the angular coordinate have been obtained. The original algorithm of experimental data statistic analysis, which enables determination of the specimens' characteristic form of section, has been described. The influence of actual doped zone geometry on the residual stress fields formed during the stress rod preform fabrication has been investigated. It has been established that the deviation of the boundary between pure silica and the doped zone from the circular shape results in dissymmetry and local concentrations of the residual stress fields along the section, which can cause preforms destruction at high degrees of doping. The observed geometry deviations of up to 10% lead to the increase of the maximum stress intensity value by over 20%.

Design and Lab Experiment of a Stress Detection Service based on Mouse Movements

OpenAIRE

Kowatsch, Tobias; Wahle, Fabian; Filler, Andreas

2017-01-01

Workplace stress can negatively affect the health condition of employees and with it, the performance of organizations. Although there exist approaches to measure work-related stress, two major limitations are the low resolution of stress data and its obtrusive measurement. The current work applies design science research with the goal to design, implement and evaluate a Stress Detection Service (SDS) that senses the degree of work-related stress solely based on mouse movements of knowledge w...

Measurement of stress strain and vibrational properties of tendons

Science.gov (United States)

Revel, Gian Marco; Scalise, Alessandro; Scalise, Lorenzo

2003-08-01

The authors present a new non-intrusive experimental procedure based on laser techniques for the measurement of mechanical properties of tendons. The procedure is based on the measurement of the first resonance frequency of the tendon by laser Doppler vibrometry during in vitro tensile experiments, with the final aim of establishing a measurement procedure to perform the mechanical characterization of tendons by extracting parameters such as the resonance frequency, also achievable during in vivo investigation. The experimental procedure is reported, taking into account the need to simulate the physiological conditions of the Achilles tendon, and the measurement technique used for the non-invasive determination of tendon cross-sectional area during tensile vibration tests at different load levels is described. The test procedure is based on a tensile machine, which measures longitudinal tendons undergoing controlled load conditions. Cross-sectional area is measured using a new non-contact procedure for the measurement of tendon perimeter (repeatability of 99% and accuracy of 2%). For each loading condition, vibration resonance frequency and damping, cross-sectional area and tensile force are measured, allowing thus a mechanical characterization of the tendon. Tendon stress-strain curves are reported. Stress-strain curves have been correlated to the first vibration resonance frequency and damping of the tendon measured using a single-point laser Doppler vibrometer. Moreover, experimental results have been compared with a theoretical model of a vibrating cord showing discrepancies. In vitro tests are reported, demonstrating the validity of the method for the comparison of different aged rabbit tendons.

Report on televiewer log and stress measurements in core hole USW G-2, Nevada Test Site, October-November, 1982

International Nuclear Information System (INIS)

Stock, J.M.; Healy, J.H.; Hickman, S.H.

1984-01-01

Hydraulic fracturing stress measurements and a borehole televiewer log were obtained in hole USW G-2 at Yucca Mountain, Nevada, to depths of 1200 m. Results indicate that at the depths tested, the minimum ad maximum horizontal stresses are less than the vertical stress, corresponding to a normal faulting stress regime. Drilling-induced hydrofractures seen in the televiewer log imply a least horizontal principal stress direction of N 60 0 W to N 65 0 W. For reasonable values of the coefficient of friction, the magnitude of the least horizontal stress is close to the value at which slip would occur on preexisting faults of optimal orientation (strike N 25 0 E to N 30 0 E and dipping 60 0 to 67 0 ). The prominent drilling-induced fractures seen in the televiewer log are believed to have been caused by excess downhole pressures applied during drilling the hole. Many throughgoing fractures are also seen in the televiewer log; most of these are high angle, stringing N 10 0 E to N 40 0 E. These fractures show a general decrease in angle of dip with depth. Stress-induced wellbore breakouts are seen at depths below 1050 m. The average N 60 0 W azimuth of these breakouts agrees very closely with the N 60 0 W to N 65 0 W direction of least horizontal principal stress inferred from the drilling-induced hydrofracs. 19 references, 13 figures, 3 tables

Rock stress measurements in ONKALO underground characterisation facility at Olkiluoto at depth of 120 m

International Nuclear Information System (INIS)

Fecker, E.

2007-04-01

In November and December 2006 overcoring stress measurements have been conducted in the boreholes ONK-PP74, ONK-PP75 and ONK-PP77 in a niche of the access tunnel of the ONKALO underground characterisation facility at the Olkiluoto site. Measurements have been done using the CSIRO 3D stress measuring cell. This cell is one of the mostly used cells in the whole world for estimation of the state of stress in rock when doing the borehole measurements. The boreholes are at a depth of about 120 m under the ground surface. The rock where the measurements have been conducted is a foliated migmatitic gneiss (subtypes veined and diatexitic gneiss). Parallel to the overcoring measurements a glue test has been conducted in the laboratory to check the quality of the bonding of the stress cells to the rock. The result showed that the glue makes a good contact between the rock and the stress cell, but air bubbles, which have normally been observed within the glue and at the edges, proved this time to be disadvantageous. Normally such air bubbles have dimensions of about one millimetre, but sometimes certain bubbles may become notably bigger. In the ONKALO overcored probes sawn apart such air bubbles were found both in wet and dry probe conditions. In the test series eight stress measurements have been provided, three of them failed for technical reasons. At one of these three tests the glue has extruded too early, at the other two tests the overcoring was not conducted deep enough. At the remaining five tests in spite of the glue test results a calculation of the stress tensor could be made. Four of these five measurements can be seen as relatively successful. The results of these measurements show a major principal stress of 14.8 MPa in average, trending northwest - southeast, and with a dipping of 11 degrees in average. (orig.)

Reynolds-Stress and Triple-Product Models Applied to a Flow with Rotation and Curvature

Science.gov (United States)

Olsen, Michael E.

2016-01-01

Turbulence models, with increasing complexity, up to triple product terms, are applied to the flow in a rotating pipe. The rotating pipe is a challenging case for turbulence models as it contains significant rotational and curvature effects. The flow field starts with the classic fully developed pipe flow, with a stationary pipe wall. This well defined condition is then subjected to a section of pipe with a rotating wall. The rotating wall introduces a second velocity scale, and creates Reynolds shear stresses in the radial-circumferential and circumferential-axial planes. Furthermore, the wall rotation introduces a flow stabilization, and actually reduces the turbulent kinetic energy as the flow moves along the rotating wall section. It is shown in the present work that the Reynolds stress models are capable of predicting significant reduction in the turbulent kinetic energy, but triple product improves the predictions of the centerline turbulent kinetic energy, which is governed by convection, dissipation and transport terms, as the production terms vanish on the pipe axis.

Stress analysis and mitigation measures for floating pipeline

Science.gov (United States)

Wenpeng, Guo; Yuqing, Liu; Chao, Li

2017-03-01

Pipeline-floating is a kind of accident with contingency and uncertainty associated to natural gas pipeline occurring during rainy season, which is significantly harmful to the safety of pipeline. Treatment measures against pipeline floating accident are summarized in this paper on the basis of practical project cases. Stress states of pipeline upon floating are analyzed by means of Finite Element Calculation method. The effectiveness of prevention ways and subsequent mitigation measures upon pipeline-floating are verified for giving guidance to the mitigation of such accidents.

Measurement of probability distributions for internal stresses in dislocated crystals

Energy Technology Data Exchange (ETDEWEB)

Wilkinson, Angus J.; Tarleton, Edmund; Vilalta-Clemente, Arantxa; Collins, David M. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Jiang, Jun; Britton, T. Benjamin [Department of Materials, Imperial College London, Royal School of Mines, Exhibition Road, London SW7 2AZ (United Kingdom)

2014-11-03

Here, we analyse residual stress distributions obtained from various crystal systems using high resolution electron backscatter diffraction (EBSD) measurements. Histograms showing stress probability distributions exhibit tails extending to very high stress levels. We demonstrate that these extreme stress values are consistent with the functional form that should be expected for dislocated crystals. Analysis initially developed by Groma and co-workers for X-ray line profile analysis and based on the so-called “restricted second moment of the probability distribution” can be used to estimate the total dislocation density. The generality of the results are illustrated by application to three quite different systems, namely, face centred cubic Cu deformed in uniaxial tension, a body centred cubic steel deformed to larger strain by cold rolling, and hexagonal InAlN layers grown on misfitting sapphire and silicon carbide substrates.

The internal stress measurement the neutron diffraction bring happiness to your country

Energy Technology Data Exchange (ETDEWEB)

Minakawa, Nobuaki [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

2003-03-01

The neutron was discovered by Chadwick in 1932. The first reactor was constructed by the USA in 1942. After that, the research and development of reactors advanced. Numbers of reactors were constructed in Europe and in the US. The researches, which use the neutron, were performed actively and excellent results were obtained in wide fields. The penetrating power of the neutron and the neutron diffraction method began to attract attention for the application to the internal stress measurement, too. In Japan, the neutron diffractometer for the residual stress measurement exclusive was installed in the JRR-3M research reactor of JAERI in 1992, and the research was started. At present, we are using it for the stress measurements of the parts of aircrafts, railways, automobiles, buildings, machines, home electronics products and so on including nuclear reactors. Reliable science must be introduced in order to support safety and long life operation and to supply them at reasonable cost. Among the various scientific probes to find faults in materials, diffraction technique is used to measure the strain distribution in materials by observing the local changes of the distance between crystallographic planes and the stress distribution is computed to improve manufacturing processes. It is only neutron diffraction that can be used to measure the strain inside the materials. Here, I present an overview of the utilization of neutron scattering research for the industrial uses and the history of the neutron scattering research in JAERI briefly. (J.P.N.)

Measurement of the residual stress distribution in a thick pre-stretched aluminum plate

Science.gov (United States)

Yuan, S. X.; Li, X. Q.; M, S.; Zhang, Y. C.; Gong, Y. D.

2008-12-01

Thick pre-stretched aluminum alloy plates are widely used in aircraft, while machining distortion caused by initial residual stress release in thick plates is a common and serious problem. To reduce the distortion, the residual stress distribution in thick plate must be measured. According to the characteristics of the thick pre-stretched aluminum alloy plate, based the elastic mechanical theory, this article deduces the modified layer-removal strain method adapting two different strain situations, which are caused by tensile and compressive stress. To validate this method, the residual stresses distribution along the thick direction of plate 2D70T351 is measured by this method, it is shown that the new method deduced in this paper is simple and accurate, and is very useful in engineering.

Standard test method for verifying the alignment of X-Ray diffraction instrumentation for residual stress measurement

CERN Document Server

American Society for Testing and Materials. Philadelphia

2010-01-01

1.1 This test method covers the preparation and use of a flat stress-free test specimen for the purpose of checking the systematic error caused by instrument misalignment or sample positioning in X-ray diffraction residual stress measurement, or both. 1.2 This test method is applicable to apparatus intended for X-ray diffraction macroscopic residual stress measurement in polycrystalline samples employing measurement of a diffraction peak position in the high-back reflection region, and in which the θ, 2θ, and ψ rotation axes can be made to coincide (see Fig. 1). 1.3 This test method describes the use of iron powder which has been investigated in round-robin studies for the purpose of verifying the alignment of instrumentation intended for stress measurement in ferritic or martensitic steels. To verify instrument alignment prior to stress measurement in other metallic alloys and ceramics, powder having the same or lower diffraction angle as the material to be measured should be prepared in similar fashion...

Educational measurement for applied researchers theory into practice

CERN Document Server

Wu, Margaret; Jen, Tsung-Hau

2016-01-01

This book is a valuable read for a diverse group of researchers and practitioners who analyze assessment data and construct test instruments. It focuses on the use of classical test theory (CTT) and item response theory (IRT), which are often required in the fields of psychology (e.g. for measuring psychological traits), health (e.g. for measuring the severity of disorders), and education (e.g. for measuring student performance), and makes these analytical tools accessible to a broader audience. Having taught assessment subjects to students from diverse backgrounds for a number of years, the three authors have a wealth of experience in presenting educational measurement topics, in-depth concepts and applications in an accessible format. As such, the book addresses the needs of readers who use CTT and IRT in their work but do not necessarily have an extensive mathematical background. The book also sheds light on common misconceptions in applying measurement models, and presents an integrated approach to differ...

Report on achievements of research and development of a technology to apply human senses to measurements in fiscal 1994. 2. Main issue (Part 1 for research and development of a physiological effect measuring technology); 1994 nendo ningen kankaku keisoku oyo gijutsu no kekyu kaihatsu. 2. Honronhen (Seiriteki eikyo keisoku gijutsu no kenkyu kaihatsu)

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-03-01

This research and development was performed on (1) a composite physiological function measuring technology for stress measurement, (2) a contact-free skin temperature measuring technology, and (3) a stress indexing substance measuring technology. With regard to the subject (1), the target for the current fiscal year is to restructure a small restraint-free skin impedance measuring device into a practical device that can be used easily at working sites. In order to achieve the goal, electric power conservation and size reduction were moved forward by improving the circuit design, and stabilized measurement, in which the measurement algorithm is made more intelligent, was realized. With regard to the subject (2), the contact-free skin temperature measurement device having been structured by the previous fiscal year was given improvements in such parts as the infrared and visible image input, image processing, and data indication and sense volume estimation. With respect to the subject (3), the technology was established to measure such stress indexing substances as CS and CA from saliva. Positioning of CS and CA as the stress indexing substance was nearly completed. The stress indexing substance measuring device was tried of structuring the prototype A and prototype B applying the semi-micro specifications for an attempt of clearing the steps toward practically usable device. (NEDO)

Measurement accuracy of a stressed contact lens during its relaxation period

Science.gov (United States)

Compertore, David C.; Ignatovich, Filipp V.

2018-02-01

We examine the dioptric power and transmitted wavefront of a contact lens as it releases its handling stresses. Handling stresses are introduced as part of the contact lens loading process and are common across all contact lens measurement procedures and systems. The latest advances in vision correction require tighter quality control during the manufacturing of the contact lenses. The optical power of contact lenses is one of the critical characteristics for users. Power measurements are conducted in the hydrated state, where the lens is resting inside a solution-filled glass cuvette. In a typical approach, the contact lens must be subject to long settling times prior to any measurements. Alternatively, multiple measurements must be averaged. Apart from potential operator dependency of such approach, it is extremely time-consuming, and therefore it precludes higher rates of testing. Comprehensive knowledge about the settling process can be obtained by monitoring multiple parameters of the lens simultaneously. We have developed a system that combines co-aligned a Shack-Hartmann transmitted wavefront sensor and a time-domain low coherence interferometer to measure several optical and physical parameters (power, cylinder power, aberrations, center thickness, sagittal depth, and diameter) simultaneously. We monitor these parameters during the stress relaxation period and show correlations that can be used by manufacturers to devise methods for improved quality control procedures.

Ultrasound stress measurements for API X65 pipes; Avaliacao por ultra-som das tensoes impostas em tubo API X-65

Energy Technology Data Exchange (ETDEWEB)

Medeiros, Raimundo C.; Santos, Ramon Loback Medeiros [TRANSPETRO - PETROBRAS Transporte S.A., Rio de Janeiro, RJ (Brazil); Bittencourt, Marcelo S.Q.; Lamy, Carlos A. [Instituto de Engenharia Nuclear (IEN), Rio de Janeiro, RJ (Brazil); Donato, Guilherme V.P. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil)

2003-07-01

Risks of damages or even premature collapse of buried pipelines caused by their interaction with geologically unstable soils are well-established phenomena. Therefore, both monitoring and measurements of the actual loads transmitted by the soil to the pipeline are mandatory requirements, and define the necessity of developing new nondestructive techniques capable to carry out through evaluations of these loads in field. The aim of this paper has been placed on the presentation of a cutting-edge ultrasonic technology applied to stress measurements. To accomplish this purpose a series of ultrasonic tests were conducted on tensile specimens extracted from API 5L Grade X-65 steel pipe to determine its acoustic birefringence. The results have evidenced the acoustic birefringence to be a technique sufficiently consistent and, consequently, it shall be considered as a promising tool for the evaluation of the structural integrity of metallic structures in the near future. In addition, it was also observed that the use of this technique allows measuring the residual stress resulting from the pipe manufacturing process. (author)

Systematic Review of Uit Parameters on Residual Stresses of Sensitized AA5456 and Field Based Residual Stress Measurements for Predicting and Mitigating Stress Corrosion Cracking

Science.gov (United States)

2014-03-01

University Press, 2009, pp. 820–824. [30] S. Kou, Welding Metallurgy , 2nd ed. Hoboken, NJ: John Wiley and Sons, Inc., 2003. [31] M. N.James et al...around welds in aluminum ship structures both in the laboratory and in the field. Tensile residual stresses are often generated during welding and, in...mitigate and even reverse these tensile residual stresses. This research uses x-ray diffraction to measure residual stresses around welds in AA5456 before

Measurement of urethral closure function in women with stress urinary incontinence

DEFF Research Database (Denmark)

Klarskov, N; Scholfield, D; Soma, K

2009-01-01

, double-blind, placebo controlled, crossover study 17 women with stress urinary incontinence or mixed urinary incontinence received 4 mg esreboxetine or placebo for 7 to 9 days followed by a washout period before crossing over treatments. Urethral pressure reflectometry and urethral pressure profilometry......, and had a positive and clinically relevant effect on urethral closure function and symptoms of stress urinary incontinence....... esreboxetine patients had significantly fewer incontinence episodes and reported a treatment benefit (global impression of change) compared to placebo. CONCLUSIONS: The opening pressure measured with urethral pressure reflectometry was less variable compared to the parameters measured with urethral pressure...

A Method Using Optical Contactless Displacement Sensors to Measure Vibration Stress of Small-Bore Piping.

Science.gov (United States)

Maekawa, Akira; Tsuji, Takashi; Takahashi, Tsuneo; Noda, Michiyasu

2014-02-01

In nuclear power plants, vibration stress of piping is frequently evaluated to prevent fatigue failure. A simple and fast measurement method is attractive to evaluate many piping systems efficiently. In this study, a method to measure the vibration stress using optical contactless displacement sensors was proposed, the prototype instrument was developed, and the instrument practicality for the method was verified. In the proposed method, light emitting diodes (LEDs) were used as measurement sensors and the vibration stress was estimated by measuring the deformation geometry of the piping caused by oscillation, which was measured as the piping curvature radius. The method provided fast and simple vibration estimates for small-bore piping. Its verification and practicality were confirmed by vibration tests using a test pipe and mock-up piping. The stress measured by both the proposed method and an accurate conventional method using strain gauges were in agreement, and it was concluded that the proposed method could be used for actual plant piping systems.

Project of integrity assessment of flawed components with structural discontinuity (IAF). Data book for residual stress analysis in weld joint. Analysis model of dissimilar metal weld joint applied post weld heat treatment (PWHT)

International Nuclear Information System (INIS)

2012-12-01

Simplified Stress Intensity Factor Calculation. 1. Surface Crack on ICM Housing for Penetration in Reactor Vessel (JNES-RE-2012-0011). Example FEM analysis results, measurements and comparisons of them for residual stresses are described in the above 6 volumes of Data Book of Residual Stress Analysis in Weld Joint. And these analyses were performed with material properties up to high temperature which were obtained in IAF project. It is proposed that evaluation formulas for K of simple structures like a cylinder and plane are applied to calculate K of complex structures and comparisons with FEM analyses and described as an evidence of reasonability and conservativeness in the above Data Book of Simplified Stress Intensity Factor Calculation. However, the analysis models and conditions are described on condition of functions of specified analysis code. It is necessary to investigate references from activity reports of IAF project if another analysis code is applied. This report is described evaluations and conclusions about residual stresses around dissimilar metal weld applied PWHT, as follows; For clad flat plate and mock-up of stub-tube weld of BWR, residual stresses were analyzed by FEM and the results were compared with measured data. Stress reduction by PWHT was able to simulated, however improvement of accuracy of residual stress analysis was recommended. Parametric analyses were carried out and creep character of low alloy steel was significant impact on stress reduction by PWHT. (author)

Design and development of a new magnetic sensor for stress measurements

International Nuclear Information System (INIS)

Aggelopoulos, S

2016-01-01

This paper describes the design and the development of a new magnetic sensor for stress measurements using the magnetic Barkhausen noise and the magnetic permeability techniques in ferromagnetic steels. Both techniques together, become an important nondestructive technique, due to its exceptional material and stress characterization capabilities. The correlation of the two methods was investigated. Conclusions were derived based on the experimental results. (paper)

Measurement of lattice rotations and internal stresses in over one hundred individual grains during a stress-induced martensitic transformation

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Hachi Younes El

2015-01-01

Full Text Available To better understand the properties of polycrystals at a microscopic scale during cyclic mechanical loading we have measured the relationship between grain orientations, their positions inside the sample and their internal stresses. In this work, in-situ 3DXRD technique was performed on over hundred grains during the stress-induced martensitic transformation in a Cu-Al-Be shape memory alloy. Information about the position, orientation, and stress field was obtained for each austenitic grain. These results have been used to develop a procedure that allows automatic processing for a large number of grains, matching them during loading and leads to a quantitative stress field. A strong heterogeneity of stress state between the grains at the surface and in the volume is evident.

[Assessment of stress in childhood: Children's Daily Stress Inventory (Inventario Infantil de Estresores Cotidiano, IIEC)].

Science.gov (United States)

Trianes Torres, María Victoria; Blanca Mena, María José; Fernández Baena, Francisco J; Escobar Espejo, Milagros; Maldonado Montero, Enrique F; Muñoz Sánchez, Angela María

2009-11-01

The present study introduces the Children's Daily Stress Inventory (Inventario Infantil de Estresores Cotidianos, IIEC) as a measure that assesses daily stress in primary school children. The inventory was applied to a sample of 1094 primary school students. The final version includes 25 dichotomic items covering the areas of health, school/peers, and family. The score is obtained by adding the total of positive answers. Analyses of items, reliability and several external pieces of evidence of validity based on relations with other variables are presented. The results show adequate psychometric properties for the assessment of daily stress in children.

Relationship between the onset of depression and stress response measured by the Brief Job Stress Questionnaire among Japanese employees: a cohort study.

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Keiko Wada

Full Text Available BACKGROUND: The proportion of Japanese workers experiencing intense worry or stress during working life is in excess of 60%, and the incidence of psychiatric disorders and suicide due to psychological burden from work duties is increasing. To confirm whether the stress response measured by the Brief Job Stress Questionnaire (BJSQ can identify risk for depression, a cohort study was conducted to evaluate whether the stress response measured by BJSQ was associated with the onset of depression. METHODS: A total of 1,810 participants aged 20-70 years in 2005 completed the stress response of the BJSQ and were followed-up until August, 2007 by examining sick pay records. Depression was defined by a description in sick pay records that included "depression" or "depressive symptoms" as a reason for sick leave according to a physician's medical certificate. The participants were divided into quartiles (Ql, Q2, Q3, and Q4 according to the total stress response score of BJSQ at baseline. Furthermore, the participants were divided into a higher score category (Q4 and a lower score category (Q1-Q3. Risk ratios of the stress response of the BJSQ for onset of depression were calculated using a multivariable Cox proportional hazard model. RESULTS: Among 1,810 participants, 14 developed depression during a mean of 1.8 years of follow-up. The risk ratio was 2.96 (95% confidence interval [CI], 1.04-8.42, p for trend = 0.002 when the higher stress response score category of BJSQ was compared with the low stress response score category for sick leave due to depression. After adjusting for gender, age, marital status, and having children, the risk ratios were similar to no adjustment. CONCLUSIONS: These findings suggest that the stress response measured by the BJSQ can demonstrate risk for the onset of depression.

X-ray diffraction residual stress measurement in the rolled-joint zone of Zr - 2.5 % Nb pressure tube

International Nuclear Information System (INIS)

Dinu, A.; Nedelcu, L.

1995-01-01

The in-service experience of Zr - 2.5 % Nb pressure tubes in CANDU-type nuclear reactors has demonstrated very good performance over a long period of time. However, analyses done by AECL specialists on most failure cases, showed that a big percentage of defects are manufacturing defects, which appear mostly at the beginning of the rolled-joint zone. It has been observed that a correct rolling ensures an acceptable distribution of residual stress, but an incorrect one leads to an accumulation of big values of residual stress. This determines a preferential radial orientation of hydrides, which during operation in the reactor can produce DHC. To ensure a suitable performance of the Zr - 2.5 % Nb pressure tubes in the CANDU reactor, it is very important to have a correct rolling as mentioned in the procedure. This work presents a methodology for the measurement of the stressing state in the surfaces layers of the rolled-joint zone. The X-ray diffraction method can also be used for establishing the residual stress distribution across the tub wall, in order to ensure a good performance at Cernavoda nuclear plant. The results obtained for the investigated tube have led to the conclusion that the rolling process was correctly applied in this case, the values obtained for the residual stress being in good agreement with those accepted in literature. (Author) 2 Figs., 2 Tabs

Residual stresses measurement by using ring-core method and 3D digital image correlation technique

International Nuclear Information System (INIS)

Hu, Zhenxing; Xie, Huimin; Zhu, Jianguo; Wang, Huaixi; Lu, Jian

2013-01-01

Ring-core method/three-dimensional digital image correlation (3D DIC) residual stresses measurement is proposed. Ring-core cutting is a mechanical stress relief method, and combining with 3D DIC system the deformation of the specimen surface can be measured. An optimization iteration method is proposed to obtain the residual stress and rigid-body motion. The method has the ability to cut an annular trench at a different location out of the field of view. A compression test is carried out to demonstrate how residual stress is determined by using 3D DIC system and outfield measurement. The results determined by the approach are in good agreement with the theoretical value. Ring-core/3D DIC has shown its robustness to determine residual stress and can be extended to application in the engineering field. (paper)

Effect of tensile stress on the 3D reversible and irreversible differential magnetic susceptibilities

International Nuclear Information System (INIS)

Mao, Weihua; Atherton, David L.

2001-01-01

Magnetic hysteresis loops in three orthogonal directions are measured for a line pipe steel sample while the external magnetic field is applied in a direction perpendicular to the tensile stress direction. The total magnetization vector is calculated. This tends to the stress direction when tensile stress is applied. The reversible and irreversible differential magnetic susceptibilities are derived. It is found that the susceptibilities in all three directions are enhanced with increasing tensile stress, although the increase in the stress direction is much larger than in the other directions. [copyright] 2001 American Institute of Physics

Structural integrity assessment and stress measurement of CHASNUPP-1 fuel assembly

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Waseem

2016-01-01

Full Text Available Fuel assembly of the PWR nuclear power plant is a long and flexible structure. This study has been made in an attempt to find the structural integrity of the fuel assembly (FA of Chashma Nuclear Power Plant-1 (CHASNUPP-1 at room temperature in air. The non-linear contact and structural tensile analysis have been performed using ANSYS 13.0, in order to determine the fuel assembly (FA elongation behaviour as well as the location and values of the stress intensity and stresses developed in axial direction under applied tensile load of 9800 N or 2 g being the fuel assembly handling or lifting load [Y. Zhang et al., Fuel assembly design report, SNERDI, China, 1994]. The finite element (FE model comprises spacer grids, fuel rods, flexible contacts between the fuel rods and grid's supports system and guide thimbles with dash-pots and flow holes, in addition to the spot welds between spacer grids and guide thimbles, has been developed using Shell181, Conta174 and Targe170 elements. FA is a non-straight structure. The actual behavior of the geometry is non-linear due to its curvature or design tolerance. It has been observed that fuel assembly elongation values obtained through FE analysis and experiment [SNERDI Tech. Doc., Mechanical strength and calculation for fuel assembly, Technical Report, F3.2.1, China, 1994] under applied tensile load are comparable and show approximately linear behaviors. Therefore, it seems that the permanent elongation of fuel assembly may not occur at the specified load. Moreover, the values of stresses obtained at different locations of the fuel assembly are also comparable with the stress values of the experiment determined at the same locations through strain gauges. Since the results of both studies (analytical and experimental are comparable, therefore, validation of the FE methodology is confirmed. The stress intensity of the FE model and maximum stresses developed along the guide thimbles in axial direction are

Measuring Photosynthetic Response to Drought Stress using Active and Passive Fluorescence

Science.gov (United States)

Helm, L.; Lerdau, M.; Wang, W.; Yang, X.

2017-12-01

Photosynthesis, the endothermic reactions involving the absorption of light and fixation and reduction of carbon dioxide by plants, plays important roles in carbon and water cycles, food security, and even weather and climate patterns. Solar radiation provides the energy for photosynthesis, but often plants absorb more solar energy than they can use to reduce carbon dioxide. This excess energy, which is briefly stored as high-energy electrons in the chloroplast, must be removed or damage to the leaf's photosynthetic machinery will occur. One important energy dissipation pathway is for the high energy electrons to return to their lower valance state and, in doing so, release radiation (fluorescence). This fluorescence (known as solar induced fluorescence (SIF) has been found to strongly correlate with gross photosynthesis. Recent advances in the remote sensing of SIF allow for large-scale real-time estimation of photosynthesis. In a warming climate with more frequent stress, remote sensing is necessary for measuring the spatial and temporal variability of photosynthesis. However, the mechanisms that link SIF and photosynthesis are unclear, particularly how the relationship may or may not change under stress. We present data from leaf-level measurements of gas exchange, pulse amplitude modulation (PAM) fluorescence, and SIF in two major tree species in North America. Water-stressed and well-watered plants were compared to determine how SIF and carbon dioxide exchange are modulated by drought diurnally and seasonally. Secondly, photosynthesis and fluorescence under high and low oxygen concentrations were compared to determine how photorespiration alters the relationship between SIF and gross photosynthesis. We find a strong correlation between SIF and steady-state fluorescence measured with conventional PAM fluorometry. Our results also indicate that drought-stress modulates the SIF-photosynthesis relationship, and this may be driven by drought-induced changes in

Residual Stress Studies Using the Cairo Fourier Diffractometer Facility

International Nuclear Information System (INIS)

Maayouf, R.M.A.; El-Shaer, Y.H.

2002-01-01

The present paper deals with residual stress studies using the Cairo Fourier diffractometer facility CFDF. The CFDF is a reverse - time of -flight (RTOF) diffractometer; applies a Fourier chopper. The measurements were performed for copper samples in order to study the residual stress after welding. The maximum modulation of the Fourier chopper during the measurements was 136 khz; leading to a time resolution half-width of about 7 μ s. It has been found from the present measurements that, the resulting diffraction spectra could be successfully used for studying the residual stress; in the wavelength range between 0.7-2.9 A degree at ∼ 0.45 % relative resolution

Thermometric measurements in notches and crack tips in steels under cyclic stress

International Nuclear Information System (INIS)

Mueller, K.

1989-01-01

The present study reports on temperature measurements with notched samples with and without incipient cracks of unalloyed steels (St 37-2 and Ck 45). Investigations were conducted on thermometric stress determination and on cyclic deformation behaviour. A thermometric concept is presented with which an effective threshold value of cyclic stress intensity can be successfully determined at a low cost with the help of a thermometric estimation method. Thermocouple measurements were performed in all of the experiments, measurements which permitted the registration of temperature range due to thermoelastic effect, besides the registration of the dissipation of deformation work due, particularly, to plastic deformations. (orig./MM) [de

Measurement and simulation of deformation and stresses in steel casting