Tensile and compressive failure modes of laminated composites loaded by fatigue with different mean stress

Science.gov (United States)

Rotem, Assa

1990-01-01

Laminated composite materials tend to fail differently under tensile or compressive load. Under tension, the material accumulates cracks and fiber fractures, while under compression, the material delaminates and buckles. Tensile-compressive fatigue may cause either of these failure modes depending on the specific damage occurring in the laminate. This damage depends on the stress ratio of the fatigue loading. Analysis of the fatigue behavior of the composite laminate under tension-tension, compression-compression, and tension-compression had led to the development of a fatigue envelope presentation of the failure behavior. This envelope indicates the specific failure mode for any stress ratio and number of loading cycles. The construction of the fatigue envelope is based on the applied stress-cycles to failure (S-N) curves of both tensile-tensile and compressive-compressive fatigue. Test results are presented to verify the theoretical analysis.

Fatigue crack growth in 2024-T3 aluminum under tensile and transverse shear stresses

Science.gov (United States)

Viz, Mark J.; Zehnder, Alan T.

1994-01-01

The influence of transverse shear stresses on the fatigue crack growth rate in thin 2024-T3 aluminum alloy sheets is investigated experimentally. The tests are performed on double-edge cracked sheets in cyclic tensile and torsional loading. This loading generates crack tip stress intensity factors in the same ratio as the values computed for a crack lying along a lap joint in a pressurized aircraft fuselage. The relevant fracture mechanics of cracks in thin plates along with the details of the geometrically nonlinear finite element analyses used for the test specimen calibration are developed and discussed. Preliminary fatigue crack growth data correlated using the fully coupled stress intensity factor calibration are presented and compared with fatigue crack growth data from pure delta K(sub I)fatigue tests.

Experimental and numerical determination of critical stress intensity factor of aluminum curved thin sheets under tensile stress

Energy Technology Data Exchange (ETDEWEB)

Heidarvand, Majid; Soltani, Naser; Hajializadeh, Farshid [University of Tehran, Tehran (Iran, Islamic Republic of)

2017-05-15

We determined the fracture toughness of aluminum curved thin sheets using tensile stress tests and finite element method. We applied Linear elastic fracture mechanics (LEFM) and Feddersen procedure to evaluate stress intensity factor of the samples with central wire-cut cracks and fatigue cracks with different lengths to investigate the notch radius effect. Special fixture design was utilized to establish uniform stress distribution at the crack zone. Less than 9 % difference was found between the wire-cut and the fatigue cracked samples. Since generating central fatigue crack with different lengths required so much effort, wire-cut cracked samples were used to determine critical stress intensity factor. Finite element analysis was also performed on one-quarter of the specimen using both the singular Borsum elements and the regular isoparametric elements to further investigate fracture toughness of the samples. It was observed that the singular elements presented better results than the isoparametric ones. A slight difference was also found between the results obtained from finite element method using singular elements and the experimental results.

The tensile deformation behavior of nuclear-grade isotropic graphite posterior to hydrostatic loading

International Nuclear Information System (INIS)

Yoda, S.; Eto, M.

1983-01-01

The effects of prehydrostatic loading on microstructural changes and tensile deformation behavior of nuclear-grade isotropic graphite have been examined. Scanning electron micrographs show that formation of microcracks associated with delamination between basal planes occurs under hydrostatic loading. Hydrostatic loading on specimens results in the decrease in tensile strength and increase in residual strain generated by the applied tensile stress at various levels, indicating that the graphite material is weakened by hydrostatic loading. A relationship between residual strain and applied tensile stress for graphite hydrostatically-loaded at several pressure levels can be approximately expressed as element of= (AP + B) sigmasup(n) over a wide range hydrostatic pressure, where element of, P and sigma denote residual strain, hydrostatic pressure and applied tensile stress, respectively; A, B and n are constant. The effects of prehydrostatic loading on the tensile stress-strain behavior of the graphite were examined in more detail. The ratio of stress after hydrostatic loading to that before hydrostatic loading on the stress-strain relationship remains almost unchanged irrespective of strain. (orig.)

Effects of tensile and compressive stresses on irradiation-induced swelling in AISI 316

International Nuclear Information System (INIS)

Lauritzen, T.; Bell, W.L.; Konze, G.M.; Rosa, J.M.; Vaidyanathan, S.; Garner, F.A.

1985-05-01

The results of two recent experiments indicate that the current perception of stress-affected swelling needs revision. It appears that compressive stresses do not delay swelling as previously modeled but actually accelerate swelling at a rate comparable to that induced by tensile stresses

Stress analysis of steam generator row-1 tubes

International Nuclear Information System (INIS)

Kim, Woo Gon; Ryu, Woo Seog; Lee, Ho Jin; Kim, Sung Chung

2000-01-01

Residual stresses induced in U-bending and tube-to-tubesheet joining processes of PWR's steam generator row-1 tube were measured by X-ray method and Hole-Drilling Method(HDM). The stresses resulting from the internal pressure and the temperature gradient in the steam generator were also estimated theoretically. In U-bent regions, the residual stresses at extrados were induced with compressive stress(-), and its maximum value reached -319 Mpa in axial direction at ψ=0 .deg. in position. Maximum tensile residual stress of 170 MPa was found to be at the flank side at position of ψ=90 deg., i.e., at apex region. In tube-to-tubesheet joining methods, the residual stresses induced by the explosive joint method were found to be lower than that by the mechanical roll method. The gradient of residual stress along the expanded tube was highest at the transition region, and the residual stress in circumferential direction was found to be higher than the residual stress in axial direction. Hoop stress due to an internal pressure between primary and secondary side was analyzed to be 76 MPa and thermal stress was 45 MPa

Effect of tensile stress on the annealed structure of a metallic glass

International Nuclear Information System (INIS)

Vianco, P.T.; Li, J.C.M.

1987-01-01

The low-temperature (120 0 --245 0 C) structural relaxation of Metglas/sup R/ 2826B (Ni 49 Fe 29 P 14 B 6 Si 2 ) amorphous alloy was investigated for samples subjected to a tensile stress in the range of 20--400 MPa during annealing. The stress-annealed samples demonstrated a much smaller increase of microhardness than was observed in similarly annealed ribbons without a stress. Further heat treatment of the stress-annealed specimens, this time without the stress, was capable of increasing the microhardnesses of only some ribbons to values equal to those of samples similarly heat treated initially without a stress. An additional exothermic peak in the differential scanning calorimetry (DSC) thermograms of the stress-annealed specimens indicated the presence of a more disordered structure at room temperature, which was found to correlate with the lower microhardness values. Otherwise, those artifacts of the DSC thermograms that were characteristic of samples annealed without a stress were still present in the stress-annealed ribbons. No effect on the crystallization temperature was noted but the glass transition temperature was increased in the stress-annealed case with respect to values attained when the stress was absent during heat treatment. A reduction in the degree of embrittlement of those samples annealed with a tensile stress was a further indication of more disorder in the stress-annealed ribbons

Tensile Instability and Artificial Stresses in Impact Problems in SPH

International Nuclear Information System (INIS)

Mehra, Vishal; Sijoy C D; Mishra, Vinayak; Chaturvedi, Shashank

2012-01-01

The smooth particle hydrodynamics (SPH) is a meshless computational technique that is popular in the modeling of impact and penetration problems. However, SPH is liable to a tensile instability that manifests itself as a bunching of nodes and formation of artificial voids and no generally accepted formulation exists to counter this instability. We examine the performance of two methods that have been proposed to deal with the tensile instability— the Monaghan artificial stresses and the Godunov-type SPH. The impact and penetration of 0.5 cm radii steel spheres on 2 mm thick aluminium plate at 3.1 km/s is chosen for comparison. We show that the artificial void formation in St-Al impact is suppressed but not eliminated by using Monaghan stresses while the void formation is entirely eliminated by using Godunov-type formulation of SPH that was proposed by Parshikov and Medin.

Development of a tensile-stress-induced anisotropy in amorphous magnetic thin films

International Nuclear Information System (INIS)

Mandal, K.; Vazquez, M.; Garcia, D.; Castano, F.J.; Prados, C.; Hernando, A.

2000-01-01

Magnetic anisotropy was induced in positive magnetostrictive Fe 80 B 20 and negative magnetostrictive Co 75 Si 15 B 10 thin films by developing a tensile stress within the samples. The films were grown on the concave surfaces of mechanically bowed glass substrates. On releasing the substrates from the substrate holders, a tensile stress was developed within the samples that modified the domain structure. As a result of it, a magnetic easy axis parallel to the direction of the stress was induced in FeB sample whereas in CoSiB sample the induced easy axis was perpendicular to the direction of the developed stress. To produce magnetic multilayers with crossed anisotropy, FeB/CoSiB bilayers and FeB/Cu/CoSiB trilayers were grown on bowed substrates. The study of magnetic properties of the multilayers indicates the development of crossed anisotropy within them, particularly when the magnetic layers are separated by a nonmagnetic Cu layer

Coulomb stress change during and after tensile fracture opening in a geothermal reservoir

NARCIS (Netherlands)

Urpi, L.; Blöcher, G.; Zimmermann, G.; Wees, J.D. van; Fokker, P.

2013-01-01

Stress shadowing and the ratio of shear to normal stress in the rock surrounding a newly created tensile fracture are investigated. Shearing on plane of weakness near the stimulated volume can be inhibited or promoted by change in poro- and thermo-elastic stress, while pore pressure increase tends

Osmotic pressure induced tensile forces in tendon collagen.

Science.gov (United States)

Masic, Admir; Bertinetti, Luca; Schuetz, Roman; Chang, Shu-Wei; Metzger, Till Hartmut; Buehler, Markus J; Fratzl, Peter

2015-01-22

Water is an important component of collagen in tendons, but its role for the function of this load-carrying protein structure is poorly understood. Here we use a combination of multi-scale experimentation and computation to show that water is an integral part of the collagen molecule, which changes conformation upon water removal. The consequence is a shortening of the molecule that translates into tensile stresses in the range of several to almost 100 MPa, largely surpassing those of about 0.3 MPa generated by contractile muscles. Although a complete drying of collagen would be relevant for technical applications, such as the fabrication of leather or parchment, stresses comparable to muscle contraction already occur at small osmotic pressures common in biological environments. We suggest, therefore, that water-generated tensile stresses may play a role in living collagen-based materials such as tendon or bone.

Prediction of tensile curves, at 673 K, of cold-worked and stress-relieved zircaloy-4 from creep data

International Nuclear Information System (INIS)

Povolo, F.; Buenos Aires Univ. Nacional; Marzocca, A.J.

1986-01-01

A constitutive creep equation, based on jog-drag cell-formation, is used to predict tensile curves from creep data obtained in the same material. The predicted tensile curve are compared with actual stress versus plastic strain data, obtained both in cold-work and stress-relieved specimens. Finally, it is shown that the general features of the tensile curves, at low strain rates, are described by the creep model. (orig.)

Stress Wave Attenuation in Aluminum Alloy and Mild Steel Specimens Under SHPB Tensile Testing

Science.gov (United States)

Pothnis, J. R.; Ravikumar, G.; Arya, H.; Yerramalli, Chandra S.; Naik, N. K.

2018-02-01

Investigations on the effect of intensity of incident pressure wave applied through the striker bar on the specimen force histories and stress wave attenuation during split Hopkinson pressure bar (SHPB) tensile testing are presented. Details of the tensile SHPB along with Lagrangian x- t diagram of the setup are included. Studies were carried out on aluminum alloy 7075 T651 and IS 2062 mild steel. While testing specimens using the tensile SHPB setup, it was observed that the force calculated from the transmitter bar strain gauge was smaller than the force obtained from the incident bar strain gauge. This mismatch between the forces in the incident bar and the transmitter bar is explained on the basis of stress wave attenuation in the specimens. A methodology to obtain force histories using the strain gauges on the specimen during SHPB tensile testing is also presented. Further, scanning electron microscope images and photomicrographs are given. Correlation between the microstructure and mechanical properties is explained. Further, uncertainty analysis was conducted to ascertain the accuracy of the results.

Analysis of threshold current of uniaxially tensile stressed bulk Ge and Ge/SiGe quantum well lasers.

Science.gov (United States)

Jiang, Jialin; Sun, Junqiang; Gao, Jianfeng; Zhang, Ruiwen

2017-10-30

We propose and design uniaxially tensile stressed bulk Ge and Ge/SiGe quantum well lasers with the stress along direction. The micro-bridge structure is adapted for introducing uniaxial stress in Ge/SiGe quantum well. To enhance the fabrication tolerance, full-etched circular gratings with high reflectivity bandwidths of ~500 nm are deployed in laser cavities. We compare and analyze the density of state, the number of states between Γ- and L-points, the carrier injection efficiency, and the threshold current density for the uniaxially tensile stressed bulk Ge and Ge/SiGe quantum well lasers. Simulation results show that the threshold current density of the Ge/SiGe quantum well laser is much higher than that of the bulk Ge laser, even combined with high uniaxial tensile stress owing to the larger number of states between Γ- and L- points and extremely low carrier injection efficiency. Electrical transport simulation reveals that the reduced effective mass of the hole and the small conduction band offset cause the low carrier injection efficiency of the Ge/SiGe quantum well laser. Our theoretical results imply that unlike III-V material, uniaxially tensile stressed bulk Ge outperforms a Ge/SiGe quantum well with the same strain level and is a promising approach for Si-compatible light sources.

Discrete fracture in quasi-brittle materials under compressive and tensile stress states

CSIR Research Space (South Africa)

Klerck, PA

2004-01-01

Full Text Available A method for modelling discrete fracture in geomaterials under tensile and compressive stress fields has been developed based on a Mohr-Coulomb failure surface in compression and three independent anisotropic rotating crack models in tension...

Influence of quenching cooling rate on residual stress and tensile properties of 2A14 aluminum alloy forgings

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yu-xun, E-mail: zhangyuxun198@163.com; Yi, You-ping, E-mail: yyp@csu.edu.cn; Huang, Shi-quan, E-mail: huangsqcsu@sina.com; Dong, Fei

2016-09-30

To balance the quenching residual stress and the mechanical properties of aluminum alloys, the influence of cooling rate on the residual stress and tensile properties was investigated by numerical simulation and quenching experiments. During the quenching experiments, 2A14 aluminum alloy samples were treated with different water temperatures (20 °C, 70 °C, 100 °C) and a step quenching process. X-ray diffraction (XRD) was used to measure the residual stress. Prior to them, the quenching sensitivity was studied. For this purpose, the time-temperature-properties (TTP) curves were measured and the alloy microstructure was observed using transmission electron microscopy (TEM). The results indicated that the mechanical properties of 2A14 aluminum alloys were mainly determined by the cooling rate within the quenching sensitive temperature range from 300 to 400 °C. Lower cooling rates reduced the tensile strength and yield strength due to a decrease amount of fine precipitates, and reduced the residual stress with the reduction of plastic strain and the degree of inhomogeneous plastic deformation. In addition, the residual stress changed faster than the tensile properties with decreasing cooling rate. Therefore, warm water (70 °C) was used to balance the residual stress and tensile properties of 140-mm-thick 2A14 aluminum alloy forgings, since it can achieve low cooling rates. Furthermore, by combining this characteristic and the material quenching sensitivity, step quenching produced similar tensile properties and lower residual stress, compared with the sample quenched in warm water (70 °C), by increasing cooling rate within quenching sensitivity range and reducing it in other ranges.

Influence of quenching cooling rate on residual stress and tensile properties of 2A14 aluminum alloy forgings

International Nuclear Information System (INIS)

Zhang, Yu-xun; Yi, You-ping; Huang, Shi-quan; Dong, Fei

2016-01-01

To balance the quenching residual stress and the mechanical properties of aluminum alloys, the influence of cooling rate on the residual stress and tensile properties was investigated by numerical simulation and quenching experiments. During the quenching experiments, 2A14 aluminum alloy samples were treated with different water temperatures (20 °C, 70 °C, 100 °C) and a step quenching process. X-ray diffraction (XRD) was used to measure the residual stress. Prior to them, the quenching sensitivity was studied. For this purpose, the time-temperature-properties (TTP) curves were measured and the alloy microstructure was observed using transmission electron microscopy (TEM). The results indicated that the mechanical properties of 2A14 aluminum alloys were mainly determined by the cooling rate within the quenching sensitive temperature range from 300 to 400 °C. Lower cooling rates reduced the tensile strength and yield strength due to a decrease amount of fine precipitates, and reduced the residual stress with the reduction of plastic strain and the degree of inhomogeneous plastic deformation. In addition, the residual stress changed faster than the tensile properties with decreasing cooling rate. Therefore, warm water (70 °C) was used to balance the residual stress and tensile properties of 140-mm-thick 2A14 aluminum alloy forgings, since it can achieve low cooling rates. Furthermore, by combining this characteristic and the material quenching sensitivity, step quenching produced similar tensile properties and lower residual stress, compared with the sample quenched in warm water (70 °C), by increasing cooling rate within quenching sensitivity range and reducing it in other ranges.

Estimation of a stress field in the earth`s crust using drilling-induced tensile fractures observed at well WD-1 in the Kakkonda geothermal field; Kakkonda WD-1 sei de kansokusareta drilling induced tensile fracture ni yoru chikaku oryokuba no suitei

Energy Technology Data Exchange (ETDEWEB)

Okabe, T. [GERD Geothermal Energy Research and Development Co. Ltd., Tokyo (Japan); Hayashi, K. [Tohoku Univ., Sendai (Japan). Inst. of Fluid Science; Kato, O.; Doi, N.; Miyazaki, S. [Japan Metals and Chemicals Co. Ltd., Tokyo (Japan); Uchida, T. [New Energy and Industrial Technology Development Organization, Tokyo, (Japan)

1997-05-27

This paper describes estimation of a stress field in the earth`s crust in the Kakkonda geothermal field. Formation micro imager (FMI) logging known as a crack detecting logging was performed in the well WD-1. This FMI logging has made observation possible on cracks along well axis thought to indicate size and direction of the crust stress, and drilling-induced tensile fractures (DTF). It was verified that these DTFs are generated initially in an azimuth determined by in-situ stress (an angle up to the DTF as measured counterclockwise with due north as a starting point, expressed in {theta}) in the well`s circumferential direction. It was also confirmed that a large number of cracks incline at a certain angle to the well axis (an angle made by the well axis and the DTF, expressed in {gamma}). The DTF is a crack initially generated on well walls as a result of such tensile stresses as mud pressure and thermal stress acting on the well walls during well excavation, caused by the in-situ stress field. Measurement was made on the {theta} and {gamma} from the FMI logging result, and estimation was given on a three-dimensional stress field. Elucidating the three-dimensional crust stress field in a geothermal reservoir is important in making clear the formation mechanism thereof and the growth of water-permeable cracks. This method can be regarded as an effective method. 9 refs., 8 figs., 1 tab.

Tensile Residual Stress Mitigation Using Low Temperature Phase Transformation Filler Wire in Welded Armor Plates

Energy Technology Data Exchange (ETDEWEB)

Feng, Zhili [ORNL; Bunn, Jeffrey R [ORNL; Tzelepis, Demetrios A [ORNL; Payzant, E Andrew [ORNL; Yu, Xinghua [ORNL

2016-01-01

Hydrogen induced cracking (HIC) has been a persistent issue in welding of high-strength steels. Mitigating residual stresses is one of the most efficient ways to control HIC. The current study develops a proactive in-process weld residual stress mitigation technique, which manipulates the thermal expansion and contraction sequence in the weldments during welding process. When the steel weld is cooled after welding, martensitic transformation will occur at a temperature below 400 C. Volume expansion in the weld due to the martensitic transformation will reduce tensile stresses in the weld and heat affected zone and in some cases produce compressive residual stresses in the weld. Based on this concept, a customized filler wire which undergoes a martensitic phase transformation during cooling was developed. The new filler wire shows significant improvement in terms of reducing the tendency of HIC in high strength steels. Bulk residual stress mapping using neutron diffraction revealed reduced tensile and compressive residual stresses in the welds made by the new filler wire.

X-ray evaluation of residual stress distributions within surface machined layer generated by surface machining and sequential welding

International Nuclear Information System (INIS)

Taniguchi, Yuu; Okano, Shigetaka; Mochizuki, Masahito

2017-01-01

The excessive tensile residual stress generated by welding after surface machining may be an important factor to cause stress corrosion cracking (SCC) in nuclear power plants. Therefore we need to understand and control the residual stress distribution appropriately. In this study, residual stress distributions within surface machined layer generated by surface machining and sequential welding were evaluated by X-ray diffraction method. Depth directional distributions were also investigated by electrolytic polishing. In addition, to consider the effect of work hardened layer on the residual stress distributions, we also measured full width at half maximum (FWHM) obtained from X-ray diffraction. Testing material was a low-carbon austenitic stainless steel type SUS316L. Test specimens were prepared by surface machining with different cutting conditions. Then, bead-on-plate welding under the same welding condition was carried out on the test specimens with different surface machined layer. As a result, the tensile residual stress generated by surface machining increased with increasing cutting speed and showed nearly uniform distributions on the surface. Furthermore, the tensile residual stress drastically decreased with increasing measurement depth within surface machined layer. Then, the residual stress approached 0 MPa after the compressive value showed. FWHM also decreased drastically with increasing measurement depth and almost constant value from a certain depth, which was almost equal regardless of the machining condition, within surface machined layer in all specimens. After welding, the transverse distribution of the longitudinal residual stress varied in the area apart from the weld center according to machining conditions and had a maximum value in heat affected zone. The magnitude of the maximum residual stress was almost equal regardless of the machining condition and decreased with increasing measurement depth within surface machined layer. Finally, the

Stress in hard metal films

NARCIS (Netherlands)

Janssen, G.C.A.M.; Kamminga, J.D.

2004-01-01

In the absence of thermal stress, tensile stress in hard metal films is caused by grain boundary shrinkage and compressive stress is caused by ion peening. It is shown that the two contributions are additive. Moreover tensile stress generated at the grain boundaries does not relax by ion

Tensile creep behavior in an advanced silicon nitride

International Nuclear Information System (INIS)

Lofaj, F.

2000-01-01

Tensile creep behavior and changes in the microstructure of the advanced silicon nitride, SN 88M, were studied at temperatures from 1250 to 1400 C to reveal the creep resistance and lifetime-controlling processes. Assuming power law dependence of the minimum strain rate on stress, stress exponents from 6 to 8 and an apparent activation energy of 780 kJ/mol were obtained. Extensive electron microscopy observations revealed significant changes in the crystalline secondary phases and creep damage development. Creep damage was classified in two groups: 'inter-granular' defects in the amorphous boundary phases, and 'intra-granular' defects in silicon nitride grains. The inter-granular defects involved multigrain junction cavities, two-grain junction cavities, microcracks and cracks. The intra-granular defects included broken large grains, small symmetrical and asymmetrical cavities, and crack-like intragranular cavities. Cavities are generated continuously during the whole deformation starting from the threshold strain of ∝0.1%, and they contribute linearly to the tensile strain. Cavities produce more than 90% of the total tensile strain, and it is concluded that cavitation is the main creep mechanism in silicon nitride ceramics. The multigrain junction cavities are considered to be the most important for generating new volume and producing tensile strain. The Luecke and Wiederhorn (L and W) creep model, based on cavitation at multigrain junctions according to an exponential law, was proven to correspond to the stress dependence of the minimum strain rate. A qualitative model based on the L and W model was suggested and expanded to include intragranular cavitation. The basic mechanisms involve a repeating of the sequence grain boundary sliding (GBS) => cavitation at multigrain junctions => viscous flow and dissolution-precipitation. (orig.)

The role and effect of residual stress on pore generation during anodization of aluminium thin films

International Nuclear Information System (INIS)

Liao, M.W.; Chung, C.K.

2013-01-01

Highlights: •Al films of varying residual stress were prepared by sputtering. •Variation of the residual stress in the Al films influences pore growth during anodization. •The change in average pore size with residual stress is fairly small. •Interaction of residual stress with oxide growth stress leads to change in structure. •Residual tensile stress increases the pore density of porous alumina. -- Abstract: The role and effect of residual stress on pore generation of anodized aluminium oxide (AAO) have been investigated into anodizing the various-residual-stresses aluminium films. The plane stresses were characterised by X-ray diffraction with sin 2 ψ method. The pore density roughly linearly increased with residual stress from 64.6 (−132.5 MPa) to 90.5 pores/μm 2 (135.9 MPa). However, the average pore size around 40 nm was not changed significantly except for the rougher film. The tensile residual stress lessened the compressive oxide growth stress to reduce AAO plastic deformation for higher pore density. The findings provide new foundations for realizing AAO films on silicon

Influence of Tensile Stresses on α+β – Titanium Alloy VT22 Corrosion Resistance in Marine Environment

Directory of Open Access Journals (Sweden)

Yu. A. Puchkov

2015-01-01

Full Text Available Tensile stresses and hydrogen render strong influence on the titanic alloys propensity for delayed fracture. The protective film serves аs a barrier for penetration in hydrogen alloy. Therefore to study the stress effect on its structure and protective properties is of significant interest.The aim of this work is to research the tensile stress influence on the passivation, indexes of corrosion, protective film structure and reveal reasons for promoting hydrogenation and emerging propensity for delayed fracture of titanium alloy VТ22 in the marine air atmosphere.The fulfillеd research has shown that:- there is а tendency to reduce the passivation abilities of the alloy VТ22 in synthetic marine water (3 % solution of NaCl with increasing tensile stresses up to 1170 МPа, namely to reduce the potential of free corrosion and the rate of its сhange, thus the alloy remains absolutely (rather resistant;- the protective film consists of a titanium hydroxide layer under which there is the titanium oxide layer adjoining to the alloy, basically providing the corrosion protection.- the factors providing hydrogenation of titanium alloys and formation in their surface zone fragile hydrides, causing the appearing propensity for delayed fracture, alongside with tensile stresses are:- substances promoting chemisorbtion of hydrogen available in the alloy and on its surface;- the cathodic polarization caused by the coupling;- the presence of the structural defects promoting the formation of pitting and local аcidifying of the environment surrounding the alloy.

2D micromechanical analysis of SiC/Al metal matrix composites under tensile, shear and combined tensile/shear loads

DEFF Research Database (Denmark)

Qing, Hai

2013-01-01

The influence of interface strength and loading conditions on the mechanical behavior of the metal-matrix composites is investigated in this paper. A program is developed to generate automatically 2D micromechanical Finite element (FE) models including interface, in which both the locations...... and dimensions of Silicon-Carbide (SiC) particles are randomly distributed. Finite element simulations of the deformation and damage evolution of SiC particle reinforced Aluminum (Al) alloy composite are carried out for different microstructures and interphase strengths under tensile, shear and combined tensile....../shear loads. 2D cohesive element is applied to describe the fracture and failure process of interphase, while the damage models based on maximum principal stress criterion and the stress triaxial indicator are developed within Abaqus/Standard Subroutine USDFLD to simulate the failure process of SiC particles...

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

The effect of tensile stress on the conformational free energy landscape of disulfide bonds.

Directory of Open Access Journals (Sweden)

Padmesh Anjukandi

Full Text Available Disulfide bridges are no longer considered to merely stabilize protein structure, but are increasingly recognized to play a functional role in many regulatory biomolecular processes. Recent studies have uncovered that the redox activity of native disulfides depends on their C-C-S-S dihedrals, χ2 and χ'2. Moreover, the interplay of chemical reactivity and mechanical stress of disulfide switches has been recently elucidated using force-clamp spectroscopy and computer simulation. The χ2 and χ'2 angles have been found to change from conformations that are open to nucleophilic attack to sterically hindered, so-called closed states upon exerting tensile stress. In view of the growing evidence of the importance of C-C-S-S dihedrals in tuning the reactivity of disulfides, here we present a systematic study of the conformational diversity of disulfides as a function of tensile stress. With the help of force-clamp metadynamics simulations, we show that tensile stress brings about a large stabilization of the closed conformers, thereby giving rise to drastic changes in the conformational free energy landscape of disulfides. Statistical analysis shows that native TDi, DO and interchain Ig protein disulfides prefer open conformations, whereas the intrachain disulfide bridges in Ig proteins favor closed conformations. Correlating mechanical stress with the distance between the two a-carbons of the disulfide moiety reveals that the strain of intrachain Ig protein disulfides corresponds to a mechanical activation of about 100 pN. Such mechanical activation leads to a severalfold increase of the rate of the elementary redox S(N2 reaction step. All these findings constitute a step forward towards achieving a full understanding of functional disulfides.

Stress gradients in CrN coatings

NARCIS (Netherlands)

Janssen, G.C.A.M.; Tichelaar, F.D.; Visser, C.C.G.

2006-01-01

Stress in hard films is the net sum of tensile stress generated at the grain boundaries, compressive stress due to ion peening, and thermal stress due to the difference in thermal expansion of the coating and substrate. The tensile part due to grain boundaries is thickness dependent. The other two

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

Corrosion of metals exposed to 25% magnesium chloride solution and tensile stress: Field and laboratory studies

Directory of Open Access Journals (Sweden)

Xianming Shi

2017-12-01

Full Text Available The use of chemicals for snow and ice control operations is a common practice for improving the safety and mobility of roadways in cold climate, but brings significant concerns over their risks including the corrosive effects on transportation infrastructure and motor vehicles. The vast majority of existing studies and methods to test the deicer corrosivity have been restricted to laboratory environments and unstressed metals, which may not reliably simulate actual service conditions. As such, we report a case study in which stainless steel SS 304 (unstressed and externally tensile stressed, aluminum (Al 1100 and low carbon steel (C1010 coupons were exposed to 25% MgCl2 under field conditions for six weeks. A new corrosion test-bed was developed in Montana to accelerate the field exposure to this deicer. To further investigate the observed effect of tensile stress on the corrosion of stainless steel, SS 304 (unstressed and externally stressed coupons were exposed to 25% MgCl2 solution under the laboratory conditions. The C 1010 exhibited the highest percentage of rust area and suffered the most weight loss as a result of field exposure and MgCl2 sprays. In terms of ultimate tensile strength, the Al 1100 coupons saw the greatest reduction and the unstressed and externally stressed SS 304 coupons saw the least. The ability of MgCl2 to penetrate deep into the matrix of aluminum alloy poses great risk to such structural material. Tensile stressed SS 304 suffered more corrosion than unstressed SS 304 in both the field and laboratory conditions. Results from this case study may shed new light on the deicer corrosion issue and help develop improved field testing methods to evaluate the deicer corrosivity to metals in service.

Stress transfer in microdroplet tensile test: PVC-coated and uncoated Kevlar-29 single fiber

Science.gov (United States)

Zhenkun, Lei; Quan, Wang; Yilan, Kang; Wei, Qiu; Xuemin, Pan

2010-11-01

The single fiber/microdroplet tensile test is applied for evaluating the interfacial mechanics between a fiber and a resin substrate. It is used to investigate the influence of a polymer coating on a Kevlar-29 fiber surface, specifically the stress transfer between the fiber and epoxy resin in a microdroplet. Unlike usual tests, this new test ensures a symmetrical axial stress on the embedded fiber and reduces the stress singularity that appears at the embedded fiber entry. Using a homemade loading device, symmetrical tensile tests are performed on a Kevlar-29 fiber with or without polyvinylchloride (PVC) coating, the surface of which is in contact with two epoxy resin microdroplets during curing. Raman spectra on the embedded fiber are recorded by micro-Raman Spectroscopy under different strain levels. Then they are transformed to the distributions of fiber axis stress based on the relationship between stress and Raman shift. The Raman results reveal that the fiber axial stresses increase with the applied loads, and the antisymmetric interfacial shear stresses, obtained by a straightforward balance of shear-to-axial forces argument, lead to the appearance of shear stress concentrations at a distance to the embedded fiber entry. The load is transferred from the outer fiber to the embedded fiber in the epoxy microdroplet. As is observed by scanning electronic microscopy (SEM), the existence of a flexible polymer coating on the fiber surface reduces the stress transfer efficiency.

Experimental residual stress evaluation of hydraulic expansion transitions in Alloy 690 steam generator tubing

International Nuclear Information System (INIS)

McGregor, R.; Doherty, P.; Hornbach, D.; Abdelsalam, U.

1995-01-01

Nuclear Steam Generator (SG) service reliability and longevity have been seriously affected worldwide by corrosion at the tube-to-tubesheet joint expansion. Current SG designs for new facilities and replacement projects enhance corrosion resistance through the use of advanced tubing materials and improved joint design and fabrication techniques. Here, transition zones of hydraulic expansions have undergone detailed experimental evaluation to define residual stress and cold-work distribution on and below the secondary-side surface. Using X-ray diffraction techniques, with supporting finite element analysis, variations are compared in tubing metallurgical condition, tube/pitch geometry, expansion pressure, and tube-to-hole clearance. Initial measurements to characterize the unexpanded tube reveal compressive stresses associated with a thin work-hardened layer on the outer surface of the tube. The gradient of cold-work was measured as 3% to 0% within .001 inch of the surface. The levels and character of residual stresses following hydraulic expansion are primarily dependent on this work-hardened surface layer and initial stress state that is unique to each tube fabrication process. Tensile stresses following expansion are less than 25% of the local yield stress and are found on the transition in a narrow circumferential band at the immediate tube surface (< .0002 inch/0.005 mm depth). The measurements otherwise indicate a predominance of compressive stresses on and below the secondary-side surface of the transition zone. Excellent resistance to SWSCC initiation is offered by the low levels of tensile stress and cold-work. Propagation of any possible cracking would be deterred by the compressive stress field that surrounds this small volume of tensile material

Influence of treatment by vibration in residual stress generated in the laser welding of HSLA and IF steels

International Nuclear Information System (INIS)

Chuvas, T.C.; Fonseca, M.P. Cindra; Castello, D.A.

2010-01-01

The stress relieving treatment by vibration is a new technology under development, which has many advantages over thermal methods. In this work was analyzed the surface residual stress generated in the laser welding of biphasic HSLA and IF steels, both used in the automotive industry. Residual stresses were measured by X-ray diffraction, by the sen 2 Ψ method. Residual stresses generated in the welding of the samples were tensile at all points measured. After welding, the samples were submitted to the mechanical vibration treatment. Some samples presented a significant reduction in the stress values. The welded joints were also characterized by optical microscopy. (author)

The tensile strength of mechanical joint prototype of lontar fiber composite

Science.gov (United States)

Bale, Jefri; Adoe, Dominggus G. H.; Boimau, Kristomus; Sakera, Thomas

2018-03-01

In the present study, an experimental activity has been programmed to investigate the effect of joint prototype configuration on tensile strength of lontar (Borassus Flabellifer) fiber composite. To do so, a series of tests were conducted to establish the tensile strength of different joint prototype configuration specimen of lontar fiber composite. In addition, post observation of macroscope was used to map damage behavior. The analysis of lontar fiber composite is a challenge since the material has limited information than others natural fiber composites materials. The results shown that, under static tensile loading, the tensile strength of 13 MPa produced by single lap joint of lontar fiber composite is highest compare to 11 MPa of tensile strength generated by step lap joint and double lap joint where produced the lowest tensile strength of 6 MPa. It is concluded that the differences of tensile strength depend on the geometric dimensions of the cross-sectional area and stress distribution of each joint prototype configuration.

The influence of the tensile stress on magnetic breakdown in niobium

International Nuclear Information System (INIS)

Alekseevskii, N.E.; Glinski, M.; Nizhankovskii, V.I.

1980-01-01

It has been shown that magnetic breakdown takes place through the spin-orbital gaps between the hole octahedron of the second Brillouin zone and the open multiply connected surface of hole of the third zone, in two junctions. It is expected that even a small deformation of the sample, lowering the lattice symmetry should eliminate the magnetic breakdown by symmetry point contacts and should change the spectrum of the magnetic breakdown thermopower oscillations. Therefore, the influence of the uniaxial tensile stress on magnetic breakdown was investigated. Experimental details and results are given. The results indicate the change of the spin-orbit gap caused by stress is most probably anisotropic. (U.K.)

Tensile twin nucleation events coupled to neighboring slip observed in three dimensions

International Nuclear Information System (INIS)

Lind, J.; Li, S.F.; Pokharel, R.; Lienert, U.; Rollett, A.D.; Suter, R.M.

2014-01-01

Low-symmetry crystals and polycrystals have anisotropic mechanical properties which, given better understanding of their deformation modes, could lead to development of next generation materials. Understanding how grains in a bulk polycrystal interact will guide and improve material modeling. Here, we show that tensile twins, in hexagonal close-packed metals, form where the macroscopic stress does not generate appropriate shear stress and vice versa. We use non-destructive high-energy X-ray diffraction microscopy to map local crystal orientations in three dimensions in a series of tensile strain states in a zirconium polycrystal. Twins and intragranular orientation variations are observed and it is found that deformation-induced rotations in neighboring grains are spatially correlated with many twins. We conclude that deformation twinning involves complex multigrain interactions which must be included in polycrystal plasticity models

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

Science.gov (United States)

Nizamuddin, Syed

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

Ocean disposal of heat generating radioactive waste

International Nuclear Information System (INIS)

1986-03-01

The objective of this study was to predict tensile stress levels in thin-walled titanium alloy and thick-walled carbon steel containers designed for the ocean disposal of heat-generating radioactive wastes. Results showed that tensile stresses would be produced in both designs by the expansion of the lead filter, for a temperature rise of 200 0 C. Tensile stress could be reduced if the waste heat output at disposal was reduced. Initial stresses for the titanium-alloy containers could be relieved by heat treatment. (UK)

Evaluation of ring tensile test results

International Nuclear Information System (INIS)

Chatterjee, S.; Anantharaman, S.; Balakrishnan, K.S.; Sivaramakrish, K.S.

1990-01-01

Ring specimens of 5-mm width cut from Zircaloy-2 cladding of reactor operated fuel elements that had experienced 5000 to 15,000 MWD/T of fuel burnup were subjected to ring tensile testing. The true stress-true strain data points up to the onset of necking from the individual load-elongation curves of these specimens were used as input data in Voce's equation. The results reveal that the uniform elongation (UE) values generated using Voce's equation were within (UE-2)% of the experimental percent uniform elongation (UE%). The corresponding ultimate tensile strength values were within ±1%. The uncertainty inherently associated in the determination of gauge length introduces extraneous deformation in the rings tested. Previous results had shown that a 14% increase in cladding diameter caused the gauge length to increase by 40%. To simulate the contribution of extraneous deformation due to an increase in cladding diameter, an analysis of the variation of the tensile parameters (uniform elongation and ultimate tensile strength) due to increase in the gauge length in the range of 10 to 40% was carried out. The results are discussed

Reduction of tensile residual stresses during the drawing process of tungsten wires

International Nuclear Information System (INIS)

Rodriguez Ripoll, Manel; Weygand, Sabine M.; Riedel, Hermann

2010-01-01

Tungsten wires are commonly used in the lighting industry as filaments for lamps. During the drawing process, the inhomogeneous deformation imparted by the drawing die causes tensile residual stresses at the wire surface in circumferential direction. These stresses have a detrimental effect for the wire because they are responsible for driving longitudinal cracks, known as splits. This work proposes two methods for reducing the residual stresses during wire drawing, namely applying an advanced die geometry and performing an inexpensive post-drawing treatment based on targeted bending operations. These two methods are analyzed with finite element simulations using material parameters obtained by mechanical tests on tungsten wires at different temperatures as input data. The computed results predict a substantial reduction of the circumferential residual stresses, thus reducing the risk of splitting.

Surface, structural and tensile properties of proton beam irradiated zirconium

Energy Technology Data Exchange (ETDEWEB)

Rafique, Mohsin; Chae, San; Kim, Yong-Soo, E-mail: yongskim@hanyang.ac.kr

2016-02-01

This paper reports the surface, structural and tensile properties of proton beam irradiated pure zirconium (99.8%). The Zr samples were irradiated by 3.5 MeV protons using MC-50 cyclotron accelerator at different doses ranging from 1 × 10{sup 13} to 1 × 10{sup 16} protons/cm{sup 2}. Both un-irradiated and irradiated samples were characterized using Field Emission Scanning Electron Microscope (FESEM), X-ray Diffraction (XRD) and Universal Testing Machine (UTM). The average surface roughness of the specimens was determined by using Nanotech WSxM 5.0 develop 7.0 software. The FESEM results revealed the formation of bubbles, cracks and black spots on the samples’ surface at different doses whereas the XRD results indicated the presence of residual stresses in the irradiated specimens. Williamson–Hall analysis of the diffraction peaks was carried out to investigate changes in crystallite size and lattice strain in the irradiated specimens. The tensile properties such as the yield stress, ultimate tensile stress and percentage elongation exhibited a decreasing trend after irradiation in general, however, an inconsistent behavior was observed in their dependence on proton dose. The changes in tensile properties of Zr were associated with the production of radiation-induced defects including bubbles, cracks, precipitates and simultaneous recovery by the thermal energy generated with the increase of irradiation dose.

Surface, structural and tensile properties of proton beam irradiated zirconium

Science.gov (United States)

Rafique, Mohsin; Chae, San; Kim, Yong-Soo

2016-02-01

This paper reports the surface, structural and tensile properties of proton beam irradiated pure zirconium (99.8%). The Zr samples were irradiated by 3.5 MeV protons using MC-50 cyclotron accelerator at different doses ranging from 1 × 1013 to 1 × 1016 protons/cm2. Both un-irradiated and irradiated samples were characterized using Field Emission Scanning Electron Microscope (FESEM), X-ray Diffraction (XRD) and Universal Testing Machine (UTM). The average surface roughness of the specimens was determined by using Nanotech WSxM 5.0 develop 7.0 software. The FESEM results revealed the formation of bubbles, cracks and black spots on the samples' surface at different doses whereas the XRD results indicated the presence of residual stresses in the irradiated specimens. Williamson-Hall analysis of the diffraction peaks was carried out to investigate changes in crystallite size and lattice strain in the irradiated specimens. The tensile properties such as the yield stress, ultimate tensile stress and percentage elongation exhibited a decreasing trend after irradiation in general, however, an inconsistent behavior was observed in their dependence on proton dose. The changes in tensile properties of Zr were associated with the production of radiation-induced defects including bubbles, cracks, precipitates and simultaneous recovery by the thermal energy generated with the increase of irradiation dose.

In vitro Comparative Evaluation of Tensile Bond Strength of 6(th), 7(th) and 8(th) Generation Dentin Bonding Agents.

Science.gov (United States)

Kamble, Suresh S; Kandasamy, Baburajan; Thillaigovindan, Ranjani; Goyal, Nitin Kumar; Talukdar, Pratim; Seal, Mukut

2015-05-01

Newer dentin bonding agents were developed to improve the quality of composite restoration and to reduce time consumption in its application. The aim of the present study was to evaluate tensile bond strength of 6(th), 7(th) and 8(th) generation bonding agents by in vitro method. Selected 60 permanent teeth were assigned into 20 in each group (Group I: 6(th) generation bonding agent-Adper SE plus 3M ESPE, Group II: 7(th) generation bonding agent-G-Bond GC Corp Japan and Group III: 8(th) generation dentin adhesives-FuturaBond, DC, Voco, Germany). With high-speed diamond disc, coronal dentin was exposed, and selected dentin bonding agents were applied, followed by composite restoration. All samples were saved in saline for 24 h and tensile bond strength testing was done using a universal testing machine. The obtained data were tabulated and statistically analyzed using ANOVA test. The tensile bond strength readings for 6(th) generation bonding agent was 32.2465, for 7(th) generation was 31.6734, and for 8(th)-generation dentine bonding agent was 34.74431. The highest tensile bond strength was seen in 8(th) generation bonding agent compared to 6(th) and 7(th) generation bonding agents. From the present study it can be conclude that 8(th) generation dentine adhesive (Futura DC, Voco, Germany) resulted in highest tensile bond strength compared to 6(th) (Adper SE plus, 3M ESPE) and 7(th) generation (G-Bond) dentin bonding agents.

Tensile Strength of Water Exposed to Pressure Pulses

DEFF Research Database (Denmark)

Andersen, Anders Peter; Mørch, Knud Aage

2012-01-01

at an extended water-solid interface by imposing a tensile stress pulse which easily causes cavitation. Next, a compressive pulse of duration ~1 ms and a peak intensity of a few bar is imposed prior to the tensile stress pulse. A dramatic increase of the tensile strength is observed immediately after......It is well known that pressurization for an extended period of time increases the tensile strength of water, but little information is available on the effect of pressure pulses of short duration. This is addressed in the present paper where we first measure the tensile strength of water...

Porosity Defect Remodeling and Tensile Analysis of Cast Steel

Directory of Open Access Journals (Sweden)

Linfeng Sun

2016-02-01

Full Text Available Tensile properties on ASTM A216 WCB cast steel with centerline porosity defect were studied with radiographic mapping and finite element remodeling technique. Non-linear elastic and plastic behaviors dependent on porosity were mathematically described by relevant equation sets. According to the ASTM E8 tensile test standard, matrix and defect specimens were machined into two categories by two types of height. After applying radiographic inspection, defect morphologies were mapped to the mid-sections of the finite element models and the porosity fraction fields had been generated with interpolation method. ABAQUS input parameters were confirmed by trial simulations to the matrix specimen and comparison with experimental outcomes. Fine agreements of the result curves between simulations and experiments could be observed, and predicted positions of the tensile fracture were found to be in accordance with the tests. Chord modulus was used to obtain the equivalent elastic stiffness because of the non-linear features. The results showed that elongation was the most influenced term to the defect cast steel, compared with elastic stiffness and yield stress. Additional visual explanations on the tensile fracture caused by void propagation were also given by the result contours at different mechanical stages, including distributions of Mises stress and plastic strain.

Theoretical Conversions of Different Hardness and Tensile Strength for Ductile Materials Based on Stress-Strain Curves

Science.gov (United States)

Chen, Hui; Cai, Li-Xun

2018-04-01

Based on the power-law stress-strain relation and equivalent energy principle, theoretical equations for converting between Brinell hardness (HB), Rockwell hardness (HR), and Vickers hardness (HV) were established. Combining the pre-existing relation between the tensile strength ( σ b ) and Hollomon parameters ( K, N), theoretical conversions between hardness (HB/HR/HV) and tensile strength ( σ b ) were obtained as well. In addition, to confirm the pre-existing σ b -( K, N) relation, a large number of uniaxial tensile tests were conducted in various ductile materials. Finally, to verify the theoretical conversions, plenty of statistical data listed in ASTM and ISO standards were adopted to test the robustness of the converting equations with various hardness and tensile strength. The results show that both hardness conversions and hardness-strength conversions calculated from the theoretical equations accord well with the standard data.

Effects of liquid lead on 316l tensile properties

International Nuclear Information System (INIS)

Ionescu, V.; Pitigoi, V.; Nitu, A.; Hororoi, M.; Voicu, F.; Cojocaru, V.

2016-01-01

The lead-cooled fast reactor (LFR) is one of the concepts of the Generation IV reactor systems. Compatibility of the candidate structural materials with the liquid lead is known to be one of the critical issues to allow development of the LFR reactors. In contact with the liquid metal, the mechanical integrity of the structural materials can be affected. The steel.s mechanical properties are assessed by tensile testing as a function of temperature in heavy liquid metal and in an air environment. RATEN ICN is involved in several European projects aimed to Generation IV research activities. In a first stage an Experimental Facility for Tensile Tests in Liquid Lead environment has been set up. This installation is adapted on the Instron testing machine, already existing in institute. 316L alloy is one of a candidate structural material for this type of reactor. This document presents the effect of liquid lead on tensile properties of 316L material tested in liquid lead (in static conditions) and in air environment at 500°C, without oxygen monitoring system. When solid metals are placed in contact to liquid metals and stress is applied, they may undergo abrupt brittle failure. Stress-strain curves of slow strain rate tests have been obtained in conformity with ASTM, E-8. Mechanical characteristics determined are in accordance with literature. (authors)

Analysis on the stress corrosion crack inception based on pit shape and size of the FV520B tensile specimen

Science.gov (United States)

Xiang, Longhao; Pan, Juyi; Chen, Songying

2018-06-01

The influence of pit shape and size on local stress concentration in the tensile specimen and the stress corrosion cracks inception was studied by employing the element remove technique. The maximum stress located in the bottom of pit on FV520B tensile specimen. The location of maximum strain was near the mouth of the pit or the shoulder and plastic strain existed in this region. Stress concentration factor and plastic deformation on four different geometrical shape pits of hemisphere, semi-ellipsoid, bullet and butterfly were numerically investigated, respectively. The simulation results showed that butterfly pit got the biggest stress concentration factor. The plastic strain rate during pit growth was in the sensitivity range of stress corrosion cracks inception, indicating that stress corrosion cracks were more likely to nucleate near the pit tip or the shoulder.

Tensile flow stress of ceramic particle-reinforced metal in the presence of particle cracking

Energy Technology Data Exchange (ETDEWEB)

Mueller, R. [Ecole Polytechnique Federale de Lausanne (EPFL), Laboratory for Mechanical Metallurgy, CH-1015 Lausanne (Switzerland); Rossoll, A. [Ecole Polytechnique Federale de Lausanne (EPFL), Laboratory for Mechanical Metallurgy, CH-1015 Lausanne (Switzerland)], E-mail: andreas.rossoll@epfl.ch; Weber, L. [Ecole Polytechnique Federale de Lausanne (EPFL), Laboratory for Mechanical Metallurgy, CH-1015 Lausanne (Switzerland); Bourke, M.A.M. [Los Alamos National Laboratory (LANL), LANSCE-12, P.O. Box 1663, MS H805, Los Alamos, NM 87545 (United States); Dunand, D.C. [Northwestern University, Department of Materials Science and Engineering, Evanston, IL 60208 (United States); Mortensen, A. [Ecole Polytechnique Federale de Lausanne (EPFL), Laboratory for Mechanical Metallurgy, CH-1015 Lausanne (Switzerland)

2008-10-15

A simplified model is proposed to quantify the effect of damage in the form of particle cracking on the elastic and plastic behaviour of particle-reinforced metal matrix composites under uniaxial tensile loading: cracked particles are simply replaced, in a mean-field model, with as much matrix. Pure aluminium reinforced with 44 vol.% alumina particles, tested in tension and unloaded at periodic plastic deformations, is analysed by neutron diffraction during each reloading elastic step, at 30%, 50%, 70% and 90% of the tensile flow stress. The data give the evolution of the elastic matrix strains in the composite and also measure the progress of internal damage by particle cracking. The test gives (i) the evolution of the in situ matrix flow stress, and (ii) the evolution of load partitioning during elastic deformation with increasing composite damage. Predictions of the present model compare favourably with relevant results in the literature, and with results from the present neutron diffraction experiments.

Tensile flow stress of ceramic particle-reinforced metal in the presence of particle cracking

International Nuclear Information System (INIS)

Mueller, R.; Rossoll, A.; Weber, L.; Bourke, M.A.M.; Dunand, D.C.; Mortensen, A.

2008-01-01

A simplified model is proposed to quantify the effect of damage in the form of particle cracking on the elastic and plastic behaviour of particle-reinforced metal matrix composites under uniaxial tensile loading: cracked particles are simply replaced, in a mean-field model, with as much matrix. Pure aluminium reinforced with 44 vol.% alumina particles, tested in tension and unloaded at periodic plastic deformations, is analysed by neutron diffraction during each reloading elastic step, at 30%, 50%, 70% and 90% of the tensile flow stress. The data give the evolution of the elastic matrix strains in the composite and also measure the progress of internal damage by particle cracking. The test gives (i) the evolution of the in situ matrix flow stress, and (ii) the evolution of load partitioning during elastic deformation with increasing composite damage. Predictions of the present model compare favourably with relevant results in the literature, and with results from the present neutron diffraction experiments

Low temperature tensile properties and stress corrosion cracking resistance in the super duplex stainless steels weldments

International Nuclear Information System (INIS)

Lee, Jeung Woo; Sung, Jang Hyun; Lee, Sung Keun

1998-01-01

Low temperature tensile properties and SCC resistances of super duplex stainless steels and their weldments are investigated. Tensile strengths increase remarkably with decreasing test temperature, while elongations decrease steeply at -196 .deg. C after showing peak or constant value down to -100 .deg. C. Owing to the low tensile deformation of weld region, elongations of welded specimen decrease in comparison to those of unwelded specimen. The welded tensile specimen is fractured through weld region at -196 .deg. C due to the fact that the finely dispersed ferrite phase in the austenite matrix increases an opportunity to supply the crack propagation path through the brittle ferrite phase at low temperature. The stress corrosion cracking initiates preferentially at the surface ferrite phase of base metal region and propagates through ferrite phase. When the corrosion crack meets with the fibrously aligned austenite phase to the tensile direction, the ferrite phase around austenite continues to corrode. Eventually, fracture of the austenite phase begins without enduring the tensile load. The addition of Cu+W to the super duplex stainless steel deteriorates the SCC resistance in boiling MgCl 2 solution, possibly due to the increment of pits in the ferrite phase and reduction of N content in the austenite phase

Effect of grain size on tensile stress and ductility in Al99.99

International Nuclear Information System (INIS)

Kovacs-Csetenyi, E.; Horvath, M.; Chinh, N.Q.; Kovacs, I.

1998-01-01

The effect of recrystallized grain size on the tensile stress and ductility of 99.99% purity aluminium was investigated at room temperature. It was proved that the grain size dependence of flow stress follows a modified Hall-Petch equation with coefficients depending linearly on ε 1/2 up to the stability limit. The uniform strain can also be described by a linear dependence on d -1/2 according to which the uniform elongation increases with increasing grain size. The post-uniform elongation changes inversely to that of the uniform one accompanied by the decrease of the strain rate sensitivity. (orig.)

Effect of Annealing on Strain-Temperature Response under Constant Tensile Stress in Cold-Worked NiTi Thin Wire

OpenAIRE

Yan, Xiaojun; Van Humbeeck, Jan

2011-01-01

The present paper aims to understand the influence of annealing on the strain-temperature response of a cold-worked NiTi wire under constant tensile stress. It was found that transformation behavior, stress-strain relationship, and strain-temperature response of the cold-worked NiTi wire are strongly affected by the annealing temperature. Large martensitic strains can be reached even though the applied stress is below the plateau stress of the martensite phase. At all stress levels transforma...

Influence of torsion and tensile stress on magnetoimpedance effect in Fe-rich amorphous microwires at high frequencies

Energy Technology Data Exchange (ETDEWEB)

Garcia, C. [Dpto. Fisica de Materiales, Fac. Quimicas, UPV/EHU, 20018 San Sebastian (Spain)]. E-mail: wubgagac@sc.ehu.es; Chizhik, A. [Dpto. Fisica de Materiales, Fac. Quimicas, UPV/EHU, 20018 San Sebastian (Spain); Zhukov, A. [Dpto. Fisica de Materiales, Fac. Quimicas, UPV/EHU, 20018 San Sebastian (Spain); Zhukova, V. [TAMAG Iberica S. L. Parque Tecnologico de Miramon, Paseo Mikeletegi 56, 1a Planta, 20009 San Sebastian (Spain); Gonzalez, J. [Dpto. Fisica de Materiales, Fac. Quimicas, UPV/EHU, 20018 San Sebastian (Spain); Blanco, J.M. [Dpto. Fisica Aplicada I. EUPDS, UPV/EHU, Plaza Europa 1, 20018 San Sebastian (Spain); Panina, L.V. [University of Plymouth, Drakes Circus, Plymouth (United Kingdom)

2007-09-15

In this work, we study the magnetoimpedance response under tensile and torsional stress of Fe{sub 76}B{sub 13}Si{sub 11} glass-coated amorphous microwires (with the metallic nucleus diameter of 17 {mu}m) prepared by Taylor-Ulitovski method. The impedance was evaluated using a Network Analyser in the frequency range of 10-500 MHz. In order to induce a helical magnetic anisotropy that modifies the magnetic domain structure and the magnetic response of the sample, the torsion stresses have been applied. The effect of such torsion on giant magnetoimpedance (GMI) has been studied in a Fe-rich amorphous microwire as a function of the driving current frequency. Unusual behaviour of the GMI with torsion has been observed up to 500 MHz: at this frequency, the change from double-peak to single-peak behaviour has been observed. It could be ascribed to changes on domain structures and surface anisotropy induced by applied torsion. For this frequency range, an abrupt decrease of the impedance with torsion has been observed. We have also studied the tensile-induced changes of GMI effect in a Fe-rich amorphous microwire. The GMI effect increases with applied tensile stress and with the frequency of AC current. Observed dependences could be attributed to the change of the overall magnetic anisotropy under applied torsion.

Effect of tensile mean stress on fatigue behavior of single-crystal and directionally solidified superalloys

Science.gov (United States)

Kalluri, Sreeramesh; Mcgaw, Michael A.

1990-01-01

Two nickel base superalloys, single crystal PWA 1480 and directionally solidified MAR-M 246 + Hf, were studied in view of the potential usage of the former and usage of the latter as blade materials for the turbomachinery of the space shuttle main engine. The baseline zero mean stress (ZMS) fatigue life (FL) behavior of these superalloys was established, and then the effect of tensile mean stress (TMS) on their FL behavior was characterized. At room temperature these superalloys have lower ductilities and higher strengths than most polycrystalline engineering alloys. The cycle stress-strain response was thus nominally elastic in most of the fatigue tests. Therefore, a stress range based FL prediction approach was used to characterize both the ZMS and TMS fatigue data. In the past, several researchers have developed methods to account for the detrimental effect of tensile mean stress on the FL for polycrystalline engineering alloys. However, the applicability of these methods to single crystal and directionally solidified superalloys has not been established. In this study, these methods were applied to characterize the TMS fatigue data of single crystal PWA 1480 and directionally solidified MAR-M 246 + Hf and were found to be unsatisfactory. Therefore, a method of accounting for the TMS effect on FL, that is based on a technique proposed by Heidmann and Manson was developed to characterize the TMS fatigue data of these superalloys. Details of this method and its relationship to the conventionally used mean stress methods in FL prediction are discussed.

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

An Examination of Radiation Induced Tensile Failure of Stressed and Unstressed Polymer Films Flown on MISSE-6

Science.gov (United States)

Miller, Sharon K.; Sechkar, Edward A.

2012-01-01

Thin film polymers are used in many spacecraft applications for thermal control (multilayer insulation and sunshields), as lightweight structural members (solar array blankets, inflatable/deployable structures) and have been proposed for propulsion (solar sails). Polymers in these applications are often under a tensile load and are directly exposed to the space environment, therefore it is important to understand the effect of stress in combination with the environment on the durability of these polymer films. The purpose of the Polymer Film Tensile Experiment, flown as part of Materials International Space Station Experiment 6 (MISSE 6), was to expose a variety of polymer films to the low Earth orbital environment under both relaxed and tension conditions. This paper describes the results of post flight tensile testing of these samples.

Influence of copper volume fraction on tensile strain/stress tolerances of critical current in a copper-plated DyBCO-coated conductor

International Nuclear Information System (INIS)

Ochiai, Shojiro; Okuda, Hiroshi; Arai, Takahiro; Sugano, Michinaka; Osamura, Kozo; Prusseit, Werner

2013-01-01

The influence of the volume fraction (V f ) of copper, plated at room temperature over a DyBa 2 Cu 3 O 7-δ -coated conductor, on the tensile strain tolerance and stress tolerance of critical current at 77 K was studied over a wide range of copper V f values. The copper plating exerts a tensile stress during cooling because copper has a higher coefficient of thermal expansion than the substrate conductor. Before application of tensile strain, the copper plated at room temperature yielded at 77 K when the copper V f was lower than a critical value, and was in an elastic state at 77 K when the copper V f was higher than the critical value. The strain tolerance of critical current increased with increasing copper V f due to an increase in thermally induced compressive strain in the substrate tape. The stress tolerance of critical current decreased with increasing copper V f because copper is softer than the substrate tape. These results, together with the trade-off between strain tolerance and stress tolerance (i.e., stress tolerance decreases with increasing strain tolerance), were analyzed by modeling. The results show that the restriction imposed by the trade-off, which limits the ability to simultaneously obtain a high strain tolerance and a high stress tolerance, can be relaxed by strengthening the copper. (author)

The theoretical tensile strength of fcc crystals predicted from shear strength calculations

International Nuclear Information System (INIS)

Cerny, M; Pokluda, J

2009-01-01

This work presents a simple way of estimating uniaxial tensile strength on the basis of theoretical shear strength calculations, taking into account its dependence on a superimposed normal stress. The presented procedure enables us to avoid complicated and time-consuming analyses of elastic stability of crystals under tensile loading. The atomistic simulations of coupled shear and tensile deformations in cubic crystals are performed using first principles computational code based on pseudo-potentials and the plane wave basis set. Six fcc crystals are subjected to shear deformations in convenient slip systems and a special relaxation procedure controls the stress tensor. The obtained dependence of the ideal shear strength on the normal tensile stress seems to be almost linearly decreasing for all investigated crystals. Taking these results into account, the uniaxial tensile strength values in three crystallographic directions were evaluated by assuming a collapse of the weakest shear system. Calculated strengths for and loading were found to be mostly lower than previously calculated stresses related to tensile instability but rather close to those obtained by means of the shear instability analysis. On the other hand, the strengths for loading almost match the stresses related to tensile instability.

Constitutive modeling of void-growth-based tensile ductile failures with stress triaxiality effects

KAUST Repository

Mora Cordova, Angel

2014-07-01

In most metals and alloys, the evolution of voids has been generally recognized as the basic failure mechanism. Furthermore, stress triaxiality has been found to influence void growth dramatically. Besides strain intensity, it is understood to be the most important factor that controls the initiation of ductile fracture. We include sensitivity of stress triaxiality in a variational porous plasticity model, which was originally derived from hydrostatic expansion. Under loading conditions rather than hydrostatic deformation, we allow the critical pressure for voids to be exceeded so that the growth due to plasticity becomes dependent on the stress triaxiality. The limitations of the spherical void growth assumption are investigated. Our improved constitutive model is validated through good agreements with experimental data. Its capacity for reproducing realistic failure patterns is also indicated by a numerical simulation of a compact tensile (CT) test. © 2013 Elsevier Inc.

Stress-deformed state of cylindrical specimens during indirect tensile strength testing

Directory of Open Access Journals (Sweden)

Levan Japaridze

2015-10-01

Full Text Available In this study, the interaction between cylindrical specimen made of homogeneous, isotropic, and linearly elastic material and loading jaws of any curvature is considered in the Brazilian test. It is assumed that the specimen is diametrically compressed by elliptic normal contact stresses. The frictional contact stresses between the specimen and platens are neglected. The analytical solution starts from the contact problem of the loading jaws of any curvature and cylindrical specimen. The contact width, corresponding loading angle (2θ0, and elliptical stresses obtained through solution of the contact problems are used as boundary conditions for a cylindrical specimen. The problem of the theory of elasticity for a cylinder is solved using Muskhelishvili's method. In this method, the displacements and stresses are represented in terms of two analytical functions of a complex variable. In the main approaches, the nonlinear interaction between the loading bearing blocks and the specimen as well as the curvature of their surfaces and the elastic parameters of their materials are taken into account. Numerical examples are solved using MATLAB to demonstrate the influence of deformability, curvature of the specimen and platens on the distribution of the normal contact stresses as well as on the tensile and compressive stresses acting across the loaded diameter. Derived equations also allow calculating the modulus of elasticity, total deformation modulus and creep parameters of the specimen material based on the experimental data of radial contraction of the specimen.

Tensile-property characterization of thermally aged cast stainless steels

International Nuclear Information System (INIS)

Michaud, W.F.; Toben, P.T.; Soppet, W.K.; Chopra, O.K.

1994-02-01

The effect of thermal aging on tensile properties of cast stainless steels during service in light water reactors has been evaluated. Tensile data for several experimental and commercial heats of cast stainless steels are presented. Thermal aging increases the tensile strength of these steels. The high-C Mo-bearing CF-8M steels are more susceptible to thermal aging than the Mo-free CF-3 or CF-8 steels. A procedure and correlations are presented for predicting the change in tensile flow and yield stresses and engineering stress-vs.-strain curve of cast stainless steel as a function of time and temperature of service. The tensile properties of aged cast stainless steel are estimated from known material information, i.e., chemical composition and the initial tensile strength of the steel. The correlations described in this report may be used for assessing thermal embrittlement of cast stainless steel components

Experimental and numerical modeling of basalt textile reinforced mortar behavior under uniaxial tensile stress

International Nuclear Information System (INIS)

Larrinaga, Pello; Chastre, Carlos; Biscaia, Hugo C.; San-José, José T.

2014-01-01

Highlights: • Making more deepen the knowledge of textile reinforced mortar in tensile stress. • Analyzing the effect of the reinforcing ratio of the composite. • To compare results with Aveston–Cooper–Kelly theory. • To develop a numerical model based on a finite element code. • Considering the importance of the bond-slip law of the mortar-to-textile-interface. - Abstract: During the last years several projects and studies have improved the knowledge about textile reinforced mortar (TRM) technology. TRM has already been used in strengthening masonry and reinforced concrete structural elements such as walls, arches, columns and beams. This material is presented as a real alternative to the use of fiber-reinforced polymers (FRP) in situations where these composites have presented some drawbacks or their use is banned. Textile reinforced mortar show a complex mechanical behavior derived from the heterogeneity of the constituent materials. This paper aims to deepen the knowledge of this composite material in terms of tensile behavior. Following this scope, this paper presents an experimental campaign focused on thirty-one TRM specimens reinforced with four different reinforcing ratios. The results are analyzed and contrasted with two distinct models. (i) The Aveston–Cooper–Kelly theory (ACK) which is based on a tri-linear analytical approach; and (ii) a non-linear numerical simulation with a 3D finite element code. The finite element analysis (FEA) of the TRM tensile tests also showed no significant dependence on the basalt-to-mortar interface, i.e., the choice of a bond-slip curve in order to reproduce the bond stresses and slippages along the interface is irrelevant and it can be simply considered as rigid interface

Evaluation of impacts of stress triaxiality on plastic deformability of RAFM steel using various types of tensile specimen

Energy Technology Data Exchange (ETDEWEB)

Kato, Taichiro, E-mail: kato.taichiro@jaea.go.jp [Japan Atomic Energy Agency, 2-166, Obuchi-omotedate, Rokkasho, Aomori 039-3212 (Japan); Ohata, Mitsuru [Osaka University, 2-1, Yamada-Oka, Suita, Osaka 565-0871 (Japan); Nogami, Shuhei [Tohoku University, 6-6-01-2, Aramaki-aza-Aoba, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Tanigawa, Hiroyasu [Japan Atomic Energy Agency, 2-166, Obuchi-omotedate, Rokkasho, Aomori 039-3212 (Japan)

2016-11-01

Highlights: • The fracture ductility is lower as the stress triaxiality is higher. • Voids of the interrupted RB1 specimen were observed along grain boundaries and expanded parallel to the tensile axis. • Voids of interrupted R0.2 specimen were rounded shape than those of RB1. • The fracture surface of specimens were observed the elongated and the equiaxed dimples. • The decrease of plastic deformability of the notched specimen was caused by the process of voids formation and crack growth due to the effect of plastic constraint of the notch. - Abstract: A case study on a fusion blanket design such as DEMO indicated that there could be some sections with high stress triaxiality, a parameter to evaluate the magnitude of plastic constraint, in the case of plasma disruption or coolant loss accident. Therefore, it is necessary to accurately understand the ductility loss limit of structural material in order to conduct the structural design assessment of the irradiated and embrittled fusion reactor blanket. Tensile tests were conducted by using three kinds of tensile specimen shapes to investigate of the plastic deformability of F82H. From the results, the fracture ductility is lower as the stress triaxiality is higher. Voids of the interrupted RB1 specimen were observed along grain boundaries and expanded parallel to the tensile axis. That of interrupted R0.2 specimen was rounded shape compared with those of RB1. The fracture surface of RB1 and R0.2 specimens were observed the elongated dimples and the equiaxed dimples without so much elongation, respectively. It is considered that the decrease of plastic deformability for the notched specimen was caused by the process of voids formation and crack growth due to the effect of plastic constraint of the notch.

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

Science.gov (United States)

Dreshfield, R. L.; Johnson, W.

1982-01-01

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

The temperature dependence of the tensile properties of thermally treated Alloy 690 tubing

International Nuclear Information System (INIS)

Harrod, D.L.; Gold, R.E.; Larsson, B.; Bjoerkman, G.

1992-01-01

Tensile tests were run in air on full tube cross-sections of 22.23 mm OD by 1.27 mm wall thickness Alloy 690 steam generator production tubes from ten (10) heats of material at eight (8) temperatures between room temperature and 760 degrees C. The tubing was manufactured to specification requirements consistent with the EPRI guidelines for Alloy 690 tubing. The room temperature stress-strain curves are described quite well by the Voce equation. Ductile fracture by dimpled rupture was observed at all test temperatures. The elevated temperature tensile properties are compared with design data given in the ASME Code

Tensile, creep and relaxation characteristics of zircaloy cladding at 3850C

International Nuclear Information System (INIS)

Murty, K.L.; McDonald, S.G.

1981-01-01

Axial creep tests were carried out at stresses ranging form 30 ksi to 50 ksi. Steady-state creep rates were evaluated from stress change tests to minimize the number of samples. The secondary creep rate was related to the applied stress through a Sinh function. The functional dependence of the strain rate on the stress was also evaluated from load relaxation tests. It is demonstrated that the strain rates derived from load relaxation tests are identical to the creep data when the relaxation testing was carried out at the point of maximum load in a tensile test. In addition, the creep and relaxation results are identical to the true ultimate tensile stress versus applied strain-rate data derived from tensile tests. (orig./HP)

Molecular Dynamics Simulations of Tensile Behavior of Copper

OpenAIRE

Sainath, G.; Srinivasan, V. S.; Choudhary, B. K.; Mathew, M. D.; Jayakumar, T.

2014-01-01

Molecular dynamics simulations on tensile deformation of initially defect free single crystal copper nanowire oriented in {100} has been carried out at 10 K under adiabatic and isothermal loading conditions. The tensile behaviour was characterized by sharp rise in stress in elastic regime followed by sudden drop at the point of dislocation nucleation. The important finding is that the variation in dislocation density is correlated with the observed stress-strain response. Several interesting ...

Spectroscopic analysis of radiation-generated changes in tensile properties of a polyetherimide film

International Nuclear Information System (INIS)

Long, E.R. Jr.; Long, S.A.T.

1985-05-01

The effects of electron radiation on Ultem, a polyetherimide were studied for doses from 2 x 10 to the 9th power to 6 x 10 to the 9th power rad. Specimens were studied for tensile property testing and for electron paramagnetic resonance and infrared spectroscopic measurements of molecular structure. A Faraday cup design and a method for remote temperature measurement were developed. The spectroscopic data show that radiation caused dehydrogenation of methyl groups, rupture of main-chain ether linkage, and opening of imide rings, all to form radicals and indicate that the so-formed atomic hydrogen attached to phenyl radicals, but not to phenoxyl radicals, which would have formed hydroxyls. The observed decays of the radiation-generated phenoxyl, gem-dimethyl, and carbonyl radicals were interpreted as a combining of the radicals to form crosslinking. This crosslinking is the probable cause of the major reduction in the elongation of the tensile specimens after irradiation. Subsequent classical solubility tests indicate that the irradiation caused massive crosslinking

Cavitation contributes substantially to tensile creep in silicon nitride

International Nuclear Information System (INIS)

Luecke, W.E.; Wiederhorn, S.M.; Hockey, B.J.; Krause, R.F. Jr.; Long, G.G.

1995-01-01

During tensile creep of a hot isostatically pressed (HIPed) silicon nitride, the volume fraction of cavities increases linearly with strain; these cavities produce nearly all of the measured strain. In contrast, compressive creep in the same stress and temperature range produces very little cavitation. A stress exponent that increases with stress (var-epsilon ∝ σ n , 2 < n < 7) characterizes the tensile creep response, while the compressive creep response exhibits a stress dependence of unity. Furthermore, under the same stress and temperature, the material creeps nearly 100 times faster in tension than in compression. Transmission electron microscopy (TEM) indicates that the cavities formed during tensile creep occur in pockets of residual crystalline silicate phase located at silicon nitride multigrain junctions. Small-angle X-ray scattering (SAXS) from crept material quantifies the size distribution of cavities observed in TEM and demonstrates that cavity addition, rather than cavity growth, dominates the cavitation process. These observations are in accord with a model for creep based on the deformation of granular materials in which the microstructure must dilate for individual grains t slide past one another. During tensile creep the silicon nitride grains remain rigid; cavitation in the multigrain junctions allows the silicate to flow from cavities to surrounding silicate pockets, allowing the dilation of the microstructure and deformation of the material. Silicon nitride grain boundary sliding accommodates this expansion and leads to extension of the specimen. In compression, where cavitation is suppressed, deformation occurs by solution-reprecipitation of silicon nitride

Texture development during tensile deformation in Al-Mg alloys

Energy Technology Data Exchange (ETDEWEB)

Ohtani, S.; Inagaki, H. [Shonan Inst. of Tech., Fujisawashi (Japan)

2002-07-01

Tensile tests were made on commercial A1050 pure Al, A5182 Al-4.4% Mg alloy and A2017 Al-4% Cu alloy by varying the test temperature and the strain rate. Textures developed at various stages of the tensile deformation were investigated with the orientation distribution function analysis. It was found that, during the tensile test of the 1050 pure Al with the strain rate of 3 x 10{sup -4}S{sup -1} at 20 C, tensile axis readily rotated toward left angle 111 right angle stable end orientation. However, such rotation occurred only at the latest stage of the tensile deformation near the ultimate tensile stress, where stress strain curve was almost flattened and work hardening was almost saturated. It was strongly suggested that, since fine and complex dislocation cell structures were developed in such a work-hardened state, smooth and long range dislocation glide such as assumed in the classical Taylor theory would not be possible. To explain the observed texture development, cooperative movement of the dislocations in the cell walls might be necessary. In fact, addition of Mg and Cu, which suppressed strongly the development of well defined cell structures due to P-L effect or dynamic strain ageing, significantly retarded the rotation of tensile axes toward left angle 111 right angle. Interesting enough, textures developed in all these materials investigated were not affected by the strain rate and the temperature of the tensile test. (orig.)

Microarray analysis of expression of cell death-associated genes in rat spinal cord cells exposed to cyclic tensile stresses in vitro

Directory of Open Access Journals (Sweden)

Roberts Sally

2010-07-01

Full Text Available Abstract Background The application of mechanical insults to the spinal cord results in profound cellular and molecular changes, including the induction of neuronal cell death and altered gene expression profiles. Previous studies have described alterations in gene expression following spinal cord injury, but the specificity of this response to mechanical stimuli is difficult to investigate in vivo. Therefore, we have investigated the effect of cyclic tensile stresses on cultured spinal cord cells from E15 Sprague-Dawley rats, using the FX3000® Flexercell Strain Unit. We examined cell morphology and viability over a 72 hour time course. Microarray analysis of gene expression was performed using the Affymetrix GeneChip System®, where categorization of identified genes was performed using the Gene Ontology (GO and Kyoto Encyclopedia of Genes and Genomes (KEGG systems. Changes in expression of 12 genes were validated with quantitative real-time reverse transcription polymerase chain reaction (RT-PCR. Results The application of cyclic tensile stress reduced the viability of cultured spinal cord cells significantly in a dose- and time-dependent manner. Increasing either the strain or the strain rate independently was associated with significant decreases in spinal cord cell survival. There was no clear evidence of additive effects of strain level with strain rate. GO analysis identified 44 candidate genes which were significantly related to "apoptosis" and 17 genes related to "response to stimulus". KEGG analysis identified changes in the expression levels of 12 genes of the mitogen-activated protein kinase (MAPK signaling pathway, which were confirmed to be upregulated by RT-PCR analysis. Conclusions We have demonstrated that spinal cord cells undergo cell death in response to cyclic tensile stresses, which were dose- and time-dependent. In addition, we have identified the up regulation of various genes, in particular of the MAPK pathway, which

Effects of stress concentration on low-temperature fracture behavior of A356 alloy

Energy Technology Data Exchange (ETDEWEB)

Ma, Guanghui; Li, Runxia; Li, Rongde

2016-06-14

The effect of stress concentration on the dislocation motion, the Si particles and the crack propagation path in A356 alloy at the temperature of 20 °C to −60 °C was analyzed by scanning electron microscope and optical microscope using a series of notched tensile specimens and normal tensile specimens. The results show that the sensitivity of A356 alloy to the stress concentration increases, the tensile strength and yield strength of normal specimens and notched specimens increase, and the elongation shows a decreasing trend with the decrease of test temperature from 20 °C to −60 °C. The yield strength is not affected by the notch, and the tensile strength is sensitive to the stress concentration. Stress concentration leads to a large number of dislocation generation. Local plastic deformation occurred in the stress concentration region during the tensile process firstly. With the stress concentration in the aluminum matrix between the Si phase and the crack further increasing, the distribution of cracks along the Si phase leads to the cracking of aluminum matrix particle.

In Situ Radiography During Tensile Tests

Science.gov (United States)

Baaklini, George Y.; Bhatt, Ramakrishna T.

1994-01-01

Laboratory system for testing specimens of metal-, ceramic-, and intermetallic-matrix composite materials incorporates both electromechanical tensile-testing subsystem and either of two imaging subsystems that take x-ray photographs of specimens before, during, and after tensile tests. Used to test specimens of reaction-bonded silicon nitride reinforced with silicon carbide fibers (SiC/RBSN) considered for high-temperature service in advanced aircraft turbine engines. Provides data on effects of preexisting flaws (e.g., high-density impurities and local variations of density) on fracture behavior. Accumulated internal damage monitored during loading. X-ray source illuminates specimen in load frame while specimen is pulled. X-ray images on film correlated with stress-vs.-strain data from tensile test.

Neutron diffraction measurements for the determination of residual stresses in MMC tensile and fatigue specimens

DEFF Research Database (Denmark)

Fiori, F.; Girardin, E.; Giuliani, A.

2000-01-01

have been performed at RISO (Roskilde, DK) and HMI-BENSC (Berlin, D), for the determination of residual stress in AA2124 + 17% SiCp and AA359 + 20% SiCp specimens, submitted to tensile and fatigue tests. For each of the investigated samples, the macrostress has been separated from the elastic......, residual stresses are present in both the matrix and the particles microstructure, prior to any macroscopic loading. They vary with the temperature and with the type and level of loading imposed to the material, having a strong influence on the mechanical behaviour of MMCs. Neutron diffraction measurements...... and thermal mismatch microstresses. The results show that, in general, the main contribution to the stress state of both matrix and reinforcement is given by the thermal microstresses, already existing due to heat treatment prior to mechanical tests. (C) 2000 Elsevier Science B.V. All rights reserved....

Determination of necking time in tensile test specimens, under high-temperature creep conditions, subjected to distribution of stresses over the cross-section

Science.gov (United States)

Lokoshchenko, A.; Teraud, W.

2018-04-01

The work describes an experimental research of creep of cylindrical tensile test specimens made of aluminum alloy D16T at a constant temperature of 400°C. The issue to be examined was the necking at different values of initial tensile stresses. The use of a developed noncontacting measuring system allowed us to see variations in the specimen shape and to estimate the true stress in various times. Based on the obtained experimental data, several criteria were proposed for describing the point of time at which the necking occurs (necking point). Calculations were carried out at various values of the parameters in these criteria. The relative interval of deformation time in which the test specimen is uniformly stretched was also determined.

The Effect of Grain Size and Strain on the Tensile Flow Stress of Aluminium at Room Temperature

DEFF Research Database (Denmark)

Hansen, Niels

1977-01-01

stress-grain size relationship was analyzed in terms of matrix strengthening and grain boundary strengthening according to the dislocation concept of Ashby. At intermediate strains this approach gives a good description of the effect of strain, grain size and purity on the flow stress.......Tensile-stress-strain data over a strain range from 0.2 to 30% were obtained at room temperature for 99.999 and 99.5% aluminium as a function of grain size. The yield stress-grain size relationship can be expressed by a Petch-Hall relation with approximately the same slope for the two materials....... The flow stress-grain size relationship can adequately be expressed by a modified Petch-Hall relation; for 99.999% aluminium material the slope increases with strain through a maximum around 15–20%, whereas for 99.5% aluminium the slope decreases with the strain to zero at strains about 10%. The flow...

Experimental Analysis of Tensile Mechanical Properties of Sprayed FRP

Directory of Open Access Journals (Sweden)

Zhao Yang

2016-01-01

Full Text Available To study the tensile mechanical properties of sprayed FRP, 13 groups of specimens were tested through uniaxial tensile experiments, being analyzed about stress-strain curve, tensile strength, elastic modulus, breaking elongation, and other mechanical properties. Influencing factors on tensile mechanical properties of sprayed FRP such as fiber type, resin type, fiber volume ratio, fiber length, and composite thickness were studied in the paper too. The results show that both fiber type and resin type have an obvious influence on tensile mechanical properties of sprayed FRP. There will be a specific fiber volume ratio for sprayed FRP to obtain the best tensile mechanical property. The increase of fiber length can lead to better tensile performance, while that of composite thickness results in property degradation. The study can provide reference to popularization and application of sprayed FRP material used in structure reinforcement.

Stress corrosion cracking of steam generator tube and primary pipe in PWR type nuclear power plants

International Nuclear Information System (INIS)

Zhang Weiguo; Gao Fengqin; Zhou Hongyi

1993-01-01

The behavior of stress corrosion cracking (SCC) is studied by slow strain rate test (SSRT), constant load test (CLT) and low frequency cyclic loading test (LFCLT). The purpose of these tests is to get the test data for evaluating the integrity of pressurized boundary of pipes in Qinshan and Guangdong nuclear power plants. Tested materials are 316 nuclear grade stainless steel (SS) for primary pipes in welded heat affected zone (WHAZ) and steam generator tubes, such as Incoloy-800, Inconel-600, Inconel-690 and 321 SS which are used for steam generator in PWR. The effects of material metallurgy, shot-peening treatment, tensile load, strain rate, cyclic load and water chemistry on the behavior of SCC are investigated

Evaluation of mechanical properties of construction joint between new and old concrete under combined tensile and shear stresses; Shinkyu concrete no uchitsugime no incho sendan oryokuka no kyodo tokusei no hyoka

Energy Technology Data Exchange (ETDEWEB)

Ujiike, I. [Ehime University, Ehime (Japan). Faculty of Engineering; Yoshida, N. [Shikoku Railway Company, Kagawa (Japan); Morishita, S. [Oriental Construction Co. Ltd., Tokyo (Japan)

1998-01-15

The objective of this study is to examine the mechanical properties of construction joints between existing and newly placed concrete under combined tensile and shear stresses. Loading tests are conducted by using push off type specimens. The joint surface of existing concrete is roughened by shot blast and a half of the specimen is reconstructed by new concrete using ultra rapid hardening cement. The insufficient treatment of joint surface of the old concrete causes the lowering of tensile rigidity, while shearing rigidity is almost the same as that of the other specimen. The shearing and tensile rigidities of non jointed concrete and concrete shot blasted properly are not dependent on the combination of shearing and tensile forces. For the jointed concrete shot blasted insufficiently, the shearing rigidity decreases with the increase of tensile force and the tensile digidity also becomes lower by the action of shearing force. Both the tensile strength and shearing strength of jointed concrete become small compared to those of non jointed concrete. The ratio of reduction in tensile strength is larger than that in shearing strength. The strength of jointed concrete under combined tensile and shear stresses can be evaluated by Mohr`s failure envelope expressed by parabola tangent to both tensile strength circle and compressive strength circle. 7 refs., 12 figs., 2 tabs.

Indigenous Design for Automatic Testing of Tensile Strength Using Graphical User Interface

OpenAIRE

Ali Rafay; Junejo Faraz; Imtiaz Rafey; Shamsi Usama Sultan

2016-01-01

Tensile Testing is a fundamental material test to measure the tenacity and tensile strength. Tensile strength means ability to take tensile stress. This Universal Testing Machine is designed using Dual Cylinder Technique in order to comply with the maximun load (tensile force) with the reduction of minimum physical effort and minimized losses.It is to provide material testing opportunity to the students of different institutions, locally and globally, at lowest price; so that they can have a ...

The effect of a single tensile overload on stress corrosion cracking growth of stainless steel in a light water reactor environment

International Nuclear Information System (INIS)

Xue He; Li Zhijun; Lu Zhanpeng; Shoji, Tetsuo

2011-01-01

Research highlights: → The affect of a single tensile overload on SCC growth rate is investigated. → A single tensile overload would produce a residual plastic strain in the SCC tip. → The residual plastic strain would decrease the plastic strain rate in the SCC tip. → A single tensile overload would cause crack growth rate retardation in the SCC tip. → SCC growth rate in the quasi-stationary crack tip is relatively lower. - Abstract: It has been found that a single tensile overload applied during constant load amplitude might cause crack growth rate retardation in various crack propagating experiments which include fatigue test and stress corrosion cracking (SCC) test. To understand the affecting mechanism of a single tensile overload on SCC growth rate of stainless steel or nickel base alloy in light water reactor environment, based on elastic-plastic finite element method (EPFEM), the residual plastic strain in both tips of stationary and growing crack of contoured double cantilever beam (CDCB) specimen was simulated and analyzed in this study. The results of this investigation demonstrate that a residual plastic strain in the region immediately ahead of the crack tips will be produced when a single tensile overload is applied, and the residual plastic strain will decrease the plastic strain rate level in the growing crack tip, which will causes crack growth rate retardation in the tip of SCC.

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)

A combined experimental and FE analysis procedure to evaluate tensile behavior of zircaloy pressure tubes

International Nuclear Information System (INIS)

Samal, M.K.; Vaze, K.K.; Balakrishnan, K.S.; Anantharaman, S.

2012-01-01

Determination of transverse mechanical properties from the ring type of specimens directly machined from the nuclear reactor pressure tubes is not straightforward because of the presence of combined membrane as well as bending stresses arising in the loaded condition. In this work, we have performed ring-tensile tests on the un-irradiated ring tensile specimen using two split semi-cylindrical mandrels as the loading device. A 3-D finite element (FE) analysis was performed in order to determine the material true stress-strain curve by comparing experimental load-displacement data with those predicted by FE analysis. In order to validate the methodology, miniaturized tensile specimens were machined from these tubes and tested. It was observed that the stress-strain data as obtained from ring tensile specimen could describe the load displacement curve of the miniaturized flat tensile specimen very well. (author)

Tensile fracture behaviors of T-ZnOw/polyamide 6 composites

International Nuclear Information System (INIS)

Shi Jing; Wang Yong; Liu Li; Bai Hongwei; Wu Jun; Jiang Chongxi; Zhou, Zuowan

2009-01-01

As a part of serial work about the application of tetra-needle-shaped zinc oxide whisker (T-ZnOw) in polymer composites, this work is focused on the crystallization and tensile fracture behaviors of T-ZnOw/polyamide 6 (T-ZnOw/PA6) composites. Our results show that the addition of T-ZnOw improves the composites tensile strength greatly. For virgin PA6, the stress-strain curve exhibits double-yielding phenomenon. Surface modified T-ZnOw reinforced PA6 composites exhibit higher yield stress and smaller strain-to-fracture compared with virgin PA6. The morphologies of tensile-fractured surfaces show that, addition of T-ZnOw changes the fracture mode from crazing-tearing/brittle fracture mode of virgin PA6 into fibrillation/brittle fracture mode of PA6 composites. Especially, the fracture process of T-ZnOw in composites during the tensile test has been characterized by scanning electronic microscope (SEM) and the corresponding reinforcement mechanism has been discussed.

The influence of tensile forces on the deflection of circular diaphragms in pressure sensors

NARCIS (Netherlands)

Voorthuyzen, J.A.; Bergveld, Piet

1984-01-01

It is known that the deflection of a diaphragm is determined by two mechanisms, bending moments or bending stress and tensile forces or membrane stress. Usually the influence of tensile forces is not taken into account when calculating the mechanical properties of thin diaphragms. Hence the

Distribution of steady state temperatures and thermoelastic stresses in a cylindrical shell with internal heat generation and cooled on both sides or only on one side

International Nuclear Information System (INIS)

Melese d'Hospital, G.B.

1979-10-01

General expressions for steady state temperatures and elastic thermal stress distributions are derived for a hollow fuel element cooled on both sides. The main simplifying assumptions consist of one dimensional heat transfer and a single medium. Dimensionless numerical results are plotted in the case of uniform internal heat generation and for constant thermal conductivity. Solid rods and flat plates are treated as special cases. As could be expected, cooling on both sides rather than on only one side, leads to significant reduction in maximum fuel temperature and thermal stresses for a given power density, or to a significant increase in power density for either given maximum temperature drop in the fuel or for maximum tensile thermal stress. Typically, for a rod diameter ratio of 2, the power density could be increased by a factor of 3 to 4 without increasing the maximum stress. Similarly, for the same power density, replacing internal cooling of a hollow fuel element by external cooling reduces the maximum fuel temperature drop by a factor of 1.5 and the average fuel temperature drop (or maximum tensile stress) by a factor of 2, with the same maximum compressive stress

Properties of aluminum alloys tensile, creep, and fatigue data at high and low temperatures

CERN Document Server

1999-01-01

This book compiles more than 300 tables listing typical average properties of a wide range of aluminum alloys. The individual test results were compiled, plotted in various ways, and analyzed. The average values from the tensile and creep tests were then normalized to the published typical room-temperature tensile properties of the respective alloys for easy comparison. This extensive project was done by Alcoa Laboratories over a period of several years. The types of data presented include: Typical Mechanical Properties of Wrought and Cast Aluminum Alloys at Various Temperatures, including tensile properties at subzero temperatures, at temperature after various holding times at the test temperature, and at room temperature after exposure at various temperatures for various holding times; creep rupture strengths for various times at various temperatures; stresses required to generate various amounts of creep in various lengths of time; rotating-beam fatigue strengths; modulus of elasticity as a function of t...

Tensile strength of concrete under static and intermediate strain rates: Correlated results from different testing methods

International Nuclear Information System (INIS)

Wu Shengxing; Chen Xudong; Zhou Jikai

2012-01-01

Highlights: ► Tensile strength of concrete increases with increase in strain rate. ► Strain rate sensitivity of tensile strength of concrete depends on test method. ► High stressed volume method can correlate results from various test methods. - Abstract: This paper presents a comparative experiment and analysis of three different methods (direct tension, splitting tension and four-point loading flexural tests) for determination of the tensile strength of concrete under low and intermediate strain rates. In addition, the objective of this investigation is to analyze the suitability of the high stressed volume approach and Weibull effective volume method to the correlation of the results of different tensile tests of concrete. The test results show that the strain rate sensitivity of tensile strength depends on the type of test, splitting tensile strength of concrete is more sensitive to an increase in the strain rate than flexural and direct tensile strength. The high stressed volume method could be used to obtain a tensile strength value of concrete, free from the influence of the characteristics of tests and specimens. However, the Weibull effective volume method is an inadequate method for describing failure of concrete specimens determined by different testing methods.

Effect of strain rate and stress triaxiality on tensile behavior of Titanium alloy Ti-10-2-3 at elevated temperatures

Energy Technology Data Exchange (ETDEWEB)

Bobbili, Ravindranadh, E-mail: ravindranadh@dmrl.drdo.in; Madhu, Vemuri

2016-06-14

In this study, Split hopkinson tension bar (SHTB) has been employed to investigate the dynamic tensile flow behavior of Ti-10-2-3 alloy at high strain rates and elevated temperatures. The combined effect of stress triaxiality, strain rate and temperature and on the tensile behavior of the alloy was evaluated. Johnson-Cook (J-C) constitutive and fracture models were developed based on high strain rate tensile data. A modified Johnson–Cook model was established and proved to have high accuracy. A comparative assessment has been done to confirm the accuracy of modified J–C model based on finite element method (FEM). The improved model provides better description on the influence of equivalent plastic strain rate and temperature on the plastic flow. The simulation results proved to be in good agreement with the experimental data. The fracture surfaces of specimens tested under various strain rates and temperatures were studied under scanning electron microscopy (SEM).

Influence of tensile stress and frequency on the longitudinal magnetic hysteresis of amorphous wires

International Nuclear Information System (INIS)

Torres, Carlos; Maria Munoz, Jose; Hernandez-Gomez, Pablo; Francisco, Carlos de

2010-01-01

This work studies the longitudinal magnetic hysteresis of amorphous wires with different Fe or Co compositions through an external magnetic field in the axial direction. Measurements have been carried out with the help of a digitally processed system in the 50 Hz-1 kHz frequency range. In addition, the influence of different tensile stresses has been also analyzed. The results show that both parameters change considerably the magnetic hysteresis of the wires but in a different way depending on their composition. This behaviour has been interpreted in terms of the different domain distribution associated with the opposite sign of the magnetostriction for Fe and Co-based wires, respectively.

An analytical model to predict and minimize the residual stress of laser cladding process

Science.gov (United States)

Tamanna, N.; Crouch, R.; Kabir, I. R.; Naher, S.

2018-02-01

Laser cladding is one of the advanced thermal techniques used to repair or modify the surface properties of high-value components such as tools, military and aerospace parts. Unfortunately, tensile residual stresses generate in the thermally treated area of this process. This work focuses on to investigate the key factors for the formation of tensile residual stress and how to minimize it in the clad when using dissimilar substrate and clad materials. To predict the tensile residual stress, a one-dimensional analytical model has been adopted. Four cladding materials (Al2O3, TiC, TiO2, ZrO2) on the H13 tool steel substrate and a range of preheating temperatures of the substrate, from 300 to 1200 K, have been investigated. Thermal strain and Young's modulus are found to be the key factors of formation of tensile residual stresses. Additionally, it is found that using a preheating temperature of the substrate immediately before laser cladding showed the reduction of residual stress.

Study on the residual stress relaxation in girth-welded steel pipes under bending load using diffraction methods

International Nuclear Information System (INIS)

Hempel, Nico; Nitschke-Pagel, Thomas; Dilger, Klaus

2017-01-01

This research is dedicated to the experimental investigation of the residual stress relaxation in girth-welded pipes due to quasi-static bending loads. Ferritic-pearlitic steel pipes are welded with two passes, resulting in a characteristic residual stress state with high tensile residual stresses at the weld root. Also, four-point bending is applied to generate axial load stress causing changes in the residual stress state. These are determined both on the outer and inner surfaces of the pipes, as well as in the pipe wall, using X-ray and neutron diffraction. Focusing on the effect of tensile load stress, it is revealed that not only the tensile residual stresses are reduced due to exceeding the yield stress, but also the compressive residual stresses for equilibrium reasons. Furthermore, residual stress relaxation occurs both parallel and perpendicular to the applied load stress.

Stress relieving procedure and facility by shot-peening the inside surface of NPP steam generators tubes

International Nuclear Information System (INIS)

Banica, I.; Maioru, H.

1994-01-01

Residual stress relieving of the transition zones between the deformed part and the non deformed part of the heat exchanger tubes expanded in tube sheets of the NPP equipment, is a technological problem attacked on international level as well as on national level through the continuing programme initiated by ICEMENERG. The most recent statistical data point out that over 75% of tube failures are taking place in the tube-to-tubesheet connection zone, a great number of them being produced in this area by intergranular attack and stress corrosion cracking. The increased occurrence of these incidents is explained first by the existence of residual stresses inside tube surfaces, induced by expanding the tubes. Relieving these residual stresses is the purpose of the outlined procedure and it is achieved by overlapping effects (compression stresses added over tensile stresses). In this paper aspects of the procedure are presented and also a facility is described for stress relieving by introducing compressive stresses from uniform and generalized collisions of the inside surface with micro balls of great kinetic energy carried by a pressurized gas. The stress relieving facility can be acted by remote control, the whole process being completely automatic. The procedure aims to the operation maintenance of the NPP steam generators. (Author)

Effects of cyclic tensile loading on stress corrosion cracking susceptibility for sensitized Type 304 stainless steel in 290 C high purity water

International Nuclear Information System (INIS)

Takaku, H.; Tokiwai, M.; Hirano, H.

1979-01-01

The effects of load waveform on intergranular stress corrosion cracking (IGSCC) susceptibility have been examined for sensitized Type 304 stainless steels in a 290 C high purity water loop. Concerning the strain rate in the trapezoidal stress waveform, it was found that IGSCC susceptibility was higher for smaller values of the strain rate. It was also shown that IGSCC susceptibility became higher when the holding time at the upper stress was prolonged, and when the upper stress was high. The occurrence of IGSCC for sensitized Type 304 stainless steel became easy due to the application of cyclic tensile stress in 290 C high purity water

Evaluation of local stress for stress corrosion crack initiation by three-dimensional polycrystal model

International Nuclear Information System (INIS)

Kamaya, Masayuki; Kitamura, Takayuki

2006-01-01

In order to understand the initiation behavior of microstructurally small cracks in a stress corrosion cracking condition, it is important to know the tensile normal stress acting on the grain boundary (normal G.B. stress). The local stress in a polycrystalline body is greatly influenced by deformation constraint which is caused by anisotropic and/or inhomogeneous property of each grain. In present study, the local normal G.B. stress on bi- and tri-crystal bodies and a three-dimensional polycrystalline body consisting of 100 grains were evaluated by the finite element method under a remote uniform tensile stress condition. The polycrystalline body was generated by using a Monte Carlo procedure and random orientations were assigned to each grain. It was revealed that the local normal G.B. stress on the polycrystalline body is inhomogeneous under uniform applied stress. The stress tends to be large near the triple points due to the deformation constraint caused by adjacent grains, even though the grain boundary inclination to the load axis has large influence. It was also shown that particular high stress was not observed at corners of the polycrystalline body. (author)

Influence of the microstructural changes and induced residual stresses on tensile properties of wrought magnesium alloy friction stir welds

International Nuclear Information System (INIS)

Commin, Loreleï; Dumont, Myriam; Rotinat, René; Pierron, Fabrice; Masse, Jean-Eric; Barrallier, Laurent

2012-01-01

Highlights: ► Study of AZ31 FSW mechanical behaviour. ► Early yielding occurs in the TMAZ, the nugget and base metal zones undergo almost no plastic strains. ► Texture gradient in the TMAZ localises the deformations in this area. ► Residual stresses have a major influence in FSW mechanical behaviour. - Abstract: Friction stir welding induces a microstructural evolution and residual stresses that will influence the resulting mechanical properties. Friction stir welds produced from magnesium alloy hot rolled plates were studied. Electron back scattered diffraction was used to determine the texture evolution, residual stresses were analysed using X ray diffraction and tensile tests coupled with speckle interferometry were performed. The residual stresses induced during friction stir welding present a major influence on the final mechanical properties.

Consolidation effects on tensile properties of an elemental Al matrix composite

Energy Technology Data Exchange (ETDEWEB)

Tang, F. [Building 4515, MS 6064, Metals and Ceramics Division, Oak Ridge National Lab, Oak Ridge, TN 37831 (United States)]. E-mail: tangf@ornl.gov; Meeks, H. [Ceracon Inc., 5150 Fairoaks Blvd. 01-330, Carmichael, CA 95628 (United States); Spowart, J.E. [UES Incorporated, AFRL/MLLM Building 655, 2230 Tenth St. Suite 1, Wright-Patterson AFB, OH 45433 (United States); Gnaeupel-Herold, T. [NIST Center for Neutron Research, 100 Bureau Dr. Stop 8562, Gaithersburg, MD 20899-8562 (United States); Prask, H. [NIST Center for Neutron Research, 100 Bureau Dr. Stop 8562, Gaithersburg, MD 20899-8562 (United States); Anderson, I.E. [Materials and Engineering Physics Program, Ames Laboratory, Iowa State University, Ames, IA 50011 (United States)

2004-11-25

In a simplified composite design, an unalloyed Al matrix was reinforced by spherical Al-Cu-Fe alloy particles (30 vol.%), using either commercial purity (99.7%) or high purity (99.99%) fine powders (diameter < 10 {mu}m). This composite material was consolidated by either vacuum hot pressing (VHP) or quasi-isostatic forging. The spatial distribution of reinforcement particles in both VHP and forged samples was shown to be almost the same by quantitative characterization with a multi-scale area fraction analysis technique. The tensile properties of all composite samples were tested and the forged materials showed significantly higher strength, while the elastic modulus values of all composite materials were close to the upper bound of theoretical predictions. Neutron diffraction measurements showed that there were high compressive residual stresses in the Al matrix of the forged samples and relatively low Al matrix residual stresses (predominantly compressive) in the VHP samples. By tensile tests and neutron diffraction measurements of the forged samples after annealing, it was shown that the high compressive residual stresses in the Al matrix were relieved and that tensile strength was also reduced to almost the same level as that of the VHP samples. Therefore, it was deduced that increased compressive residual stresses and enhanced dislocation densities in the forged composites raised the tensile strength to higher values than those of the VHP composites.

Behaviour of eggshell membranes at tensile loading

Czech Academy of Sciences Publication Activity Database

Strnková, M.J.; Nedomová, Š.; Trnka, Jan; Buchar, J.; Kumbár, V.

46 B, December (2014), s. 44-48 ISSN 0324-1130 Institutional support: RVO:61388998 Keywords : eggshell membrane * tensile loading * loading rate * stress * strain strength Subject RIV: GM - Food Processing Impact factor: 0.201, year: 2014

Effect of prior machining deformation on the development of tensile residual stresses in weld-fabricated nuclear components

International Nuclear Information System (INIS)

Prevey, P.S.; Mason, P.W.; Hornbach, D.J.; Molkenthin, J.P.

1996-01-01

Austenitic alloy weldments in nuclear systems may be subject to stress-corrosion cracking (SCC) failure if the sum of residual and applied stresses exceeds a critical threshold. Residual stresses developed by prior machining and welding may either accelerate or retard SCC, depending on their magnitude and sign. A combined x-ray diffraction and mechanical procedure was used to determine the axial and hoop residual stress and yield strength distributions into the inside-diameter surface of a simulated Alloy 600 penetration J-welded into a reactor pressure vessel. The degree of cold working and the resulting yield strength increase caused by prior machining and weld shrinkage were calculated from the line-broadening distributions. Tensile residual stresses on the order of +700 MPa were observed in both the axial and the hoop directions at the inside-diameter surface in a narrow region adjacent to the weld heat-affected zone. Stresses exceeding the bulk yield strength were found to develop due to the combined effects of cold working of the surface layers during initial machining and subsequent weld shrinkage. The residual stress and cold work distributions produced by prior machining were found to influence strongly the final residual stress state developed after welding

Mechanical Behavior of Red Sandstone under Incremental Uniaxial Cyclical Compressive and Tensile Loading

Directory of Open Access Journals (Sweden)

Baoyun Zhao

2017-01-01

Full Text Available Uniaxial experiments were carried out on red sandstone specimens to investigate their short-term and creep mechanical behavior under incremental cyclic compressive and tensile loading. First, based on the results of short-term uniaxial incremental cyclic compressive and tensile loading experiments, deformation characteristics and energy dissipation were analyzed. The results show that the stress-strain curve of red sandstone has an obvious memory effect in the compressive and tensile loading stages. The strains at peak stresses and residual strains increase with the cycle number. Energy dissipation, defined as the area of the hysteresis loop in the stress-strain curves, increases nearly in a power function with the cycle number. Creep test of the red sandstone was also conducted. Results show that the creep curve under each compressive or tensile stress level can be divided into decay and steady stages, which cannot be described by the conventional Burgers model. Therefore, an improved Burgers creep model of rock material is constructed through viscoplastic mechanics, which agrees very well with the experimental results and can describe the creep behavior of red sandstone better than the Burgers creep model.

Influence of scan strategy and molten pool configuration on microstructures and tensile properties of selective laser melting additive manufactured aluminum based parts

Science.gov (United States)

Dai, Donghua; Gu, Dongdong; Zhang, Han; Xiong, Jiapeng; Ma, Chenglong; Hong, Chen; Poprawe, Reinhart

2018-02-01

Selective laser melting additive manufacturing of the AlSi12 material parts through the re-melting of the previously solidified layer using the continuous two layers 90° rotate scan strategy was conducted. The influence of the re-melting behavior and scan strategy on the formation of the ;track-track; and ;layer-layer; molten pool boundaries (MPBs), dimensional accuracy, microstructure feature, tensile properties, microscopic sliding behavior and the fracture mechanism as loaded a tensile force has been studied. It showed that the defects, such as the part distortion, delamination and cracks, were significantly eliminated with the deformation rate less than 1%. The microstructure of a homogeneous distribution of the Si phase, no apparent grain orientation on both sides of the MPBs, was produced in the as-fabricated part, promoting the efficient transition of the load stress. Cracks preferentially initiate at the ;track-track; MPBs when the tensile stress increases to a certain value, resulting in the formation of the cleavage steps along the tensile loading direction. The cracks propagate along the ;layer-layer; MPBs, generating the fine dimples. The mechanical behavior of the SLM-processed AlSi12 parts can be significantly enhanced with the ultimate tensile strength, yield strength and elongation of 476.3 MPa, 315.5 MPa and 6.7%, respectively.

Acquirement of true stress-strain curve using true fracture strain obtained by tensile test and FE analysis

International Nuclear Information System (INIS)

Lee, Kyoung Yoon; Kim, Tae Hyung; Lee, Hyung Yil

2009-01-01

In this work, we predict a true fracture strain using load-displacement curves from tensile test and Finite Element Analysis (FEA), and suggest a method for acquiring true Stress-Strain (SS) curves by predicted fracture strain. We first derived the true SS curve up to necking point from load-displacement curve. As the beginning, the posterior necking part of true SS curve is linearly extrapolated with the slope at necking point. The whole SS curve is then adopted for FE simulation of tensile test. The Bridgman factor or suitable plate correction factors are applied to pre and post FEA. In the load-true strain curve from FEA, the true fracture strain is determined as the matching point to test fracture load. The determined true strain is validated by comparing with test fracture strain. Finally, we complete the true SS curve by combining the prior necking part and linear part, the latter of which connects necking and predicted fracture points.

Acquirement of true stress-strain curve using true fracture strain obtained by tensile test and FE analysis

Energy Technology Data Exchange (ETDEWEB)

Lee, Kyoung Yoon; Kim, Tae Hyung; Lee, Hyung Yil [Sogang University, Seoul (Korea, Republic of)

2009-07-01

In this work, we predict a true fracture strain using load-displacement curves from tensile test and Finite Element Analysis (FEA), and suggest a method for acquiring true Stress-Strain (SS) curves by predicted fracture strain. We first derived the true SS curve up to necking point from load-displacement curve. As the beginning, the posterior necking part of true SS curve is linearly extrapolated with the slope at necking point. The whole SS curve is then adopted for FE simulation of tensile test. The Bridgman factor or suitable plate correction factors are applied to pre and post FEA. In the load-true strain curve from FEA, the true fracture strain is determined as the matching point to test fracture load. The determined true strain is validated by comparing with test fracture strain. Finally, we complete the true SS curve by combining the prior necking part and linear part, the latter of which connects necking and predicted fracture points.

Acquirement of True Stress-strain Curve Using True Fracture Strain Obtained by Tensile Test and FE Analysis

Energy Technology Data Exchange (ETDEWEB)

Lee, Kyoung Yoon; Lee, Hyung Yil [Sogang University, Seoul (Korea, Republic of); Kim, Tae Hyung [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2009-10-15

In this work, we predict a true fracture strain using load-displacement curves from tensile test and finite element analysis (FEA), and suggest a method for acquiring true stress-strain (SS) curves by predicted fracture strain. We first derived the true SS curve up to necking point from load-displacement curve. As the beginning, the posterior necking part of true SS curve is linearly extrapolated with the slope at necking point. The whole SS curve is then adopted for FE simulation of tensile test. The Bridgman factor or suitable plate correction factors are applied to pre and post FEA. In the load-true strain curve from FEA, the true fracture strain is determined as the matching point to test fracture load. The determined true strain is validated by comparing with test fracture strain. Finally, we complete the true SS curve by combining the prior necking part and linear part, the latter of which connects necking and predicted fracture points.

EXPERIMENTAL INVESTIGATION ON TENSILE STRENGTH OF JACQUARD KNITTED FABRICS

Directory of Open Access Journals (Sweden)

BRAD Raluca

2015-05-01

Full Text Available An objective approach to select the best fabric for technical and home textiles consists in mechanical properties evaluation. The goal of this study is to analyze the behavior of knitted fabrics undergoing stretch stress. In this respect, three types of 2 colors Rib structure (backstripes jacquard, twillback jacquard and double-layered 3x3 rib fabric have been presented and tested for tensile strength and elongation on three directions. First, the elasticity and the behavior of knitted Rib fabrics were described The fabrics were knitted using 100% PAN yarns with Nm 1/15x2 on a E5 CMS 330 Stoll V-bed knitting machine, and have been tested using INSTROM 5587 Tensile Testing Machine in respect of standards conditions. After a relaxation period, 15 specimens were prepared, being disposed at 0°, 45 and 90 angles to the wale direction on the flat knitted panel. The tensile strength and the elongation values were recorded and mean values were computed. After strength and tensile elongation testing for 3 types of rib based knitted fabrics, one can see that the double layer knit presents the best mechanical behavior, followed by birds-eyebacking 2 colors Jacquard and then back striped Jacquard. For tensile stress in bias direction, the twillbacking Jacquard has a good breakage resistance value due to the higher number of rib sinker loops in structure that are positioned on the same direction with the tensile force. The twillbacking Jacquard structure could be considered as an alternative for the base material for decorative and home textile products.

Effect of the weld joint configuration on stressed components, residual stresses and mechanical properties

Energy Technology Data Exchange (ETDEWEB)

Cevik, Bekir; Oezer, Alpay; Oezcatalbas, Yusuf [Gazi Univ., Ankara (Turkey)

2014-03-01

The effect of the weld joint configuration on components has been studied, which are under service loads, under repair or construction and the residual stresses as well as the mechanical properties of the joint have been determined. For this purpose, a horizontal positioned tensile testing device and a semi-automatic MIG welding machine have been used and then the weld joints of the plates were subjected to different elastic stresses. When the temperature of the joined elements decreased to room temperature, applied elastic stresses were released. By this means, the effects of the existing tensile stresses in the joined parts and the tensile stresses created by the welding processes were investigated. The tensile stresses occurring in the joined elements were determined by using the photo-elasticity analysis method and the hole-drilling method. Also, tensile-shear tests were applied in order to determine the effect of permanent tensile loads on the mechanical properties of the joint. Experimental results showed that the application of corner welded lap joints for components under tensile loading significantly decrease the shear strength and yielding capacities of the joint. (orig.)

Effects of gamma-ray irradiation on tensile properties of ultradrawn polyethylene

International Nuclear Information System (INIS)

Iida, Shozo; Sakami, Hiroshi

1977-01-01

The deformation of ultradrawn polyethylene was previously shown that crystalline chains were pulled out by the tension applied to tie chains which connected crystal blocks. This paper deals with the effects of γ-ray irradiation on crosslinking which prevent crystalline chains being pulled out and to improve the tensile properties. The tensile strength of high density polyethylene, drawn by a factor of 40, increased from 73 to 113 kg/mm 2 at 20 0 C and from 13 to 42 kg/mm 2 at 80 0 C with increasing irradiation dose from zero to 100 Mrad. The tensile elongation, the residual strain measured by cyclic strain test, and the rate of stress decrease by the stress relaxation measurement diminished with increasing irradiation dose. These facts showed the existence of preventive effects by crosslinks on pulling. The stress-strain relation of crosslinked polymer was calculated thermodynamically from the melting of crystalline chains accompanied by the sliding of chains, assuming that the sliding of crystalline chains was brought about by an unbalance of the tension applied to tie chains with which both sides of crystalline chains were connected. The equation of stress was derived; stress increased with increasing strain and was proportional to the Gibbs' free energy of fusion. The observed stress-strain relations obeyed the above mentioned equation. (auth.)

Assessment of possibility of primary water stress corrosion cracking occurrence based on residual stress analysis in pressurizer safety nozzle of nuclear power plant

International Nuclear Information System (INIS)

Lee, Kyoung Soo; Kim, W.; Lee, Jeong Geun

2012-01-01

Primary water stress corrosion cracking (PWSCC) is a major safety concern in the nuclear power industry worldwide. PWSCC is known to initiate only in the condition in which sufficiently high tensile stress is applied to alloy 600 tube material or alloy 82/182 weld material in pressurized water reactor operating environments. However, it is still uncertain how much tensile stress is required to generate PWSCC or what causes such high tensile stress. This study was performed to predict the magnitude of weld residual stress and operating stress and compare it with previous experimental results for PWSCC initiation. For the study, a pressurizer safety nozzle was selected because it is reported to be vulnerable to PWSCC in overseas plants. The assessment was conducted by numerical analysis. Before performing stress analysis for plant conditions, a preliminary mock-up analysis was done. The result of the preliminary analysis was validated by residual stress measurement in the mockup. After verification of the analysis methodology, an analysis under plant conditions was conducted. The analysis results show that the stress level is not high enough to initiate PWSCC. If a plant is properly welded and operated, PWSCC is not likely to occur in the pressurizer safety nozzle.

Exploring the tensile strain energy absorption of hybrid modified epoxies containing soft particles

International Nuclear Information System (INIS)

Abadyan, M.; Bagheri, R.; Kouchakzadeh, M.A.; Hosseini Kordkheili, S.A.

2011-01-01

Research highlights: → Two epoxy systems have been modified by combination of fine and coarse modifiers. → While both hybrid systems reveal synergistic K IC , no synergism is observed in tensile test. → It is found that coarse particles induce stress concentration in hybrid samples. → Stress concentration leads to fracture of samples at lower energy absorption levels. -- Abstract: In this paper, tensile strain energy absorption of two different hybrid modified epoxies has been systematically investigated. In one system, epoxy has been modified by amine-terminated butadiene acrylonitrile (ATBN) and hollow glass spheres as fine and coarse modifiers, respectively. The other hybrid epoxy has been modified by the combination of ATBN and recycled Tire particles. The results of fracture toughness measurement of blends revealed synergistic toughening for both hybrid systems in some formulations. However, no evidence of synergism is observed in tensile test of hybrid samples. Scanning electron microscope (SEM), transmission optical microscope (TOM) and finite element (FEM) simulation were utilized to study deformation mechanisms of hybrid systems in tensile test. It is found that coarse particles induce stress concentration in hybrid samples. This produces non-uniform strain localized regions which lead to fracture of hybrid samples at lower tensile loading and energy absorption levels.

An Experimental Study of the Influence of in-Plane Fiber Waviness on Unidirectional Laminates Tensile Properties

Science.gov (United States)

Zhao, Cong; Xiao, Jun; Li, Yong; Chu, Qiyi; Xu, Ting; Wang, Bendong

2017-12-01

As one of the most common process induced defects of automated fiber placement, in-plane fiber waviness and its influences on mechanical properties of fiber reinforced composite lack experimental studies. In this paper, a new approach to prepare the test specimen with in-plane fiber waviness is proposed in consideration of the mismatch between the current test standard and actual fiber trajectory. Based on the generation mechanism of in-plane fiber waviness during automated fiber placement, the magnitude of in-plane fiber waviness is characterized by axial compressive strain of prepreg tow. The elastic constants and tensile strength of unidirectional laminates with in-plane fiber waviness are calculated by off-axis and maximum stress theory. Experimental results show that the tensile properties infade dramatically with increasing magnitude of the waviness, in good agreement with theoretical analyses. When prepreg tow compressive strain reaches 1.2%, the longitudinal tensile modulus and strength of unidirectional laminate decreased by 25.5% and 57.7%, respectively.

Residual stress improved by water jet peening using cavitation for small-diameter pipe inner surfaces

International Nuclear Information System (INIS)

Yasuo, Nakamura; Toshizo, Ohya; Koji, Okimura

2001-01-01

As one of degradation conditions on components used in water, the overlapping effect of environment, material and stress might cause stress corrosion cracking (SCC). Especially, for the tensile residual stress produced by welding, it is particularly effective to reduce the tensile residual stress on the material surface to prevent SCC. In this paper, the residual stress improvement method using cavitation impact generated by a water jet, called Water Jet Peening (WJP), has been developed as the maintenance technology for the inner surfaces of small-diameter Ni-Cr-Fe alloy (Alloy 600) pipes. As the results, by WJP for the inner surface of Alloy 600 pipe (inner diameter; approximately 10-15 mm), we confirmed that the compressive stress generated within the range from the surface to the inner part about 0.5 mm deep and took a maximum value about 350 MPa on the surface. (author)

Full-Field Stress Determination Around Circular Discontinuity in a Tensile-Loaded Plate using x-displacements Only

Science.gov (United States)

Baek, Tae Hyun; Chung, Tae Jin; Panganiban, Henry

The significant effects of stress raisers demand well-defined evaluation techniques to accurately determine the stress along the geometric boundary. A simple and accurate method for the determination of stress concentration around circular geometric discontinuity in a tensile-loaded plate is illustrated. The method is based on the least-squares technique, mapping functions, and a complex power series representation (Laurent series) of the stress functions for the calculation of tangential stress around the hole. Traction-free conditions were satisfied at the geometric discontinuity using conformal mapping and analytic continuation. In this study, we use only a relatively small amount of x-component displacement data of points away from the discontinuity of concern with their respective coordinates. Having this information we can easily obtain full-field stresses at the edge of the geometric discontinuity. Excellent results were obtained when the number of terms of the power series expansions, m=1. The maximum stress concentration calculation results using the present method and FEM using ANSYS agree well by less than one per cent difference. Experimental advantage of the method underscores the use of relatively small amount of data which are conveniently determined being away from the edge. Moreover, the small amount of measured input data needed affords the approach suitable for applications such as the multi-parameter concept used to obtain stress intensity factors from measured data. The use of laser speckle interferometry and moiré interferometry are also potential future related fields since the optical system for one-directional measurement is much simple.

Using hardness to model yield and tensile strength

Energy Technology Data Exchange (ETDEWEB)

Hawk, Jeffrey A.; Dogan, Omer N.; Schrems, Karol K.

2005-02-01

The current direction in hardness research is towards smaller and smaller loads as nano-scale materials are developed. There remains, however, a need to investigate the mechanical behavior of complex alloys for severe environment service. In many instances this entails casting large ingots and making numerous tensile samples as the bounds of the operating environment are explored. It is possible to gain an understanding of the tensile strength of these alloys using room and elevated temperature hardness in conjunction with selected tensile tests. The approach outlined here has its roots in the work done by Tabor for metals and low alloy and carbon steels. This research seeks to extend the work to elevated temperatures for multi-phase, complex alloys. A review of the approach will be given after which the experimental data will be examined. In particular, the yield stress and tensile strength will be compared to their corresponding hardness based values.

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

DEFF Research Database (Denmark)

Oddershede, Jette; Camin, Bettina; Schmidt, Søren

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...

Ab initio elastic properties and tensile strength of crystalline hydroxyapatite.

Science.gov (United States)

Ching, W Y; Rulis, Paul; Misra, A

2009-10-01

We report elastic constant calculation and a "theoretical" tensile experiment on stoichiometric hydroxyapatite (HAP) crystal using an ab initio technique. These results compare favorably with a variety of measured data. Theoretical tensile experiments are performed on the orthorhombic cell of HAP for both uniaxial and biaxial loading. The results show considerable anisotropy in the stress-strain behavior. It is shown that the failure behavior of the perfect HAP crystal is brittle for tension along the z-axis with a maximum stress of 9.6 GPa at 10% strain. Biaxial failure envelopes from six "theoretical" loading tests show a highly anisotropic pattern. Structural analysis of the crystal under various stages of tensile strain reveals that the deformation behavior manifests itself mainly in the rotation of the PO(4) tetrahedron with concomitant movements of both the columnar and axial Ca ions. These results are discussed in the context of mechanical properties of bioceramic composites relevant to mineralized tissues.

Study on residual stress across the pipes' thickness using outer surface rapid heating. Development of pipe outer surface irradiated laser stress improvement process (L-SIP)

International Nuclear Information System (INIS)

Ohta, Takahiro; Terasaki, Toshio

2009-01-01

The new process called L-SIP (outer surface irradiated Laser Stress Improvement Process) is developed to improve the tensile residual stress of the inner surface near the butt welded joints of pipes in the compression stress. The temperature gradient occurs in the thickness of pipes in heating the outer surface rapidly by laser beam. By the thermal expansion difference between the inner surface and the outer surface, the compression plastic strain generates near the outer surface and the tensile plastic strain generates near the inner surface of pipes. The compression stress occurs near the inner surface of pipes by the plastic deformation. In this paper, the theoretical equation which calculates residual stress distribution from the inherent strain distribution in the thickness of pipes is derived. And, the relation between the distribution of temperature and the residual stress in the thickness is examined for various pipes size. (1) By rapidly heating from the outer surface, the residual stress near the inner surface of the pipe is improved to the compression stress. (2) Pipes size hardly affects the distribution of the residual stress in the stainless steel pipes for piping (JISG3459). (3) The temperature rising area from the outside is smaller, the area of the compression residual stress near the inner surface becomes wider. (author)

Comparative evaluation of preventive measures against primary side stress corrosion cracking of mill annealed Inconel 600 steam generator tubes

International Nuclear Information System (INIS)

Frederick, G.; Hernalsteen, P.

1986-01-01

Significant amounts of primary side cracking have been reported in the mechanically expanded area of the tubes of PWR steam generators in Europe, in Japan and to a lesser extent in the USA. The Belgian utilities are faced with the same problem. At Doel 2, where the tubes are rolled for only a part of the tubesheet, primary side cracking appeared in the roll transition. The Doel 3 and Tihange 2 steam generators, whose tubes are expanded for the full depth of the tube sheet, have experienced cracking after about 10 000 h of operation not only in the roll transition but also at roll overlaps. While some leaks and eddy current indications are associated with tubesheet or rolling anomalies, many of them are found on normal tubes. A programme was launched by the Belgian utilities and was further co-sponsored by the Electric Power Research Institute (EPRI) to develop preventive actions applicable not only to hot steam generators but also to cold steam generators already installed on site. These preventive measures include stress relaxation and metallurgical improvement of the material by an in situ heat treatment of the whole tube sheet (a steam generator model was used to evaluate the feasibility of this treatment), and the introduction of residual compressive stresses on ID by rotopeening or shotpeening without inducing unacceptable tensile stresses on OD. A comparative evaluation of these measures was established on the basis of tests performed on representative mock-ups and specimens. (author)

Simulation of tensile stress-strain properties of irradiated type 316 SS by heavily cold-worked material

International Nuclear Information System (INIS)

Muto, Yasushi; Jitsukawa, Shiro; Hishinuma, Akimichi

1995-07-01

Type 316 stainless steel is one of the most promising candidate materials to be used for the structural parts of plasma facing components in the nuclear fusion reactor. The neutron irradiation make the material brittle and reduces its uniform elongation to almost zero at heavy doses. In order to apply such a material of reduced ductility to structural components, the structural integrity should be examined and assured by the fracture mechanics. The procedure requires a formulated stress-strain relationship. However, the available irradiated tensile test data are very limited at present, so that the cold-worked material was used as a simulated material in this study. Property changes of 316 SS, that is, a reduction of uniform elongation and an enhancement of yield stress are seemingly very similar for both the irradiated 316 SS and the cold-worked one. The specimens made of annealed 316 SS, 20% (or 15%) cold worked one and 40% cold worked one were prepared. After the formulation of stress strain behavior, the equation for the cold-worked 316 SS was fitted to the data on irradiated material under the assumption that the yield stress is the same for both materials. In addition, the upper limit for the plastic strain was introduced using the data on the irradiated material. (author)

Stress induced reorientation of vanadium hydride

International Nuclear Information System (INIS)

Beardsley, M.B.

1977-10-01

The critical stress for the reorientation of vanadium hydride was determined for the temperature range 180 0 to 280 0 K using flat tensile samples containing 50 to 500 ppM hydrogen by weight. The critical stress was observed to vary from a half to a third of the macroscopic yield stress of pure vanadium over the temperature range. The vanadium hydride could not be stress induced to precipitate above its stress-free precipitation temperature by uniaxial tensile stresses or triaxial tensile stresses induced by a notch

Development of Embedded EM Sensors for Estimating Tensile Forces of PSC Girder Bridges

Science.gov (United States)

Kim, Ju-Won; Lee, Chaggil; Park, Seunghee

2017-01-01

The tensile force of pre-stressed concrete (PSC) girders is the most important factor for managing the stability of PSC bridges. The tensile force is induced using pre-stressing (PS) tendons of a PSC girder. Because the PS tendons are located inside of the PSC girder, the tensile force cannot be measured after construction using conventional NDT (non-destructive testing) methods. To monitor the induced tensile force of a PSC girder, an embedded EM (elasto-magnetic) sensor was proposed in this study. The PS tendons are made of carbon steel, a ferromagnetic material. The magnetic properties of the ferromagnetic specimen are changed according to the induced magnetic field, temperature, and induced stress. Thus, the tensile force of PS tendons can be estimated by measuring their magnetic properties. The EM sensor can measure the magnetic properties of ferromagnetic materials in the form of a B (magnetic density)-H (magnetic force) loop. To measure the B-H loop of a PS tendon in a PSC girder, the EM sensor should be embedded into the PSC girder. The proposed embedded EM sensor can be embedded into a PSC girder as a sheath joint by designing screw threads to connect with the sheath. To confirm the proposed embedded EM sensors, the experimental study was performed using a down-scaled PSC girder model. Two specimens were constructed with embedded EM sensors, and three sensors were installed in each specimen. The embedded EM sensor could measure the B-H loop of PS tendons even if it was located inside concrete, and the area of the B-H loop was proportionally decreased according to the increase in tensile force. According to the results, the proposed method can be used to estimate the tensile force of unrevealed PS tendons. PMID:28867790

Characteristics of the tensile mechanical properties of fresh and dry forewings of beetles

Energy Technology Data Exchange (ETDEWEB)

Tuo, Wanyong [School of Civil Engineering & International Institute for Urban Systems Engineering, Southeast University, Nanjing 210096 (China); School of Civil & Architectural Engineering, Anyang Institute of Technology, Anyang 455000 (China); Chen, Jinxiang, E-mail: chenjpaper@yahoo.co.jp [School of Civil Engineering & International Institute for Urban Systems Engineering, Southeast University, Nanjing 210096 (China); Wu, Zhishen; Xie, Juan [School of Civil Engineering & International Institute for Urban Systems Engineering, Southeast University, Nanjing 210096 (China); Wang, Yong [Nantong Vocational University, Nantong, Jiangsu 226007 (China)

2016-08-01

Based on a tensile experiment and observations by scanning electron microscopy (SEM), this study demonstrated the characteristics of the tensile mechanical properties of the fresh and dry forewings of two types of beetles. The results revealed obvious differences in the tensile fracture morphologies and characteristics of the tensile mechanical properties of fresh and dry forewings of Cybister tripunctatus Olivier and Allomyrina dichotoma. For fresh forewings of these two types of beetles, a viscous, flow-like, polymer matrix plastic deformation was observed on the fracture surfaces, with soft morphologies and many fibers being pulled out, whereas on the dry forewings, the tensile fracture surfaces were straightforward, and there were no features resembling those found on the fresh forewings. The fresh forewings exhibited a greater fracture strain than the dry forewings, which was caused by the relative slippage of hydroxyl inter-chain bonds due to the presence of water in the fibers and proteins in the fresh forewings. Our study is the first to demonstrate the phenomenon of sudden stress drops caused by the fracturing of the lower skin because the lower skin fractured before the forewings of A. dichotoma reached their ultimate tensile strength. We also investigated the reasons underlying this phenomenon. This research provides a much better understanding of the mechanical properties of beetle forewings and facilitates the correct selection of study objects for biomimetic materials and development of the corresponding applications. - Highlights: • There is a phenomenon of sudden stress drop on the tensile stress-train curve of forewing. • The causes of the differences of mechanical properties of fresh and dry forewings are explained. • The hypothesis raised in a previous review paper is verified. • This study brings better ideas into correct understanding of the mechanical properties that the biomimetic object exhibits.

Tensile stress-strain and work hardening behaviour of P9 steel for wrapper application in sodium cooled fast reactors

Science.gov (United States)

Christopher, J.; Choudhary, B. K.; Isaac Samuel, E.; Mathew, M. D.; Jayakumar, T.

2012-01-01

Tensile flow behaviour of P9 steel with different silicon content has been examined in the framework of Hollomon, Ludwik, Swift, Ludwigson and Voce relationships for a wide temperature range (300-873 K) at a strain rate of 1.3 × 10 -3 s -1. Ludwigson equation described true stress ( σ)-true plastic strain ( ɛ) data most accurately in the range 300-723 K. At high temperatures (773-873 K), Ludwigson equation reduces to Hollomon equation. The variations of instantaneous work hardening rate ( θ = dσ/ dɛ) and θσ with stress indicated two-stage work hardening behaviour. True stress-true plastic strain, flow parameters, θ vs. σ and θσ vs. σ with respect to temperature exhibited three distinct temperature regimes and displayed anomalous behaviour due to dynamic strain ageing at intermediate temperatures. Rapid decrease in flow stress and flow parameters, and rapid shift in θ- σ and θσ- σ towards lower stresses with increase in temperature indicated dominance of dynamic recovery at high temperatures.

Influence of flow stress choice on the plastic collapse estimation of axially cracked steam generator tubes

International Nuclear Information System (INIS)

Tonkovic, Zdenko; Skozrit, Ivica; Alfirevic, Ivo

2008-01-01

The influence of the choice of flow stress on the plastic collapse estimation of axially cracked steam generator (SG) tubes is considered. The plastic limit and collapse loads of thick-walled tubes with external axial semi-elliptical surface cracks are investigated by three-dimensional non-linear finite element (FE) analyses. The limit pressure solution as a function of the crack depth, length and tube geometry has been developed on the basis of extensive FE limit load analyses employing the elastic-perfectly plastic material behaviour and small strain theory. Unlike the existing solutions, the newly developed analytical approximation of the plastic limit pressure for thick-walled tubes is applicable to a wide range of crack dimensions. Further, the plastic collapse analysis with a real strain-hardening material model and a large deformation theory is performed and an analytical approximation for the estimation of the flow stress is proposed. Numerical results show that the flow stress, defined by some failure assessment diagram (FAD) methods, depends not only on the tube material, but also on the crack geometry. It is shown that the plastic collapse pressure results, in the case of deeper cracks obtained by using the flow stress as the average of the yield stress and the ultimate tensile strength, can become unsafe

Stress corrosion cracking of steam generator tube and primary pipe in PWR type nuclear power plants

International Nuclear Information System (INIS)

Zhang Weiguo; Gao Fengqin; Zhou Hongyi

1992-03-01

The behavior of stress corrosion cracking (SCC) was studied by slow strain rate test (SSRT), constant load test (CLT) and low frequency cyclic loading test (LFCLT). The purpose of these tests is to get the test data for evaluating the integrity of pressurized boundary of pipes in Qinshan and Guangdong nuclear power plants (NPPs). Tested materials are 316 nuclear grade stainless steel (SS) for primary pipes in welded heat affected zone (WHAZ) and tubes of heat transfer, such as Incoloy-800, Inconel-600 and 321 SS which are used for steam generator in PWR NPPs. The effects of material metallurgy, shot peening treatment, tensile load, strain rate, cyclic load and water chemistry on the behavior of SCC were considered

Tensile testing

CERN Document Server

2004-01-01

A complete guide to the uniaxial tensile test, the cornerstone test for determining the mechanical properties of materials: Learn ways to predict material behavior through tensile testing. Learn how to test metals, alloys, composites, ceramics, and plastics to determine strength, ductility and elastic/plastic deformation. A must for laboratory managers, technicians, materials and design engineers, and students involved with uniaxial tensile testing. Tensile Testing , Second Edition begins with an introduction and overview of the test, with clear explanations of how materials properties are determined from test results. Subsequent sections illustrate how knowledge gained through tensile tests, such as tension properties to predict the behavior (including strength, ductility, elastic or plastic deformation, tensile and yield strengths) have resulted in improvements in materals applications. The Second Edition is completely revised and updated. It includes expanded coverage throughout the volume on a variety of ...

Improvement in tensile properties of PVC–montmorillonite ...

Indian Academy of Sciences (India)

mechanical properties of PVC–montmorillonite materials are also currently of huge ... Its hard form can withstand a tensile stress in the order of 46–52 MPa before .... 2θ at 25 mA and 40 kV using Cu-Kα radiation. X-ray diffraction patterns of the ...

The evolution of internal stress and dislocation during tensile deformation in a 9Cr ferritic/martensitic (F/M) ODS steel investigated by high-energy X-rays

International Nuclear Information System (INIS)

Zhang, Guangming; Zhou, Zhangjian; Mo, Kun; Miao, Yinbin; Liu, Xiang; Almer, Jonathan; Stubbins, James F.

2015-01-01

An application of high-energy wide angle synchrotron X-ray diffraction to investigate the tensile deformation of 9Cr ferritic/martensitic (F/M) ODS steel is presented. With tensile loading and in-situ X-ray exposure, the lattice strain development of matrix was determined. The lattice strain was found to decrease with increasing temperature, and the difference in Young's modulus of six different reflections at different temperatures reveals the temperature dependence of elastic anisotropy. The mean internal stress was calculated and compared with the applied stress, showing that the strengthening factor increased with increasing temperature, indicating that the oxide nanoparticles have a good strengthening impact at high temperature. The dislocation density and character were also measured during tensile deformation. The dislocation density decreased with increasing of temperature due to the greater mobility of dislocation at high temperature. The dislocation character was determined by best-fit methods for different dislocation average contrasts with various levels of uncertainty. The results shows edge type dislocations dominate the plastic strain at room temperature (RT) and 300 °C, while the screw type dislocations dominate at 600 °C. The dominance of edge character in 9Cr F/M ODS steels at RT and 300 °C is likely due to the pinning effect of nanoparticles for higher mobile edge dislocations when compared with screw dislocations, while the stronger screw type of dislocation structure at 600 °C may be explained by the activated cross slip of screw segments. - Highlights: • The tensile deformation of 9Cr ODS steel was studied by synchrotron irradiation. • The evolution of internal mean stress was calculated. • The evolution of dislocation character was determined by best-fit method. • Edge type dominates plasticity at RT and 300 °C, while screw type dominates at 600 °C.

The evolution of internal stress and dislocation during tensile deformation in a 9Cr ferritic/martensitic (F/M) ODS steel investigated by high-energy X-rays

Energy Technology Data Exchange (ETDEWEB)

Zhang, Guangming [School of Materials Science and Engineering, University of Science and Technology, Beijing, Beijing 100083 (China); Department of Nuclear, Plasma and Radiological Engineering, University of Illinois at Urbana-Champaign, IL 61801 (United States); Zhou, Zhangjian, E-mail: zhouzhj@mater.ustb.edu.cn [School of Materials Science and Engineering, University of Science and Technology, Beijing, Beijing 100083 (China); Mo, Kun [Nuclear Engineering Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Miao, Yinbin; Liu, Xiang [Department of Nuclear, Plasma and Radiological Engineering, University of Illinois at Urbana-Champaign, IL 61801 (United States); Almer, Jonathan [X-ray Science Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Stubbins, James F. [Department of Nuclear, Plasma and Radiological Engineering, University of Illinois at Urbana-Champaign, IL 61801 (United States)

2015-12-15

An application of high-energy wide angle synchrotron X-ray diffraction to investigate the tensile deformation of 9Cr ferritic/martensitic (F/M) ODS steel is presented. With tensile loading and in-situ X-ray exposure, the lattice strain development of matrix was determined. The lattice strain was found to decrease with increasing temperature, and the difference in Young's modulus of six different reflections at different temperatures reveals the temperature dependence of elastic anisotropy. The mean internal stress was calculated and compared with the applied stress, showing that the strengthening factor increased with increasing temperature, indicating that the oxide nanoparticles have a good strengthening impact at high temperature. The dislocation density and character were also measured during tensile deformation. The dislocation density decreased with increasing of temperature due to the greater mobility of dislocation at high temperature. The dislocation character was determined by best-fit methods for different dislocation average contrasts with various levels of uncertainty. The results shows edge type dislocations dominate the plastic strain at room temperature (RT) and 300 °C, while the screw type dislocations dominate at 600 °C. The dominance of edge character in 9Cr F/M ODS steels at RT and 300 °C is likely due to the pinning effect of nanoparticles for higher mobile edge dislocations when compared with screw dislocations, while the stronger screw type of dislocation structure at 600 °C may be explained by the activated cross slip of screw segments. - Highlights: • The tensile deformation of 9Cr ODS steel was studied by synchrotron irradiation. • The evolution of internal mean stress was calculated. • The evolution of dislocation character was determined by best-fit method. • Edge type dominates plasticity at RT and 300 °C, while screw type dominates at 600 °C.

Evolution of microstructure and residual stress on L1{sub 0} ordering in FePt thin films with different initial stress states

Energy Technology Data Exchange (ETDEWEB)

Hsiao, S.N., E-mail: pmami.hsiao@gmail.com [Department of Materials Science and Engineering, Feng Chia University, Taichung 407, Taiwan (China); Yuan, F.T. [iSentek Ltd., Advanced Sensor Laboratory, New Taipei City 221, Taiwan (China); Chen, S.K. [Department of Materials Science and Engineering, Feng Chia University, Taichung 407, Taiwan (China); Sun, A.C. [Department of Chemical Engineering and Materials Science, Yuan Ze University, Jungli 320, Taiwan (China); Su, S.H.; Chiu, K.F. [Department of Materials Science and Engineering, Feng Chia University, Taichung 407, Taiwan (China)

2016-01-15

We have characterized the dependence of microstructure, and internal strain/stress on L1{sub 0} ordering in 40 nm thick FePt films with different initial stresses. The microstructural and crystallographic results indicate that defect annihilation and grain growth induced an increase in tensile stress of ~1 GPa before extensive L1{sub 0} ordering. The induced tensile stress can efficiently facilitate the nucleation of L1{sub 0} phase owing to that the volume expansion of L1{sub 0} ordering and atomic rearrangement neutralizes the tensile stress. If the as-deposited FePt film has a highly compressive state, the induced tensile stress will be canceled out and ordering is retarded, which results in a higher ordering temperature. - Highlights: • Microstructure-stress connection in FePt films was studied. • Initial stress alters microstructure and stress evolution during annealing. • Densification induces tensile stress of ~1 GPa before extensive L1{sub 0} ordering. • Induced tensile stress can efficiently facilitate the nucleation of L1{sub 0} phase. • Compressively initial stress results in a higher ordering temperature .

Effects of mean tensile stresses on high-cycle fatigue life and strain accumulation in some reactor materials

International Nuclear Information System (INIS)

Soo, P.; Chow, J.G.Y.

1977-05-01

An assessment has been made of the effects of mean tensile stresses on the high-cycle fatigue behavior of solution-treated Type 304 stainless steel, normalized and tempered 2 1 / 4 Cr-1Mo steel, Incoloy-800H, and low-carbon Incoloy-800. Mean stresses are usually detrimental to fatigue strength, especially at high temperatures and stress levels, where significant creep can occur during fatigue cycling. Depending on the magnitudes of the alternating and mean stresses, failure may be creep or fatigue controlled. Strain accumulation is also affected by these stress levels and possibly, also, by the cyclic work-hardening characteristics of the material. It is shown that the Goodman Law for estimating mean stress effects is inadequate, since it does not account for time-dependent deformation. An alternative expression not having such a limitation was, therefore, derived and this relates the alternating and mean stresses to the time to failure. Based on limited metallographic observations of fatigue striations in the 2 1 / 4 Cr-1Mo steel an estimate was made of the crack propagation rate. It was found that a crack of critical size could, under certain conditions, propagate through most of the specimen diameter in a matter of seconds. This presents a more significant safety problem than the case for a crack extending under low-cycle conditions since preventative measures probably could not be implemented before the crack had grown to a large size

Fracture behavior of nuclear graphites under tensile impact loading

International Nuclear Information System (INIS)

Ugachi, Hirokazu; Ishiyama, Shintaro; Eto, Motokuni

1994-01-01

Impact tensile strength test was performed with two kinds of HTTR graphites, fine grained isotropic graphite, IG-11 and coarse grained near isotropic graphite, PGX and deformation and fracture behavior under the strain rate of over 100s -1 was measured and the following results were derived: (1) Tensile strength for IG-11 graphite does not depend on the strain rate less than 1 s -1 , but over 1 s -1 , tensile strength for IG-11 graphite increase larger than that measured under 1 s -1 . At the strain rate more than 100 s -1 , remarkable decrease of tensile strength for IG-11 graphite was found. Tensile strength of PGX graphite does not depend on the strain rate less than 1 s -1 , but beyond this value, the sharp tensile strength decrease occurs. (2) Under 100 s -1 , fracture strain for both graphites increase with increase of strain rate and over 100 s -1 , drastic increase of fracture strain for IG-11 graphite was found. (3) At the part of gage length, volume of specimen increase with increase of tensile loading level and strain rate. (4) Poisson's ratio for both graphites decrease with increase of tensile loading level and strain rate. (5) Remarkable change of stress-strain curve for both graphites under 100 s -1 was not found, but over 100 s -1 , the slope of these curve for IG-11 graphite decrease drastically. (author)

Reduction method for residual stress of welded joint using harmonic vibrational load

International Nuclear Information System (INIS)

Aoki, Shigeru; Nishimura, Tadashi; Hiroi, Tetsumaro; Hirai, Seiji

2007-01-01

Welding is widely used for construction of many structures. Since welding is a process using locally given heat, residual stress is generated near the bead. Tensile residual stress degrades fatigue strength. Some reduction methods of residual stress have been presented and, for example, heat treatment and shot peening are practically used. However, those methods need special tools and are time consuming. In this paper, a new method for reduction of residual stress using harmonic vibrational load during welding is proposed. The proposed method is examined experimentally for some conditions. Two thin plates are supported on the supporting device and butt-welded using an automatic CO 2 gas shielded arc welding machine. Residual stress in the direction of the bead is measured by using a paralleled beam X-ray diffractometer with scintillation counter after removing quenched scale chemically. First, the welding of rolled steel for general structure for some excitation frequencies is examined. Specimens are welded along the groove on both sides. For all frequencies, tensile residual stress near the bead is significantly reduced. Second, welding of the specimen made of high tensile strength steel is examined. In this case, tensile residual stress near the bead is also reduced. Finally, the proposed method is examined by an analytical method. An analytical model which consists of mass and preloaded springs with elasto-plastic characteristic is used. Reduction of residual stress is demonstrated using this model

Tensile stress in hard metal films

NARCIS (Netherlands)

Janssen, G.C.A.M.; Dammers, A.J.; Sivel, V.G.M.; Wang, W.R.

2003-01-01

Thin films on substrates are usually in a stressed state. An important, but trivial, contribution to that stress stems from the difference in thermal expansion coefficient of substrate and film. Much more interesting are the intrinsic stresses, resulting from the growth and/or microstructure of the

Stress field determination in an alloy 600 stress corrosion crack specimen

International Nuclear Information System (INIS)

Rassineux, B.; Labbe, T.

1995-05-01

In the context of EDF studies on stress corrosion cracking rates in the Alloy 600 steam generators tubes, we studied the influence of strain hardened surface layers on the different stages of cracking for a tensile smooth specimen (TLT). The stress field was notably assessed to try and explain the slow/rapid-propagation change observed beyond the strain hardened layers. The main difficulty is to simulate in a finite element model the inner and outer surfaces of these strain hardened layers, produced by the final manufacturing stages of SG tubes which have not been heat treated. In the model, the strain hardening is introduced by simulating a multi-layer material. Residual stresses are simulated by an equivalent fictitious thermomechanical calculation, realigned with respect to X-ray measurements. The strain hardening introduction method was validated by an analytical calculation giving identical results. Stress field evolution induced by specimen tensile loading were studied using an elastoplastic 2D finite element calculations performed with the Aster Code. The stress profile obtained after load at 660 MPa shows no stress discontinuity at the boundary between the strain hardened layer and the rest of the tube. So we propose that a complementary calculation be performed, taking into account the multi-cracked state of the strain hardened zones by means of a damage variable. In fact, this state could induce stress redistribution in the un-cracked area, which would perhaps provide an explanation of the crack-ground rate change beyond the strain hardened zone. The calculations also evidence the harmful effects of plastic strains on a strain hardened layer due to the initial state of the tube (not heat-treated), to grit blasting or to shot peening. The initial compressive stress condition of this surface layer becomes, after plastic strain, a tensile stress condition. These results are confirmed by laboratory test. (author). 10 refs., 18 figs., 9 tabs., 2 appends

Fibrocartilage tissue engineering: the role of the stress environment on cell morphology and matrix expression.

Science.gov (United States)

Thomopoulos, Stavros; Das, Rosalina; Birman, Victor; Smith, Lester; Ku, Katherine; Elson, Elliott L; Pryse, Kenneth M; Marquez, Juan Pablo; Genin, Guy M

2011-04-01

Although much is known about the effects of uniaxial mechanical loading on fibrocartilage development, the stress fields to which fibrocartilaginous regions are subjected to during development are mutiaxial. That fibrocartilage develops at tendon-to-bone attachments and in compressive regions of tendons is well established. However, the three-dimensional (3D) nature of the stresses needed for the development of fibrocartilage is not known. Here, we developed and applied an in vitro system to determine whether fibrocartilage can develop under a state of periodic hydrostatic tension in which only a single principal component of stress is compressive. This question is vital to efforts to mechanically guide morphogenesis and matrix expression in engineered tissue replacements. Mesenchymal stromal cells in a 3D culture were exposed to compressive and tensile stresses as a result of an external tensile hydrostatic stress field. The stress field was characterized through mechanical modeling. Tensile cyclic stresses promoted spindle-shaped cells, upregulation of scleraxis and type one collagen, and cell alignment with the direction of tension. Cells experiencing a single compressive stress component exhibited rounded cell morphology and random cell orientation. No difference in mRNA expression of the genes Sox9 and aggrecan was observed when comparing tensile and compressive regions unless the medium was supplemented with the chondrogenic factor transforming growth factor beta3. In that case, Sox9 was upregulated under static loading conditions and aggrecan was upregulated under cyclic loading conditions. In conclusion, the fibrous component of fibrocartilage could be generated using only mechanical cues, but generation of the cartilaginous component of fibrocartilage required biologic factors in addition to mechanical cues. These studies support the hypothesis that the 3D stress environment influences cell activity and gene expression in fibrocartilage development.

Coated Conductors under Tensile Stress

International Nuclear Information System (INIS)

Antonevici, Anca; Villaume, Alain; Villard, Catherine; Sulpice, Andre; Maron, Pierre Brosse; Bourgault, Daniel; Porcar, Laureline

2006-01-01

Critical current dependence versus strain is obtained for in-situ axial stress experiments on ISD YBCO and DyBCO coated conductors. The drop of critical current due to the apparition of first cracks in the superconducting ceramics is related to the passage in the plastic region of the substrate for a strain of about 0.3% and a stress higher then 500MPa. The superconductivity is preserved between the cracks

Development of Tensile Softening Model for Plain Concrete

Energy Technology Data Exchange (ETDEWEB)

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

2002-07-01

Large-scale direct tensile softenng tests using plate concrete specimens(4000, 5000psi) with notch were performed under uniaxial stress. There were presented the basic physical properties and the complete load-CMOD(Crack Mouth Opening Displacement) curves for them And them the fracture energy was evaluated using the complete load-CMOD curves respectively, and there was presents optimal tensile softening model which is modified by a little revision of an existing one. Therefore, here provided the real verification data through the tests for developing other nonlinear concrete finite element models. (author). 32 refs., 38 figs., 4 tabs.

Effect of the Volume Fraction of Jute Fiber on the Interlaminar Shear Stress and Tensile Behavior Characteristics of Hybrid Glass/Jute Fiber Reinforced Polymer Composite Bar for Concrete Structures

Directory of Open Access Journals (Sweden)

Chan-Gi Park

2016-01-01

Full Text Available Hybrid glass/jute fiber reinforced polymer (HGJFRP composite bars were manufactured for concrete structures, and their interlaminar shear stress and tensile performance were evaluated. HGJFRP composite bars were manufactured using a combination of pultrusion and braiding processes. Jute fiber was surface-treated with a silane coupling agent. The mixing ratio of the fiber to the vinyl ester used in the HGJFRP composite bars was 7 : 3. Jute fiber was used to replace glass fiber in proportions of 0, 30, 50, 70, and 100%. The interlaminar shear stress decreased as the proportion of jute fiber increased. Fractures appeared due to delamination between the surface-treated component and the main part of the HGJFRP composite bar. Tensile load-strain curves with 50% jute fiber exhibited linear behavior. With a jute fiber volume fraction of 70%, some plastic deformation occurred. A jute fiber mixing ratio of 100% resulted in a display of linear elastic brittle behavior from the fiber; however, when the surface of the fiber was coated with poly(vinyl acetate, following failure, the jute fiber exhibited partial load resistance. The tensile strength decreased as the jute fiber content increased; however, the tensile strength did not vary linearly with jute fiber content.

The tensile effect on crack formation in single crystal silicon irradiated by intense pulsed ion beam

Science.gov (United States)

Liang, Guoying; Shen, Jie; Zhang, Jie; Zhong, Haowen; Cui, Xiaojun; Yan, Sha; Zhang, Xiaofu; Yu, Xiao; Le, Xiaoyun

2017-10-01

Improving antifatigue performance of silicon substrate is very important for the development of semiconductor industry. The cracking behavior of silicon under intense pulsed ion beam irradiation was studied by numerical simulation in order to understand the mechanism of induced surface peeling observed by experimental means. Using molecular dynamics simulation based on Stillinger Weber potential, tensile effect on crack growth and propagation in single crystal silicon was investigated. Simulation results reveal that stress-strain curves of single crystal silicon at a constant strain rate can be divided into three stages, which are not similar to metal stress-strain curves; different tensile load velocities induce difference of single silicon crack formation speed; the layered stress results in crack formation in single crystal silicon. It is concluded that the crack growth and propagation is more sensitive to strain rate, tensile load velocity, stress distribution in single crystal silicon.

Effects of stress on the oxide layer thickness and post-oxidation creep strain of zircaloy-4

International Nuclear Information System (INIS)

Lim, Sang Ho; Yoon, Young Ku

1986-01-01

Effects of compressive stress generated in the oxide layer and its subsequent relief on oxidation rate and post-oxidation creep characteristics of zircaloy-4 were investigated by oxidation studies in steam with and without applied tensile stress and by creep testing at 700 deg C in high purity argon. The thickness of oxide layer increased with the magnitude of tensile stress applied during oxidation at 650 deg C in steam whereas similar phenomenon was not observed during oxidation at 800 deg C. Zircaloy-4 specimens oxidized at 600 deg C in steam without applied stress exhibited higher creep strain than that shown by unoxidized specimens when creep-tested in argon. Zircaloy-4 specimens oxidized at 600 deg C steam under the applied stress of 8.53MPa and oxidized at 800 deg C under the applied stress of 0 and 8.53MPa exhibited lower strain than that shown by unoxidized specimen. The above experimental results were accounted for on the basis of interactions among applied stress during oxidation, compressive stress generated in the oxide layer and elasticity of zircaloy-4 matrix. (Author)

SOLID BURNT BRICKS’ TENSILE STRENGTH

Directory of Open Access Journals (Sweden)

Aneta Maroušková

2017-11-01

Full Text Available This paper deals with experimental testing of solid burnt bricks and mortar in pure (axial tension. The obtained working diagrams will be further use for a detailed numerical analysis of whole brick masonry column under concentric compressive load. Failure mechanism of compressed brick masonry column is characterized by the appearance and development of vertical tensile cracks in masonry units (bricks passing in the direction of principal stresses and is accompanied by progressive growth of horizontal deformations. These cracks are caused by contraction and interaction between two materials with different mechanical characteristics (brick and mortar. The aim of this paper is more precisely describe the response of quasi-brittle materials to uniaxial loading in tension (for now only the results from three point bending test are available. For these reasons, bricks and mortar tensile behavior is experimentally tested and the obtained results are discussed.

Assessment of models predicting irradiation effects on tensile properties of reactor pressure vessel steels

International Nuclear Information System (INIS)

Pineau, L.; Landron, C.

2015-01-01

In this paper, an analysis of tensile data acquired as part of the French Reactor Vessel Surveillance Program (RVSP) is produced. This program contains amongst other mechanical tests, tensile tests at 20 and 300 C degrees on non irradiated base metals and at 300 C degrees only on irradiated materials. It shows that irradiation leads to an increase in the yield strength and a decrease in the strain hardening. The exploitation of tensile results has permitted to express a relationship between yield strength increase measured and fluence value, as well as between strain hardening decrease and yield strength evolution. The use of these relations in the aim at predicting evolution of tensile properties with irradiation has then permitted to propose a methodology to model entire stress-strain curves of irradiated base metal only based on the non irradiated stress-strain curve. These predictions were successfully compared with an experimental standard case. (authors)

Evaluation of the tensile strength of the human ureter--preliminary results.

Science.gov (United States)

Shilo, Yaniv; Pichamuthu, Joseph E; Averch, Timothy D; Vorp, David A

2014-12-01

Ureteral injuries such as avulsion are directly related to mechanical damage of the ureter. Understanding the tensile strength of this tissue may assist in prevention of iatrogenic injuries. Few published studies have looked at the mechanical properties of the animal ureter and, of those, none has determined the tensile strength of the human ureter. Therefore, the purpose of this work was to determine the tensile strength of the human ureter. We harvested 11 human proximal ureters from patients who were undergoing nephrectomy for either kidney tumors or nonfunctioning kidney. The specimens were then cut into multiple circumferentially and longitudinally oriented tissue strips for tensile testing. Strips were uniaxially stretched to failure in a tensile testing machine. The corresponding force and displacement were recorded. Finally, stress at failure was noted as the tensile strength of the sample. Circumferential tensile strength was also compared in the proximal and distal regions of the specimens. The tensile strength of the ureter in circumferential and longitudinal orientations was found to be 457.52±33.74 Ncm(-2) and 902.43±122.08 Ncm(-2), respectively (Ptensile strength of the ureter was found to be significantly lower than the longitudinal strength. Circumferential tensile strength was also lower with more proximal parts of the ureter. This information may be important for the design of "intelligent" devices and simulators to prevent complications.

Behaviour of filamentary MgB2 wires subjected to tensile stress at 4.2 K

International Nuclear Information System (INIS)

Kováč, P; Kopera, L; Melišek, T; Hušek, I; Rindfleisch, M; Haessler, W

2013-01-01

Different filamentary MgB 2 wires have been subjected to tensile stress at 4.2 K. Stress–strain and critical current versus stress and strain characteristics of wires differing by filament architecture, sheath materials, deformation and heat treatment were measured and compared. It was found that the linear increase of critical current due to the pre-compression effect (ranging from 5% up to ≈20%) is affected by thermal expansion and the strength of used metallic sheaths. The values of irreversible strain ε irr and stress σ irr depend dominantly on the applied outer sheath and its final heat treatment conditions. Consequently, the strain-tolerance of MgB 2 wires is influenced by several parameters and it is difficult to see a clear relation between I c (ε) and σ(ε) characteristics. The lowest ε irr was measured for Monel sheathed wires (0.3–0.6%), medium for GlidCop ® sheath (0.48–0.6%), and the highest ε irr = 0.6–0.9% were obtained for MgB 2 wires reinforced by the stainless steel 316L annealed at temperature between 600 and 800 ° C. The highest ε irr = 0.9% and σ irr = 900 MPa were measured for the work-hardened steel, which is not considerably softened by the heat treatment at 600 ° C/2.5 h. (paper)

Effects of stacking sequence on fracture mechanisms in quasi-isotropic Carbon/epoxy laminates under tensile loading

International Nuclear Information System (INIS)

Hessabi, Z. R.; Majidi, B.; Aghazadeh, J.

2006-01-01

The progress of damage in quasi-isotropic carbon/epoxy laminates under tensile loading has been Investigated microscopically. One significant mode of failure in laminated composites is delamination initiating at free edges. The interlaminar stress in the boundary ply along the free edges of a laminated composite is the main factor to cause delamination. The laminate stacking sequence affects the interlaminar stress distribution and consequently may change the mode of failure. It is of design importance to determine a suitable criterion based on stress analysis to obtain the best stacking sequence. In the present work, tensile properties of six samples with different stacking sequences have been examined. Results showed that stress analysis at distance very close to the free edges is a suitable criterion to predict the initiation of delamination and the stacking sequence of [90/45/0/-45] s , has the highest strength among the others. Furthermore finite element analysis showed that the adjacent ±45 plies cause premature delamination during tensile loading

Prediction of residual stress distributions due to surface machining and welding and crack growth simulation under residual stress distribution

International Nuclear Information System (INIS)

Ihara, Ryohei; Katsuyama, JInya; Onizawa, Kunio; Hashimoto, Tadafumi; Mikami, Yoshiki; Mochizuki, Masahito

2011-01-01

Research highlights: → Residual stress distributions due to welding and machining are evaluated by XRD and FEM. → Residual stress due to machining shows higher tensile stress than welding near the surface. → Crack growth analysis is performed using calculated residual stress. → Crack growth result is affected machining rather than welding. → Machining is an important factor for crack growth. - Abstract: In nuclear power plants, stress corrosion cracking (SCC) has been observed near the weld zone of the core shroud and primary loop recirculation (PLR) pipes made of low-carbon austenitic stainless steel Type 316L. The joining process of pipes usually includes surface machining and welding. Both processes induce residual stresses, and residual stresses are thus important factors in the occurrence and propagation of SCC. In this study, the finite element method (FEM) was used to estimate residual stress distributions generated by butt welding and surface machining. The thermoelastic-plastic analysis was performed for the welding simulation, and the thermo-mechanical coupled analysis based on the Johnson-Cook material model was performed for the surface machining simulation. In addition, a crack growth analysis based on the stress intensity factor (SIF) calculation was performed using the calculated residual stress distributions that are generated by welding and surface machining. The surface machining analysis showed that tensile residual stress due to surface machining only exists approximately 0.2 mm from the machined surface, and the surface residual stress increases with cutting speed. The crack growth analysis showed that the crack depth is affected by both surface machining and welding, and the crack length is more affected by surface machining than by welding.

Evaluation of stresses generated in steel finger joint of bridge by X-ray stress measurement

International Nuclear Information System (INIS)

Kohri, Ami; Kawano, Yutaka; Nishido, Takayuki

2017-01-01

In a steel bridge, the evaluation of the stress generated in the finger joint without a gap to absorb temperature change can be an index when evaluating the remaining life. This study chose as the object the finger joint of a diagonal bridge, where the generated stress state is considered to be more complicated, prepared a finger joint test specimen that simulated an actual part, and performed a load test. For judgment, FEM analysis, non-destructive X-ray stress measurement, and measurement of the generated stress using strain gauge were applied. Compared with the FEM analysis results, the difference in the stress value was generated due to the difference in the contact state, but the trends of the stress distribution were equivalent. In addition, the same measurement value as the strain gauge was obtained, and the validity of the X-ray stress measurement method was confirmed. As a result, it was found that the stress measurement method by X-ray is effective for measuring the generated stress including the residual stress of the finger joint without gap at a bridge. (A.O.)

Tensile stress-dependent fracture behavior and its influences on photovoltaic characteristics in flexible PbS/CdS thin-film solar cells.

Science.gov (United States)

Lee, Seung Min; Yeon, Deuk Ho; Mohanty, Bhaskar Chandra; Cho, Yong Soo

2015-03-04

Tensile stress-dependent fracture behavior of flexible PbS/CdS heterojunction thin-film solar cells on indium tin oxide-coated polyethylene terephthalate (PET) substrates is investigated in terms of the variations of fracture parameters with applied strains and their influences on photovoltaic properties. The PbS absorber layer that exhibits only mechanical cracks within the applied strain range from ∼0.67 to 1.33% is prepared by chemical bath deposition at different temperatures of 50, 70, and 90 °C. The PbS thin films prepared at 50 °C demonstrate better mechanical resistance against the applied bending strain with the highest crack initiating bending strain of ∼1.14% and the lowest saturated crack density of 0.036 μm(-1). Photovoltaic properties of the cells depend on the deposition temperature and the level of applied tensile stress. The values of short-circuit current density and fill factor are dramatically reduced above a certain level of applied strain, while open-circuit voltage is nearly maintained. The dependency of photovoltaic properties on the progress of fractures is understood as related to the reduced fracture energy and toughness, which is limitedly controllable by microstructural features of the absorber layer.

Inertial effects on the stress generation of active fluids

Science.gov (United States)

Takatori, S. C.; Brady, J. F.

2017-09-01

Suspensions of self-propelled bodies generate a unique mechanical stress owing to their motility that impacts their large-scale collective behavior. For microswimmers suspended in a fluid with negligible particle inertia, we have shown that the virial swim stress is a useful quantity to understand the rheology and nonequilibrium behaviors of active soft matter systems. For larger self-propelled organisms such as fish, it is unclear how particle inertia impacts their stress generation and collective movement. Here we analyze the effects of finite particle inertia on the mechanical pressure (or stress) generated by a suspension of self-propelled bodies. We find that swimmers of all scales generate a unique swim stress and Reynolds stress that impact their collective motion. We discover that particle inertia plays a similar role as confinement in overdamped active Brownian systems, where the reduced run length of the swimmers decreases the swim stress and affects the phase behavior. Although the swim and Reynolds stresses vary individually with the magnitude of particle inertia, the sum of the two contributions is independent of particle inertia. This points to an important concept when computing stresses in computer simulations of nonequilibrium systems: The Reynolds and the virial stresses must both be calculated to obtain the overall stress generated by a system.

Direct assessment of tensile stress-crack opening behavior of Strain Hardening Cementitious Composites (SHCC)

DEFF Research Database (Denmark)

Pereira, Eduardo B.; Fischer, Gregor; Barros, Joaquim A.O.

2012-01-01

-deformation behavior of these materials is therefore of great importance and is frequently carried out by characterizing the material tensile stress–strain behavior. In this paper an alternative approach to evaluate the tensile performance of SHCC is investigated. The behavior of the material in tension is studied...

Microhardness and Stress Analysis of Laser-Cladded AISI 420 Martensitic Stainless Steel

Science.gov (United States)

Alam, Mohammad K.; Edrisy, Afsaneh; Urbanic, Jill; Pineault, James

2017-03-01

Laser cladding is a surface treatment process which is starting to be employed as a novel additive manufacturing. Rapid cooling during the non-equilibrium solidification process generates non-equilibrium microstructures and significant amounts of internal residual stresses. This paper investigates the laser cladding of 420 martensitic stainless steel of two single beads produced by different process parameters (e.g., laser power, laser speed, and powder feed rate). Metallographic sample preparation from the cross section revealed three distinct zones: the bead zone, the dilution zone, and the heat-affected zone (HAZ). The tensile residual stresses were in the range of 310-486 MPa on the surface and the upper part of the bead zone. The compressive stresses were in the range of 420-1000 MPa for the rest of the bead zone and the dilution zone. The HAZ also showed tensile residual stresses in the range of 140-320 MPa for both samples. The post-cladding heat treatment performed at 565 °C for an hour had significantly reduced the tensile stresses at the surface and in the subsurface and homogenized the compressive stress throughout the bead and dilution zones. The microstructures, residual stresses, and microhardness profiles were correlated for better understanding of the laser-cladding process.

Optical stress investigations of notched bars with superimposed types of loads

International Nuclear Information System (INIS)

Richard, H.A.; Theis, W.

1982-01-01

Starting from the notch effect for various types of load, notch stresses are determined by optical methods for superimposed tensile and shearing stress and for superimposed tensile and bending stress. The superimposed stresses are induced by a device developed at the Technical Mechanics Department of Kaiserslautern University; only tensile stress needs to be applied to this testing device. The investigations have shown that in notched bars subject to superimposed tensile and shearing stress, stress increases will be higher than the maximum values of the two types of stress. For superimposed tensile and bending stress, notches on the outer side of the test piece and eccentric notches on the inner side may lead to a considerable stress increase. However, the stress distribution can be improved by an optimum arrangement of notches. (orig.) [de

Tensile properties of commercially pure vanadium from room temperature to 1200 degree C

International Nuclear Information System (INIS)

Henshall, G.A.; Torres, S.G.

1993-12-01

The tensile properties of vanadium are sensitive to interstitial impurity content, on grain size and strain rate. Thus, it is problematic to use published tensile data for materials potentially varying in these quantities. This investigation was undertaken to fully characterize the tensile properties of the commercially pure vanadium used at Lawrence Livermore. Both sheet and rod stock were tested in vacuum from ambient temperature to 1200C at strain rates 6.67 x 10 -5 to 6.67 x 10 -2 s -1 . The results of these experiments show that vanadium behaves in a manner typical of many bcc metals containing interstitial impurities. Local peaks in yield stress and ultimate tensile stress vs temperature curves are observed at intermediate temperatures. Serrated yielding also is observed in some temperature ranges. Changes in strain rate within the quasi-static regime have a relatively small, predictable effect. The rod and sheet stock have similar properties, except that the lower yield stress of the rod is less than that of the sheet over most of the temperature range studied. No plateau in yield strength vs temperature curve was observed for the rod. In both forms, and for all temperatures, vanadium is ductile. The elongation to failure reaches a minimum of approximately 35% at a temperature of 500C and a maximum of approximately 140% at 1200C

The long range migration of hydrogen through Zircaloy in response to tensile and compressive stress gradients

International Nuclear Information System (INIS)

Kammenzind, B.F.; Berquist, B.M.; Bajaj, R.; Kreyns, P.H.; Franklin, D.G.

1998-01-01

Zircaloy-4, which is used widely as a core structural material in pressurized water reactors (PWRs), picks up hydrogen during service. Hydrogen solubility in Zircaloy-4 is low and zirconium hydride phases precipitate after the Zircaloy-4 lattice becomes supersaturated with hydrogen. These hydrides embrittle the Zircaloy-4, degrading its mechanical performance as a structural material. Because hydrogen can move rapidly through the Zircaloy-4 lattice, the potential exists for large concentrations of hydride to accumulate in local regions of a Zircaloy component remote from its point of entry into the component. Much has been reported in the literature regarding the long range migration of hydrogen through Zircaloy under concentration gradients and temperature gradients. Relatively little has been reported, however, regarding the long range migration of hydrogen under stress gradients. This paper presents experimental results regarding the long range migration of hydrogen through Zircaloy in response to both tensile and compressive stress gradients. The importance of this driving force for hydrogen migration relative to concentration and thermal gradients is discussed

Influence of sodium evnironment on the uniaxial tensile behavior of titanium modified type 316 stainless steel

International Nuclear Information System (INIS)

Natesan, K.; Chopra, O.K.; Kassner, T.F.

1978-01-01

True stress-true strain tensile data have been obtained for titanium modified type 316 stainless steel in the solution annealed condition and after exposure to a flowing sodium environment at temperature of 700, 650, 600 and 550 0 C. The specimens were exposed to sodium for times between 120 and 5012 h to produce carbon penetration depths in the range 0.05-0.30 mm. The Voce equation was used to describe tensile flow curves for plastic strains above 0.005. The results showed that, when compared with solution annealed specimens, the tensile flow behavior of the sodium exposed specimens is characterized by a higher strain hardening rate, which decreases rapidly as the flow stress increases. The loss in tensile ductility of the material due to carburization in sodium environment was found to be minimal. (Auth.)

Co-Rumination Exacerbates Stress Generation among Adolescents with Depressive Symptoms.

Science.gov (United States)

Rose, Amanda J; Glick, Gary C; Smith, Rhiannon L; Schwartz-Mette, Rebecca A; Borowski, Sarah K

2017-07-01

Through stress generation, individuals' own thoughts and behaviors can actually lead to increases in their experience of stress. Unfortunately, stress generation is especially common among individuals who are already suffering from elevated depressive symptoms. However, despite the acknowledgement that some individuals with depressive symptoms generate greater stress than others, few studies have identified specific factors that could exacerbate stress generation among individuals with depressive symptoms. The present study examines co-rumination as a factor that might exacerbate stress generation among adolescents with depressive symptoms using a short-term longitudinal design. Considering these processes among adolescents was critical given that many youth experience increases in depressive symptoms at this developmental stage and that co-rumination also becomes more common at adolescence. Participants were 628 adolescents (326 girls; 302 boys) who reported on their depressive symptoms, experiences of stress, and co-rumination with a best friend. Interpersonal stressors (peer and family stress) and non-interpersonal stressors (school and sports stress) were assessed. Consistent with past research, adolescents with depressive symptoms experienced greater interpersonal and non-interpersonal stress over time. Importantly, co-rumination interacted with both depressive symptoms and gender in predicting increases in peer stress. Depressive symptoms predicted the generation of peer stress only for girls who reported high levels of co-rumination with friends. Implications for protecting youth with depressive symptoms against stress generation are discussed.

Creep theories compared by means of high sensitivity tensile creep data

International Nuclear Information System (INIS)

Salim, A.

1987-01-01

Commonly used creep theories include time-hardening, strain-hardening and Rabotnov's modified strain-hardening. In the paper they are examined by using high sensitivity tensile creep data produced on 1% CrMoV steel at a temperatue of 565 0 C. A special creep machine designed and developed by the author is briefly described and is compared with other existing machines. Tensile creep data reported cover a stress range of 100-260 MN m -2 ; four variable-creep tests each in duplicate are also reported. Test durations are limited to 3000 h, or failure, whichever occurs earlier. The strain-hardening theory and Rabotnov's modified strain-hardening theory are found to give good prediction of creep strain under variable stress conditions. The time-hardening theory shows a relatively poor agreement and considerably underestimates the accumulated inelastic strain under increasing stress condition. This discrepancy increases with the increased stress rate. The theories failed to predict the variable stress results towards the later part of the test where tertiary effects were significant. The use of creep equations which could account for creep strain at higher stress levels seems to improve the situation considerably. Under conditions of variable stress, it is suggested that a theory based on continuous damage mechanics concepts might give a better prediction. (author)

Effect of tensile overloads on fatigue crack growth of high strength steel wires

International Nuclear Information System (INIS)

Haag, J.; Reguly, A.; Strohaecker, T.R.

2013-01-01

Highlights: • A proof load process may be an option to increase the fatigue life of flexible pipelines. • There is possibility to produce plastic deformation at crack tip of tensile armor wires. • Controlled overloads provide effective crack growth retardation. • Crack growth retardation is also evident at higher stress ratios. - Abstract: Fatigue of the tensile armor wires is the main failure mode of flexible risers. Techniques to increase the life of these components are required to improve the processes safety on oil exploration. This work evaluates the crack growth retardation of high strength steel wires used in flexible pipelines. Fracture toughness tests were performed to establish the level of stress intensity factor wherein the wires present significant plastic deformation at the crack tip. The effect of tensile overload on fatigue behavior was assessed by fatigue crack growth testing under constant ΔK control and different overload ratios with two different load ratios. The outcomes show that the application of controlled overloads provides crack retardation and increases the fatigue life of the wires more than 31%. This behavior is also evident at stress ratio of 0.5, in spite of the crack closure effect being minimized by increasing the applied mean stress

Coolant compatibility studies. The effect of irradiation on tensile properties and stress corrosion cracking sensitivity of martensitic steels. MANET 4 - complementary studies

International Nuclear Information System (INIS)

Nystrand, A.C.

1994-02-01

Tensile and stress corrosion cracking tests have been carried out on MANET-type (1.4914 and FV448) and reduced activation (LA12TaLC) high-chromium martensitic steels. The materials had previously been exposed up to 5000 h at ∼275 degrees C in the core, above the core and remote from the core of a high pressure water loop in the Studsvik R2 reactor. After the mechanical testing the materials were examined visually and metallographically. The steel samples exposed in the core section showed large increases in tensile yield strengths when tested at 250 degrees C. However, the magnitude of the radiation hardening was considerably smaller in the reduced activation steel compared to the commercial steels; this observation is consistent with published data on other high-chromium martensitic steels and is associated with the lower chromium content of the LA12TaLC steel (8.9%) compared with those of the commercial steels (10.6 and 11.3%). Irradiation assisted stress corrosion cracking (IASCC) was not detected in any of the stressed steel samples after autoclave testing for times up to 1500 h at 250 degrees C in air-saturated high purity water. This apparent resistance to IASCC may be due to the high chromium martensitic steels not being sensitized by the irradiation in a comparable manner to that shown by the austenitic steels. However, additional studies are required to clarify some of the existing uncertainties with respect to IASCC of these martensitic steels

Two new tensile devices for X-ray diffraction experiments

Energy Technology Data Exchange (ETDEWEB)

Freri, N.; Tintori, A.; Depero, L.E.; Sangaletti, L. [Brescia Univ. (Italy); Cernuschi, F.; Ghia, S. [Ente Nazionale per l`Energia Elettrica, Milan (Italy)

1995-12-01

Two tensile devices were designed to be used with parallel beam and parafocusing-geometry diffractometers. In thefirst case the device was designed to be attached to a strainflex diffractometer by Rigaku Inc., dedicated to stress analysis and commonly used in metallurgical industry. Since the sample does not move during the measurement, the tensile device can be kept fixed on the experimental table. The device design takes into account the steric hindrance by moving parts of diffractometer. The maximun load that can be applied to the sample is 60.000 N. An attachement to a Siemens D5000 diffractometer with Eulerian cradle has also benn designed for applying a load up tp 6000 N to a sample in the parafocusing-geometry. The installation does not require a re-alignment of the diffractometer. In both cases strain gages were applied to both sides of the specimen for the simultaneous determination of the macroscopic strains. Experiments based on the use of these devices are planned to determine the crystallographic elastic constants and study the influence of the microstructure on the mechanical behaviour of residual stresses in the zone of almost static stresses as well as the influence of residual stresses on uniaxially loaded samples. In addition, by using these devices, it is possible to measure the unstressed d-0 spacings providing useful information in the neutron diffraction study fo stress fields in steel samples.

Modelling and Simulation of Tensile Fracture in High Velocity Compacted Metal Powder

International Nuclear Information System (INIS)

Jonsen, P.; Haeggblad, H.-A.

2007-01-01

In cold uniaxial powder compaction, powder is formed into a desired shape with rigid tools and a die. After pressing, but before sintering, the compacted powder is called green body. A critical property in the metal powder pressing process is the mechanical properties of the green body. Beyond a green body free from defects, desired properties are high strength and uniform density. High velocity compaction (HVC) using a hydraulic operated hammer is a production method to form powder utilizing a shock wave. Pre-alloyed water atomised iron powder has been HVC-formed into circular discs with high densities. The diametral compression test also called the Brazilian disc test is an established method to measure tensile strength in low strength material like e.g. rock, concrete, polymers and ceramics. During the test a thin disc is compressed across the diameter to failure. The compression induces a tensile stress perpendicular to the compressed diameter. In this study the test have been used to study crack initiation and the tensile fracture process of HVC-formed metal powder discs with a relative density of 99%. A fictitious crack model controlled by a stress versus crack-width relationship is utilized to model green body cracking. Tensile strength is used as a failure condition and limits the stress in the fracture interface. The softening rate of the model is obtained from the corresponding rate of the dissipated energy. The deformation of the powder material is modelled with an elastic-plastic Cap model. The characteristics of the tensile fracture development of the central crack in a diametrically loaded specimen is numerically studied with a three dimensional finite element simulation. Results from the finite element simulation of the diametral compression test shows that it is possible to simulate fracturing of HVC-formed powder. Results from the simulation agree reasonably with experiments

Tensile stress corrosion cracking of type 304 stainless steel irradiated to very high dose

Energy Technology Data Exchange (ETDEWEB)

Chung, H. M.; Ruther, W. E.; Strain, R. V.; Shack, W. J.

2001-09-01

Certain safety-related core internal structural components of light water reactors, usually fabricated from Type 304 or 316 austenitic stainless steels (SSs), accumulate very high levels of irradiation damage (20--100 displacement per atom or dpa) by the end of life. The data bases and mechanistic understanding of, the degradation of such highly irradiated components, however, are not well established. A key question is the nature of irradiation-assisted intergranular cracking at very high dose, i.e., is it purely mechanical failure or is it stress-commotion cracking? In this work, hot-cell tests and microstructural characterization were performed on Type 304 SS from the hexagonal fuel can of the decommissioned EBR-11 reactor after irradiation to {approximately}50 dpa at {approximately}370 C. Slow-strain-rate tensile tests were conducted at 289 C in air and in water at several levels of electrochemical potential (ECP), and microstructural characteristics were analyzed by scanning and transmission electron microcopies. The material deformed significantly by twinning and exhibited surprisingly high ductility in air, but was susceptible to severe intergranular stress corrosion cracking (IGSCC) at high ECP. Low levels of dissolved O and ECP were effective in suppressing the susceptibility of the heavily irradiated material to IGSCC, indicating that the stress corrosion process associated with irradiation-induced grain-boundary Cr depletion, rather than purely mechanical separation of grain boundaries, plays the dominant role. However, although IGSCC was suppressed, the material was susceptible to dislocation channeling at low ECP, and this susceptibility led to poor work-hardening capability and low ductility.

Evaluation of the tensile strength of the human ureter - Preliminary results.

Science.gov (United States)

Shilo, Yaniv; Pichamuthu, Joseph E; Averch, Timothy D; Vorp, David A

2014-09-15

Introduction: Ureteral injuries such as avulsion are directly related to mechanical damage of the ureter. Understanding the tensile strength of this tissue may assist in prevention of iatrogenic injuries. Few published studies have looked at the mechanical properties of the animal ureter, and of those none have determined the tensile strength of the human ureter. Therefore, the purpose of this work was to determine the tensile strength of the human ureter. Materials and Methods: We harvested 11 human proximal ureters from patients who were undergoing nephrectomy for either kidney tumors or non-functioning kidney. The specimens were then cut into multiple circumferentially and longitudinally-oriented tissue strips for tensile testing. Strips were uniaxially stretched to failure in a tensile testing machine. The corresponding force and displacement were recorded. Finally, stress at failure was noted as the tensile strength of the sample. Circumferential tensile strength was also compared in the proximal and distal regions of the specimens. Results: The tensile strength of the ureter in circumferential and longitudinal orientations was found to be 457.52±33.74 Ncm-2 and 902.43±122.08 Ncm-2, respectively (ptensile strength of the ureter was found to be significantly lower than the longitudinal strength. Circumferential tensile strength was also lower with more proximal parts of the ureter. This information may be important for the design of "intelligent" devices and simulators in order to prevent complications.

Cyclic fatigue of near-isotopic graphite: influence of stress cycle and neutron irradiation

International Nuclear Information System (INIS)

Price, R.J.

1977-11-01

Near-isotropic graphites H-451 and PGX were tested in uniaxial cyclic fatigue, and fatigue life (S-N) curves were generated to a maximum of 10 5 cycles. The stress ratio, R (minimum stress during a cycle divided by maximum stress) ranged from -1 to +0.5. With R = - 1, the homologous stress limits (maximum applied fatigue stress divided by the tensile strength) for 50% specimen survival to 10 5 cycles averaged 0.63 in the axial direction and 0.74 in the radial direction. Corresponding homologous stress limits for 99% specimen survival (99/95 tolerance limits) were 0.48 and 0.53. Higher R-values resulted in longer fatigue lives and increased stress limits. H-451 graphite specimens irradiated with fast neutrons at 1173 to 1263 0 K at fluences of up to 10 26 n/m 2 (equivalent fission fluence) showed fatigue stress limits of about twice the unirradiated levels when the unirradiated tensile strength was used as the basis for normalization

Cracking and Deformation Modelling of Tensile RC Members Using Stress Transfer Approach

Directory of Open Access Journals (Sweden)

Ronaldas Jakubovskis

2016-12-01

Full Text Available The paper presents a modeling technique for bond, cracking and deformation analysis of RC members. The proposed mod-eling technique is not restricted by the geometrical dimensions of the analyzed member and may be applied for various load-ing conditions. Tensile as well as bending RC members may be analyzed using the proposed technique. Adequacy of the modeling strategy was evaluated by the developed numerical discrete crack algorithm, which allows modeling deformation and cracking behavior of tensile RC members. Comparison of experimental and numerical results proved the applicability of the proposed modeling strategy.

Numerical Simulation on the Dynamic Splitting Tensile Test of reinforced concrete

Science.gov (United States)

Zhao, Zhuan; Jia, Haokai; Jing, Lin

2018-03-01

The research for crack resistance was of RC was based on the split Hopkinson bar and numerical simulate software LS-DYNA3D. In the research, the difference of dynamic splitting failure modes between plane concrete and reinforced concrete were completed, and the change rule of tensile stress distribution with reinforcement ratio was studied; also the effect rule with the strain rate and the crack resistance was also discussed by the radial tensile stress time history curve of RC specimen under different loading speeds. The results shows that the reinforcement in the concrete can impede the crack extension, defer the failure time of concrete, increase the tension intensity of concrete; with strain rate of concrete increased, the crack resistance of RC increased.

An investigation of the dynamic separation of spot welds under plane tensile pulses

International Nuclear Information System (INIS)

Ma, Bohan; Fan, Chunlei; Chen, Danian; Wang, Huanran; Zhou, Fenghua

2014-01-01

We performed ultra-high-speed tests for purely opening spot welds using plane tensile pulses. A gun system generated a parallel impact of a projectile plate onto a welded plate. Induced by the interactions of the release waves, the welded plate opened purely under the plane tensile pulses. We used the laser velocity interferometer system for any reflector to measure the velocity histories of the free surfaces of the free part and the spot weld of the welded plate. We then used a scanning electron microscope to investigate the recovered welded plates. We found that the interfacial failure mode was mainly a brittle fracture and the cracks propagated through the spot nugget, while the partial interfacial failure mode was a mixed fracture comprised ductile fracture and brittle fracture. We used the measured velocity histories to evaluate the tension stresses in the free part and the spot weld of the welded plate by applying the characteristic theory. We also discussed the different constitutive behaviors of the metals under plane shock loading and under uniaxial split Hopkinson pressure bar tests. We then compared the numerically simulated velocity histories of the free surfaces of the free part and the spot weld of the welded plate with the measured results. The numerical simulations made use of the fracture stress criteria, and then the computed fracture modes of the tests were compared with the recovered results

Welding residual stress improvement in internal components by water jet peening

International Nuclear Information System (INIS)

Enomoto, K.; Hirano, K.; Hayashi, M.; Hayashi, E.

1996-01-01

Cavitations are generated when highly pressurized water is jetted in water. Surface residual stress is improved remarkably due to the peening effect of extremely high pressure caused by the collapse of cavitation bubbles. This technique is called water jet peening (WJP). WJP is expected to be an effective maintenance technique for the prevention of stress corrosion cracking caused by residual stress in various components of power generating plants. Various kinds of specimens were water jet peened to evaluate the fundamental characteristics of WJP and to select the most appropriate conditions for the residual stress improvement. Test results showed that WJP markedly improved the tensile residual stress caused by welding and grinding to the high compressive residual stress and seems to prevent the stress corrosion cracking

The influence of void and porosity on deformation behaviour of nanocrystalline Ni under tensile followed by compressive loading

Science.gov (United States)

Meraj, Md.; Nayak, Shradha; Krishanjeet, Kumar; Pal, Snehanshu

2018-03-01

In this paper, we present a lucid understanding about the deformation behaviour of nanocrystalline (NC) Ni with and without defects subjected to tensile followed by compressive loading using molecular dynamic (MD) simulations. The embedded atom method (EAM) potential have been incorporated in the simulation for three kinds of samples-i.e. for NC Ni (without any defect), porous NC Ni and NC Ni containing a centrally located void. All the three samples, which have been prepared by implementing the Voronoi method and using Atom Eye software, consist of 16 uniform grains. The total number of atoms present in NC Ni, porous NC Ni and NC Ni containing a void are 107021, 105968 and 107012 respectively. The stress-strain response of NC Ni under tensile followed by compressive loading are simulated at a high strain rate of 107 s-1 and at a constant temperature of 300K. The stress-strain curves for the NC Ni with and without defects have been plotted for three different types of loading: (a) tensile loading (b) compressive loading (c) forward tensile loading followed by reverse compressive loading. Prominent change in yield strength of the NC Ni is observed due to the introduction of defects. For tensile followed by compressive loading (during forward loading), the yield point for NC Ni with void is lesser than the yield point of NC Ni and porous NC Ni. The saw tooth shape or serration portion of the stress-strain curve is mainly due to three characteristic phenomena, dislocation generation and its movement, dislocation pile-up at the junctions, and dislocation annihilation. Both twins and stacking faults are observed due to plastic deformation as the deformation mechanism progresses. The dislocation density, number of clusters and number of vacancy of the NC sample with and without defects are plotted against the strain developed in the sample. It is seen that introduction of defects brings about change in mechanical properties of the NC Ni. The crystalline nature of NC Ni

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.

Tensile strength of 67P/Churyumov-Gerasimenko nucleus material from overhangs

Science.gov (United States)

Attree, N.; Groussin, O.; Jorda, L.; Nébouy, D.; Thomas, N.; Brouet, Y.; Kührt, E.; Preusker, F.; Scholten, F.; Knollenberg, J.; Hartogh, P.; Sierks, H.; Barbieri, C.; Lamy, P.; Rodrigo, R.; Koschny, D.; Rickman, H.; Keller, H. U.; A'Hearn, M. F.; Auger, A.-T.; Barucci, M. A.; Bertaux, J.-L.; Bertini, I.; Bodewits, D.; Boudreault, S.; Cremonese, G.; Da Deppo, V.; Davidsson, B.; Debei, S.; De Cecco, M.; Deller, J.; El-Maarry, M. R.; Fornasier, S.; Fulle, M.; Gutiérrez, P. J.; Güttler, C.; Hviid, S.; Ip, W.-H.; Kovacs, G.; Kramm, J. R.; Küppers, M.; Lara, L. M.; Lazzarin, M.; Lopez Moreno, J. J.; Lowry, S.; Marchi, S.; Marzari, F.; Mottola, S.; Naletto, G.; Oklay, N.; Pajola, M.; Toth, I.; Tubiana, C.; Vincent, J.-B.; Shi, X.

2018-03-01

We directly measured twenty overhanging cliffs on the surface of comet 67P/Churyumov-Gerasimenko extracted from the latest shape model and estimated the minimum tensile strengths needed to support them against collapse under the comet's gravity. We find extremely low strengths of around 1 Pa or less (1 to 5 Pa, when scaled to a metre length). The presence of eroded material at the base of most overhangs, as well as the observed collapse of two features andthe implied previous collapse of another, suggests that they are prone to failure and that the true material strengths are close to these lower limits (although we only consider static stresses and not dynamic stress from, for example, cometary activity). Thus, a tensile strength of a few pascals is a good approximation for the tensile strength of the 67P nucleus material, which is in agreement with previous work. We find no particular trends in overhang properties either with size over the 10-100 m range studied here or location on the nucleus. There are no obvious differences, in terms of strength, height or evidence of collapse, between the populations of overhangs on the two cometary lobes, suggesting that 67P is relatively homogenous in terms of tensile strength. Low material strengths are supportive of cometary formation as a primordial rubble pile or by collisional fragmentation of a small body (tens of km).

The residual stress evaluation for expansion process of steam generator tubes

International Nuclear Information System (INIS)

King, C.-S.; Lee, S.-C.; Shim, D.-N.

2004-01-01

The reliability of a nuclear power plant is affected by the reliability of steam generator tube and the reliability of steam generator tube is affected by stress corrosion cracking(SCC). Many steam generator tubes were experiencing stress corrosion cracking and stress corrosion cracking is affected material characteristics, corrosive environments and added stresses. The added stresses have the manufacturing stresses and operating stresses, the manufacturing stresses include the residual stresses generating in the tube manufacture and tube expanding procedure. We will investigate for influence which affected to residual stresses with tube plastic deformation method and measurement region. (author)

Tensile properties and flow behavior analysis of modified 9Cr-1Mo steel clad tube material

Science.gov (United States)

Singh, Kanwarjeet; Latha, S.; Nandagopal, M.; Mathew, M. D.; Laha, K.; Jayakumar, T.

2014-11-01

The tensile properties and flow behavior of modified 9Cr-1Mo steel clad tube have been investigated in the framework of various constitutive equations for a wide range of temperatures (300-923 K) and strain rates (3 × 10-3 s-1, 3 × 10-4 s-1 and 3 × 10-5 s-1). The tensile flow behavior of modified 9Cr-1Mo steel clad tube was most accurately described by Voce equation. The variation of instantaneous work hardening rate (θ = dσ/dε) and σθ with stress (σ) indicated two stage behavior characterized by rapid decrease at low stresses (transient stage) followed by a gradual decrease in high stresses (Stage III). The variation of work hardening parameters and work hardening rate in terms of θ vs. σ and σθ vs. σ with temperature exhibited three distinct regimes. Rapid decrease in flow stress and work hardening parameters and rapid shift of θ vs. σ and σθ vs. σ towards low stresses with increase in temperature indicated dynamic recovery at high temperatures. Tensile properties of the material have been best predicted from Voce equation.

Tensile properties and flow behavior analysis of modified 9Cr–1Mo steel clad tube material

International Nuclear Information System (INIS)

Singh, Kanwarjeet; Latha, S.; Nandagopal, M.; Mathew, M.D.; Laha, K.; Jayakumar, T.

2014-01-01

The tensile properties and flow behavior of modified 9Cr–1Mo steel clad tube have been investigated in the framework of various constitutive equations for a wide range of temperatures (300–923 K) and strain rates (3 × 10 −3 s −1 , 3 × 10 −4 s −1 and 3 × 10 −5 s −1 ). The tensile flow behavior of modified 9Cr–1Mo steel clad tube was most accurately described by Voce equation. The variation of instantaneous work hardening rate (θ = dσ/dε) and σθ with stress (σ) indicated two stage behavior characterized by rapid decrease at low stresses (transient stage) followed by a gradual decrease in high stresses (Stage III). The variation of work hardening parameters and work hardening rate in terms of θ vs. σ and σθ vs. σ with temperature exhibited three distinct regimes. Rapid decrease in flow stress and work hardening parameters and rapid shift of θ vs. σ and σθ vs. σ towards low stresses with increase in temperature indicated dynamic recovery at high temperatures. Tensile properties of the material have been best predicted from Voce equation

Influence of surface defects on the tensile strength of carbon fibers

Science.gov (United States)

Vautard, F.; Dentzer, J.; Nardin, M.; Schultz, J.; Defoort, B.

2014-12-01

The mechanical properties of carbon fibers, especially their tensile properties, are affected by internal and surface defects. In order to asses in what extent the generation of surface defects can result in a loss of the mechanical properties, non-surface treated carbon fibers were oxidized with three different surface treatment processes: electro-chemical oxidation, oxidation in nitric acid, and oxidation in oxygen plasma. Different surface topographies and surface chemistries were obtained, as well as different types and densities of surface defects. The density of surface defects was measured with both a physical approach (Raman spectroscopy) and a chemical approach (Active Surface Area). The tensile properties were evaluated by determining the Weibull modulus and the scale parameter of each reference, after measuring the tensile strength for four different gauge lengths. A relationship between the tensile properties and the nature and density of surface defects was noticed, as large defects largely control the value of the tensile strength. When optimized, some oxidation surface treatment processes can generate surface functional groups as well as an increase of the mechanical properties of the fibers, because of the removal of the contamination layer of pyrolytic carbon generated during the carbonization of the polyacrylonitrile precursor. Oxidation in oxygen plasma revealed to be a promising technology for alternative surface treatment processes, as high levels of functionalization were achieved and a slight improvement of the mechanical properties was obtained too.

Relationship of microstructure and tensile properties for neutron-irradiated vanadium alloys

International Nuclear Information System (INIS)

Loomis, B.A.; Smith, D.L.

1990-01-01

The microstructures in V-15Cr-5Ti, V-10Cr-5RTi, V-3Ti-1Si, V-15Ti-7.5Cr, and V-20Ti alloys were examined by transmission electron microscopy after neutron irradiation at 600 degree C to 21--84 atom displacements per atom in the Materials Open Test Assembly of the Fast Flux Test Facility. The microstructures in these irradiated alloys were analyzed to determine the radiation-produced dislocation density, precipitate number density and size, and void number density and size. The results of these analyses were used to compute increases in yield stress and swelling of the irradiated alloys. The computed increase in yield stress was compared with the increase in yield stress determined from tensile tests on these irradiated alloys. This comparison made it possible to evaluate the influence of alloy composition on the evolution of radiation-damaged microstructures and the resulting tensile properties. 11 refs

Stiff and tough: a comparative study on the tensile properties of shark skin.

Science.gov (United States)

Creager, Shelby B; Porter, Marianne E

2018-02-01

In sharks, the skin is a biological composite with mineralized denticles embedded within a collagenous matrix. Swimming performance is enhanced by the dermal denticles on the skin, which have drag reducing properties produced by regional morphological variations and changes in density along the body. We used mechanical testing to quantify the effect of embedded mineralized denticles on the quasi-static tensile properties of shark skin to failure in four coastal species. We investigated regional differences in denticle density and skin properties by dissecting skin from the underlying fascia and muscle at 10 anatomical landmarks. Hourglass-shaped skin samples were extracted in the cranial to caudal orientation. Denticle density was quantified and varied significantly among both regions and species. We observed the greatest denticle densities in the cranial region of the body for the bonnethead, scalloped hammerhead, and bull sharks. Skin samples were then tested in tension until failure, stress strain curves were generated, and mechanical properties calculated. We found significant species and region effects for all three tensile mechanical properties. We report the greatest ultimate tensile strength, stiffness, and toughness near the cranial and lateral regions of the body for all 4 of the coastal species. We also report that denticle density increases with skin stiffness but decreases with toughness. Copyright © 2017 Elsevier GmbH. All rights reserved.

FEM Modeling of In-Plane Stress Distribution in Thick Brittle Coatings/Films on Ductile Substrates Subjected to Tensile Stress to Determine Interfacial Strength.

Science.gov (United States)

Wang, Kaishi; Zhang, Fangzhou; Bordia, Rajendra K

2018-03-27

The ceramic-metal interface is present in various material structures and devices that are vulnerable to failures, like cracking, which are typically due to their incompatible properties, e.g., thermal expansion mismatch. In failure of these multilayer systems, interfacial shear strength is a good measure of the robustness of interfaces, especially for planar films. There is a widely-used shear lag model and method by Agrawal and Raj to analyse and measure the interfacial shear strength of thin brittle film on ductile substrates. The use of this classical model for a type of polymer derived ceramic coatings (thickness ~18 μm) on steel substrate leads to high values of interfacial shear strength. Here, we present finite element simulations for such a coating system when it is subjected to in-plane tension. Results show that the in-plane stresses in the coating are non-uniform, i.e., varying across the thickness of the film. Therefore, they do not meet one of the basic assumptions of the classical model: uniform in-plane stress. Furthermore, effects of three significant parameters, film thickness, crack spacing, and Young's modulus, on the in-plane stress distribution have also been investigated. 'Thickness-averaged In-plane Stress' (TIS), a new failure criterion, is proposed for estimating the interfacial shear strength, which leads to a more realistic estimation of the tensile strength and interfacial shear strength of thick brittle films/coatings on ductile substrates.

Influence of strain rate and temperature on tensile properties and flow behaviour of a reduced activation ferritic-martensitic steel

Energy Technology Data Exchange (ETDEWEB)

Vanaja, J., E-mail: jvanaja4@gmail.com [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Laha, K. [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Sam, Shiju [Institute for Plasma Research, Gandhinagar, Gujarat (India); Nandagopal, M.; Panneer Selvi, S.; Mathew, M.D.; Jayakumar, T. [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Rajendra Kumar, E. [Institute for Plasma Research, Gandhinagar, Gujarat (India)

2012-05-15

Tensile strength and flow behaviour of a Reduced Activation Ferritic-Martensitic (RAFM) steel (9Cr-1W-0.06Ta-0.22V-0.08C) have been investigated over a temperature range of 300-873 K at different strain rates. Tensile strength of the steel decreased with temperature and increased with strain rate except at intermediate temperatures. Negative strain rate sensitivity of flow stress of the steel at intermediate temperatures revealed the occurrence of dynamic strain ageing in the steel, even though no serrated flow was observed. The tensile flow behaviour of the material was well represented by the Voce strain hardening equation for all the test conditions. Temperature and strain rate dependence of the various parameters of Voce equation were interpreted with the possible deformation mechanisms. The equivalence between the saturation stress at a given strain rate in tensile test and steady state deformation rate at a given stress in creep test was found to be satisfied by the RAFM steel.

Influence of strain rate and temperature on tensile properties and flow behaviour of a reduced activation ferritic-martensitic steel

Science.gov (United States)

Vanaja, J.; Laha, K.; Sam, Shiju; Nandagopal, M.; Panneer Selvi, S.; Mathew, M. D.; Jayakumar, T.; Rajendra Kumar, E.

2012-05-01

Tensile strength and flow behaviour of a Reduced Activation Ferritic-Martensitic (RAFM) steel (9Cr-1W-0.06Ta-0.22V-0.08C) have been investigated over a temperature range of 300-873 K at different strain rates. Tensile strength of the steel decreased with temperature and increased with strain rate except at intermediate temperatures. Negative strain rate sensitivity of flow stress of the steel at intermediate temperatures revealed the occurrence of dynamic strain ageing in the steel, even though no serrated flow was observed. The tensile flow behaviour of the material was well represented by the Voce strain hardening equation for all the test conditions. Temperature and strain rate dependence of the various parameters of Voce equation were interpreted with the possible deformation mechanisms. The equivalence between the saturation stress at a given strain rate in tensile test and steady state deformation rate at a given stress in creep test was found to be satisfied by the RAFM steel.

Influence of strain rate and temperature on tensile properties and flow behaviour of a reduced activation ferritic–martensitic steel

International Nuclear Information System (INIS)

Vanaja, J.; Laha, K.; Sam, Shiju; Nandagopal, M.; Panneer Selvi, S.; Mathew, M.D.; Jayakumar, T.; Rajendra Kumar, E.

2012-01-01

Tensile strength and flow behaviour of a Reduced Activation Ferritic–Martensitic (RAFM) steel (9Cr–1W–0.06Ta–0.22V–0.08C) have been investigated over a temperature range of 300–873 K at different strain rates. Tensile strength of the steel decreased with temperature and increased with strain rate except at intermediate temperatures. Negative strain rate sensitivity of flow stress of the steel at intermediate temperatures revealed the occurrence of dynamic strain ageing in the steel, even though no serrated flow was observed. The tensile flow behaviour of the material was well represented by the Voce strain hardening equation for all the test conditions. Temperature and strain rate dependence of the various parameters of Voce equation were interpreted with the possible deformation mechanisms. The equivalence between the saturation stress at a given strain rate in tensile test and steady state deformation rate at a given stress in creep test was found to be satisfied by the RAFM steel.

Influence of repair length on residual stress in the repair weld of a clad plate

International Nuclear Information System (INIS)

Jiang Wenchun; Xu, X.P.; Gong, J.M.; Tu, S.T.

2012-01-01

Highlights: ► Residual stress in the repair weld of a stainless steel clad plate is investigated. ► The effect of repair length on residual stress has been studied. ► Large tensile residual stress is generated in the repair weld and heat affected zone. ► With the increase of repair length, transverse stress is decreased. ► Repair length has little effect on longitudinal stress. - Abstract: A 3-D sequential coupling finite element simulation is performed to investigate the temperature field and residual stress in the repair weld of a stainless steel clad plate. The effect of repair length on residual stress has been studied, aiming to provide a reference for repairing the cracked clad plate. The results show that large tensile residual stresses are generated in the repair weld and heat affected zone (HAZ), and then decrease gradually away from the weld and HAZ. The residual stresses through thickness in the clad layer are relative uniform, while they are non-uniform in the base metal. A discontinuous stress distribution is generated across the interface between weld metal and base metal. The repair length has a great effect on transverse stress. With the increase of repair length, the transverse stress is decreased. When the repair length is increased to 14 cm, the peak of transverse stress has been decreased below yield strength, and the transverse stress in the weld and HAZ has also been greatly decreased. But the repair length has little effect on longitudinal stress.

Deformation features of aluminium in tensile tests

International Nuclear Information System (INIS)

Quadros, N.F. de.

1984-01-01

It is presented a method to analyse stress-strain curves. Plastic and elastic strains were studied. The strains were done by tensile tests in four types of materials: highly pure aluminium, pure aluminium, commercially pure aluminium and aluminium - uranium. The chemical compositions were obtained by spectroscopy analysis and neutron activation analysis. Tensile tests were carried out at three strain rates, at room temperature, 100,200, 300 and 400 0 C, with knives extensometer and strain-gages to studied the elastic strain region. A multiple spring model based on two springs model to analyse elastic strain caused by tests without extensometers, taking in account moduli of elasticity and, an interactive analysis system with graphic capability were developed. It was suggested a qualitative model to explain the quantized multielasticity of Bell. (M.C.K.) [pt

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

Science.gov (United States)

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

2018-06-01

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

The influence of temperature on the tensile properties of a super duplex stainless steel

International Nuclear Information System (INIS)

Girones, A.; Mateo, A.; Llanes, L.; Anglada, M

2001-01-01

Tensile tests, at temperatures ranging between 275 and 475 degree centigree were performed in a superduplex stainless steel EN 1.4410. The dependence of yield stress and ultimate tensile strength on temperature indicates the existence of dynamic strain aging (DSA). In order to evaluate the influence of strain rate on this phenomenon, tests were conducted at two different strain rates, both at 325 degree centigree, temperature at which DSA is maximum for this materials. The results shows that the flow stress has an inverse strain rate sensitivity which confirms the existence of DSA in the steel under study. (Author) 10 refs

Tensile properties of polymethyl methacrylate coated natural fabric Sterculia urens

CSIR Research Space (South Africa)

Jayaramudu, J

2009-04-01

Full Text Available stress, Young's modulus and % elongation at break were determined using a Universal Testing Machine. The effect of alkali treatment and the polymethyl methacrylate coating on tensile properties of the fabric was studied. The morphology of the fabric...

Texture evolution during tensile necking of copper processed by equal channel angular extrusion

DEFF Research Database (Denmark)

Pantleon, Wolfgang; Richter, S.; Martin, S.

2010-01-01

Two copper samples, pre-deformed in tension to 5% plastic strain, are subjected to an in situ tensile deformation of 1% plastic strain while X-ray peak profiles from individual bulk grains are obtained. One sample is oriented with the in situ tensile axis parallel to the pre-deformation axis......, and peak profiles are obtained with the scattering vector parallel to this direction. The profiles show the expected asymmetry explained by the composite model as caused by intra-grain stresses. The other sample is oriented with the in situ tensile axis perpendicular to the pre-deformation axis, and peak...

Residual stresses in laser direct metal deposited Waspaloy

Energy Technology Data Exchange (ETDEWEB)

Moat, R.J., E-mail: richard.moat@manchester.ac.uk [School of Materials, University of Manchester, Grosvenor Street, Manchester M1 7HS (United Kingdom); Pinkerton, A.J.; Li, L. [Laser Processing Research Centre, School of Mechanical, Aerospace and Civil Engineering, University of Manchester, M60 1QD (United Kingdom); Withers, P.J.; Preuss, M. [School of Materials, University of Manchester, Grosvenor Street, Manchester M1 7HS (United Kingdom)

2011-03-15

Research highlights: {yields} Neutron diffraction and the contour method show good agreement. {yields} Tensile stresses found parallel to the surfaces. {yields} Compressive stresses within the bulk of the structures. {yields} Residual stress weakly dependent on the laser pulse parameters. {yields} Maximum tensile residual stress unaffected across range of pulse parameters used. - Abstract: This paper reports a study into the effect of laser pulse length and duty cycle on the residual stress distributions in multi-track laser direct metal deposits of Waspaloy onto an Inconel 718 substrate. The residual stresses have been evaluated using neutron diffraction and the contour method, while electron microscopy and micro hardness indentation have been used to map the concomitant microstructural variation. In all cases, near the tops of the deposited walls, the longitudinal stresses are tensile towards the mid-length of the wall, while the stresses perpendicular to the substrate are negligible. By contrast near the base of the walls, the stresses along the direction of deposition are small, while the stresses perpendicular to the substrate are compressive at the centre and tensile towards the ends. Consistent with previous observations, the stresses parallel to free surfaces are tensile, balanced by compressive stresses in the interior (an inverse quench stress profile). These profiles have been found to be weakly dependent on the laser pulse parameters, most notably an increase in tensile stress gradient with increasing duty cycle, but the maximum residual stresses are largely unaffected. Furthermore, microstructural analysis has shown that the effect of laser pulse parameters on grain morphology in multi-track thick walls is less marked than previously reported for single-track wall structures.

Residual stresses in laser direct metal deposited Waspaloy

International Nuclear Information System (INIS)

Moat, R.J.; Pinkerton, A.J.; Li, L.; Withers, P.J.; Preuss, M.

2011-01-01

Research highlights: → Neutron diffraction and the contour method show good agreement. → Tensile stresses found parallel to the surfaces. → Compressive stresses within the bulk of the structures. → Residual stress weakly dependent on the laser pulse parameters. → Maximum tensile residual stress unaffected across range of pulse parameters used. - Abstract: This paper reports a study into the effect of laser pulse length and duty cycle on the residual stress distributions in multi-track laser direct metal deposits of Waspaloy onto an Inconel 718 substrate. The residual stresses have been evaluated using neutron diffraction and the contour method, while electron microscopy and micro hardness indentation have been used to map the concomitant microstructural variation. In all cases, near the tops of the deposited walls, the longitudinal stresses are tensile towards the mid-length of the wall, while the stresses perpendicular to the substrate are negligible. By contrast near the base of the walls, the stresses along the direction of deposition are small, while the stresses perpendicular to the substrate are compressive at the centre and tensile towards the ends. Consistent with previous observations, the stresses parallel to free surfaces are tensile, balanced by compressive stresses in the interior (an inverse quench stress profile). These profiles have been found to be weakly dependent on the laser pulse parameters, most notably an increase in tensile stress gradient with increasing duty cycle, but the maximum residual stresses are largely unaffected. Furthermore, microstructural analysis has shown that the effect of laser pulse parameters on grain morphology in multi-track thick walls is less marked than previously reported for single-track wall structures.

Negative life events and symptoms of depression and anxiety: stress causation and/or stress generation.

Science.gov (United States)

Phillips, Anna C; Carroll, Douglas; Der, Geoff

2015-01-01

Stressful life events are known to contribute to development of depression; however, it is possible this link is bidirectional. The present study examined whether such stress generation effects are greater than the effects of stressful life events on depression, and whether stress generation is also evident with anxiety. Participants were two large age cohorts (N = 732 aged 44 years; N = 705 aged 63 years) from the West of Scotland Twenty-07 study. Stressful life events, depression, and anxiety symptoms were measured twice five years apart. Cross-lagged panel analysis examined the mutual influences of stressful life events on depression and on anxiety over time. Life events predicted later depressive symptomatology (p = .01), but the depression predicting life events relationship was less strong (p = .06), whereas earlier anxiety predicted life events five years later (p = .001). There was evidence of sex differences in the extent to which life events predicted later anxiety. This study provides evidence of stress causation for depression and weaker evidence for stress generation. In contrast, there was strong evidence of stress generation for anxiety but weaker evidence for stress causation, and that differed for men and women.

Tensile creep of beta phase zircaloy-2

International Nuclear Information System (INIS)

Burton, B.; Reynolds, G.L.; Barnes, J.P.

1977-08-01

The tensile creep and creep rupture properties of beta-phase zircaloy-2 are studied under vacuum in the temperature and stress range 1300-1550 K and 0.5-2 MN/m 2 . The new results are compared with previously reported uniaxial and biaxial data. A small but systematic difference is noted between the uniaxial and biaxial creep data and reasons for this discrepancy are discussed. (author)

Two new tensile devices for X-ray diffraction experiments

International Nuclear Information System (INIS)

Freri, N.; Tintori, A.; Depero, L.E.; Sangaletti, L.; Cernuschi, F.; Ghia, S.

1995-12-01

Two tensile devices were designed to be used with parallel beam and parafocusing-geometry diffractometers. In the first case the device was designed to be attached to a strainflex diffractometer by Rigaku Inc., dedicated to stress analysis and commonly used in metallurgical industry. Since the sample does not move during the measurement, the tensile device can be kept fixed on the experimental table. The device design takes into account the steric hindrance by moving parts of diffractometer. The maximun load that can be applied to the sample is 60.000 N. An attachement to a Siemens D5000 diffractometer with Eulerian cradle has also benn designed for applying a load up tp 6000 N to a sample in the parafocusing-geometry. The installation does not require a re-alignment of the diffractometer. In both cases strain gages were applied to both sides of the specimen for the simultaneous determination of the macroscopic strains. Experiments based on the use of these devices are planned to determine the crystallographic elastic constants and study the influence of the microstructure on the mechanical behaviour of residual stresses in the zone of almost static stresses as well as the influence of residual stresses on uniaxially loaded samples. In addition, by using these devices, it is possible to measure the unstressed d-0 spacings providing useful information in the neutron diffraction study fo stress fields in steel samples

Specimen alignment in an axial tensile test of thin films using direct imaging and its influence on the mechanical properties of BeCu

International Nuclear Information System (INIS)

Kang, Dong-Joong; Park, Jun-Hyub; Shin, Myung-Soo; Ha, Jong-Eun; Lee, Hak-Joo

2010-01-01

This paper proposes a new system for verification of the alignment of loading fixtures and test specimens during tensile testing of thin film with a micrometer size through direct imaging. The novel and reliable image recognition system to evaluate the misalignment between the load train and the specimen axes during tensile test of thin film was developed using digital image processing technology with CCD. The decision of whether alignment of the tensile specimen is acceptable or not is based on a probabilistic analysis through the edge feature extraction of digital imaging. In order to verify the performance of the proposed system and investigate the effect of the misalignment of the specimen on tensile properties, the tensile tests were performed as displacement control in air and at room temperature for metal thin film, the beryllium copper (BeCu) alloys. In the case of the metal thin films, bending stresses caused by misalignment are insignificant because the films are easily bent during tensile tests to eliminate the bending stresses. And it was observed that little effects and scatters on tensile properties occur by stress gradient caused by twisting at in-plane misalignment, and the effects and scatters on tensile properties are insignificant at out-of-plane misalignment, in the case of the BeCu thin film.

Microscopic observation and statics consideration of tensile fracture of TiC coating on stainless steel

International Nuclear Information System (INIS)

Okawa, Akira; Hasiguti, Ryukiti

1986-01-01

We have measured the tensile fracture properties of the TiC coated SUS316L stainless steel, applying a stress perpendicular to the plane of interface between the coating and the substrate. The fracture of the as grown or non-annealed specimens occurred partially within the TiC layer. A tensile fracture of the TiC coated specimens after vacuum annealing at about 1373 K (1100 deg C) presented arc-shape curved fracture surfaces which can be understood by statics consideration taking into account the maximum stress plane theory and the residual thermal stress. The strengths of non-annealed and annealed specimens are 34.4 MPa (350 kgf/cm 2 ) and 30.2 MPa (308 kgf/cm 2 ), respectively, expressed in terms of Weibull's 50 % fracture stresses. (author)

Normal personality traits, rumination and stress generation among early adolescent girls

Science.gov (United States)

Stroud, Catherine B.; Sosoo, Effua E.; Wilson, Sylia

2017-01-01

This study examined associations between personality and stress generation. Expanding upon prior work, we examined (a) the role of Positive Emotionality (PE), Negative Emotionality (NE), and Constraint (CON), and their lower-order facets, as predictors of acute and chronic interpersonal stress generation; (b) whether personality moderated effects of rumination on stress generation; and (c) whether personality increased exposure to independent (uncontrollable) stress. These questions were examined in a one-year study of 126 adolescent girls (M age = 12.39 years) using contextual stress interviews. NE predicted increases in acute and chronic interpersonal stress generation, but not independent stress. NE, CON and affiliative PE each moderated the effect of rumination on chronic interpersonal stress generation. These effects were driven by particular lower-order traits. PMID:28845067

Effect of elevated temperature on the tensile strength of Napier/glass-epoxy hybrid reinforced composites

Science.gov (United States)

Ridzuan, M. J. M.; Majid, M. S. Abdul; Afendi, M.; Firdaus, A. Z. Ahmad; Azduwin, K.

2017-11-01

The effects of elevated temperature on the tensile strength of Napier/glass-epoxy hybrid reinforced composites and its morphology of fractured surfaces are discussed. Napier/glass-epoxy hybrid reinforced composites were fabricated by using vacuum infusion method by arranging Napier fibres in between sheets of woven glass fibres. Napier and glass fibres were laminated with estimated volume ratios were 24 and 6 vol. %, respectively. The epoxy resin was used as matrix estimated to 70 vol. %. Specimens were tested to failure under tension at a cross-head speed of 1 mm/min using Universal Testing Machine (Instron) with a load cell 100 kN at four different temperatures of RT, 40°C, 60°C and 80°C. The morphology of fractured surface of hybrid composites was investigated by field emission scanning electron microscopy. The result shows reduction in tensile strength at elevated temperatures. The increase in the temperature activates the process of diffusion, and generates critical stresses which cause the damage at first-ply or at the centre of the hybrid plate, as a result lower the tensile strength. The observation of FESEM images indicates that the fracture mode is of evolution of localized damage, from fibre/matrix debonding, matric cracking, delamination and fibre breakage.

The effect of strain rate and temperature on the elevated temperature tensile flow behavior of service-exposed 2.25Cr-1Mo steel

International Nuclear Information System (INIS)

Girish Shastry, C.; Parameswaran, P.; Mathew, M.D.; Bhanu Sankara Rao, K.; Mannan, S.L.

2007-01-01

The elevated temperature tensile flow behavior of service-exposed 2.25Cr-1Mo steel has been critically examined with respect to strain rate sensitivity (m) and apparent activation energy (Q) for tensile deformation. The predominant role of forest dislocations in determining the relative flow response at true plastic strains greater than 0.01 is inferred from the profile of 'm' against flow stress. The variation of 'm' with temperature and strain is discussed based on the kinetics of dislocation generation and recovery. The decrease in Q with the increase in strain rate or temperature is attributed to the increase in recovery processes like dislocation annihilation and subcell/subgrain formation. This suggestion has been supported by transmission electron microscopy

A technique to remove the tensile instability in weakly compressible SPH

Science.gov (United States)

Xu, Xiaoyang; Yu, Peng

2018-01-01

When smoothed particle hydrodynamics (SPH) is directly applied for the numerical simulations of transient viscoelastic free surface flows, a numerical problem called tensile instability arises. In this paper, we develop an optimized particle shifting technique to remove the tensile instability in SPH. The basic equations governing free surface flow of an Oldroyd-B fluid are considered, and approximated by an improved SPH scheme. This includes the implementations of the correction of kernel gradient and the introduction of Rusanov flux into the continuity equation. To verify the effectiveness of the optimized particle shifting technique in removing the tensile instability, the impacting drop, the injection molding of a C-shaped cavity, and the extrudate swell, are conducted. The numerical results obtained are compared with those simulated by other numerical methods. A comparison among different numerical techniques (e.g., the artificial stress) to remove the tensile instability is further performed. All numerical results agree well with the available data.

Finite Element Simulation of Aluminium/GFRP Fibre Metal Laminate under Tensile Loading

Science.gov (United States)

Merzuki, M. N. M.; Rejab, M. R. M.; Romli, N. K.; Bachtiar, D.; Siregar, J.; Rani, M. F.; Salleh, Salwani Mohd

2018-03-01

The response of a fibre metal laminate (FML) model to the tensile loading is predicted through a computational approach. The FML consisted with layers of aluminum alloy and embedded with one layer of composite material, Glass fibre Reinforced Plastic (GFRP). The glass fibre and aluminium alloy 2024-0 was laminated by using thermoset epoxy. A compression moulding technique was used in the process of a FML fabrication. The aluminium has been roughen by a metal sanding method which to improve the bonding between the fibre and metal layer. The main objective of this paper is to determine the failure behaviour of the FML under the tensile loading. The responses on the FML under the tensile loading were numerically performed. The FML was modelled and analysed by using Abaqus/CAE 6.13 version. Based on the experimental and FE data of the tensile, the ultimate tensile stress is 120 MPa where delamination and fibre breakage happened. A numerical model was developed and agreed well with the experimental results. The laminate has an inelastic respond to increase the tensile loads which due to the plasticity of the aluminium layers.

Tensile properties and flow behavior analysis of modified 9Cr–1Mo steel clad tube material

Energy Technology Data Exchange (ETDEWEB)

Singh, Kanwarjeet, E-mail: kanwar722@yahoo.com; Latha, S.; Nandagopal, M.; Mathew, M.D.; Laha, K.; Jayakumar, T.

2014-11-15

The tensile properties and flow behavior of modified 9Cr–1Mo steel clad tube have been investigated in the framework of various constitutive equations for a wide range of temperatures (300–923 K) and strain rates (3 × 10{sup −3} s{sup −1}, 3 × 10{sup −4} s{sup −1} and 3 × 10{sup −5} s{sup −1}). The tensile flow behavior of modified 9Cr–1Mo steel clad tube was most accurately described by Voce equation. The variation of instantaneous work hardening rate (θ = dσ/dε) and σθ with stress (σ) indicated two stage behavior characterized by rapid decrease at low stresses (transient stage) followed by a gradual decrease in high stresses (Stage III). The variation of work hardening parameters and work hardening rate in terms of θ vs. σ and σθ vs. σ with temperature exhibited three distinct regimes. Rapid decrease in flow stress and work hardening parameters and rapid shift of θ vs. σ and σθ vs. σ towards low stresses with increase in temperature indicated dynamic recovery at high temperatures. Tensile properties of the material have been best predicted from Voce equation.

The evolution of internal stress and dislocation during tensile deformation in a 9Cr ferritic/martensitic (F/M) ODS steel investigated by high-energy X-rays

Energy Technology Data Exchange (ETDEWEB)

Zhang, Guangming; Zhou, Zhangjian; Mo, Kun; Miao, Yinbin; Liu, Xiang; Almer, Jonathan; Stubbins, James F.

2015-12-01

An application of high-energy wide angle synchrotron X-ray diffraction to investigate the tensile deformation of 9Cr ferritic/martensitic (F/M) ODS steel is presented. With tensile loading and in-situ Xray exposure, the lattice strain development of matrix was determined. The lattice strain was found to decrease with increasing temperature, and the difference in Young's modulus of six different reflections at different temperatures reveals the temperature dependence of elastic anisotropy. The mean internal stress was calculated and compared with the applied stress, showing that the strengthening factor increased with increasing temperature, indicating that the oxide nanoparticles have a good strengthening impact at high temperature. The dislocation density and character were also measured during tensile deformation. The dislocation density decreased with increasing of temperature due to the greater mobility of dislocation at high temperature. The dislocation character was determined by best-fit methods for different dislocation average contrasts with various levels of uncertainty. The results shows edge type dislocations dominate the plastic strain at room temperature (RT) and 300 C, while the screw type dislocations dominate at 600 C. The dominance of edge character in 9Cr F/M ODS steels at RT and 300 C is likely due to the pinning effect of nanoparticles for higher mobile edge dislocations when compared with screw dislocations, while the stronger screw type of dislocation structure at 600 C may be explained by the activated cross slip of screw segments.

Evaluation of the histological and mechanical features of tendon healing in a rabbit model with the use of second-harmonic-generation imaging and tensile testing.

Science.gov (United States)

Hase, E; Sato, K; Yonekura, D; Minamikawa, T; Takahashi, M; Yasui, T

2016-11-01

This study aimed to evaluate the histological and mechanical features of tendon healing in a rabbit model with second-harmonic-generation (SHG) imaging and tensile testing. A total of eight male Japanese white rabbits were used for this study. The flexor digitorum tendons in their right leg were sharply transected, and then were repaired by intratendinous stitching. At four weeks post-operatively, the rabbits were killed and the flexor digitorum tendons in both right and left legs were excised and used as specimens for tendon healing (n = 8) and control (n = 8), respectively. Each specimen was examined by SHG imaging, followed by tensile testing, and the results of the two testing modalities were assessed for correlation. While the SHG light intensity of the healing tendon samples was significantly lower than that of the uninjured tendon samples, 2D Fourier transform SHG images showed a clear difference in collagen fibre structure between the uninjured and the healing samples, and among the healing samples. The mean intensity of the SHG image showed a moderate correlation (R 2 = 0.37) with Young's modulus obtained from the tensile testing. Our results indicate that SHG microscopy may be a potential indicator of tendon healing.Cite this article: E. Hase, K. Sato, D. Yonekura, T. Minamikawa, M. Takahashi, T. Yasui. Evaluation of the histological and mechanical features of tendon healing in a rabbit model with the use of second-harmonic-generation imaging and tensile testing. Bone Joint Res 2016;5:577-585. DOI: 10.1302/2046-3758.511.BJR-2016-0162.R1. © 2016 Yasui et al.

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.

The development of a tensile-shear punch correlation for yield properties of model austenitic alloys

Energy Technology Data Exchange (ETDEWEB)

Hankin, G.L.; Faulkner, R.G. [Loughborough Univ. (United Kingdom); Hamilton, M.L.; Garner, F.A. [Pacific Northwest National Lab., Richland, WA (United States)

1997-08-01

The effective shear yield and maximum strengths of a set of neutron-irradiated, isotopically tailored austentic alloys were evaluated using the shear punch test. The dependence on composition and neutron dose showed the same trends as were observed in the corresponding miniature tensile specimen study conducted earlier. A single tensile-shear punch correlation was developed for the three alloys in which the maximum shear stress or Tresca criterion was successfully applied to predict the slope. The correlation will predict the tensile yield strength of the three different austenitic alloys tested to within {+-}53 MPa. The accuracy of the correlation improves with increasing material strength, to within {+-} MPa for predicting tensile yield strengths in the range of 400-800 MPa.

Optimization of tensile method and specimen geometry in modified ring tensile test

International Nuclear Information System (INIS)

Kitano, Koji; Fuketa, Toyoshi; Sasajima, Hideo; Uetsuka, Hiroshi

2001-03-01

Several techniques in ring tensile test are proposed in order to evaluate mechanical properties of cladding under hoop loading condition caused by pellet/cladding mechanical interaction (PCMI). In the modified techniques, variety of tensile methods and specimen geometry are being proposed in order to limit deformation within the gauge section. However, the tensile method and the specimen geometry were not determined in the modified techniques. In the present study, we have investigated the tensile method and the specimen geometry through finite element method (FEM) analysis of specimen deformation and tensile test on specimens with various gauge section geometries. In using two-piece tensile tooling, the mechanical properties under hoop loading condition can be correctly evaluated when deformation part (gauge section) is put on the top of a half-mandrel, and friction between the specimen and the half-mandrel is reduced with Teflon tape. In addition, we have shown the optimum specimen geometry for PWR 17 by 17 type cladding. (author)

The role of local stress perturbation on the simultaneous opening of orthogonal fractures

Science.gov (United States)

Boersma, Quinten; Hardebol, Nico; Barnhoorn, Auke; Bertotti, Giovanni; Drury, Martyn

2016-04-01

Orthogonal fracture networks (ladder-like networks) are arrangements that are commonly observed in outcrop studies. They form a particularly dense and well connected network which can play an important role in the effective permeability of tight hydrocarbon or geothermal reservoirs. One issue is the extent to which both the long systematic and smaller cross fractures can be simultaneously critically stressed under a given stress condition. Fractures in an orthogonal network form by opening mode-I displacements in which the main component is separation of the two fracture walls. This opening is driven by effective tensile stresses as the smallest principle stress acting perpendicular to the fracture wall, which accords with linear elastic fracture mechanics. What has been well recognized in previous field and modelling studies is how both the systematic fractures and perpendicular cross fractures require the minimum principle stress to act perpendicular to the fracture wall. Thus, these networks either require a rotation of the regional stress field or local perturbations in stress field. Using a mechanical finite element modelling software, a geological case of layer perpendicular systematic mode I opening fractures is generated. New in our study is that we not only address tensile stresses at the boundary, but also address models using pore fluid pressure. The local stress in between systematic fractures is then assessed in order to derive the probability and orientation of micro crack propagation using the theory of sub critical crack growth and Griffith's theory. Under effective tensile conditions, the results indicate that in between critically spaced systematic fractures, local effective tensile stresses flip. Therefore the orientation of the least principle stress will rotate 90°, hence an orthogonal fracture is more likely to form. Our new findings for models with pore fluid pressures instead of boundary tension show that the magnitude of effective tension

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.

Fatigue life of bovine meniscus under longitudinal and transverse tensile loading.

Science.gov (United States)

Creechley, Jaremy J; Krentz, Madison E; Lujan, Trevor J

2017-05-01

The knee meniscus is composed of a fibrous extracellular matrix that is subjected to large and repeated loads. Consequently, the meniscus is frequently torn, and a potential mechanism for failure is fatigue. The objective of this study was to measure the fatigue life of bovine meniscus when applying cyclic tensile loads either longitudinal or transverse to the principal fiber direction. Fatigue experiments consisted of cyclic loads to 60%, 70%, 80% or 90% of the predicted ultimate tensile strength until failure occurred or 20,000 cycles was reached. The fatigue data in each group was fit with a Weibull distribution to generate plots of stress level vs. cycles to failure (S-N curve). Results showed that loading transverse to the principal fiber direction gave a two-fold increase in failure strain, a three-fold increase in creep, and a nearly four-fold increase in cycles to failure (not significant), compared to loading longitudinal to the principal fiber direction. The S-N curves had strong negative correlations between the stress level and the mean cycles to failure for both loading directions, where the slope of the transverse S-N curve was 11% less than the longitudinal S-N curve (longitudinal: S=108-5.9ln(N); transverse: S=112-5.2ln(N)). Collectively, these results suggest that the non-fibrillar matrix is more resistant to fatigue failure than the collagen fibers. Results from this study are relevant to understanding the etiology of atraumatic radial and horizontal meniscal tears, and can be utilized by research groups that are working to develop meniscus implants with fatigue properties that mimic healthy tissue. Copyright © 2017 Elsevier Ltd. All rights reserved.

Influence of the quenching rate and step-wise cooling temperatures on microstructural and tensile properties of PER72 ® Ni-based superalloy

Directory of Open Access Journals (Sweden)

Le Baillif Paul

2014-01-01

Full Text Available The PER72® grade is used as a wrought engine turbine disk, which is a critical high temperature component. During the heat treatment process, residual stresses are generated during the quench, which may lead to irreversible damages on the workpiece. The aim of this study is to better understand the mechanisms involved in the residual stress generation. Therefore, the influence of quenching conditions on the high temperature tensile properties and the multi-scale microstructure evolutions are investigated after cooling. PER72® specimens are annealed above the solvus temperature, directly on the servo-hydraulic testing machine. Three quenching rates are used: 30 ∘C/min, 120 ∘C/min, and 300 ∘C/min. For each condition, the cooling is interrupted at 1000 ∘C, 850 ∘C, 600 ∘C and 20 ∘C to perform isothermal tensile test. Specimens are post-mortem analysed. On one hand the fracture surface is investigated using SEM. On the other hand the microstructure evolution was observed and quantified at different scales using SEM directly on the bulk or after the chemical extraction of precipitation. The precipitation size and volume fraction statistics, X-Ray diffraction for the crystallography and composition of the different phases are investigated. It was shown that the testing temperature does not significantly influence the γ′ distribution of particles. Conversely, the γ′ precipitation is strongly influenced by the cooling rate. Notably, the average size, the distance between particles as well as the number density of γ′ precipitates are significantly modified by the cooling rate. Changes in tensile properties are related to microstructural.

Effects of Temperature and Strain Rate on Tensile Deformation Behavior of 9Cr-0.5Mo-1.8W-VNb Ferritic Heat-Resistant Steel

Science.gov (United States)

Guo, Xiaofeng; Weng, Xiaoxiang; Jiang, Yong; Gong, Jianming

2017-09-01

A series of uniaxial tensile tests were carried out at different strain rate and different temperatures to investigate the effects of temperature and strain rate on tensile deformation behavior of P92 steel. In the temperature range of 30-700 °C, the variations of flow stress, average work-hardening rate, tensile strength and ductility with temperature all show three temperature regimes. At intermediate temperature, the material exhibited the serrated flow behavior, the peak in flow stress, the maximum in average work-hardening rate, and the abnormal variations in tensile strength and ductility indicates the occurrence of DSA, whereas the sharp decrease in flow stress, average work-hardening rate as well as strength values, and the remarkable increase in ductility values with increasing temperature from 450 to 700 °C imply that dynamic recovery plays a dominant role in this regime. Additionally, for the temperature ranging from 550 to 650 °C, a significant decrease in flow stress values is observed with decreasing in strain rate. This phenomenon suggests the strain rate has a strong influence on flow stress. Based on the experimental results above, an Arrhenius-type constitutive equation is proposed to predict the flow stress.

High-Tensile Strength Tape Versus High-Tensile Strength Suture: A Biomechanical Study.

Science.gov (United States)

Gnandt, Ryan J; Smith, Jennifer L; Nguyen-Ta, Kim; McDonald, Lucas; LeClere, Lance E

2016-02-01

To determine which suture design, high-tensile strength tape or high-tensile strength suture, performed better at securing human tissue across 4 selected suture techniques commonly used in tendinous repair, by comparing the total load at failure measured during a fixed-rate longitudinal single load to failure using a biomechanical testing machine. Matched sets of tendon specimens with bony attachments were dissected from 15 human cadaveric lower extremities in a manner allowing for direct comparison testing. With the use of selected techniques (simple Mason-Allen in the patellar tendon specimens, whip stitch in the quadriceps tendon specimens, and Krackow stitch in the Achilles tendon specimens), 1 sample of each set was sutured with a 2-mm braided, nonabsorbable, high-tensile strength tape and the other with a No. 2 braided, nonabsorbable, high-tensile strength suture. A total of 120 specimens were tested. Each model was loaded to failure at a fixed longitudinal traction rate of 100 mm/min. The maximum load and failure method were recorded. In the whip stitch and the Krackow-stitch models, the high-tensile strength tape had a significantly greater mean load at failure with a difference of 181 N (P = .001) and 94 N (P = .015) respectively. No significant difference was found in the Mason-Allen and simple stitch models. Pull-through remained the most common method of failure at an overall rate of 56.7% (suture = 55%; tape = 58.3%). In biomechanical testing during a single load to failure, high-tensile strength tape performs more favorably than high-tensile strength suture, with a greater mean load to failure, in both the whip- and Krackow-stitch models. Although suture pull-through remains the most common method of failure, high-tensile strength tape requires a significantly greater load to pull-through in a whip-stitch and Krakow-stitch model. The biomechanical data obtained in the current study indicates that high-tensile strength tape may provide better repair

Twinning and martensitic transformations in nickel-enriched 304 austenitic steel during tensile and indentation deformations

Energy Technology Data Exchange (ETDEWEB)

Gussev, M.N., E-mail: gussevmn@ornl.gov; Busby, J.T.; Byun, T.S.; Parish, C.M.

2013-12-20

Twinning and martensitic transformation have been investigated in nickel-enriched AISI 304 stainless steel subjected to tensile and indentation deformation. Using electron backscatter diffraction (EBSD), the morphology of α- and ε-martensite and the effect of grain orientation to load axis on phase and structure transformations were analyzed in detail. It was found that the twinning occurred less frequently under indentation than under tension; also, twinning was not observed in [001] and [101] grains. In tensile tests, the martensite particles preferably formed at the deformation twins, intersections between twins, or at the twin-grain boundary intersections. Conversely, martensite formation in the indentation tests was not closely associated with twinning; instead, the majority of martensite was concentrated in the dense colonies near grain boundaries. Martensitic transformation seemed to be obstructed in the [001] grains in both tensile and indentation test cases. Under a tensile stress of 800 MPa, both α- and ε-martensites were found in the microstructure, but at 1100 MPa only α-martensite presented in the specimen. Under indentation, α- and ε-martensite were observed in the material regardless of the stress level.

Non-linearities in tensile creep of concrete at early age

DEFF Research Database (Denmark)

Hauggaard-Nielsen, Anders Boe; Damkilde, Lars

1997-01-01

A meterial model for creep is proposed which takes into consideration some of the couplings in early age concrete. The model is in incremental form and reflect the hydration process where new layers of cement gel are formed in a stress free state. In the present context attention is on non......-linear creep at high stress levels. The parameteres in the model develop in time as a result of hydration. The creep model has been used to analyse the tensile experiments at different stress levels carried out in the HETEK project. The tests were made on dogbone shaped specimen and the test procedure...

Effect of elastic and plastic tensile mechanical loading on the magnetic properties of NGO electrical steel

Energy Technology Data Exchange (ETDEWEB)

Leuning, N., E-mail: nora.leuning@iem.rwth-aachen.de [Institute of Electrical Machines, RWTH Aachen University, D-52062 Aachen (Germany); Steentjes, S. [Institute of Electrical Machines, RWTH Aachen University, D-52062 Aachen (Germany); Schulte, M.; Bleck, W. [Steel Institute, RWTH Aachen University, D-52072 Aachen (Germany); Hameyer, K. [Institute of Electrical Machines, RWTH Aachen University, D-52062 Aachen (Germany)

2016-11-01

The magnetic properties of non-grain-oriented (NGO) electrical steels are highly susceptible to mechanical stresses, i.e., residual, external or thermal ones. For rotating electrical machines, mechanical stresses are inevitable and originate from different sources, e.g., material processing, machine manufacturing and operating conditions. The efficiency and specific losses are largely altered by different mechanical stress states. In this paper the effect of tensile stresses and plastic deformations on the magnetic properties of a 2.9 wt% Si electrical steel are studied. Particular attention is paid to the effect of magnetic anisotropy, i.e., the influence of the direction of applied mechanical stress with respect to the rolling direction. Due to mechanical stress, the induced anisotropy has to be evaluated as it is related to the stress-dependent magnetostriction constant and the grain alignment. - Highlights: • A detailed look at magnetic anisotropy of FeSi NGO electrical steel. • Study of magnetic behavior under elastic as well as plastic tensile stresses. • Correlation of magnetic behavior with microscopic deformation mechanisms. • Discussion of detrimental and beneficial effects of external stresses. • Loss separation at different polarizations and frequencies under increasing stress.

Effect of elastic and plastic tensile mechanical loading on the magnetic properties of NGO electrical steel

International Nuclear Information System (INIS)

Leuning, N.; Steentjes, S.; Schulte, M.; Bleck, W.; Hameyer, K.

2016-01-01

The magnetic properties of non-grain-oriented (NGO) electrical steels are highly susceptible to mechanical stresses, i.e., residual, external or thermal ones. For rotating electrical machines, mechanical stresses are inevitable and originate from different sources, e.g., material processing, machine manufacturing and operating conditions. The efficiency and specific losses are largely altered by different mechanical stress states. In this paper the effect of tensile stresses and plastic deformations on the magnetic properties of a 2.9 wt% Si electrical steel are studied. Particular attention is paid to the effect of magnetic anisotropy, i.e., the influence of the direction of applied mechanical stress with respect to the rolling direction. Due to mechanical stress, the induced anisotropy has to be evaluated as it is related to the stress-dependent magnetostriction constant and the grain alignment. - Highlights: • A detailed look at magnetic anisotropy of FeSi NGO electrical steel. • Study of magnetic behavior under elastic as well as plastic tensile stresses. • Correlation of magnetic behavior with microscopic deformation mechanisms. • Discussion of detrimental and beneficial effects of external stresses. • Loss separation at different polarizations and frequencies under increasing stress.

Stress generation by myosin minifilaments in actin bundles

International Nuclear Information System (INIS)

Dasanayake, Nilushi L; Carlsson, Anders E

2013-01-01

Forces and stresses generated by the action of myosin minifilaments are analyzed in idealized computer-generated actin bundles, and compared to results for isotropic actin networks. The bundles are generated as random collections of actin filaments in two dimensions with constrained orientations, crosslinked and attached to two fixed walls. Myosin minifilaments are placed on actin filament pairs and allowed to move and deform the network so that it exerts forces on the walls. The vast majority of simulation runs end with contractile minifilament stress, because minifilaments rotate into energetically stable contractile configurations. This process is aided by the bending and stretching of actin filaments, which accomodate minifilament rotation. Stresses for bundles are greater than those for isotropic networks, and antiparallel filaments generate more tension than parallel filaments. The forces transmitted by the actin network to the walls of the simulation cell often exceed the tension in the minifilament itself. (paper)

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

Science.gov (United States)

Ren, Shangkun; Ren, Xianzhi

2018-03-01

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

Negative life events and symptoms of depression and anxiety: stress causation and/or stress generation

OpenAIRE

Phillips, Anna C.; Carroll, Douglas; Der, Geoffrey

2015-01-01

Background and Objectives: Stressful life events are known to contribute to development of depression, however, it is possible this link is bi-directional. The present study examined whether such stress generation effects are greater than the effects of stressful life events on depression, and whether stress generation is also evident with anxiety. Design: Participants were two large age cohorts (N = 732 aged 44 years; N = 705 aged 63 years) from the West of Scotland Twenty-07 study. Methods:...

X-ray study of residual stress distribution of ground ceramics

International Nuclear Information System (INIS)

Sakaida, Yoshihisa; Tanaka, Keisuke; Ikuhara, Yuichi; Suzuki, Kenzi.

1997-01-01

The residual stress distribution of ground ceramics was determined from the eigen strain existing in the ground surface. The eigen strain of ground ceramics was tensile, and exponentially decreased with the distance from the surface. The residual stress distribution is given as a superposition of an exponential function of compression and a linear function. It is found that the actual residual stress distribution can be approximated by a compressive exponential function because the magnitude of tensile residual stress is negligibly small compared to the compressive residual stress. In the experiments, the diffraction angle was measured on ground silicon nitride for a wide range of sin 2 ψ using the glancing incidence X-ray diffraction technique. A strong nonlinearity was found in the 2θ-sin 2 ψ diagram at very high ψ-angles. From the analysis of nonlinearity, the residual stress distribution was determined. The residual stress distribution of silicon nitride coincided with the distribution calculated from the eigen strain distribution. Transmission electron microscopy was used to clarify the origin of generation of the residual stress. Both strain contrasts and microcracks were observed below the ground surface ; straight dislocations were also observed within silicon nitride grains near the ground surface. (author)

Normal personality traits, rumination and stress generation among early adolescent girls

OpenAIRE

Stroud, Catherine B.; Sosoo, Effua E.; Wilson, Sylia

2015-01-01

This study examined associations between personality and stress generation. Expanding upon prior work, we examined (a) the role of Positive Emotionality (PE), Negative Emotionality (NE), and Constraint (CON), and their lower-order facets, as predictors of acute and chronic interpersonal stress generation; (b) whether personality moderated effects of rumination on stress generation; and (c) whether personality increased exposure to independent (uncontrollable) stress. These questions were exam...

FEM Modeling of In-Plane Stress Distribution in Thick Brittle Coatings/Films on Ductile Substrates Subjected to Tensile Stress to Determine Interfacial Strength

Directory of Open Access Journals (Sweden)

Kaishi Wang

2018-03-01

Full Text Available The ceramic-metal interface is present in various material structures and devices that are vulnerable to failures, like cracking, which are typically due to their incompatible properties, e.g., thermal expansion mismatch. In failure of these multilayer systems, interfacial shear strength is a good measure of the robustness of interfaces, especially for planar films. There is a widely-used shear lag model and method by Agrawal and Raj to analyse and measure the interfacial shear strength of thin brittle film on ductile substrates. The use of this classical model for a type of polymer derived ceramic coatings (thickness ~18 μm on steel substrate leads to high values of interfacial shear strength. Here, we present finite element simulations for such a coating system when it is subjected to in-plane tension. Results show that the in-plane stresses in the coating are non-uniform, i.e., varying across the thickness of the film. Therefore, they do not meet one of the basic assumptions of the classical model: uniform in-plane stress. Furthermore, effects of three significant parameters, film thickness, crack spacing, and Young’s modulus, on the in-plane stress distribution have also been investigated. ‘Thickness-averaged In-plane Stress’ (TIS, a new failure criterion, is proposed for estimating the interfacial shear strength, which leads to a more realistic estimation of the tensile strength and interfacial shear strength of thick brittle films/coatings on ductile substrates.

Tensile and superelastic fatigue characterization of NiTi shape memory cables

Science.gov (United States)

Sherif, Muhammad M.; Ozbulut, Osman E.

2018-01-01

This paper discusses the tensile response and functional fatigue characteristics of a NiTi shape memory alloy (SMA) cable with an outer diameter of 5.5 mm. The cable composed of multiple strands arranged as one inner core and two outer layers. The results of the tensile tests revealed that the SMA cable exhibits good superelastic behavior up to 10% strain. Fatigue characteristics were investigated under strain amplitudes ranging from 3% to 7% and a minimum of 2500 loading cycles. The evolutions of maximum tensile stress, residual strains, energy dissipation, and equivalent viscous damping under a number of loading cycles were analyzed. The fracture surface of a specimen subjected to 5000 loading cycles and 7% strain was discussed. Functional fatigue test results indicated a very high superelastic fatigue life cycle for the tested NiTi SMA cable.

Influence of Simulated Acid Rain Corrosion on the Uniaxial Tensile Mechanical Properties of Concrete

Directory of Open Access Journals (Sweden)

Ying-zi Zhang

2012-01-01

Full Text Available An experimental study on the uniaxial tensile property of concrete exposed to the acid rain environment was carried out. Acid rain with pH level of 1.0 was deposed by the mixture of sulfate and nitric acid solution in the laboratory. Dumbbell-shaped concrete specimens were immersed in the simulated acid rain completely. After being exposed to the deposed mixture for a certain period, uniaxial tensile test was performed on the concrete specimens. The results indicate that elastic modulus, tensile strength, and peak strain have a slight increase at the initial corrosion stage, and with the extension of corrosion process, elastic modulus and tensile strength decrease gradually, while the peak strain still increases. It is found that the compressive strength is more sensitive than the tensile strength in aggressive environment. Based on the experimental results, an equation was proposed to describe the ascending branch of the stress-strain curve of the concrete corroded by acid rain.

ANALYSIS OF THE TENSILE STRENGTH OF 100% WOOL YARN FROM DIFFERENT CLIMATIC AREAS

Directory of Open Access Journals (Sweden)

OANA Dorina

2017-05-01

Full Text Available One of the basic conditions required of yarns is to have enough tensile strength to allow them to be turned into textiles and also to give the final product durability. During processing, threads are subjected to various unavoidable forms of mechanical stress, simple or compounded, but the amount of stress can be kept under control by adjusting the corresponding operating parameters (speed, gauges, push force on the cylinders of the rolling train etc.. The values of the operating parameters of the spinning operation are set so as to obtain uniform products in large scale production, but also to ensure the preservation of the properties of the fibers and yarns, for further processing. To this end we analyzed the tensile strength of three batches of 100% wool yarn meant for knitting, from three different geo-climatic areas. These are fine woolen yarn of 25 tex and torque of 620 twists/meter. The study of the tensile strength was carried out using a Uster R Tensojet 4 (UTj4 tension meter, analyzing ten samples of 500 m from each batch. The statistical and mathematical processing of the data obtained after analyzing the samples indicated that the yarns from South Africa have better tensile strength and a lower mechanical impedance variation coefficient than yarns from Asia and England.

Effects of short fiber reinforcement and mean stress on tensile fatigue strength characteristics of polyethersulfone; Tansen`i kyoka porieterusaruhon no hippari hiro tokusei ni oyobosu heikin oryoku no eikyo

Energy Technology Data Exchange (ETDEWEB)

Furue, H.; Nonaka, K. [Mechanical Engineering Lab., Tsukuba, Ibaraki (Japan)

1996-01-15

Thermoplastics are often reinforced with short fibers with aims of improvement of their strengths, rigidities and hardness or maintenance of their dimensional stabilities. Such short fiber reinforced plastic materials have more expectation for high performance plastics. Authors already examined of some effects of reinforced fiber and of orientation in injection molding on flexural fatigue characteristics of the injection-molded high performance thermoplastic materials. However, the examination of short fiber reinforced effects on fatigue strength characteristics was not always sufficient. In this study, in order to obtain a guiding principle for fatigue resistant design of the short fiber reinforced injection molding materials, polyethersulfones (PES) was examined on its tensile fatigue strength and an effect of short fiber reinforcement for improvement of its fundamental dynamic properties on its fatigue characteristics. Especially, its fatigue life characteristics was elucidated mainly on relationship of mean stress, stress amplitude and number of repeating fracture in tensile fatigue behavior. 10 refs., 15 figs., 2 tabs.

Ethylene propylene cable degradation during LOCA research tests: tensile properties at the completion of accelerated aging

International Nuclear Information System (INIS)

Bustard, L.D.

1982-05-01

Six ethylene-propylene rubber (EPR) insulation materials were aged at elevated temperature and radiation stress exposures common in cable LOCA qualification tests. Material samples were subjected to various simultaneous and sequential aging simulations in preparation for accident environmental exposures. Tensile properties subsequent to the aging exposure sequences are reported. The tensile properties of some, but not all, specimens were sensitive to the order of radiation and elevated temperature stress exposure. Other specimens showed more severe degradation when simultaneously exposed to radiation and elevated temperature as opposed to the sequential exposure to the same stresses. Results illustrate the difficulty in defining a single test procedure for nuclear safety-related qualification of EPR elastomers. A common worst-case sequential aging sequence could not be identified

The development of a tensile-shear punch correlation for yield properties of model austenitic alloys

International Nuclear Information System (INIS)

Hankin, G.L.; Faulkner, R.G.; Hamilton, M.L.; Garner, F.A.

1997-01-01

The effective shear yield and maximum strengths of a set of neutron-irradiated, isotopically tailored austentic alloys were evaluated using the shear punch test. The dependence on composition and neutron dose showed the same trends as were observed in the corresponding miniature tensile specimen study conducted earlier. A single tensile-shear punch correlation was developed for the three alloys in which the maximum shear stress or Tresca criterion was successfully applied to predict the slope. The correlation will predict the tensile yield strength of the three different austenitic alloys tested to within ±53 MPa. The accuracy of the correlation improves with increasing material strength, to within ± MPa for predicting tensile yield strengths in the range of 400-800 MPa

Investigations into the tensile failure of doubly-convex cylindrical tablets under diametral loading using finite element methodology.

Science.gov (United States)

Podczeck, Fridrun; Drake, Kevin R; Newton, J Michael

2013-09-15

In the literature various solutions exist for the calculation of the diametral compression tensile strength of doubly-convex tablets and each approach is based on experimental data obtained from single materials (gypsum, microcrystalline cellulose) only. The solutions are represented by complex equations and further differ for elastic and elasto-plastic behaviour of the compacts. The aim of this work was to develop a general equation that is applicable independently of deformation behaviour and which is based on simple tablet dimensions such as diameter and total tablet thickness only. With the help of 3D-FEM analysis the tensile failure stress of doubly-convex tables with central cylinder to total tablet thickness ratios W/D between 0.06 and 0.50 and face-curvature ratios D/R between 0.25 and 1.85 were evaluated. Both elastic and elasto-plastic deformation behaviour were considered. The results of 80 individual simulations were combined and showed that the tensile failure stress σt of doubly-convex tablets can be calculated from σt=(2P/πDW)(W/T)=2P/πDT with P being the failure load, D the diameter, W the central cylinder thickness, and T the total thickness of the tablet. This equation converts into the standard Brazilian equation (σt=2P/πDW) when W equals T, i.e. is equally valid for flat cylindrical tablets. In practice, the use of this new equation removes the need for complex measurements of tablet dimensions, because it only requires values for diameter and total tablet thickness. It also allows setting of standards for the mechanical strength of doubly-convex tablets. The new equation holds both for elastic and elasto-plastic deformation behaviour of the tablets under load. It is valid for all combinations of W/D-ratios between 0.06 and 0.50 with D/R-ratios between 0.00 and 1.85 except for W/D=0.50 in combination with D/R-ratios of 1.85 and 1.43 and for W/D-ratios of 0.40 and 0.30 in combination with D/R=1.85. FEM-analysis indicated a tendency to

A study on fatigue crack growth behavior subjected to a single tensile overload

International Nuclear Information System (INIS)

Lee, S.Y.; Liaw, P.K.; Choo, H.; Rogge, R.B.

2011-01-01

Neutron diffraction and electric potential experiments were carried out to investigate the growth behavior of a fatigue crack subjected to a single tensile overload. The specific objectives were to (i) probe the crack tip deformation and fracture behaviors under applied loads; (ii) examine the overload-induced transient crack growth micromechanism; (iii) validate the effective stress intensity factor range based on the crack closure approach as the fatigue crack tip driving force; and (iv) establish a quantitative relationship between the crack tip driving force and crack growth behavior. Immediately after a single tensile overload was introduced and then unloaded, the crack tip became blunt and enlarged compressive residual stresses in both magnitude and zone size were observed around the crack tip. The results show that the combined contributions of the overload-induced enlarged compressive residual stresses and crack tip blunting with secondary cracks are responsible for the observed changes in the crack opening load and the resultant post-overload transient crack growth behavior.

Mini-tensile load cell design for diffractometry study of 2d nanostructures

Czech Academy of Sciences Publication Activity Database

Hošek, J.; Frank, Otakar; Diez, V.

2014-01-01

Roč. 2014, č. 45 (2014), s. 89-93 ISSN 1584-5982 R&D Projects: GA ČR GA14-15357S Institutional support: RVO:61388955 Keywords : Tensile stress * measurement * mini sample Subject RIV: CF - Physical ; Theoretical Chemistry

Countermeasures to stress corrosion cracking by stress improvement

International Nuclear Information System (INIS)

Umemoto, Tadahiro

1983-01-01

One of the main factors of the grain boundary stress corrosion cracking occurred in the austenitic stainless steel pipes for reactor cooling system was the tensile residual stress due to welding, and a number of methods have been proposed to reduce the residual stress or to change it to compressive stress. In this paper, on the method of improving residual stress by high frequency heating, which has been applied most frequently, the principle, important parameters and the range of application are explained. Also the other methods of stress improvement are outlined, and the merit and demerit of respective methods are discussed. Austenitic stainless steel and high nickel alloys have good corrosion resistance, high toughness and good weldability, accordingly they have been used for reactor cooling system, but stress corrosion cracking was discovered in both BWRs and PWRs. It occurs when the sensitization of materials, tensile stress and the dissolved oxygen in high temperature water exceed certain levels simultaneously. The importance of the residual stress due to welding, induction heating stress improvement, and other methods such as heat sink welding, last pass heat sink welding, back lay welding and TIG torch heating stress improvement are described. (Kako, I.)

Laser quench hardening of steel: Effects of superimposed elastic pre-stress on the hardness and residual stress distribution

Science.gov (United States)

Meserve, Justin

Cold drawn AISI 4140 beams were LASER surface hardened with a 2 kW CO2 LASER. Specimens were treated in the free state and while restrained in a bending fixture inducing surface tensile stresses of 94 and 230 MPa. Knoop hardness indentation was used to evaluate the through thickness hardness distribution, and a layer removal methodology was used to evaluate the residual stress distribution. Results showed the maximum surface hardness attained was not affected by pre-stress during hardening, and ranged from 513 to 676 kg/mm2. The depth of effective hardening varied at different magnitudes of pre-stress, but did not vary proportionately to the pre-stress. The surface residual stress, coinciding with the maximum compressive residual stress, increased as pre-stress was increased, from 1040 MPa for the nominally treated specimens to 1270 MPa for specimens pre-stressed to 230 MPa. The maximum tensile residual stress observed in the specimens decreased from 1060 MPa in the nominally treated specimens to 760 MPa for specimens pre-stressed to 230 MPa. Similarly, thickness of the compressive residual stress region increased and the depth at which maximum tensile residual stress occurred increased as the pre-stress during treatment was increased Overall, application of tensile elastic pre-stress during LASER hardening is beneficial to the development of compressive residual stress in AISI 4140, with minimal impact to the hardness attained from the treatment. The newly developed approach for LASER hardening may support efforts to increase both the wear and fatigue resistance of parts made from hardenable steels.

Static tensile deformation behavior of a lean duplex stainless steel studied by in situ neutron diffraction and synchrotron radiation white x-rays

International Nuclear Information System (INIS)

Tsuchida, Noriyuki; Kawahata, Taiji; Ishimaru, Eiichiro; Takahashi, Akihiko; Suzuki, Hiroshi; Shobu, Takahisa

2013-01-01

To investigate the tensile deformation behavior of a lean duplex stainless steel (S32101) from the viewpoints of plastic deformability among phases or grains, we performed static tensile tests, in situ neutron diffraction, and white x-ray diffraction experiments at room temperature. In the static tensile tests, the S32101 steel displayed a larger uniform elongation and a better tensile strength-uniform elongation balance than a commercial SUS329J4L duplex stainless steel. A larger uniform elongation of S32101 is associated with the macroscopic work hardening behavior that a work hardening rate higher than the flow stress can maintain up until high true strains. From the experimental results of synchrotron radiation white x-ray diffraction experiments, the hard phase of S32101 was changed from the ferrite (α) phase to austenite (γ) one during tensile deformation. This led to a larger stress partitioning between the phases at the latter stage of deformation. From the experimental results of in situ neutron diffraction, it was found that the stress partitioning of the γ phase in the S32101 was the largest among the present results. Therefore, the larger work hardening rate of S32101 can be explained by the large stress partitioning of the γ phase, that between γ and α phases and γ volume fraction. (author)

Stability of machining induced residual stresses in Inconel 718 under quasi-static loading at room temperature

International Nuclear Information System (INIS)

Madariaga, A.; Esnaola, J.A.; Arrazola, P.J.; Ruiz-Hervias, J.; Muñoz, P.; Ostolaza, K.

2015-01-01

Tensile residual stresses are very often generated on the surface when machining nickel alloys. In order to determine their influence on the final mechanical behaviour of the component residual stress stability should be considered. In the present work the evolution of surface residual stresses induced by machining in Inconel 718 under static loading at room temperature was studied experimentally and numerically. An Inconel 718 disc was face turned employing industrial working conditions and specimens for tensile tests were extracted from the disc. Surface residual stresses were measured by X-ray diffraction for initial state and after applying different loads over the material's yield stress. Then, a finite element model based on the surface–core approach was fitted to experimental results and the study was extended to analyse the influence of load level, degree of work-hardening and initial surface conditions. For the studied case, initial tensile surface residual stress (776 MPa) became even more tensile when applying loads higher than the material yield stress, but a shift was observed at the highest applied load (1350 MPa) and initial residual stress was relaxed about 170 MPa. This particular behaviour is associated to the modified stress–strain properties of the machined affected surface layer which was strongly work-hardened. Moreover, if the work-hardened properties are not considered in the finite element model results differ substantially from experiments. Surface residual stress stability also depends on the initial surface residual stress, but the degree of work-hardening induced by the machining process must be considered as well. If the difference between the yield stress of the surface and the yield stress of the core is lower than the initial surface residual stress, the surface begins yielding first and consequently the surface residual stress is decreased. In contrast, if the difference between the yield stress of the surface and the

Stability of machining induced residual stresses in Inconel 718 under quasi-static loading at room temperature

Energy Technology Data Exchange (ETDEWEB)

Madariaga, A., E-mail: amadariaga@mondragon.edu [Mechanical and Industrial Production Department, Faculty of Engineering, Mondragon Unibertsitatea, Loramendi 4, Mondragon 20500 Gipuzkoa (Spain); Esnaola, J.A.; Arrazola, P.J. [Mechanical and Industrial Production Department, Faculty of Engineering, Mondragon Unibertsitatea, Loramendi 4, Mondragon 20500 Gipuzkoa (Spain); Ruiz-Hervias, J.; Muñoz, P. [Departamento Ciencia de Materiales, ETSI Caminos, Universidad Politécnica de Madrid, c/Profesor Aranguren s/n, Madrid 28040 (Spain); Ostolaza, K. [Materials and Processes Technology Department, ITP S.A., Parque Tecnológico, Edificio 300, 48170 Zamudio (Spain)

2015-01-03

Tensile residual stresses are very often generated on the surface when machining nickel alloys. In order to determine their influence on the final mechanical behaviour of the component residual stress stability should be considered. In the present work the evolution of surface residual stresses induced by machining in Inconel 718 under static loading at room temperature was studied experimentally and numerically. An Inconel 718 disc was face turned employing industrial working conditions and specimens for tensile tests were extracted from the disc. Surface residual stresses were measured by X-ray diffraction for initial state and after applying different loads over the material's yield stress. Then, a finite element model based on the surface–core approach was fitted to experimental results and the study was extended to analyse the influence of load level, degree of work-hardening and initial surface conditions. For the studied case, initial tensile surface residual stress (776 MPa) became even more tensile when applying loads higher than the material yield stress, but a shift was observed at the highest applied load (1350 MPa) and initial residual stress was relaxed about 170 MPa. This particular behaviour is associated to the modified stress–strain properties of the machined affected surface layer which was strongly work-hardened. Moreover, if the work-hardened properties are not considered in the finite element model results differ substantially from experiments. Surface residual stress stability also depends on the initial surface residual stress, but the degree of work-hardening induced by the machining process must be considered as well. If the difference between the yield stress of the surface and the yield stress of the core is lower than the initial surface residual stress, the surface begins yielding first and consequently the surface residual stress is decreased. In contrast, if the difference between the yield stress of the surface and the

A longitudinal examination of stress generation in depressive and anxiety disorders.

Science.gov (United States)

Uliaszek, Amanda A; Zinbarg, Richard E; Mineka, Susan; Craske, Michelle G; Griffith, James W; Sutton, Jonathan M; Epstein, Alyssa; Hammen, Constance

2012-02-01

The current study compared two competing theories of the stress generation model of depression (stress causation vs. stress continuation) using interview-based measures of episodic life stress, as well as interpersonal and noninterpersonal chronic life stress. We also expanded on past research by examining anxiety disorders as well as depressive disorders. In addition, we examined the role of neuroticism and extraversion in these relationships. Participants were 627 adolescents enrolled in a two-site, longitudinal study of risk factors for depressive and anxiety disorders. Baseline and follow-up assessments were approximately one year apart. Results supported the stress causation theory for episodic stress generation for anxiety disorders, with neuroticism partially accounting for this relationship. The stress causation theory was also supported for depression, but only for more moderate to severe stressors; neuroticism partially accounted for this relationship as well. Finally, we found evidence for interpersonal and noninterpersonal chronic life stress continuation in both depressive and anxiety disorders. The present findings have implications regarding the specificity of the stress generation model to depressive disorders, as well as variables involved in the stress generation process. PsycINFO Database Record (c) 2012 APA, all rights reserved.

Interface waves propagating along tensile fractures in dolomite

International Nuclear Information System (INIS)

Roy, S.; Pyrak-Nolte, L.J.

1995-01-01

Elastic interface waves have been observed in induced tensile fractures in dolomite rock cores. Multiscaling wavelet analysis distinguishes the interface wave from bulk shear waves, quantifies the interface wave spectral content, and determines the arrival time of peak energy. The dominant seismic energy is concentrated in the slow interface wave, with little or no detectable energy in the fast wave. As stress across the fracture increases, the slow interface wave velocity increases, and the frequency of the spectral peak shifts to higher frequencies. The shear dynamic specific stiffness of the fracture was calculated from the peak energy arrival time as a function of stress. 13 refs., 5 figs., 1 tab

High strain rate tensile properties of annealed 2 1/4 Cr--1 Mo steel

International Nuclear Information System (INIS)

Klueh, R.L.; Oakes, R.E. Jr.

1975-01-01

The high strain rate tensile properties of annealed 2 1 / 4 Cr-1 Mo steel were determined and the tensile behavior from 25 to 566 0 C and strain rates of 2.67 x 10 -6 to 144/s were described. Above 0.1/s at 25 0 C, both the yield stress and the ultimate tensile strength increased rapidly with increasing strain rate. As the temperature was increased, a dynamic strain aging peak appeared in the ultimate tensile strength-temperature curves. The peak height was a maximum at about 350 0 C and 2.67 x 10 -6 /s. With increasing strain rate, a peak of decreased height occurred at progressively higher temperatures. The major effect of strain rate on ductility occurred at elevated temperatures, where a decrease in strain rate caused an increase in total elongation and reduction in area

Effects of overload on the threshold stress intensity factor for SCC

International Nuclear Information System (INIS)

Takahashi, Koji; Ando, Kotoji; Miyazaki, Yuji; Hashikura, Yasuaki

2009-01-01

The effects of overload on the threshold stress intensity factor for stress corrosion crack (K ISCC ) of stainless steel were studied. Tensile overload was applied to a wedge opening loaded (WOL) specimen of SUS316. Then, SCC tests were carried out to determine the resultant K ISCC . As a result, the apparent value of K ISCC increases as increasing a stress intensity factor by tensile overload (K OV ). The effects of tensile overload on K ISCC and the threshold stress intensity factor range for fatigue (ΔK th ) were compared. It was found that the effects of tensile overload on K ISCC were larger than that on ΔK th . (author)

Influence of disinfectant solutions on the tensile bond strength of a fourth generation dentin bonding agent

Directory of Open Access Journals (Sweden)

BOCANGEL Jorge Saldivar

2000-01-01

Full Text Available The purpose of the present study was to evaluate the influence of different disinfectant solutions on the tensile bond strength of a fourth generation dentin bonding agent. Forty non carious human molars were selected. Teeth were embedded in acrylic resin and ground until the exposure of a flat superficial dentin surface. Teeth were randomly divided in 4 groups and treated as follows: Group 1 - 2.5% NaOCl for 40 seconds; Group 2 - 2% chlorhexidine for 40 seconds; Group 3 - 1.23% acidulated fluoride for 4 minutes; and Group 4 - control (without disinfectant solution. Following treatments, Scotchbond Multipurpose Plus® (3M was used according to the manufacturer's instructions. After that, the test specimens were built with composite resin (Z100®-3M, using a standard Teflon matrix. The specimens were stored in distilled water for 24 hours at a temperature of 37ºC. The tensile strength test was performed using a Mini Instrom testing machine. The mean values obtained for each group, in MPa, were: Group 1 - 7.37 (± 2.51; Group 2 - 11.25 (± 4.65; Group 3 - 9.80 (± 3.11; and Group 4 - 10.96 (± 3.37. The results were submitted to statistical analysis using the ANOVA test, and no statistical significant differences among the groups were found. It can be concluded that the different disinfectant substances used in this research do not adversely affect dentin adhesion.

Characterization and modeling of tensile behavior of ceramic woven fabric composites

Science.gov (United States)

Kuo, Wen-Shyong; Chen, Wennei Y.; Parvizi-Majidi, Azar; Chou, Tsu-Wei

1991-01-01

This paper examines the tensile behavior of SiC/SiC fabric composites. In the characterization effort, the stress-strain relation and damage evolution are studied with a series of loading and unloading tensile test experiments. The stress-strain relation is linear in response to the initial loading and becomes nonlinear when loading exceeds the proportional limit. Transverse cracking has been observed to be a dominant damage mode governing the nonlinear deformation. The damage is initiated at the inter-tow pores where fiber yarns cross over each other. In the modeling work, the analysis is based upon a fiber bundle model, in which fiber undulation in the warp and fill directions and gaps among fiber yarns have been taken into account. Two limiting cases of fabric stacking arrangements are studied. Closed form solutions are obtained for the composite stiffness and Poisson's ratio. Transverse cracking in the composite is discussed by applying a constant failure strain criterion.

The investigation of stress in freestanding GaN crystals grown from Si substrates by HVPE.

Science.gov (United States)

Lee, Moonsang; Mikulik, Dmitry; Yang, Mino; Park, Sungsoo

2017-08-17

We investigate the stress evolution of 400 µm-thick freestanding GaN crystals grown from Si substrates by hydride vapour phase epitaxy (HVPE) and the in situ removal of Si substrates. The stress generated in growing GaN can be tuned by varying the thickness of the MOCVD AlGaN/AlN buffer layers. Micro Raman analysis shows the presence of slight tensile stress in the freestanding GaN crystals and no stress accumulation in HVPE GaN layers during the growth. Additionally, it is demonstrated that the residual tensile stress in HVPE GaN is caused only by elastic stress arising from the crystal quality difference between Ga- and N-face GaN. TEM analysis revealed that the dislocations in freestanding GaN crystals have high inclination angles that are attributed to the stress relaxation of the crystals. We believe that the understanding and characterization on the structural properties of the freestanding GaN crystals will help us to use these crystals for high-performance opto-electronic devices.

Reynolds stress and shear flow generation

DEFF Research Database (Denmark)

Korsholm, Søren Bang; Michelsen, Poul; Naulin, V.

2001-01-01

The so-called Reynolds stress may give a measure of the self-consistent flow generation in turbulent fluids and plasmas by the small-scale turbulent fluctuations. A measurement of the Reynolds stress can thus help to predict flows, e.g. shear flows in plasmas. This may assist the understanding...... of improved confinement scenarios such as H-mode confinement regimes. However, the determination of the Reynolds stress requires measurements of the plasma potential, a task that is difficult in general and nearly impossible in hot plasmas in large devices. In this work we investigate an alternative method......, based on density measurements, to estimate the Reynolds stress, and demonstrate the validity range of this quantity, which we term the pseudo-Reynolds stress. The advantage of such a quantity is that accurate measurements of density fluctuations are much easier to obtain experimentally. Prior...

High temperature tensile properties of 316 stainless steel implanted with helium

International Nuclear Information System (INIS)

Hasegawa, Akira; Yamamoto, Norikazu; Shiraishi, Haruki

1993-01-01

Helium embrittlement is one of the problems in structural materials for fusion reactors. Recently, martensitic steels have been developed which have a good resistance to high-temperature helium embrittlement, but the mechanism has not yet been clarified. In this paper, tensile behaviors of helium implanted austenitic stainless steels, which are sensitive to the helium embrittlement, were studied and compared with those of martensitic steels under the same experimental conditions, and the effect of microstructure on helium embrittlement was discussed. Helium was implanted by 300 appm at 573-623 K to miniature tensile speciments of 316 austenitic steels using a cyclotron accelerator. Solution annealed (316SA) and 20% cold worked (316CW) specimens were used. Post-implantation tensile tests were carried out at 573, 873 and 973 K. Yield stress at 573 K increased with the helium implantation in 316SA and 316CW, but the yield stress changes of 316SA at 873 and 973 K were different from that of 316CW. Black-dots were observed in the as-implanted specimen and bubbles were observed in the speciments tensile-tested at 873 and 973 K. Intergranular fracture was observed at only 973 K in both of the 316SA and 316CW specimens. Therefore, cold work did not suppress the high-temperature helium embrittlement under this experimental condition. The difference in the influence of helium on type 316 steel and 9Cr martensitic steels were discussed. Test temperature change of reduction in are showed clearly that helium embrittlement did not occur in 9Cr martensitic steels but occurred in 316 austenitic steels. Fine microstructures of 9Cr martensitic steels should suppress helium embrittlement at high temperatures. (author)

Oxidatively generated DNA/RNA damage in psychological stress states

DEFF Research Database (Denmark)

Jørgensen, Anders

2013-01-01

age-related somatic disorders. The overall aim of the PhD project was to investigate the relation between psychopathology, psychological stress, stress hormone secretion and oxidatively generated DNA and RNA damage, as measured by the urinary excretion of markers of whole-body DNA/RNA oxidation (8...... between the 24 h urinary cortisol excretion and the excretion of 8-oxodG/8-oxoGuo, determined in the same samples. Collectively, the studies could not confirm an association between psychological stress and oxidative stress on nucleic acids. Systemic oxidatively generated DNA/RNA damage was increased......Both non-pathological psychological stress states and mental disorders are associated with molecular, cellular and epidemiological signs of accelerated aging. Oxidative stress on nucleic acids is a critical component of cellular and organismal aging, and a suggested pathogenic mechanism in several...

The relationship between hardness to the tensile properties of kenaf/ unsaturated polyester composite

Science.gov (United States)

Ghaztar, Muhammad Mustakim Mohd; Romli, Ahmad Zafir; Ibrahim, Nik Noor Idayu Nik

2017-12-01

The level of fibre-matrix interaction and consolidation are essential aspects to determine the composite deformation but, less attention is given to the effect of small fibre weight increment (5 wt%), chemical treatment coalition (NaOH/ silane), fibre's length and aspect ratio to the physical and mechanical properties of the composite. Hence, this paper studies the correlation between these parameters towards hardness and tensile properties of Kenaf fibre and unsaturated polyester (UP) matrix. The study was carried out by fabricating the sample into two (2) types of fibre categories and fibre loadings and tested to determine its properties. The results showed that the hardness and tensile stress were significantly influenced by the fibre loading and dispersion of the fabricated samples. At low filler loading, the treated samples for both fibre sizes showed lower hardness property compared to the untreated samples. The chemical treatment coalition might diffuse out the pectin and hemicellulose which affect the ability of the fibre to absorb the force applied by the hardness indenter. Good fibre dispersion observed for the treated samples also resulted in the fibre-dominating composite system where the fibres were efficiently absorbed and distributed the indentation force. However, chemical treatments and good fibre dispersion contributed to the higher tensile stress of the treated fibre samples especially for smaller fibre length and aspect ratio compared to the untreated samples. At high fibre loading, treated fibre samples showed higher hardness property compared to the untreated samples since the treatment resulted in better fibre wetting by the matrix and the formation of pack structure. However, high fibre loading caused the mutual abrasion among the fibre which led to the lower tensile stress compared to the low fibre loading samples. In conclusion, by understanding the factors that influenced the reinforcing mechanism of the composite, the inconsistency of

Welding induced residual stress evaluation using laser-generated Rayleigh waves

Science.gov (United States)

Ye, Chong; Zhou, Yuanlai; Reddy, Vishnu V. B.; Mebane, Aaron; Ume, I. Charles

2018-04-01

Welding induced residual stress could affect the dimensional stability, fatigue life, and chemical resistance of the weld joints. Ultrasonic method serves as an important non-destructive tool for the residual stress evaluation due to its easy implementation, low cost and wide application to different materials. Residual stress would result in the ultrasonic wave velocity variation, which is the so called acoustoelastic effect. In this paper, Laser/EMAT ultrasonic technique was proposed to experimentally study the relative velocity variation ΔV/V of Rayleigh wave, which has the potential to evaluate surface/subsurface longitudinal residual stress developed during the Gas Metal Arc Welding process. Broad band ultrasonic waves were excited by pulsed Q-Switched Nd: YAG laser. An electromagnetic acoustic transducer (EMAT) attached to the welded plates was used to capture the Rayleigh wave signals propagating along the weld seam direction. Different time of flight measurements were conducted by varying the distance between the weld seam and Rayleigh wave propagating path in the range of 0 to 45 mm. The maximum relative velocity difference was found on the weld seam. With the increasing distance away from the weld seam, the relative velocity difference sharply decreased to negative value. With further increase in distance, the relative velocity difference slowly increased and approached zero. The distribution of relative velocity variations indicates that tensile stress appears in the melted zone as it becomes compressive near the heat-affected zone.

Analysis and modeling of simulated residual stress of mold injected plastic parts by using robust correlations

OpenAIRE

Vargas, Carlos; Sierra, Juan; Posada, Juan; Botero-Cadavid, Juan F.

2017-01-01

ABSTRACT The injection molding process is the most widely used processing technique for polymers. The analysis of residual stresses generated during this process is crucial for the part quality assessment. The present study evaluates the residual stresses in a tensile strength specimen using the simulation software Moldex3D for two polymers, polypropylene and polycarbonate. The residual stresses obtained under a simulated design of experiment were modeled using a robust multivariable regressi...

Model for field-induced reorientation strain in magnetic shape memory alloy with tensile and compressive loads

International Nuclear Information System (INIS)

Zhu Yuping; Dui Guansuo

2008-01-01

A model based on the micromechanical and the thermodynamic theory is presented for field-induced martensite reorientation in magnetic shape memory alloy (MSMA) single crystals. The influence of variants morphology and the material property to constitutive behavior is considered. The nonlinear and hysteretic strain and magnetization response of MSMA are investigated for two main loading cases, namely the magnetic field-induced reorientation of variants under constant compressive stress and tensile stress. The predicted results have shown that increasing tensile loading reduces the required field for actuation, while increasing compressive loads result in the required magnetic field growing considerably. It is helpful to design the intelligent composite with MSMA fibers

Tensile behaviour of radiata pine with different moisture contents at elevated temperatures

DEFF Research Database (Denmark)

Pearson, Hamish; Gabbitas, Brian; Ormarsson, Sigurdur

2012-01-01

that moisture and temperature can play a significant role in reducing stress during drying, regardless of the drying time. Properties of wood, such as tensile elastic information at elevated temperatures, are important for mechanical design, distortion modelling and understanding the fundamental behaviour...

The elevated temperature tensile properties of S-200E commercially pure beryllium

International Nuclear Information System (INIS)

Henshall, G.A.; Torres, S.G.; Hanafee, J.E.

1995-01-01

The tensile properties of commercially pure beryllium are sensitive to temperature, impurity content, texture, grain size, and prior processing. Therefore, tensile tests have been conducted using the commercially pure S-200E Be commonly employed at Lawrence Livermore National Laboratory. These experiments were performed at temperatures ranging from 300 to 1100 degrees C in the longitudinal and transverse orientations at the quasi-static strain rate of 5.5 x 10 -4 s -1 . The results of these experiments reveal that the stress-strain curve is smooth, ie. without yield points or serrations, over the entire temperature range studied. The yield stress (YS) and ultimate tensile stress (UTS) decrease monotonically with increasing temperature. Similar strengths were measured for both the longitudinal and transverse orientations, with the latter exhibiting slightly lower YS and UTS values. The measured failure elongation (e f ) vs. temperature curve is complex due to the competing effects of increasing basal-plane fracture stress with increasing temperature combined with the presence of hot shortness at intermediate temperatures. The latter is believed to be caused, at least partially, by the presence of free aluminum impurities at the grain boundaries. This hypothesis is supported by the measured increase in e f at 700 degrees C following a 100-hr anneal at 750 degrees C, which would remove free Al from the grain boundaries. Texture also was found to influence e f . The favorable orientation of the basal planes for initiation and propagation of cleavage cracks in longitudinal specimens results in a significantly decreased failure elongation compared with the transverse orientation. The effects of testing temperature and specimen orientation on the reduction in area were found to be similar to those described for e f

Microscopic Characterization of Tensile and Shear Fracturing in Progressive Failure in Marble

Science.gov (United States)

Cheng, Yi; Wong, Louis Ngai Yuen

2018-01-01

Compression-induced tensile and shear fractures were reported to be the two fundamental fracture types in rock fracturing tests. This study investigates such tensile and shear fracturing process in marble specimens containing two different flaw configurations. Observations first reveal that the development of a tensile fracture is distinct from shear fracture with respect to their nucleation, propagation, and eventual formation in macroscale. Second, transgranular cracks and grain-scale spallings become increasingly abundant in shear fractures as loading increases, which is almost not observed in tensile fractures. Third, one or some dominant extensional microcracks are commonly observed in the center of tensile fractures, while such development of microcracks is almost absent in shear fractures. Microcracks are generally of a length comparable to grain size and distribute uniformly within the damage zone of the shear fracture. Fourth, the width of densely damaged zone in the shear fracture is nearly 10 times of that in the tensile fracture. Quantitative measurement on microcrack density suggests that (1) microcrack density in tensile and shear fractures display distinct characteristics with increasing loading, (2) transgranular crack density in the shear fracture decreases logarithmically with the distance away from the shear fracture center, and (3) whatever the fracture type, the anisotropy can only be observed for transgranular cracks with a large density, which partially explains why microcrack anisotropy usually tends to be unobvious until approaching peak stress in specimens undergoing brittle failure. Microcracking characteristics observed in this work likely shed light to some phenomena and conclusions generalized in seismological studies.

Applicability of Voce equation for tensile flow and work hardening behaviour of P92 ferritic steel

International Nuclear Information System (INIS)

Sainath, G.; Choudhary, B.K.; Christopher, J.; Isaac Samuel, E.; Mathew, M.D.

2015-01-01

Detailed analysis of true stress (σ)-true plastic strain (ε) data indicated that tensile flow behaviour of P92 ferritic steel can be adequately described by Voce equation at strain rates ranging from 3.16 × 10 −5 to 1.26 × 10 −3  s −1 over a temperature range 300–923 K. The steel exhibited two-stage work hardening in the variations of instantaneous work hardening rate (θ = dσ/dε) with stress. At all the strain rates, the variations in σ-ε, θ-σ and work hardening parameters associated with Voce equation with temperature exhibited three distinct temperature regimes. At intermediate temperatures, the variations in σ-ε, θ-σ and work hardening parameters with temperature and strain rate exhibited anomalous behaviour due to the occurrence of dynamic strain ageing in the steel. The shift in θ-σ towards low stresses, and rapid decrease in flow stress and work hardening parameters with increasing temperature and decreasing strain rate suggested dominance of dynamic recovery at high temperatures. - Highlights: • Tensile flow and work hardening behaviour of P92 steel has been examined. • Applicability of Voce equation to P92 steel is demonstrated. • Three temperature regimes in flow and work hardening has been observed. • Good match between predicted and the experimental tensile properties has been shown

Residual stresses in U-bending deformations and expansion joints of heat exchanger tubes

International Nuclear Information System (INIS)

Kim, Woo Gon; Kim, Sun Jae; Jang, Jin Sung; Kuk, Ii Hiun; Bae, Kang Gug; Kim, Sung Chung

2000-01-01

Residual stress induced in U-bending and tube-to-tubesheet joint processes of PWR's rew-1 heat exchanger tube was measured by X-ray method and Hole-Drilling Method(HDM). Compressive residual stresses(-) at the extrados surface were induced in U-bending, and its maximum value reached -319MPa in axial direction at the position of ψ=0 deg. Tensile residual stresses (+) of 0σ zz =45 MPa and σ θθ =25MPa were introduced in the intrados surface at the position of ψ=0 deg. Maximum tensile residual stress of 170 MPa was measured at the flank side at the position of ψ=90 deg, i.e., at apex region. It was observed that higher stress gradient was generated at the irregular transition regions (ITR). The trend of residual stress induced by U-bending process of the tubes was found to be related with the change of ovality. The residual stress induced by the explosive joint method was found to be lower than that by the mechanical roll method. The gradient of residual stress along the expanded tube was highest at the transition region (TR), and the residual stress in circumferential direction was found to be higher than the residual stress in axial direction

On the evaluation of residual stress and mechanical properties of FeCrBSi coatings by nanoindentation

International Nuclear Information System (INIS)

Zhu Lina; Xu Binshi; Wang Haidou; Wang Chengbiao

2012-01-01

Highlights: ► Ni/Al coating can reduce the mismatch degree between the coating and substrate. ► No obvious pile-up is observed for the nanoindents of the FeCrBSi coating. ► The higher the tensile residual stress, the lower the hardness and elastic modulus. - Abstract: In this paper, the residual stress in the plasma-sprayed FeCrBSi coating was determined by nanoindentation and X-ray diffraction (XRD). The XRD results showed that tensile residual stress was generated in the FeCrBSi coating, and the through-thickness values range between 40 MPa and 112 MPa. The residual stress measured by nanoindentation is 753 MPa. The difference between the XRD and nanoindentation results was discussed. It is found that the factors limiting the nanoindentation measurement of residual stress include the ‘sink-in’ deformation around the indenter, the roughness of the FeCrBSi coating, and the use of reference sample without residual stress. The above three factors lead to the over-prediction of residual stress by nanoindentation.

Insights into the effects of tensile and compressive loadings on human femur bone.

Science.gov (United States)

Havaldar, Raviraj; Pilli, S C; Putti, B B

2014-01-01

Fragile fractures are most likely manifestations of fatigue damage that develop under repetitive loading conditions. Numerous microcracks disperse throughout the bone with the tensile and compressive loads. In this study, tensile and compressive load tests are performed on specimens of both the genders within 19 to 83 years of age and the failure strength is estimated. Fifty five human femur cortical samples are tested. They are divided into various age groups ranging from 19-83 years. Mechanical tests are performed on an Instron 3366 universal testing machine, according to American Society for Testing and Materials International (ASTM) standards. The results show that stress induced in the bone tissue depends on age and gender. It is observed that both tensile and compression strengths reduces as age advances. Compressive strength is more than tensile strength in both the genders. The compression and tensile strength of human femur cortical bone is estimated for both male and female subjecting in the age group of 19-83 years. The fracture toughness increases till 35 years in male and 30 years in female and reduces there after. Mechanical properties of bone are age and gender dependent.

Compressive residual stresses as a preventive measure against stress corrosion cracking on turbine components

International Nuclear Information System (INIS)

Berger, C.; Ewald, J.; Fischer, K.; Gruendler, O.; Potthast, E.; Stuecker, E.; Winzen, G.

1987-01-01

Disk type low pressure turbine rotors have been designed for a large variety of power plant applications. Developing disk type rotors required a concerted effort to design a shaft/disk shrink fit with a minimum of tensile stress concentrations in order to aim for the lowest possible susceptibility to corrosive attack, i.e. stress corrosion cracking. As a result of stresses, the regions of greatest concern are the shrink fit boundaries and the keyways of turbine disks. These stresses are caused by service loading, i.e. centrifugal and shrinkage stresses and by manufacturing procedure, i.e. residual stresses. The compressive residual stresses partly compensate the tensile service stresses so that an increase of compressive residual stresses decreases the whole stress state of the component. Special manufacturing procedures, e.g. accelerated cooling after tempering can induce compressive residual stresses up to about 400 MPa in the hub bore region of turbine disk

Residual stress and crack initiation in laser clad composite layer with Co-based alloy and WC + NiCr

International Nuclear Information System (INIS)

Lee, Changmin; Park, Hyungkwon; Yoo, Jaehong; Lee, Changhee; Woo, WanChuck; Park, Sunhong

2015-01-01

Highlights: • Major problem, clad cracking in laser cladding process, was researched. • Residual stress measurements were performed quantitatively by neutron diffraction method along the surface of specimens. • Relationship between the residual stress and crack initiation was showed clearly. • Ceramic particle effect in the metal matrix was showed from the results of residual stress measurements. • Initiation sites of generating clad cracks were specifically studied in MMC coatings. - Abstract: Although laser cladding process has been widely used to improve the wear and corrosion resistance, there are unwanted cracking issues during and/or after laser cladding. This study investigates the tendency of Co-based WC + NiCr composite layers to cracking during the laser cladding process. Residual stress distributions of the specimen are measured using neutron diffraction and elucidate the correlation between the residual stress and the cracking in three types of cylindrical specimens; (i) no cladding substrate only, (ii) cladding with 100% stellite#6, and (iii) cladding with 55% stellite#6 and 45% technolase40s. The microstructure of the clad layer was composed of Co-based dendrite and brittle eutectic phases at the dendritic boundaries. And WC particles were distributed on the matrix forming intermediate composition region by partial melting of the surface of particles. The overlaid specimen exhibited tensile residual stress, which was accumulated through the beads due to contraction of the coating layer generated by rapid solidification, while the non-clad specimen showed compressive. Also, the specimen overlaid with 55 wt% stellite#6 and 45 wt% technolase40s showed a tensile stress higher than the specimen overlaid with 100% stellite#6 possibly, due to the difference between thermal expansion coefficients of the matrix and WC particles. Such tensile stresses can be potential driving force to provide an easy crack path ways for large brittle fractures

Residual stress and crack initiation in laser clad composite layer with Co-based alloy and WC + NiCr

Energy Technology Data Exchange (ETDEWEB)

Lee, Changmin; Park, Hyungkwon; Yoo, Jaehong [Division of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Lee, Changhee, E-mail: chlee@hanyang.ac.kr [Division of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Woo, WanChuck [Neutron Science Division, Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of); Park, Sunhong [Research Institute of Industrial Science & Technology, Hyo-ja-dong, Po-Hang, Kyoung-buk, San 32 (Korea, Republic of)

2015-08-01

Highlights: • Major problem, clad cracking in laser cladding process, was researched. • Residual stress measurements were performed quantitatively by neutron diffraction method along the surface of specimens. • Relationship between the residual stress and crack initiation was showed clearly. • Ceramic particle effect in the metal matrix was showed from the results of residual stress measurements. • Initiation sites of generating clad cracks were specifically studied in MMC coatings. - Abstract: Although laser cladding process has been widely used to improve the wear and corrosion resistance, there are unwanted cracking issues during and/or after laser cladding. This study investigates the tendency of Co-based WC + NiCr composite layers to cracking during the laser cladding process. Residual stress distributions of the specimen are measured using neutron diffraction and elucidate the correlation between the residual stress and the cracking in three types of cylindrical specimens; (i) no cladding substrate only, (ii) cladding with 100% stellite#6, and (iii) cladding with 55% stellite#6 and 45% technolase40s. The microstructure of the clad layer was composed of Co-based dendrite and brittle eutectic phases at the dendritic boundaries. And WC particles were distributed on the matrix forming intermediate composition region by partial melting of the surface of particles. The overlaid specimen exhibited tensile residual stress, which was accumulated through the beads due to contraction of the coating layer generated by rapid solidification, while the non-clad specimen showed compressive. Also, the specimen overlaid with 55 wt% stellite#6 and 45 wt% technolase40s showed a tensile stress higher than the specimen overlaid with 100% stellite#6 possibly, due to the difference between thermal expansion coefficients of the matrix and WC particles. Such tensile stresses can be potential driving force to provide an easy crack path ways for large brittle fractures

The theoretical strength of rubber: numerical simulations of polyisoprene networks at high tensile strains evidence the role of average chain tortuosity

International Nuclear Information System (INIS)

Hanson, David E; Barber, John L

2013-01-01

The ultimate stress and strain of polyisoprene rubber were studied by numerical simulations of three-dimensional random networks, subjected to tensile strains high enough to cause chain rupture. Previously published molecular chain force extension models and a numerical network construction procedure were used to perform the simulations for network crosslink densities between 2 × 10 19 and 1 × 10 20 cm −3 , corresponding to experimental dicumyl-peroxide concentrations of 1–5 parts per hundred. At tensile failure (defined as the point of maximum stress), we find that the fraction of network chains ruptured is between 0.1% and 1%, depending on the crosslink density. The fraction of network chains that are taut, i.e. their end-to-end distance is greater than their unstretched contour length, ranges between 10% and 15% at failure. Our model predicts that the theoretical (defect-free) failure stress should be about twice the highest experimental value reported. For extensions approaching failure, tensile stress is dominated by the network morphology and purely enthalpic bond distortion forces and, in this regime, the model has essentially no free parameters. The average initial chain tortuosity (τ) appears to be an important statistical property of rubber networks; if the stress is scaled by τ and the tensile strain is scaled by τ −1 , we obtain a master curve for stress versus strain, valid for all crosslink densities. We derive an analytic expression for the average tortuosity, which is in agreement with values calculated in the simulations. (paper)

Accelerated Stress-Corrosion Testing

Science.gov (United States)

1986-01-01

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

The stress field and transient stress generation at shallow depths in the Canadian shield

International Nuclear Information System (INIS)

Hasegawa, H.S.

1984-01-01

A prominent feature of the stress field in eastern Canada is the high horizontal stress at shallow depths. Possible causative factors to this shallow stress field are remanent stresses from a previous tectonic orogeny, plate tectonic stresses and glacial-related stresses (glacial drag and flexual stress). The inherent difficulty in differentiating residual from current stress is one of the reasons why the relative contributions to the stress field from the phenomena described above are not properly understood. Maximum stress-strain changes an underground vault is likely to encounter from natural phenomena should occur when the periphery of the advancing or retreating glacier is near the vault. Theoretical calculations indicate that lithospheric flexure, differential postglacial uplift and possibly glacial drag may be able to generate significant horizontal stresses around a vault. In order to calculate the earthquake potential of these induced stress changes, the ambient tectonic stress field should also be included and a suitable failure criterion (e.g. Coulomb-Mohr) used. For earthquakes to generate appreciable stress-strain concentrations near a vault; the seismic signal must contain appreciable energy at appropriate frequencies (wavelengths comparable to vault dimensions) and be of appreciable duration; the particle velocity must be high (> 10 cm/s), induced strain is a function of particle velocity; and, the hypocentre must be less than half a fault length from the vault for residual deformation (strain and tilt) to be significant. The most severe case is when the causative fault intersects the vault

Influence of laboratory annealing on tensile properties and design stress intensity limits for Type 304 stainless steel

International Nuclear Information System (INIS)

Sikka, V.K.; Booker, M.K.

1977-01-01

The influence of reannealing (laboratory annealing) on yield and ultimate tensile strength values of 19 heats of type 304 stainless steel was determined. Most heats were reannealed at 1065 0 C for 0.5 hr. The reannealed properties were used to determine the influence of reannealing on time-independent design stress intensity limits (S/sub m/). The major findings are as follows: 1. Reannealing lowered the 0.2 percent yield strength versus temperature curve by approximately 42 MPa over the range from room temperature to 649 0 C. 2. The estimated S/sub m/ values for reannealed material were 24 to 28 MPa lower than the current code values. 3. Reannealing appears to influence the S/sub m/ value sufficiently to warrant the consideration of separate values of S/sub m/ in Sect. III of the Boiler and Pressure Vessel Code and Code Case 1592 for ''as-received'' and reannealed material

Residual stresses around Vickers indents

International Nuclear Information System (INIS)

Pajares, A.; Guiberteau, F.; Steinbrech, R.W.

1995-01-01

The residual stresses generated by Vickers indentation in brittle materials and their changes due to annealing and surface removal were studied in 4 mol% yttria partially stabilized zirconia (4Y-PSZ). Three experimental methods to gain information about the residual stress field were applied: (i) crack profile measurements based on serial sectioning, (ii) controlled crack propagation in post indentation bending tests and (iii) double indentation tests with smaller secondary indents located around a larger primary impression. Three zones of different residual stress behavior are deduced from the experiments. Beneath the impression a crack free spherical zone of high hydrostatic stresses exists. This core zone is followed by a transition regime where indentation cracks develop but still experience hydrostatic stresses. Finally, in an outward third zone, the crack contour is entirely governed by the tensile residual stress intensity (elastically deformed region). Annealing and surface removal reduce this crack driving stress intensity. The specific changes of the residual stresses due to the post indentation treatments are described and discussed in detail for the three zones

Effect of helium on tensile properties of vanadium alloys

Energy Technology Data Exchange (ETDEWEB)

Chung, H.M.; Billone, M.C.; Smith, D.L. [Argonne National Lab., IL (United States)

1997-08-01

Tensile properties of V-4Cr-4Ti (Heat BL-47), 3Ti-1Si (BL-45), and V-5Ti (BL-46) alloys after irradiation in a conventional irradiation experiment and in the Dynamic Helium Charging Experiment (DHCE) were reported previously. This paper presents revised tensile properties of these alloys, with a focus on the effects of dynamically generated helium of ductility and work-hardening capability at <500{degrees}C. After conventional irradiation (negligible helium generation) at {approx}427{degrees}C, a 30-kg heat of V-4Cr-4Ti (BL-47) exhibited very low uniform elongation, manifesting a strong susceptibility to loss of work-hardening capability. In contrast, a 15-kg heat of V-3Ti-1Si (BL -45) exhibited relatively high uniform elongation ({approx}4%) during conventional irradiation at {approx}427{degrees}C, showing that the heat is resistant to loss of work-hardening capability.

The effect of tungsten on the tensile and creep rupture strength of 12 CrMoV steels

International Nuclear Information System (INIS)

Oakes, G.; Orr, J.

1978-01-01

A collaborative project involving the Brown-Firth Research Laboratories, the Sheffield Laboratories of the British Steel Corporation and Tube Investments Limited has been carried out to assess the effect of a controlled tungsten addition (0.5%) on the tensile and rupture properties of 12 CrMoV steel. The results obtained indicate that 0.5% tungsten increases the tensile properties at room temperature by approximately 3% but this diminishes with increasing test temperature. The creep rupture properties of the tungsten-bearing material showed a marked short time (500-1000 hours) strength advantage over the tungsten-free material at temperatures up to 650 0 C. At longer times and higher temperatures this stress advantage was reduced considerably so that at times in the region of 10,000 to 15,000 hours it was approximately 5%. In view of the limited data generated, it was found impossible to extrapolate with confidence to longer times but there was, however, no indication that a significant strength advantage is to be anticipated at 100,000 hours for the tungsten-bearing material. (author)

Tensile and stress corrosion cracking properties of type 304 stainless steel irradiated to a very high dose

International Nuclear Information System (INIS)

Chung, H.M.; Strain, R.V.; Shack, W.J.

2001-01-01

Certain safety-related core internal structural components of light water reactors, usually fabricated from Type 304 or 316 austenitic stainless steels (SSs), accumulate very high levels of irradiation damage (20-100 displacement per atom or dpa) by the end of life. Our databases and mechanistic understanding of the degradation of such highly irradiated components, however, are not well established. A key question is the nature of irradiation-assisted intergranular cracking at very high doses, i.e. is it purely mechanical failure or is it stress-corrosion cracking? In this work, hot-cell tests and microstructural characterization were performed on Type 304 SS from the hexagonal fuel can of the decommissioned EBR-II reactor after irradiation to ∼50 dpa at ∼370 deg. C. Slow-strain-rate tensile tests were conducted at 289 degree sign C in air and in water at several levels of electrochemical potential (ECP), and microstructural characteristics were analyzed by scanning and transmission electron microscopies. The material deformed significantly by twinning and exhibited surprisingly high ductility in air, but was susceptible to severe intergranular stress corrosion cracking (IGSCC) at high ECP. Low levels of dissolved O and ECP were effective in suppressing the susceptibility of the heavily irradiated material to IGSCC, indicating that the stress corrosion process associated with irradiation-induced grain-boundary Cr depletion, rather than purely mechanical separation of grain boundaries, plays the dominant role. However, although IGSCC was suppressed, the material was susceptible to dislocation channeling at a low ECP, and this susceptibility led to a poor work-hardening capability and low ductility

Residual Stress Evaluation of Weld Inlay Process on Reactor Vessel Nozzles

Energy Technology Data Exchange (ETDEWEB)

Cho, Kihyun; Cho, Hong Seok [KEPCO KPS, Naju (Korea, Republic of)

2015-10-15

Weld overlay, weld inlay and stress improvement are mitigation technologies for butt joints. Weld overlay is done on pressurizer nozzles which are the highest potential locations occurring PWSCC due to high temperature in Korea. Reactor vessel nozzles are other big safety concerns for butt joints. Weld overlay and stress improvement should be so difficult to apply to those locations because space is too limited. Weld inlay should be one of the solutions. KEPCO KPS has developed laser welding system and process for reactor nozzles. Welding residual stress analysis is necessary for flaw evaluation. United States nuclear regulatory commission has calculated GTAW(Gas Tungsten Arc Welding) residual stress using ABAQUS. To confirm effectiveness of weld inlay process, welding residual stress analysis was performed. and difference between GTAW and LASER welding process was compared. Evaluation of weld inlay process using ANSYS and ABAQUS is performed. All of the both results are similar. The residual stress generated after weld inlay was on range of 450-500 MPa. Welding residual stresses are differently generated by GTAW and LASER welding. But regardless of welding process type, residual tensile stress is generated on inside surface.

Tensile properties of orthodontic elastomeric ligatures.

Science.gov (United States)

Ahrari, F; Jalaly, T; Zebarjad, M

2010-01-01

Tensile properties of elastomeric ligatures become important when efficiency of orthodontic appliances is considered. The aim of this study was to compare tensile strength, extension to tensile strength, toughness and modulus of elasticity of elastomeric ligatures in both the as--received condition and after 28 days of immersion in the simulated oral environment. Furthermore, the changes that occurred in tensile properties of each brand of ligatures after 28 days were evaluated. Experimental-laboratory based. Elastomeric ligatures were obtained from different companies and their tensile properties were measured using Zwick testing machine in both the as-received condition and after 28 days of immersion in the simulated oral environment. The data were analyzed using independent sample t-tests, analysis of variance and Tukey tests. After 28 days, all the ligatures experienced a significant decrease in tensile strength, extension to tensile strength and toughness ( P tensile properties of different brands of ligatures in both conditions ( P tensile properties of different brands of ligatures, which should be considered during selection of these products.

Vulnerability-specific stress generation: An examination of negative cognitive and interpersonal styles

Science.gov (United States)

Liu, Richard T.; Alloy, Lauren B.; Mastin, Becky M.; Choi, Jimmy Y.; Boland, Elaine M.; Jenkins, Abby L.

2014-01-01

Although there is substantial evidence documenting the stress generation effect in depression (i.e., the tendency for depression-prone individuals to experience higher rates of life stress to which they contribute), additional research is required to advance current understanding of the specific types of dependent stress (i.e., events influenced by characteristics and attendant behaviors of the individual) relevant to this effect. The present study tested an extension of the stress generation hypothesis, in which the content of dependent stress that is produced by depression-prone individuals is contingent upon, and matches, the nature of their particular vulnerabilities. This extension was tested within the context of two cognitive models (i.e., hopelessness theory [Abramson, Metalsky, & Alloy, 1989] and Cole’s [1990, 1991] competency-based model) and two interpersonal models (i.e., Swann’s [1987] self-verification theory and Coyne’s [1976] interpersonal theory) of depression. Overall, support was obtained for vulnerability-specific stress generation. Specifically, in analyses across vulnerability domains, evidence of stress-generation specificity was found for all domain-specific cognitive vulnerabilities except self-perceived social competence. The within-domain analyses for cognitive vulnerabilities produced more mixed results, but were largely supportive. Additionally, excessive reassurance-seeking was specifically predictive of dependent stress in the social domain, and moderated, but did not mediate, the relation between negative inferential styles overall and in the interpersonal domain and their corresponding generated stress. Finally, no evidence was found for a stress generation effect with negative feedback-seeking. PMID:24679143

Strain transfer through film-substrate interface and surface curvature evolution during a tensile test

Science.gov (United States)

He, Wei; Han, Meidong; Goudeau, Philippe; Bourhis, Eric Le; Renault, Pierre-Olivier; Wang, Shibin; Li, Lin-an

2018-03-01

Uniaxial tensile tests on polyimide-supported thin metal films are performed to respectively study the macroscopic strain transfer through an interface and the surface curvature evolution. With a dual digital image correlation (DIC) system, the strains of the film and the substrate can be simultaneously measured in situ during the tensile test. For the true strains below 2% (far beyond the films' elastic limit), a complete longitudinal strain transfer is present irrespective of the film thickness, residual stresses and microstructure. By means of an optical surface profiler, the three-dimensional (3D) topography of film surface can be obtained during straining. As expected, the profile of the specimen center remains almost flat in the tensile direction. Nevertheless, a relatively significant curvature evolution (of the same order with the initial curvature induced by residual stresses) is observed along the transverse direction as a result of a Poisson's ratio mismatch between the film and the substrate. Furthermore, finite element method (FEM) has been performed to simulate the curvature evolution considering the geometric nonlinearity and the perfect strain transfer at the interface, which agrees well with the experimental results.

Mechanical Properties and Tensile Fatigue of Graphene Nanoplatelets Reinforced Polymer Nanocomposites

Directory of Open Access Journals (Sweden)

Ming-Yuan Shen

2013-01-01

Full Text Available Graphene nanoplatelets (GNPs are novel nanofillers possessing attractive characteristics, including robust compatibility with most polymers, high absolute strength, and cost effectiveness. In this study, GNPs were used to reinforce epoxy composite and epoxy/carbon fiber composite laminates to enhance their mechanical properties. The mechanical properties of GNPs/epoxy nanocomposite, such as ultimate tensile strength and flexure properties, were investigated. The fatigue life of epoxy/carbon fiber composite laminate with GPs-added 0.25 wt% was increased over that of neat laminates at all levels of cyclic stress. Consequently, significant improvement in the mechanical properties of ultimate tensile strength, flexure, and fatigue life was attained for these epoxy resin composites and carbon fiber-reinforced epoxy composite laminates.

Validatin of miniaturised tensile testing on DMLS TI6AL4V (ELI specimens

Directory of Open Access Journals (Sweden)

Van Zyl, Ian

2016-11-01

Full Text Available Direct metal laser sintering (DMLS is a relatively new technology that is developing rapidly. Since DMLS material is created by melting/solidifying tracks and layers from powder, even building geometry can influence the mechanical properties. To certify a material, the testing specimens must be designed and manufactured according to the appropriate standards. Miniaturised tensile DMLS samples could be a good alternative for express quality control, and could reduce the cost of DMLS-specific testing. In this study, as-built and stress-relieved miniaturised tensile DMLS Ti6Al4V (ELI specimens with different surface qualities were investigated. The fracture surfaces and mechanical properties of the mini-tensile specimens were analysed and compared with standard full-sized specimens also manufactured by DMLS. The obtained data showed the applicability of mini-tensile tests for the express analysis of DMLS objects if a correction factor is applied for the calculation of the load-bearing cross-section of the specimen.

Effect of holes on the room temperature tensile behaviors of thin wall specimens with (210) side surface of Ni-base single crystal superalloy

Energy Technology Data Exchange (ETDEWEB)

Zhou, Z.J.; Liu, T.; Pu, S. [Superalloys Division, Institute of Metal Research, Chinese Academy of Sciences, No. 72, Wenhua Road, Shenyang 110016 (China); Xu, H. [Materials Fatigue and Fracture Division, Institute of Metal Research, Chinese Academy of Sciences, No. 72, Wenhua Road, Shenyang 110016 (China); Wang, L., E-mail: wangli@imr.ac.cn [Superalloys Division, Institute of Metal Research, Chinese Academy of Sciences, No. 72, Wenhua Road, Shenyang 110016 (China); Lou, L.H. [Superalloys Division, Institute of Metal Research, Chinese Academy of Sciences, No. 72, Wenhua Road, Shenyang 110016 (China)

2015-10-25

Tensile properties of Ni-base single crystal superalloy plate specimens with and without a hole at room temperature were studied in the present paper. During the testing process, an ARAMIS system based on the digital image correlation technique and in-situ scanning electron microscopy were employed to in-situ observe the strain distribution and slip traces development on the sample surfaces. It was demonstrated that the yield stress was decreased with the appearance of a hole due to the stress concentration. The results were analyzed based on the stress and strain states of specimens and the slip traces development observed on specimen surfaces. - Graphical abstract: The strain distribution for samples without and with a hole, respectively. - Highlights: • Tensile tests of plate specimens without and with a hole were performed. • Surface strain fields were in-situ observed by ARAMIS system. • Slip traces development on sample surfaces was in-situ observed by SEM. • The hole deteriorated both the tensile strength and elongation of the samples. • Tensile strength of specimens without and with a hole was discussed respectively.

Assessment of tensile and creep data for types 304 and 316 stainless steel

International Nuclear Information System (INIS)

Sikka, V.K.; Booker, M.K.

1976-01-01

Austenitic stainless steels of types 304 and 316 are prime construction materials for nuclear fast breeder reactors and will be used in the temperature range where elevated-temperature, tensile, creep, and fatigue properties are required to calculate the design stress limits. This report examines the possible variations in such properties, using data from several sources including data from Japan and the United Kingdom. United States data were shown to contain the largest variations in both tensile and creep properties, with Japanese data the least. For a given country no distinction could be made in variations in tensile properties of types 304 and 316 stainless steels, but variations in standard error of estimate for all creep properties analyzed were significantly lower for type 316 stainless steel than corresponding variations in creep properties of type 304 stainless steel. The data from each of these countries showed the same creep rupture strength (at 10 4 h) for type 316 stainless steel; this was not true for the type 304 stainless steel. Results of the analysis performed in this paper showed that the U.S. and foreign data on types 304 and 316 stainless steels could possibly be combined for the determination of design stress intensity limits

The influence of tensile strain to critical current of Bi2223 composite tape

International Nuclear Information System (INIS)

Mukai, Y.; Shin, J.K.; Ochiai, S.; Okuda, H.; Sugano, M.; Osamura, K.

2008-01-01

As the stress-induced damage evolution is different from position to position in the sample, the local critical current is scattered in a sample, affecting on the overall current. The present work aimed to describe the distribution of local critical current and its relation to overall critical current under tensile stress for Bi2223/Ag superconducting composite tape. In the experiment, seven voltage probes were attached in a step of 10 mm. The local critical current and n-value at 77 K under various applied stress levels were measured for a voltage probe distance 10 mm and the overall ones for a probe distance 60 mm. Main results are summarized as follows. The overall critical current and n-value were described well by using the voltage summation model in which the sample was regarded as a one dimensional series circuit. For the low applied stress, the distribution of local critical current was described with the three parameter Weibull distribution function. Using the measured distribution of the local critical current, an experimental relation of critical current to n-value and the voltage summation model, and applying the Monte Carlo method, the overall critical current was predicted, which was in good agreement with the experimental results. Based on these results, the sample length dependence of critical current of the sample damaged by tensile stress was discussed

Thermal stress evaluation of the Viking RTG heat shield

International Nuclear Information System (INIS)

Stadter, J.T.; Weiss, R.O.

1976-03-01

Thermal stress analyses of the Viking RTG heat shield are presented. The primary purpose of the analyses was to determine the effects of the end cap and the finite length of the heat shield on the peak tensile stress in the barrel wall. The SAAS III computer code was used to calculate the thermal stresses; axisymmetric and plane section analyses were performed for a variety of temperature distributions. The study consisted of three parts. In the first phase, the influence of the end cap on the barrel wall stresses was examined by parametrically varying the modulus of elasticity of the contact zone between the end cap and the barrel. The second phase was concerned with stresses occurring as a result of an orbital decay reentry trajectory, and the effects of the magnitude and shape of the axial temperature gradient. The final part of the study was concerned with the circumferentially nonuniform temperature distribution which develops during a side-on stable reentry. The last part includes a comparison of stresses generated for a hexagonal cross section with those generated for a circular cross section

Study on Tensile Fatigue Behavior of Thermal Butt Fusion in Safety Class III High-Density Polyethylene Buried Piping in Nuclear Power Plants

Energy Technology Data Exchange (ETDEWEB)

Kim, Jong Sung; Lee, Young Ju [Sunchon National University, Suncheon (Korea, Republic of); Oh, Young Jin [KEPCO E and C, Yongin (Korea, Republic of)

2015-01-15

High-density polyethylene (HDPE) piping, which has recently been applied to safety class III piping in nuclear power plants, can be butt-joined through the thermal fusion process, which heats two fused surfaces and then subject to axial pressure. The thermal fusion process generates bead shapes on the butt fusion. The stress concentrations caused by the bead shapes may reduce the fatigue lifetime. Thus, investigating the effect of the thermal butt fusion beads on fatigue behavior is necessary. This study examined the fatigue behavior of thermal butt fusion via a tensile fatigue test under stress-controlled conditions using finite element elastic stress analysis. Based on the results, the presence of thermal butt fusion beads was confirmed to reduce the fatigue lifetime in the low-cycle fatigue region while having a negligible effect in the medium- and high-cycle fatigue regions.

Study on Tensile Fatigue Behavior of Thermal Butt Fusion in Safety Class III High-Density Polyethylene Buried Piping in Nuclear Power Plants

International Nuclear Information System (INIS)

Kim, Jong Sung; Lee, Young Ju; Oh, Young Jin

2015-01-01

High-density polyethylene (HDPE) piping, which has recently been applied to safety class III piping in nuclear power plants, can be butt-joined through the thermal fusion process, which heats two fused surfaces and then subject to axial pressure. The thermal fusion process generates bead shapes on the butt fusion. The stress concentrations caused by the bead shapes may reduce the fatigue lifetime. Thus, investigating the effect of the thermal butt fusion beads on fatigue behavior is necessary. This study examined the fatigue behavior of thermal butt fusion via a tensile fatigue test under stress-controlled conditions using finite element elastic stress analysis. Based on the results, the presence of thermal butt fusion beads was confirmed to reduce the fatigue lifetime in the low-cycle fatigue region while having a negligible effect in the medium- and high-cycle fatigue regions

Effects on Machining on Surface Residual Stress of SA 508 and Austenitic Stainless Steel

International Nuclear Information System (INIS)

Lee, Kyoung Soo; Lee, Seong Ho; Park, Chi Yong; Yang, Jun Seok; Lee, Jeong Geun; Park, Jai Hak

2011-01-01

Primary water stress corrosion cracking has occurred in dissimilar weld areas in nuclear power plants. Residual stress is a driving force in the crack. Residual stress may be generated by weld or surface machining. Residual stress due to surface machining depends on the machining method, e.g., milling, grinding, or EDM. The stress is usually distributed on or near the surface of the material. We present the measured residual stress for machining on SA 508 and austenitic stainless steels such as TP304 and F316. The residual stress can be tensile or compressive depending on the machining method. The depth and the magnitude of the residual stress depend on the material and the machining method

Residual stress reduction in the penetration nozzle weld joint by overlay welding

International Nuclear Information System (INIS)

Jiang, Wenchun; Luo, Yun; Wang, B.Y.; Tu, S.T.; Gong, J.M.

2014-01-01

Highlights: • Residual stress reduction in penetration weld nozzle by overlay welding was studied. • The overlay weld can decrease the residual stress in the weld root. • Long overlay welding is proposed in the actual welding. • Overlay weld to decrease residual stress is more suitable for thin nozzle. - Abstract: Stress corrosion cracking (SCC) in the penetration nozzle weld joint endangers the structural reliability of pressure vessels in nuclear and chemical industries. How to decrease the residual stress is very critical to ensure the structure integrity. In this paper, a new method, which uses overlay welding on the inner surface of nozzle, is proposed to decrease the residual stresses in the penetration joint. Finite element simulation is used to study the change of weld residual stresses before and after overlay welding. It reveals that this method can mainly decrease the residual stress in the weld root. Before overlay welding, large tensile residual stresses are generated in the weld root. After overlay weld, the tensile hoop stress in weld root has been decreased about 45%, and the radial stress has been decreased to compressive stress, which is helpful to decrease the susceptibility to SCC. With the increase of overlay welding length, the residual stress in weld root has been greatly decreased, and thus the long overlay welding is proposed in the actual welding. It also finds that this method is more suitable for thin nozzle rather than thick nozzle

Tensile and high cycle fatigue behaviors of high-Mn steels at 298 and 110 K

Energy Technology Data Exchange (ETDEWEB)

Seo, Wongyu; Jeong, Daeho; Sung, Hyokyung; Kim, Sangshik, E-mail: sang@gnu.ac.kr

2017-02-15

Tensile and high cycle fatigue behaviors of high-Mn austenitic steels, including 25Mn, 25Mn0.2Al, 25Mn0.5Cu, 24Mn4Cr, 22Mn3Cr and 16Mn2Al specimens, were investigated at 298 and 110 K. Depending on the alloying elements, tensile ductility of high-Mn steels either increased or decreased with decreasing temperature from 298 to 110 K. Reasonable correlation between the tendency for martensitic tranformation, the critical twinning stress and the percent change in tensile elongation suggested that tensile deformation of high-Mn steels was strongly influenced by SFE determining TRIP and TWIP effects. Tensile strength was the most important parameter in determining the resistance to high cycle fatigue of high-Mn steels with an exceptional work hardening capability at room and cryogenic temperatures. The fatigue crack nucleation mechanism in high-Mn steels did not vary with decreasing tempertature, except Cr-added specimens with grain boundary cracking at 298 K and slip band cracking at 110 K. The EBSD (electron backscatter diffraction) analyses suggested that the deformation mechanism under fatigue loading was significantly different from tensile deformation which could be affected by TRIP and TWIP effects. - Highlights: •The resistances to HCF of various high-Mn steels were measured. •The variables affecting tensile and HCF behaviors of high-Mn steels were assessed. •The relationship between tensile and the HCF behaviors of high-Mn steels was established.

Elastic interaction between twins during tensile deformation of austenitic stainless steel

DEFF Research Database (Denmark)

Juul, Nicolai Ytterdal; Winther, Grethe; Dale, Darren

2016-01-01

. However, the components of the Type II stress normal to the twin boundary plane exhibit the same large variations as for the grain boundaries. Elastic grain interactions are therefore complex and must involve the entire set of neighbouring grains. The elastic-regime stress along the tensile direction......In austenite, the twin boundary normal is a common elastically stiff direction shared by the two twins, which may induce special interactions. By means of three-dimensional X-ray diffraction this elastic interaction has been analysed and compared to grains separated by conventional grain boundaries...

Static Tensile and Transient Dynamic Response of Cracked Aluminum Plate Repaired with Composite Patch - Numerical Study

Science.gov (United States)

Khalili, S. M. R.; Shariyat, M.; Mokhtari, M.

2014-06-01

In this study, the central cracked aluminum plates repaired with two sided composite patches are investigated numerically for their response to static tensile and transient dynamic loadings. Contour integral method is used to define and evaluate the stress intensity factors at the crack tips. The reinforcement for the composite patches is carbon fibers. The effect of adhesive thickness and patch thickness and configuration in tensile loading case and pre-tension, pre-compression and crack length effect on the evolution of the mode I stress intensity factor (SIF) (KI) of the repaired structure under transient dynamic loading case are examined. The results indicated that KI of the central cracked plate is reduced by 1/10 to 1/2 as a result of the bonded composite patch repair in tensile loading case. The crack length and the pre-loads are more effective in repaired structure in transient dynamic loading case in which, the 100 N pre-compression reduces the maximum KI for about 40 %, and the 100 N pre-tension reduces the maximum KI after loading period, by about 196 %.

Effect of pre-existing shear bands on the tensile mechanical properties of a bulk metallic glass

International Nuclear Information System (INIS)

Cao, Q.P.; Liu, J.W.; Yang, K.J.; Xu, F.; Yao, Z.Q.; Minkow, A.; Fecht, H.J.; Ivanisenko, J.; Chen, L.Y.; Wang, X.D.; Qu, S.X.; Jiang, J.Z.

2010-01-01

Bulk Zr 64.13 Cu 15.75 Ni 10.12 Al 10 metallic glass has been rolled at room temperature in two different directions, and the dependences of microstructure and tensile mechanical property on the degree of deformation and rolling directions have been investigated. No deformation-induced crystallization occurs except for shear bands. Shear band formation in conjugated directions is achieved in the specimen rolled in two directions, while rolling in one direction induces shear band formation only in a single direction. Pre-existing properly spaced soft inhomogeneities can stabilize shear bands and lead to tensile plastic strain, and the efficient intersection of shear bands in conjugated directions results in work-hardening behavior, which is further confirmed by in situ tensile scanning electron microscopic observation. Based on the experimental results obtained in two different specimen geometries and finite element analysis, it is deduced that a normal-stress-modified maximum shear stress criterion rather than a shear plane criterion can describe the conditions for the formation of shear bands in uniaxial tension.

The manufacturing of Stress Corrosion Crack (SCC) on Inconel 600 tube

International Nuclear Information System (INIS)

Bae, Seunggi; Bak, Jaewoong; Kim, Seongcheol; Lee, Sangyul; Lee, Boyoung

2014-01-01

The Stress Corrosion Crack (SCC), taken a center stage in recently accidents about nuclear power plants, is one of the environmentally induced cracking occurred when a metallic structure under tensile stress is exposed to corrosive environment. In this study, the SCC was manufactured in the simulated corrosive environmental conditions on Inconel 600 tube that widely applied in the nuclear power plants. The tensile stress which is one of the main factors to induce SCC was given by GTAW welding in the inner surface of the specimen. The corrosive environment was simulated by using the sodium hydroxide (NaOH) and sodium sulfide (Na 2 S). In this study, SCC was manufactured in the simulated corrosive environmental conditions with Inconel 600 tube that widely applied in the nuclear power plants. 1) The SCC was manufactured on Inconel 600 tube in simulated operational environments of nuclear power plants. In the experiment, the welding heat input which is enough to induce the cracking generated the SCC near the welding bead. So, in order to prevent the SCC, the residual stress on structure should be relaxed. 2) The branch-type cracking was detected

Study of the concrete tensile creep: application for the containment vessel of the nuclear power plants (PWR)

International Nuclear Information System (INIS)

Reviron, Nanthilde

2009-01-01

The aim of this work is to study experimentally and to conduct numerical simulations on the creep of concrete subjected to tensile stresses. The main purpose is to predict the behaviour of containment vessels of nuclear power plants (PWR) in the case of decennial test or accident. In order to satisfy to these industrial needs, it is necessary to characterize the behaviour of concrete under uniaxial tension. Thus, an important experimental study of tensile creep in concrete has been performed for different loading levels (50%, 70% and 90% of the tensile strength). In these tests, load was kept constant during 3 days. Several tests were performed: measurements of elastic properties and strength (in tension and in compression), monitoring of drying, shrinkage, basic creep and drying creep strains. Moreover, compressive creep tests were also performed and showed a difference with tensile creep. Furthermore, decrease of tensile strength and failure under tensile creep for large loading levels were observed. A numerical model has been proposed and developed in Cast3m finite element code. (author)

Electrically, Chemically, and Photonically Powered Torsional and Tensile Actuation of Hybrid Carbon Nanotube Yarn Muscles

Science.gov (United States)

Lima, Márcio D.; Li, Na; Jung de Andrade, Mônica; Fang, Shaoli; Oh, Jiyoung; Spinks, Geoffrey M.; Kozlov, Mikhail E.; Haines, Carter S.; Suh, Dongseok; Foroughi, Javad; Kim, Seon Jeong; Chen, Yongsheng; Ware, Taylor; Shin, Min Kyoon; Machado, Leonardo D.; Fonseca, Alexandre F.; Madden, John D. W.; Voit, Walter E.; Galvão, Douglas S.; Baughman, Ray H.

2012-11-01

Artificial muscles are of practical interest, but few types have been commercially exploited. Typical problems include slow response, low strain and force generation, short cycle life, use of electrolytes, and low energy efficiency. We have designed guest-filled, twist-spun carbon nanotube yarns as electrolyte-free muscles that provide fast, high-force, large-stroke torsional and tensile actuation. More than a million torsional and tensile actuation cycles are demonstrated, wherein a muscle spins a rotor at an average 11,500 revolutions/minute or delivers 3% tensile contraction at 1200 cycles/minute. Electrical, chemical, or photonic excitation of hybrid yarns changes guest dimensions and generates torsional rotation and contraction of the yarn host. Demonstrations include torsional motors, contractile muscles, and sensors that capture the energy of the sensing process to mechanically actuate.

Tensile tests and metallography of brazed AISI 316L specimens after irradiation

International Nuclear Information System (INIS)

Groot, P.; Franconi, E.

1994-01-01

Stainless steel type 316L tensile specimens were vacuum brazed with three kinds of alloys: BNi-5, BNi-6, and BNi-7. The specimens were irradiated up to 0.7 dpa at 353 K in the High Flux Reactor at JRC Petten, the Netherlands. Tensile tests were performed at a constant displacement rate of 10 -3 s -1 at room temperature in the ECN hot cell facility. BNi-5 brazed specimens showed ductile behaviour. Necking and fractures were localized in the plate material. BNi-6 and BNi-7 brazed specimens failed brittle in the brazed zone. This was preceded by uniform deformation of the plate material. Tensile test results of irradiated specimens showed higher stresses due to radiation hardening and a reduction of the elongation of the plate material compared to the reference. SEM examination of the irradiated BNi-6 and BNi-7 fracture surfaces showed nonmetallic phases. These phases were not found in the reference specimens. ((orig.))

Practical stress evaluation method of RC slab for bending moment in consideration of additional in-plane stress caused by boundary condition

International Nuclear Information System (INIS)

Kobayashi, Toshio; Adachi, Naohito; Masuda, Kiyoshi

1998-01-01

In a design of a thick RC slab such as a basemat of a nuclear reactor building, the design method as same as for RC column is usually used. In this method, bending moment and axial force which are obtained by linear Finite Element Method (FEM) for external force are considered. But the assumption for linear FEM in which concrete participates for tensile stress is different from that for reinforcement design in which concrete does not participate for tensile stress. This difference of the assumption results that in-plane tensile strain at the center of the slab depth in the reinforcement design is larger than that in linear FEM. Some effects will appear in stress distribution if this tensile strain is constrained by boundary condition. In this paper, a practical method to evaluate the boundary constrain effects for this in-plane tensile strain is proposed and a simulation analysis of a thick reinforced concrete slab with a large opening for out-of-plane force is also reported. (author)

Dynamic tensile tests with superimposed ultrasonic oscillations for stainless steel type 321 at room temperature

International Nuclear Information System (INIS)

Schinke, B.; Malmberg, T.

1987-01-01

In recent years various containment codes for Fast Breeder Reactor accidents have been assessed by comparison with explosion tests in water-filled vessels (COVA experiments). Common to the various codes, a systematic underestimation of the circumferential vessel strains was found. In the COVA tests high frequency pressure oscillations in the ultrasonic range were observed and thus it has been conjectured that the phenomenon of ''acoustic softening'' might be relevant in explaining the discrepancies in the strains. To validate this conjecture a hydro-pneumatic tensile test apparatus was developed which allows dynamic tensile testing at room temperature with and without superimposed ultrasonic oscillations. The dynamic tensile tests on the COVA sheet material (stainless steel AISI 321) without ultrasonic insonation show a linear dependence of the flow stress on the logarithm of the strain rate. The results at low strain rates (10 -3 s -1 ) agree favourably with previous measurements but at high rates (50 s -1 ) at 20% lower flow stress is observed. The dynamic tensile tests with continuous and intermittent insonation show the phenomenon of ''acoustic softening'': The average flow stress is reduced by an amount of about half the oscillating amplitude. At high strain rates the reduction is less. A severe ''acoustic softening'' observed by several authors for various metals at low strain rates was not observed. The experimental results were compared with the theory of the superpositon mechanism assuming a rate-independent elastic-plastic and an elastic-viscoplastic constitutive model. Although the rate-independent model is capable to predict qualitatively some of the observed effects, a better description is obtained with the viscoplastic model. The conclusion is that the ''acoustic softening'' of the COVA material is far too small to explain the discrepancies between measured and computed strains found in the containment code validation studies. (orig.)

HYBRID CONTINUUM-DISCONTINUUM MODELLING OF ROCK FRACUTRE PROCESS IN BRAZILIAN TENSILE STRENGTH TEST

Directory of Open Access Journals (Sweden)

Huaming An

2017-10-01

Full Text Available A hybrid continuum-discontinuum method is introduced to model the rock failure process in Brazilian tensile strength (BTS test. The key component of the hybrid continuum-discontinuum method, i.e. transition from continuum to discontinuum through fracture and fragmentation, is introduced in detail. A laboratory test is conducted first to capture the rock fracture pattern in the BTS test while the tensile strength is calculated according to the peak value of the loading forces. Then the proposed method is used to model the rock behaviour during BTS test. The stress propagation is modelled and compared with those modelled by finite element method in literatures. In addition, the crack initiation and propagation are captured and compared with the facture patter in laboratory test. Moreover, the force-loading displacement curve is obtained which represents a typical brittle material failure process. Furthermore, the stress distributions along the vertical direction are compared with the theoretical solution. It is concluded that the hybrid continuum-discontinuum method can model the stress propagation process and the entire rock failure process in BTS test. The proposed method is a valuable numerical tool for studying the rock behaviour involving the fracture and fragmentation processes.

A Simulation Model for Tensile Fracture Procedure Analysis of Graphite Material based on Damage Evolution

International Nuclear Information System (INIS)

Zhao Erqiang; Ma Shaopeng; Wang Hongtao

2014-01-01

Graphite material is generally easy to be damaged by the widely distributed micro-cracks when subjects to load. For numerically analyzing of the structure made of graphite material, the influences of the degradation of the material in damaged areas need to be considered. In this paper, an axial tension test method is proposed to obtain the dynamic damage evolution rule of the material. Using the degradation rule (variation of elastic modulus), the finite element model is then constructed to analyze the tensile fracture process of the L-shaped graphite specimen. An axial tension test of graphite is performed to obtain the stress-strain curve. Based on the variation of the measured curve, the damage evolution rule of the material are fitted out. A simulation model based on the above measured results is then constructed on ABAQUS by user subroutine. Using this simulation model, the tension failure process of L-shaped graphite specimen with fillet are simulated. The calculated and experimental results on fracture load are in good agreement. The damage simulation model based on the stress-strain curve of axial tensile test can be used in other tensile fracture analysis. (author)

Stress corrosion cracking prevention using solar electricity

International Nuclear Information System (INIS)

Harijan, K.; Uqaaili, M.A; Mirani, M.

2004-01-01

Metallic structures exposed to soil and water naturally experience corrosion due to electrolytic action. These structures are also subjected to sustained tensile stresses. The combined effects of corrosion and stress results stress corrosion cracking (SCC). Removal of either of these i.e. stress or corrosion prevents SCC. The cathodic protection (CP) prevents corrosion, and hence prevents stress corrosion. Solar Photo voltaic (PV) generated electricity can be best external power source for CP systems especially in remote areas. This paper presents CP system using solar PV generated electricity as an external power source for prevention of SCC of metallic structures. The paper also compares CP systems using solar electricity with those of CP systems using conventional electricity. The paper concludes that a solar electricity power system provides a reliable solution for powering CP stations especially in remote areas, enables the placing of CP units in any location, and thus ensures optimal current distribution for the exact protection requirements. The paper also concludes that solar electricity CP systems are well suited for SCC protection of metallic structures especially in remote areas of an energy deficit country like Pakistan. (author)

Tailoring of in-plane magnetic anisotropy in polycrystalline cobalt thin films by external stress

Energy Technology Data Exchange (ETDEWEB)

Kumar, Dileep, E-mail: dkumar@csr.res.in [UGC-DAE Consortium for Scientic Research, Khandwa Road, Indore 452001 (India); Singh, Sadhana [UGC-DAE Consortium for Scientic Research, Khandwa Road, Indore 452001 (India); Vishawakarma, Pramod [School of Nanotechnology, RGPV, Bhopal 462036 (India); Dev, Arun Singh; Reddy, V.R. [UGC-DAE Consortium for Scientic Research, Khandwa Road, Indore 452001 (India); Gupta, Ajay [Amity Center for Spintronic Materials, Amity University, Sector 125, Noida 201303 (India)

2016-11-15

Polycrystalline Co films of nominal thickness ~180 Å were deposited on intentionally curved Si substrates. Tensile and compressive stresses of 100 MPa and 150 MPa were induced in the films by relieving the curvature. It has been found that, within the elastic limit, presence of stress leads to an in-plane magnetic anisotropy in the film and its strength increases with increasing stress. Easy axis of magnetization in the films is found to be parallel/ transverse to the compressive /tensile stresses respectively. The origin of magnetic anisotropy in the stressed films is understood in terms of magneto- elastic coupling, where the stress try to align the magnetic moments in order to minimize the magneto-elastic as well as anisotropy energy. Tensile stress is also found to be responsible for the surface smoothening of the films, which is attributed to the movement of the atoms associated with the applied stress. The present work provides a possible way to tailor the magnetic anisotropy and its direction in polycrystalline and amorphous films using external stress. - Highlights: • Tensile and compressive stresses were induced in Co films by removing the bending force from the substrates after film deposition. • Controlled external mechanical stress is found to be responsible for magnetic anisotropies in amorphous and polycrystalline thin films, where crystalline anisotropy is absent. • Tensile stress leads to surface smoothening of the polycrystalline Co films.

Measurements of the tensile and compressive properties of micro-concrete used in the Winfrith missile impact experiments

International Nuclear Information System (INIS)

Wilson, P.A.

1982-10-01

Tests to determine the tensile and compressive properties of a micro-concrete mix are described. The material is a nominally 40MPa ultimate compressive strength concrete used in impact tests with scale models in the prediction of responses in prototype concrete structures. Compressive tests were intended to give complete stress-strain relationships beyond initial failure. Tensile properties were measured by the Brazilian splitting technique and direct tension dog-bone specimens for comparison reasons. (U.K.)

Metastability and relaxation in tensile SiGe on Ge(001) virtual substrates

International Nuclear Information System (INIS)

Frigerio, Jacopo; Lodari, Mario; Chrastina, Daniel; Mondiali, Valeria; Isella, Giovanni; Bollani, Monica

2014-01-01

We systematically study the heteroepitaxy of SiGe alloys on Ge virtual substrates in order to understand strain relaxation processes and maximize the tensile strain in the SiGe layer. The degree of relaxation is measured by high-resolution x-ray diffraction, and surface morphology is characterized by atomic force microscopy. The results are analyzed in terms of a numerical model, which considers dislocation nucleation, multiplication, thermally activated glide, and strain-dependent blocking. Relaxation is found to be sensitive to growth rate and substrate temperature as well as epilayer misfit and thickness, and growth parameters are found which allow a SiGe film with over 4 GPa of tensile stress to be obtained.

Effects of Ultrasonic Nanocrystal Surface Modification on the Residual Stress, Microstructure, and Corrosion Resistance of 304 Stainless Steel Welds

Science.gov (United States)

Ye, Chang; Telang, Abhishek; Gill, Amrinder; Wen, Xingshuo; Mannava, Seetha R.; Qian, Dong; Vasudevan, Vijay K.

2018-03-01

In this study, ultrasonic nanocrystal surface modification (UNSM) of 304 stainless steel welds was carried out. UNSM effectively eliminates the tensile stress generated during welding and imparts beneficial compressive residual stresses. In addition, UNSM can effectively refine the grains and increase hardness in the near-surface region. Corrosion tests in boiling MgCl2 solution demonstrate that UNSM can significantly improve the corrosion resistance due to the compressive residual stresses and changes in the near-surface microstructure.

Modeling the Monotonic and Cyclic Tensile Stress-Strain Behavior of 2D and 2.5D Woven C/SiC Ceramic-Matrix Composites

Science.gov (United States)

Li, L. B.

2018-05-01

The deformation of 2D and 2.5 C/SiC woven ceramic-matrix composites (CMCs) in monotonic and cyclic loadings has been investigated. Statistical matrix multicracking and fiber failure models and the fracture mechanics interface debonding approach are used to determine the spacing of matrix cracks, the debonded length of interface, and the fraction of broken fibers. The effects of fiber volume fraction and fiber Weibull modulus on the damage evolution in the composites and on their tensile stress-strain curves are analyzed. When matrix multicracking and fiber/matrix interface debonding occur, the fiber slippage relative to the matrix in the debonded interface region of the 0° warp yarns is the main reason for the emergance of stress-strain hysteresis loops for 2D and 2.5D woven CMCs. A model of these loops is developed, and histeresis loops for the composites in cyclic loadings/unloadings are predicted.

Modeling of hot tensile and short-term creep strength for LWR piping materials under severe accident conditions

International Nuclear Information System (INIS)

Harada, Y.; Maruyama, Y.; Chino, E.; Shibazaki, H.; Kudo, T.; Hidaka, A.; Hashimoto, K.; Sugimoto, J.

2000-01-01

The analytical study on severe accident shows the possibility of the reactor coolant system (RCS) piping failure before reactor pressure vessel failure under the high primary pressure sequence at pressurized water reactors. The establishment of the high-temperature strength model of the realistic RCS piping materials is important in order to predict precisely the accident progression and to evaluate the piping behavior with small uncertainties. Based on material testing, the 0.2% proof stress and the ultimate tensile strength above 800degC were given by the equations of second degree as a function of the reciprocal absolute temperature considering the strength increase due to fine precipitates for the piping materials. The piping materials include type 316 stainless steel, type 316 stainless steel of nuclear grade, CF8M cast duplex stainless steel and STS410 carbon steel. Also the short-term creep rupture time and the minimum creep rate at high-temperature were given by the modified Norton's Law as a function of stress and temperature considering the effect of the precipitation formation and resolution on the creep strength. The present modified Norton's Law gives better results than the conventional Larson-Miller method. Correlating the creep data (the applied stress versus the minimum creep rate) with the tensile data (the 0.2% proof stress or the ultimate tensile strength versus the strain rate), it was found that the dynamic recrystallization significantly occurred at high-temperature. (author)

Elastic-plastic analysis of the SS-3 tensile specimen

International Nuclear Information System (INIS)

Majumdar, S.

1998-01-01

Tensile tests of most irradiated specimens of vanadium alloys are conducted using the miniature SS-3 specimen which is not ASTM approved. Detailed elastic-plastic finite element analysis of the specimen was conducted to show that, as long as the ultimate to yield strength ratio is less than or equal to 1.25 (which is satisfied by many irradiated materials), the stress-plastic strain curve obtained by using such a specimen is representative of the true material behavior

High temperature aqueous stress corrosion testing device

International Nuclear Information System (INIS)

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

1975-01-01

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

Tensile testing study of dynamic interactions between dislocations and precipitate in vanadium alloys

International Nuclear Information System (INIS)

Tougou, Kouichi; Nogiwa, Kimihiro; Tachikawa, Kazuhiro; Fukumoto, Ken-ichi

2013-01-01

To investigate the hardening of fine Ti(OCN) precipitate, we performed in situ transmission electron microscopy (TEM) observations during tensile testing of dislocations gliding through fine Ti(OCN) precipitates in thermally aged V–4Cr–4Ti alloys. The obstacle strength parameter was estimated from the critical bow-out angle, ϕ, of the dislocation lines from the microstructural change during tensile deformation observed in the TEM images. From image processing analysis of the dislocation motion, the value of the obstacle strength parameter of Ti(OCN) precipitates of 4-nm size was determined to be 0.30. The increase in yield stress calculated from the measured dislocation behavior pinned around precipitates was Δσ in situ = 43 MPa, and the increase in yield stress measured by the micro-Vickers hardness test was Δσ HV = 49.5 MPa. Data from in situ TEM observations during tensile testing and from micro-Vickers hardness tests were in good agreement; thus, the obstacle strength parameter of the Ti(OCN) precipitates of 4-nm size was successfully obtained experimentally. The obstacle strength parameter also was compared with data from a previous study, and there was also quite good agreement. Therefore, the obstacle strength parameter obtained from this study is measurable and is a reliable measure of mechanical property changes following precipitation in V–4Cr–4Ti alloys

Stresses in sulfuric acid anodized coatings on aluminum

Science.gov (United States)

Alwitt, R. S.; Xu, J.; Mcclung, R. C.

1993-01-01

Stresses in porous anodic alumina coatings have been measured for specimens stabilized in air at different temperatures and humidities. In ambient atmosphere the stress is tensile after anodic oxidation and is compressive after sealing. Exposure to dry atmosphere causes the stress to change to strongly tensile, up to 110 MPa. The stress increase is proportional to the loss of water from the coating. These changes are reversible with changes in humidity. Similar reversible effects occur upon moderate temperature changes. The biaxial modulus of the coating is about 100 GPa.

Residual stresses and stress corrosion effects in cast steel nuclear waste overpacks

International Nuclear Information System (INIS)

Attinger, R.O.; Mercier, O.; Knecht, B.; Rosselet, A.; Simpson, J.P.

1991-01-01

In the concepts for final disposal of high-level radioactive waste in Switzerland, one engineered barrier consists of an overpack made out of cast steel GS-40. Whenever tensile stresses are expected in the overpack, the issue of stress corrosion cracking must be expected. A low-strength steel was chosen to minimize potential problems associated with stress corrosion cracking. A series of measurements on stress corrosion cracking under the conditions as expected in the repository confirmed that the corrosion allowance of 50 mm used for the design of the reference overpack is sufficient over the 1000 years design lifetime. Tensile stresses are introduced by the welding process when the overpack is closed. For a multipass welding, the evolution of deformations, strains and stresses were determined in a finite-element calculation. Assuming an elastic-plastic material behavior without creep, the residual stresses are high; considering creep would reduce them. A series of creep tests revealed that the initial creep rate is important for cast steel already at 400deg C. (orig.)

A study of stress reorientation of hydrides in zircaloy

Energy Technology Data Exchange (ETDEWEB)

Yourong, Jiang; Bangxin, Zhou [Nuclear Power Inst. of China, Chengdu, SC (China)

1994-10-01

Under the conditions of circumferential tensile stress from 70 to 180 MPa for Zircaloy tubes or the tensile stress from 55 to 180 MPa for Zircaloy-4 plates and temperature cycling between 150 and 400 degree C, the effects of stress and the number of temperature cycling on hydride reorientation in Zircaloy-4 tubes and plates and Zircaloy-2 tubes containing about 220 {mu}g/g hydrogen have been investigated. With the increase of stress and/or the number of temperature cycling, the level of hydride reorientation increases. When hydride reorientation takes place, there is a threshold stress concerned with the number of temperature cycling. Below the threshold stress, hydride reorientation is not obvious. When applied stress is higher than the threshold stress, the level of hydride reorientation increases with the increase of stress and the number of temperature cycling. Hydride reorientation in Zircaloy-4 tubes develops gradually from the outer surface to inner surface. It might be related to the difference of texture between outer surface and inner surface. The threshold stress is affected by both the texture and the value of B. So controlling texture could still restrict hydride reorientation under tensile stress.

Tensile Properties of the Deep Transverse Metatarsal Ligament in Hallux Valgus

Science.gov (United States)

Abdalbary, Sahar Ahmed; Elshaarawy, Ehab A.A.; Khalid, Bahaa E.A.

2016-01-01

Abstract The deep transverse metatarsal ligament (DTML) connects the neighboring 2 metatarsal heads and is one of the stabilizers connecting the lateral sesamoid and second metatarsal head. In this study, we aimed to determine the tensile properties of the DTML in normal specimens and to compare these results with hallux valgus specimens. We hypothesized that the tensile properties of the DTML would be different between the 2 groups of specimens. The DTML in the first interspace was dissected from 12 fresh frozen human cadaveric specimens. Six cadavers had bilateral hallux valgus and the other 6 cadavers had normal feet. The initial length (L0) and cross-sectional area (A0) of the DTML were measured using a digital caliper, and tensile tests with load failure were performed using a material testing machine. There were significant between-groups differences in the initial length (L0) P = 0.009 and cross-sectional area (A0) of the DTML P = 0.007. There were also significant between-groups differences for maximum force (N) P = 0.004, maximum distance (mm) P = 0.005, maximum stress (N/mm2) P = 0.003, and maximum strain (%) P = 0.006. The DTML is an anatomical structure for which the tensile properties differ in hallux valgus. PMID:26937914

Stress envelope of silicon carbide composites at elevated temperatures

International Nuclear Information System (INIS)

Nozawa, Takashi; Kim, Sunghun; Ozawa, Kazumi; Tanigawa, Hiroyasu

2014-01-01

To identify a comprehensive stress envelope, i.e., strength anisotropy map, of silicon carbide fiber-reinforced silicon carbide matrix composite (SiC/SiC composite) for practical component design, tensile and compressive tests were conducted using the small specimen test technique specifically tailored for high-temperature use. In-plane shear properties were, however, estimated using the off-axial tensile method and assuming that the mixed mode failure criterion, i.e., Tsai–Wu criterion, is valid for the composites. The preliminary test results indicate no significant degradation to either proportional limit stress (PLS) or fracture strength by tensile loading at temperatures below 1000 °C. A similarly good tolerance of compressive properties was identified at elevated temperatures, except for a slight degradation in PLS. With the high-temperature test data of tensile, compressive and in-plane shear properties, the stress envelopes at elevated temperatures were finally obtained. A slight reduction in the design limit was obvious at elevated temperatures when the compressive mode is dominant, whereas a negligibly small impact on the design is expected by considering the tensile loading case

Stress envelope of silicon carbide composites at elevated temperatures

Energy Technology Data Exchange (ETDEWEB)

Nozawa, Takashi, E-mail: nozawa.takashi67@jaea.go.jp [Japan Atomic Energy Agency, 2-166 Omotedate, Obuchi, Rokkasho, Aomori 039-3212 (Japan); Kim, Sunghun [Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Ozawa, Kazumi; Tanigawa, Hiroyasu [Japan Atomic Energy Agency, 2-166 Omotedate, Obuchi, Rokkasho, Aomori 039-3212 (Japan)

2014-10-15

To identify a comprehensive stress envelope, i.e., strength anisotropy map, of silicon carbide fiber-reinforced silicon carbide matrix composite (SiC/SiC composite) for practical component design, tensile and compressive tests were conducted using the small specimen test technique specifically tailored for high-temperature use. In-plane shear properties were, however, estimated using the off-axial tensile method and assuming that the mixed mode failure criterion, i.e., Tsai–Wu criterion, is valid for the composites. The preliminary test results indicate no significant degradation to either proportional limit stress (PLS) or fracture strength by tensile loading at temperatures below 1000 °C. A similarly good tolerance of compressive properties was identified at elevated temperatures, except for a slight degradation in PLS. With the high-temperature test data of tensile, compressive and in-plane shear properties, the stress envelopes at elevated temperatures were finally obtained. A slight reduction in the design limit was obvious at elevated temperatures when the compressive mode is dominant, whereas a negligibly small impact on the design is expected by considering the tensile loading case.

Stress map for ion irradiation: Depth-resolved dynamic competition between radiation-induced viscoelastic phenomena in SiO2

International Nuclear Information System (INIS)

Dillen, T. van; Siem, M.Y.S.; Polman, A.

2004-01-01

The dynamic competition between structural transformation, Newtonian viscous flow, and anisotropic strain generation during ion irradiation of SiO 2 , leads to strongly depth-dependent evolution of the mechanical stress, ranging between compressive and tensile. From independent in situ stress measurements during irradiation, generic expressions are derived of the nuclear stopping dependence of both the structural transformation rate and the radiation-induced viscosity. Using these data we introduce and demonstrate the concept of a 'stress map' that predicts the depth-resolved saturation stress in SiO 2 for any irradiation up to several MeV

The effect of strain rate and temperature on the tensile behaviour of uranium 2 w/o molybdenum

International Nuclear Information System (INIS)

Harding, J.; Boyd, G.A.C.

1983-01-01

This report describes the uniaxial tensile behaviour of uranium 2 w/o molybdenum alloy over a wide range of temperature and strain rate. Specimen blanks taken from co-reduced and extruded U 2 w/o Mo rods were given one of two heat treatments. Longitudinal tensile test pieces, taken from these blanks at near surface locations were tested in the temperature range -150 deg C to +100 deg C at strain rates from quasistatic (10 -4 s -1 ) to 10 3 s -1 . To achieve this range of testing rates three machines were required: an Instron screw driven machine for rates up to 0.1 s -1 , a second specially constructed hydraulic machine for the range 0.1 s -1 to 50 s -1 and a drop weight machine for the highest strain rates. The ways in which the mechanical properties - elongation to fracture, flow stresses and ultimate tensile stress - vary with both temperature and strain rate are presented and discussed for material in both heat treatment conditions. (author)

Stress field determination in an alloy 600 stress corrosion crack specimen; Determination du champ de contraintes dans une eprouvette de corrosion sous contrainte de l`alliage 600

Energy Technology Data Exchange (ETDEWEB)

Rassineux, B.; Labbe, T.

1995-05-01

In the context of EDF studies on stress corrosion cracking rates in the Alloy 600 steam generators tubes, we studied the influence of strain hardened surface layers on the different stages of cracking for a tensile smooth specimen (TLT). The stress field was notably assessed to try and explain the slow/rapid-propagation change observed beyond the strain hardened layers. The main difficulty is to simulate in a finite element model the inner and outer surfaces of these strain hardened layers, produced by the final manufacturing stages of SG tubes which have not been heat treated. In the model, the strain hardening is introduced by simulating a multi-layer material. Residual stresses are simulated by an equivalent fictitious thermomechanical calculation, realigned with respect to X-ray measurements. The strain hardening introduction method was validated by an analytical calculation giving identical results. Stress field evolution induced by specimen tensile loading were studied using an elastoplastic 2D finite element calculations performed with the Aster Code. The stress profile obtained after load at 660 MPa shows no stress discontinuity at the boundary between the strain hardened layer and the rest of the tube. So we propose that a complementary calculation be performed, taking into account the multi-cracked state of the strain hardened zones by means of a damage variable. In fact, this state could induce stress redistribution in the un-cracked area, which would perhaps provide an explanation of the crack-ground rate change beyond the strain hardened zone. The calculations also evidence the harmful effects of plastic strains on a strain hardened layer due to the initial state of the tube (not heat-treated), to grit blasting or to shot peening. The initial compressive stress condition of this surface layer becomes, after plastic strain, a tensile stress condition. These results are confirmed by laboratory test. (author). 10 refs., 18 figs., 9 tabs., 2 appends.

LPTR irradiation of LLL vanadium tensile specimens and LLL Nb--1Zr tensile specimens

International Nuclear Information System (INIS)

MacLean, S.C.; Rowe, C.L.

1977-01-01

The LPTR irradiation of 14 LLL vanadium tensile specimens and 14 LLL Nb-1Zr tensile specimens is described. Sample packaging, the irradiation schedule and neutron fluences for three energy ranges are given

Influence of laser peening on the tensile strength and impact toughness of dissimilar welds of Inconel 625 and UNS S32205

Energy Technology Data Exchange (ETDEWEB)

Ramkumar, K. Devendranath, E-mail: ramdevendranath@gmail.com [School of Mechanical Engineering, VIT University, Vellore 632014 (India); Kumar, P. Siva Goutham; Krishna, V. Radha; Chandrasekhar, Aditya; Dev, Sidharth; Abraham, Winston Sunny [School of Mechanical Engineering, VIT University, Vellore 632014 (India); Prabhakaran, S.; Kalainathan, S. [Centre for Crystal Growth, VIT University, Vellore 632014 (India); Sridhar, R. [Saraswathi Velu Engineering College, Sholinghur, Vellore 632501 (India)

2016-10-31

The present study addresses the effect of fillers on the microstructure and tensile strength of dissimilar joints of Inconel 625 and UNS S32205 by pulsed current gas tungsten arc welding (PCGTAW) employing ERNiCrMo-10 and ERNiCrMo-14 fillers. This study attested that tensile failure occurred in the fusion zone of the dissimilar joints for both the cases in the as-welded un-peened condition. Double shot laser shock peening (DLSP) was performed on the fusion zone of these PCGTA welds on the cap and root regions of the weldments. It was assimilated that after DLSP on the cap and root regions of the weldments, the yield and tensile strength of the welded joints employing these fillers were improved considerably. Residual stress analysis were carried out on the dissimilar coupons using X-ray Diffraction analysis. The results demonstrated that after subjecting to double sided DLSP, the fusion zones were subjected to compressive residual stresses. The present study articulated that shot peening using low energy laser beam resulted in better tensile strength.

Microstructure evolution of a pre-compression nickel-base single crystal superalloy during tensile creep

International Nuclear Information System (INIS)

Yu Xingfu; Tian Sugui; Du Hongqiang; Yu Huichen; Wang Minggang; Shang Lijuan; Cui Shusen

2009-01-01

By pre-compressive creep treatment, the cubical γ' phase in the nickel-base single crystal superalloy is transformed into the P-type rafted structure along the direction parallel to the applied stress axis. And the microstructure evolution of the P-type γ' rafted alloy during tensile creep is investigated by means of the measurement of the creep curve and microstructure observation. Results show that the P-type γ' rafted phase in the alloy is transformed into the N-type structure along the direction perpendicular to the applied stress axis in the initial stage of the tensile creep. In the role of the tensile stress at high temperature, the change of the element's equilibrium concentration in the different regions of P-type γ' rafted phase occurs, which promotes the inhomogeneous coarsening of the P-type γ' phase. And then, the decomposition of the P-type γ' rafted phase in the alloy occurs to form the groove structure. As of result of the directional diffusion of the elements, the fact that the P-type γ' rafted phase is decomposed to transform into the cubical-like structure is attributed to the increment of the solute elements M(Ta, Al) chemical potential in the groove regions. Further, the lattice constriction in the horizontal interfaces of the cubical-like γ' phase may repel out the Al and Ta atoms with higher radius due to the role of the shearing stress, and the lattice expanding in the upright interfaces of the cubical-like γ' phase, due to the role of the tension stress, may trap the Ta and Al atoms, which promotes the directional growing of γ' phase into the N-type rafted structure. Therefore, the change of the strain energy density in different interfaces of the cubical-like γ' phase is thought to be the driving force of the elements diffusing and the directional coarsening of γ' phase

Investigation of Tensile Creep of a Normal Strength Overlay Concrete.

Science.gov (United States)

Drexel, Martin; Theiner, Yvonne; Hofstetter, Günter

2018-06-12

The present contribution deals with the experimental investigation of the time-dependent behavior of a typical overlay concrete subjected to tensile stresses. The latter develop in concrete overlays, which are placed on existing concrete structures as a strengthening measure, due to the shrinkage of the young overlay concrete, which is restrained by the substrate concrete. Since the tensile stresses are reduced by creep, creep in tension is investigated on sealed and unsealed specimens, loaded at different concrete ages. The creep tests as well as the companion shrinkage tests are performed in a climatic chamber at constant temperature and constant relative humidity. Since shrinkage depends on the change of moisture content, the evolution of the mass water content is determined at the center of each specimen by means of an electrolytic resistivity-based system. Together with the experimental results for compressive creep from a previous study, a consistent set of time-dependent material data, determined for the same composition of the concrete mixture and on identical specimens, is now available. It consists of the hygral and mechanical properties, creep and shrinkage strains for both sealed and drying conditions, the respective compliance functions, and the mass water contents in sealed and unsealed, loaded and load-free specimens.

Strain rate dependent tensile behavior of advanced high strength steels: Experiment and constitutive modeling

International Nuclear Information System (INIS)

Kim, Ji-Hoon; Kim, Daeyong; Han, Heung Nam; Barlat, F.; Lee, Myoung-Gyu

2013-01-01

High strain rate tensile tests were conducted for three advanced high strength steels: DP780, DP980 and TRIP780. A high strain rate tensile test machine was used for applying the strain rate ranging from 0.1/s to 500/s. Details of the measured stress–strain responses were comparatively analyzed for the DP780 and TRIP780 steels which show similar microstructural feature and ultimate tensile strength, but different strengthening mechanisms. The experimental observations included: usual strain rate dependent plastic flow stress behavior in terms of the yield stress (YS), the ultimate tensile strength (UTS), the uniform elongation (UE) and the total elongation (TE) which were observed for the three materials. But, higher strain hardening rate at early plastic strain under quasi-static condition than that of some increased strain rates was featured for TRIP780 steel, which might result from more active transformation during deformation with lower velocity. The uniform elongation that explains the onset of instability and the total elongation were larger in case of TRIP steel than the DP steel for the whole strain rate range, but interestingly the fracture strain measured by the reduction of area (RA) method showed that the TRIP steel has lower values than DP steel. The fractographs using scanning electron microscopy (SEM) at the fractured surfaces were analyzed to relate measured fracture strain and the microstructural difference of the two materials during the process of fracture under various strain rates. Finally, constitutive modeling for the plastic flow stresses under various strain rates was provided in this study. The proposed constitutive law could represent both Hollomon-like and Voce-like hardening laws and the ratio between the two hardening types was efficiently controlled as a function of strain rate. The new strength model was validated successfully under various strain rates for several grades of steels such as mild steels, DP780, TRIP780, DP980 steels.

Residual tensile stresses and piezoelectric properties in BiFeO3-Bi(Zn1/2Ti1/2O3-PbTiO3 ternary solid solution perovskite ceramics

Directory of Open Access Journals (Sweden)

Weilin Zheng

2016-08-01

Full Text Available For low dielectric loss perovskite-structured (1-x-yBiFeO3-xBi(Zn1/2Ti1/2O3-yPbTiO3 (BF-BZT-PT (x = 0.04-0.15 and y = 0.15-0.26 ceramics in rhombohedral/tetragonal coexistent phase, structural phase transitions were studied using differential thermal analyzer combined with temperature-dependent dielectric measurement. Two lattice structural phase transitions are disclosed in various BF-BZT-PT perovskites, which is different from its membership of BiFeO3 exhibiting just one lattice structural phase transition at Curie temperature TC= 830oC. Consequently, residual internal tensile stresses were revealed experimentally through XRD measurements on ceramic pellets and counterpart powders, which are reasonably attributed to special structural phase transition sequence of BF-BZT-PT solid solution perovskites. Low piezoresponse was observed and argued extrinsically resulting from residual tensile stresses pinning ferroelectric polarization switching. Post-annealing and subsequent quenching was found effective for eliminating residual internal stresses in those BZT-less ceramics, and good piezoelectric property of d33 ≥ 28 pC/N obtained for 0.70BF-0.08BZT-0.22PT and 0.05 wt% MnO2-doped 0.70BF-0.04BZT-0.26PT ceramics with TC ≥ 640oC, while it seemed no effective for those BZT-rich BF-BZT-PT ceramics with x = 0.14 and 0.15 studied here.

Modelling of thermal stress in vapor generator supports

International Nuclear Information System (INIS)

Halpert, S.; Vazquez, L.

1997-01-01

To assure safety and availability of a nuclear power plant components or equipment stress analysis are done. When thermal loads are involved it's necessary to know the temperature field of the component or equipment. This paper describes the structural analysis of a steam generator lug with thermal load including the model used for computer simulation and presents the evolution of the temperature profile, the stress intensity and principal stress during start up and shut down of a nuclear power reactor. Temperature field obtained from code calculation show good agreement with the experimental data while stress analysis results are in agreement with a preview estimation. (author) [es

Vulnerability-specific stress generation: An examination of negative cognitive and interpersonal styles

OpenAIRE

Liu, Richard T.; Alloy, Lauren B.; Mastin, Becky M.; Choi, Jimmy Y.; Boland, Elaine M.; Jenkins, Abby L.

2014-01-01

Although there is substantial evidence documenting the stress generation effect in depression (i.e., the tendency for depression-prone individuals to experience higher rates of life stress to which they contribute), additional research is required to advance current understanding of the specific types of dependent stress (i.e., events influenced by characteristics and attendant behaviors of the individual) relevant to this effect. The present study tested an extension of the stress generation...

Low cycle fatigue of 2.25Cr1Mo steel with tensile and compressed hold loading at elevated temperature

Energy Technology Data Exchange (ETDEWEB)

Zhang, Junfeng; Yu, Dunji; Zhao, Zizhen; Zhang, Zhe; Chen, Gang; Chen, Xu, E-mail: xchen@tju.edu.cn

2016-06-14

A series of uniaxial strain-controlled fatigue and creep-fatigue tests of the bainitic 2.25Cr1Mo steel forging were performed at 455 °C in air. Three different hold periods (30 s, 120 s, 300 s) were employed at maximum tensile strain and compressive strain under fully reversed strain cycling. Both tensile and compressive holds significantly reduce the fatigue life. Fatigue life with tensile hold is shorter than that with compressive hold. A close relationship is found between the reduction of fatigue life and the amount of stress relaxation. Microstructural examination by scanning electron microscope reveals that strain hold introduces more crack sources, which can be probably ascribed to the intensified oxidation and the peeling-off of oxide layers. A modified plastic strain energy approach considering stress relaxation effect is proposed to predict the creep-fatigue life, and the predicted lives are in superior agreement with the experimental results.

The Effect of Peak Temperatures and Hoop Stresses on Hydride Reorientations of Zirconium Alloy Cladding Tubes under Interim Dry Storage Condition

International Nuclear Information System (INIS)

Cha, Hyun Jin; Jang, Ki Nam; Kim, Kyu Tae

2016-01-01

In this study, the effect of peak temperatures and hoop tensile stresses on hydride reorientation in cladding was investigated. It was shown that the 250ppm-H specimens generated larger radial hydride fractions and longer radial hydrides than the 500ppm-H ones. The precipitated hydride in radial direction severely degrades mechanical properties of spent fuel rod. Hydride reorientation is related to cladding material, cladding temperature, hydrogen contents, thermal cycling, hoop stress and cooling rate. US NRC established the regulation on cladding temperature during the dry storage, which is the maximum fuel cladding temperature should not exceed 400 .deg. C for all fuel burnups under normal conditions of storage. However, if it is proved that the best estimate cladding hoop stress is equal to or less than 90MPa for the temperature limit proposed, a higher short-term temperature limit is allowed for low burnup fuel. In this study, 250ppm and 500ppm hydrogen-charged Zr-Nb alloy cladding tubes were selected to evaluate the effect of peak temperatures and hoop tensile stresses on the hydride reorientation during the dry storage. In order to evaluate threshold stresses in relation to various peak temperatures, four peak temperatures of 250, 300, 350, and 400 .deg. C and three tensile hoop stresses of 80, 100, 120MPa were selected.

The physical interpretation of the parameters measured during the tensile testing of materials at elevated temperatures

International Nuclear Information System (INIS)

Burton, B.

1984-01-01

Hot tensile (or compression) testing, where the stress developed in a material is measured under an imposed strain rate, is often used as an alternative to conventional creep testing. The advantages of the hot tensile test are that its duration can be more closely controlled by the experimenter and also that the technique is more convenient, since high precision testing machines are available. The main disadvantage is that the interpretation of results is more complex. The present paper relates the parameters which are measured in hot tensile tests, to physical processes which occur in materials deforming by a variety of mechanisms. For cases where no significant structural changes occur, as in viscous or superplastic flow, analytical expressions are derived which relate the stresses measured in these tests to material constants. When deformation is controlled by recovery processes, account has to be taken of the structural changes which occur concurrently. A wide variety of behaviour may then be exhibited which depends on the initial dislocation density, the presence of second-phase particles and the relative values of the recovery rate parameters and the velocity imposed by the testing machine. Numerical examples are provided for simple recovery models. (author)

Transient thermal stresses in circular cylinder under intermittently sudden heat generation

International Nuclear Information System (INIS)

Sugano, Y.; Saito, K.; Takeuti, Y.

1975-01-01

The thermal stresses associated with the transient temperature distribution arising in a circular cylinder under intermittently changing sudden heat generation over a finite band and with heat loss to a surrounding medium on the remainder of the cylinder surface are exactly analysed. For the first time the temperature field in a circular cylinder under sudden heat generation over a finite band of the cylinder surface is determined by combined use of Fourier cosine, Laplace transforms in axial position and time, respectively. Secondly it is assumed that the temperature fields in a circular cylinder subjected to heat generation Qsub(i) (i=0, 1, 2, ...) independently over a finite band are given by T 0 (r,z,t), T 1 (r,z,t), T 2 (r,z,t),... respectively. Tsub(i)(r,z,t) indicates the temperature field before the i-th heat generation Qsub(i). The thermal stresses associated with the temperature field described above are analysed by using the Hoyle stress functions. Numerical calculations are carried out for the extensive case of the ratio of the heat-generating length to the diameter of cylinder. It is found that the time in which the maximum stresses occur on the cylinder surface does not depend on the heat-generating length-to-diameter ratio

Thermal and stress analyses in thermoelectric generator with tapered and rectangular pin configurations

International Nuclear Information System (INIS)

Yilbas, Bekir Sami; Akhtar, S.S.; Sahin, A.Z.

2016-01-01

Thermal stress developed in thermoelectric generators is critical for long service applications. High temperature gradients, due to a large temperature difference across the junctions, causes excessive stress levels developed in the device pins and electrodes at the interfaces. In the present study, a thermoelectric generator with horizontal pin configuration is considered and thermal stress analysis in the device is presented. Ceramic wafer is considered to resemble the high temperature plate and copper electrodes are introduced at the pin junctions to reduce the electrical resistance between the pins and the high and low temperature junction plates during the operation. Finite element code is used to simulate temperature and stress fields in the thermoelectric generator. In the simulations, convection and radiation losses from the thermoelectric pins are considered and bismuth telluride pin material with and without tapering is incorporated. It is found that von Mises stress attains high values at the interface between the hot and cold junctions and the copper electrodes. Thermal stress developed in tapered pin configuration attains lower values than that of rectangular pin cross-section. - Highlights: • Different cold junction temperatures improves thermoelectric generator performance. • von Mises stress remains high across copper electrodes and hot junction ceramics. • von Mises stress reduces along pin length towards cold junction. • Pin tapering lowers stress levels in thermoelectric generator.

Tensile and dimensional properties of wood strands made from plantation southern pine lumber

Science.gov (United States)

Qinglin Wu; Zhiyong Cai; Jong N. Lee

2005-01-01

Working stresses and performance of strand composite lumber largely depend upon the properties of each individual strand. Southern pine strands from plantation lumber grown in southern Louisiana were investigated in this study in order to understand strand behaviors. The effects of hot-pressing and resin application on tensile modulus, strength, and dimensional...

The tensile behavior of GH3535 superalloy at elevated temperature

Energy Technology Data Exchange (ETDEWEB)

Han, F.F.; Zhou, B.M.; Huang, H.F.; Leng, B.; Lu, Y.L. [Thorium Molten Salts Reactor Center, Shanghai Institute of Applied Physics, Chinese Academy of Sciences (China); Dong, J.S. [Superalloy Division, Institute of Metal Research, Chinese Academy of Sciences (China); Li, Z.J., E-mail: lizhijun@sinap.ac.cn [Thorium Molten Salts Reactor Center, Shanghai Institute of Applied Physics, Chinese Academy of Sciences (China); Zhou, X.T. [Thorium Molten Salts Reactor Center, Shanghai Institute of Applied Physics, Chinese Academy of Sciences (China)

2016-10-01

The tensile behavior of GH3535 alloy has been investigated at strain rates of 8.33 × 10{sup −5}/s{sup −1}–8.33 × 10{sup −3}/s{sup −1}, in the temperature range of 25–800 °C. The results showed that the ultimate tensile strength was decreased with increasing temperature and increased with rising strain rate, whereas the yield strength kept almost a constant value at the temperature range from 550 to 800 °C in all strain rates test. The formation of M{sub 12}C carbides at the grain boundary during the tension process played an important role in increasing the yield strength of the alloy at elevated temperatures. But inhomogeneous deformation at 650 °C resulted in the minimum ductility of the alloy. Additionally, various types of serrations were noticed on the stress-strain curves for the alloy tested in the temperature range of 500–800 °C. Normal Portevin-Le Chatelier (PLC) effect and positive strain rate sensitivity were observed in this alloy. Type A and A + B serrations were presented to stress-strain curves at temperatures below 650 °C, whereas type C serration was noticed when the temperature rose above 650 °C. The analysis suggested that the interactions between substitutional solutes migration and mobile dislocations were the main reason for the serrated flow behavior in this alloy. - Highlights: • The tensile behavior of GH3535 alloy at elevated temperature was studied. • The yield strength anomaly was observed in the temperature range from 550 to 800 °C. • The formation of M{sub 12}C improves the grain boundary strength to a certain extent. • Inhomogeneous deformation at 650 °C results in the ductility loss of the alloy. • The interaction between solute atoms and dislocations results in the PLC effect.

Influence of grain size on the tensile and creep properties of a type 316 stainless steel

International Nuclear Information System (INIS)

Mannan, S.L.; Samuel, K.G.; Rodriguez, P.

The influence of grain size, on the tensile deformation behaviour in the temperature range 300-1223 K and on the creep rate at 873 and 973 K over a wide range of applied stresses, in a type 316 stainless steel has been investigated. For the tensile results, the Hall-Petch relation was found to be valid up to 1023 K. The variations of flow stress and work hardening rate with temperature and grain size have been found to be influenced by dynamic strain aging which occurs in the temperature range 523-923 K. The creep experiments revealed that grain boundaries contribute to strengthening at high stresses (180-260 MPa) at 873 K but this strengthening does not correlate with the available models which attempt to incorporate the Hall-Petch strengthening effect into creep rate equations. At 973 K the creep rate was generally constant but increased at small grain sizes and at lower stresses due to increased contribution from grain boundary sliding. The difference in the grain size effects on creep at the two temperatures is attributed to the difference in the substructures developed during creep. (author)

Elastic stress transmission and transformation (ESTT) by confined liquid: A new mechanics for fracture in elastic lithosphere of the earth

Science.gov (United States)

Xu, Xing-Wang; Peters, Stephen; Liang, Guang-He; Zhang, Bao-Lin

2016-01-01

We report on a new mechanical principle, which suggests that a confined liquid in the elastic lithosphere has the potential to transmit a maximum applied compressive stress. This stress can be transmitted to the internal contacts between rock and liquid and would then be transformed into a normal compressive stress with tangential tensile stress components. During this process, both effective compressive normal stress and tensile tangential stresses arise along the liquid–rock contact. The minimum effective tensile tangential stress causes the surrounding rock to rupture. Liquid-driven fracture initiates at the point along the rock–liquid boundary where the maximum compressive stress is applied and propagates along a plane that is perpendicular to the minimum effective tensile tangential stress and also is perpendicular to the minimum principal stress.

Microstructure and elevated-temperature tensile properties of differential pressure sand cast Mg-4Y-3Nd-0.5Zr alloy

Directory of Open Access Journals (Sweden)

Hong-hui Liu

2016-01-01

Full Text Available The microstructures of an Mg-4Y-3Nd-0.5Zr alloy by differential pressure casting were investigated using scanning electron microscopy (SEM and transmission electron microscopy (TEM, and its tensile deformation behavior was measured using a Gleeble1500D themo-simulation machine in the temperature range of 200 to 400 °C at initial strain rates of 5×10-4 to 10-1 s-1. Results show that the as-cast microstructure consists of primary α-Mg phase and bone-shaped Mg5RE eutectic phase distributed along the grain boundary. The eutectic phase is dissolved into the matrix after solution treatment and subsequently precipitates during peak aging. Tensile deformation tests show that the strain rate has little effect on stress under 300 °C. Tensile stress decreases with an increase in temperature and the higher strain rate leads to an increase in stress above 300 °C. The fracture mechanism exhibits a mixed quasi-cleavage fracture at 200 °C, while the fracture above 300 °C is a ductile fracture. The dimples are melted at 400 °C with the lowest strain rate of 10-4 s-1.

Stress evaluation of chemical vapor deposited silicon dioxide films

International Nuclear Information System (INIS)

Maeda, Masahiko; Itsumi, Manabu

2002-01-01

Film stress of chemical vapor deposited silicon dioxide films was evaluated. All of the deposited films show tensile intrinsic stresses. Oxygen partial pressure dependence of the intrinsic stress is very close to that of deposition rate. The intrinsic stress increases with increasing the deposition rate under the same deposition temperature, and decreases with increasing substrate temperature. Electron spin resonance (ESR) active defects in the films were observed when the films were deposited at 380 deg. C and 450 deg. C. The ESR signal intensity decreases drastically with increasing deposition temperature. The intrinsic stress correlates very closely to the intensity of the ESR-active defects, that is, the films with larger intrinsic stress have larger ESR-active defects. It is considered that the intrinsic stress was generated because the voids caused by local bond disorder were formed during random network formation among the SiO 4 tetrahedra. This local bond disorder also causes the ESR-active defects

The effect of strain rate and temperature on the tensile behaviour of uranium - 2sup(w)/o molybdenum

International Nuclear Information System (INIS)

Harding, J.; Boyd, G.A.C.

1983-01-01

This report describes the uniaxial tensile behaviour of uranium 2 w/o molybdenum alloy over a wide range of temperature and strain rate. Specimen blanks taken from co-reduced and extruded U2 w/o Mo rods were given one of two heat treatments. Longitudinal tensile test pieces, taken from these blanks at near surface locations were tested in the temperature range -150 deg C to +100 deg C at strain rates from quasistatic (10 -4 s -1 ) to 10 3 s -1 . To achieve this range of testing rates three machines were required: an Instron screw driven machine for rates up to 0.1 s -1 , a second specially constructed hydraulic machine for the range 0.1 s -1 to 50 s -1 and a drop weight machine for the highest strain rates. The ways in which the mechanical properties - elongation to fracture, flow stresses and ultimate tensile stress - vary with both temperature and strain rate are presented and discussed for material in both heat treatment conditions. (author)

The design of bonded reinforcement for thermal stresses in prestressed concrete reactor vessels

International Nuclear Information System (INIS)

Kotulla, B.; Hansson, V.

1977-01-01

This paper deals with examples of thermal loadings where instationary growth of tensile zones and redistribution of stresses by cracking are of importance. Temperatures produce, in addition to prestressing and internal pressure, the most important stresses in a prestressed concrete reactor pressure vessel. Characteristic of thermal stresses is that they are influenced to a large extent by creep of concrete and that they influence stress redistributions by temperature dependent creep data. Computations show that during the first instationary heating process of the vessel stresses are reduced by creep effects to about fifty percent of the values of the stationary elastic case at the hot face. With a following cooling, creep effects are generally much less, so this case may produce tensile stresses on the internal face of the wall which lead to cracking of the concrete. Tensile stresses first occur due to the instationary growth of the temperature field in a narrow zone near the liner. If outside this zone compressive stresses exist due to prestressing then crack spreading is limited and restraint by the parts of the wall under compression causes crack distribution even without reinforcement in this zone. Growth of cracks with the instationary spreading of tensile zones according to temperature development was calculated. These calculations take into account discrete cracks, reinforcement and different assumptions for tensile strength. Reinforcement of small diameter near the surface has the best influence on crack spacing. Calculations show that for the stationary state of cooling the forces in the reinforcement may be as low as twenty to thirty percent of the tensile force not taking into account cracking of the concrete

Knitting Technologies And Tensile Properties Of A Novel Curved Flat-Knitted Three-Dimensional Spacer Fabrics

Directory of Open Access Journals (Sweden)

Li Xiaoying

2015-09-01

Full Text Available This paper introduces a knitting technique for making innovative curved three-dimensional (3D spacer fabrics by the computer flat-knitting machine. During manufacturing, a number of reinforcement yarns made of aramid fibres are inserted into 3D spacer fabrics along the weft direction to enhance the fabric tensile properties. Curved, flat-knitted 3D spacer fabrics with different angles (in the warp direction were also developed. Tensile tests were carried out in the weft and warp directions for the two spacer fabrics (with and without reinforcement yarns, and their stress–strain curves were compared. The results showed that the reinforcement yarns can reduce the fabric deformation and improve tensile stress and dimensional stability of 3D spacer fabrics. This research can help the further study of 3D spacer fabric when applied to composites.

Analysis of Ninety Degree Flexure Tests for Characterization of Composite Transverse Tensile Strength

Science.gov (United States)

OBrien, T. Kevin; Krueger, Ronald

2001-01-01

Finite element (FE) analysis was performed on 3-point and 4-point bending test configurations of ninety degree oriented glass-epoxy and graphite-epoxy composite beams to identify deviations from beam theory predictions. Both linear and geometric non-linear analyses were performed using the ABAQUS finite element code. The 3-point and 4-point bending specimens were first modeled with two-dimensional elements. Three-dimensional finite element models were then performed for selected 4-point bending configurations to study the stress distribution across the width of the specimens and compare the results to the stresses computed from two-dimensional plane strain and plane stress analyses and the stresses from beam theory. Stresses for all configurations were analyzed at load levels corresponding to the measured transverse tensile strength of the material.

Neutron diffraction measurements for the determination of heat treatment effectiveness in generating compressive residual stress in an automotive crown gear

International Nuclear Information System (INIS)

Albertini, G.; Fiori, F.; Girardin, E.; Giuliani, A.; Pyzalla, A.; Quadrini, E.

1999-01-01

Complete text of publication follows. Thermal austenitizing and tempering treatments are being developed in automotive industry to prevent crack initiation and avoid crack propagation, especially in components where stress intensity factors influence the stress field and then the fatigue life of the component itself. This is the case of crown gears, where the teeth root undergoes frequently to cracking when tensile residual stresses are present at the surface, as typical loads are impulsive and very high. The sign reversal of these stresses is the aim of austenitizing and tempering treatments. In this work residual stress measurements carried out at HMI-BENSC are presented, in a UNI55Cr3 steel crown gear submitted to such kind of treatments, performed with a new multi-frequency induction technique whose effectiveness is checked. (author)

Nuclear steam generator tube to tubesheet joint optimization

International Nuclear Information System (INIS)

McGregor, Rod

1999-01-01

Industry-wide problems with Stress Corrosion Cracking in the Nuclear Steam Generator tube-to-tubesheet joint have led to costly repairs, plugging, and replacement of entire vessels. To improve corrosion resistance, new and replacement Steam Generator developments typically employ the hydraulic tube expansion process (full depth) to minimize tensile residual stresses and cold work at the critical transition zone between the expanded and unexpanded tube. These variables have undergone detailed study using specialized X-ray diffraction and analytical techniques. Responding to increased demands from Nuclear Steam Generator operators and manufacturers to credit the leak-tightness and strength contributions of the hydraulic expansion, various experimental tasks with complimentary analytical modelling were applied to improve understanding and control of tube to hole contact pressure. With careful consideration to residual stress impact, design for strength/leak tightness optimization addresses: Experimentally determined minimum contact pressure levels necessary to preclude incipient leakage into the tube/hole interface. The degradation of contact pressure at surrounding expansions caused by the sequential expansion process. The transient and permanent contact pressure variation associated with tubesheet hole dilation during Steam Generator operation. An experimental/analytical simulation has been developed to reproduce cyclic Steam Generator operating strains on the tubesheet and expanded joint. Leak tightness and pullout tests were performed during and following simulated Steam Generator operating transients. The overall development has provided a comprehensive understanding of the fabrication and in-service mechanics of hydraulically expanded joints. Based on this, the hydraulic expansion process can be optimized with respect to critical residual stress/cold work and the strength/leakage barrier criteria. (author)

Construction of finite element model and stress analysis of anterior cruciate ligament tibial insertion.

Science.gov (United States)

Dai, Can; Yang, Liu; Guo, Lin; Wang, Fuyou; Gou, Jingyue; Deng, Zhilong

2015-01-01

The aim of the present study was to develop a more realistic finite element (FE) model of the human anterior cruciate ligament (ACL) tibial insertion and to analyze the stress distribution in the ACL internal fibers under load. The ACL tibial insertions were processed histologically. With Photoshop software, digital images taken from the histological slides were collaged, contour lines were drawn, and different gray values were filled based on the structure. The data were exported to Amira software and saved as ".hmascii" file. This document was imported into HyperMesh software. The solid mesh model generated using HyperMesh software was imported into Abaqus software. The material properties were introduced, boundary conditions were set, and load was added to carry out the FE analysis. The stress distribution of the ACL internal fibers was uneven. The lowest stress could be observed in the ACL lateral fibers under tensile and shear load. The establishment of ACL tibial insertion FE model and mechanical analysis could reveal the stress distribution in the ACL internal fibers under load. There was greater load carrying capacity in the ACL lateral fibers which could sustain greater tensile and shear forces.

Local stresses, dyke arrest and surface deformation in volcanic edificesand rift zones

Directory of Open Access Journals (Sweden)

L. S. Brenner

2004-06-01

Full Text Available Field studies indicate that nearly all eruptions in volcanic edifices and rift zones are supplied with magma through fractures (dykes that are opened by magmatic overpressure. While (inferred dyke injections are frequent during unrest periods, volcanic eruptions are, in comparison, infrequent, suggesting that most dykes become arrested at certain depths in the crust, in agreement with field studies. The frequency of dyke arrest can be partly explained by the numerical models presented here which indicate that volcanic edifices and rift zones consisting of rocks of contrasting mechanical properties, such as soft pyroclastic layers and stiff lava flows, commonly develop local stress fields that encourage dyke arrest. During unrest, surface deformation studies are routinely used to infer the geometries of arrested dykes, and some models (using homogeneous, isotropic half-spaces infer large grabens to be induced by such dykes. Our results, however, show that the dyke-tip tensile stresses are normally much greater than the induced surface stresses, making it difficult to explain how a dyke can induce surface stresses in excess of the tensile (or shear strength while the same strength is not exceeded at the (arrested dyke tip. Also, arrested dyke tips in eroded or active rift zones are normally not associated with dyke-induced grabens or normal faults, and some dykes arrested within a few metres of the surface do not generate faults or grabens. The numerical models show that abrupt changes in Young's moduli(stiffnesses, layers with relatively high dyke-normal compressive stresses (stress barriers, and weak horizontal contacts may make the dyke-induced surface tensile stresses too small for significant fault or graben formation to occur in rift zones or volcanic edifices. Also, these small surface stresses may have no simple relation to the dyke geometry or the depth to its tip. Thus, for a layered crust with weak contacts, straightforward

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.

Stress generation in a developmental context: the role of youth depressive symptoms, maternal depression, the parent-child relationship, and family stress.

Science.gov (United States)

Chan, Priscilla T; Doan, Stacey N; Tompson, Martha C

2014-02-01

The present study examined stress generation in a developmental and family context among 171 mothers and their preadolescent children, ages 8-12 years, at baseline (Time 1) and 1-year follow-up (Time 2). In the current study, we examined the bidirectional relationship between children's depressive symptoms and dependent family stress. Results suggest that children's baseline level of depressive symptoms predicted the generation of dependent family stress 1 year later. However, baseline dependent family stress did not predict an increase in children's depressive symptoms 1 year later. In addition, we examined whether a larger context of both child chronic strain (indicated by academic, behavioral, and peer stress) and family factors, including socioeconomic status and parent-child relationship quality, would influence the stress generation process. Although both chronic strain and socioeconomic status were not associated with dependent family stress at Time 2, poorer parent-child relationship quality significantly predicted greater dependent family stress at Time 2. Child chronic strain, but neither socioeconomic status nor parent-child relationship quality, predicted children's depression symptoms at Time 2. Finally, gender, maternal depression history, and current maternal depressive symptoms did not moderate the relationship between level of dependent family stress and depressive symptoms. Overall, findings provide partial support for a developmental stress generation model operating in the preadolescent period.

Tensile properties of V-Cr-Ti alloys after exposure in helium and low-partial-pressure oxygen environments

Energy Technology Data Exchange (ETDEWEB)

Natesan, K.; Soppet, W.K. [Argonne National Lab., IL (United States)

1997-04-01

A test program is in progress to evaluate the effect of oxygen at low pO{sub 2} on the tensile properties of V-(4-5)wt% Cr-(4-5)wt% Ti alloys. Some of the tensile specimens were precharged with oxygen at low pO{sub 2} at 500{degrees}C and reannealed in vacuum at 500{degrees}C in environments with various pO{sub 2} levels and subsequently tensile tested at room temperature. The preliminary results indicate that both approaches are appropriate for evaluating the effect of oxygen uptake on the tensile properties of the alloys. The data showed that in the relatively short-time tests conducted thus far, the maximum engineering stress slightly increased after oxygen exposure but the uniform and total elongation values exhibited significant decrease after exposure in oxygen-containing environments. The data for a specimen exposed to a helium environment were similar to those obtained in low pO{sub 2} environments.

Tensile properties of V-Cr-Ti alloys after exposure in helium and low-partial-pressure oxygen environments

International Nuclear Information System (INIS)

Natesan, K.; Soppet, W.K.

1997-01-01

A test program is in progress to evaluate the effect of oxygen at low pO 2 on the tensile properties of V-(4-5)wt% Cr-(4-5)wt% Ti alloys. Some of the tensile specimens were precharged with oxygen at low pO 2 at 500 degrees C and reannealed in vacuum at 500 degrees C in environments with various pO 2 levels and subsequently tensile tested at room temperature. The preliminary results indicate that both approaches are appropriate for evaluating the effect of oxygen uptake on the tensile properties of the alloys. The data showed that in the relatively short-time tests conducted thus far, the maximum engineering stress slightly increased after oxygen exposure but the uniform and total elongation values exhibited significant decrease after exposure in oxygen-containing environments. The data for a specimen exposed to a helium environment were similar to those obtained in low pO 2 environments

Generating material strength standards of aluminum alloys for research reactors. Pt. 1. Yield strength values Sy and tensile strength values Su

International Nuclear Information System (INIS)

Tsuji, H.; Miya, K.

1995-01-01

Aluminum alloys are frequently used as structural materials for research reactors. The material strength standards, however, such as the yield strength values (S y ), the tensile strength values (S u ) and the design fatigue curve -which are needed to use aluminum alloys as structural materials in ''design by analysis'' - for those materials have not been determined yet. Hence, a series of material tests was performed and the results were statistically analyzed with the aim of generating these material strength standards. This paper, the first in a series on material strength standards of aluminum alloys, describes the aspects of the tensile properties of the standards. The draft standards were compared with MITI no. 501 as well as with the ASME codes, and the trend of the available data also was examined. It was revealed that the draft proposal could be adopted as the material strength standards, and that the values of the draft standards at and above 150 C for A6061-T6 and A6063-T6 could be applied only to the reactor operating conditions III and IV. Also the draft standards have already been adopted in the Science and Technology Agency regulatory guide (standards for structural design of nuclear research plants). (orig.)

Nucleation and growth characteristics of cavities during the early stages of tensile creep deformation in a superplastic zirconia-20 wt% alumina composite

International Nuclear Information System (INIS)

Owen, D.M.; Chokshi, A.H.; Nutt, S.R.

1997-01-01

Constant-stress tensile creep experiments on a superplastic 3-mol%-yttria-stabilized tetragonal zirconia composite with 20 wt% alumina revealed that cavities nucleate relatively early during tensile deformation. The number of cavities nucleated increases with increasing imposed stress. The cavities nucleate at triple points associated largely with an alumina grain, and then grow rapidly in a cracklike manner to attain dimensions on the order of the grain facet size. It is suggested that coarser-grained superplastic ceramics exhibit lower ductility due to the ease in formation of such grain boundary facet-cracks and their interlinkage to form a macroscopic crack of critical dimensions

The combined effect of gamma radiation and stress cracking in polycarbonate;Efeito combinado da radiacao gama e stress cracking no policarbonato

Energy Technology Data Exchange (ETDEWEB)

Melo, Raphaela N. de; Rabello, Marcelo S., E-mail: marcelo@dema.ufcg.edu.b [Universidade Federal de Campina Grande (DEMa/UFCG), PB (Brazil). Dept. de Engenharia de Materiais; Silva, Leonardo G.A. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2009-07-01

In this work the combined effect of gamma irradiation and stress cracking was studied in polycarbonate (PC). Tensile test bars were produced by injection moulding and then exposed to different doses of gamma radiation. After that they were submitted to the contact with isopropanol, the stress cracking agent used in this work. The specimens were tested for mechanical properties, viscosity molecular weight and fractography. The results indicated that the previous radiation intensified the stress cracking effects, as evidenced by the reduction in tensile properties and surface damage caused to the samples. (author)

Neutron-diffraction measurements of stress

International Nuclear Information System (INIS)

Holden, T.M.

1995-01-01

Experiments on bent steam-generator tubing have shown that different diffraction peaks, (1 1 1) or (0 0 2), give different results for the sign and magnitude of the stress and strain. From an engineering standpoint, the macroscopic stress field cannot be both positive and negative in the same volume, so this difference must be due to intergranular effects superposed on the macroscopic stress field. Uniaxial tensile test experiments with applied stresses beyond the 0.2% offset yield stress, help to understand this anomaly, by demonstrating the different strain response to applied stress along different crystallographic axes.When Zr-alloys are cooled from elevated temperatures, thermal stresses always develop, so that it is difficult to obtain a stress-free lattice spacing from which residual strains may be derived. From measurements of the temperature dependence of lattice spacing, the temperature at which the thermal stresses vanish may be found. From the lattice spacing at this temperature the stress-free lattice spacings at room temperature can be obtained readily.To interpret the measured strains in terms of macroscopic stress fields it is necessary to know the diffraction elastic constants. Neutron diffraction measurements of the diffraction elastic constants in a ferritic steel for the [1 1 0], [0 0 2] and [2 2 2] crystallographic axes, in directions parallel and perpendicular to the applied stress are compared with theoretical diffraction elastic constants. (orig.)

Behaviour of MZFR-type Zircaloy-4 cans under tensile stress

International Nuclear Information System (INIS)

Bordoni, R.A.; Casario, J.A.; Coroli, Graciela; Povolo, Francisco

1981-01-01

The paper describes the experimental procedure and results from the tensile tests of Zircaloy-4 fuel cans of the MZFR-type, performed at temperatures ranging from 250 to 450 deg C and for a relative deformation velocity of about 0.5%/min. In the representation of the results by a curve of the type sigma = K epsilon/sup n/, two different stages are observed. By statistically fitting the experimental curves, the values for the K and n parameters were obtained for each stage as a function of temperature. The results are discussed and compared with similar data found in current literature. It is concluded that new tests on tubes of different characteristics are necessary in order to obtain a clearer idea about the mechanical behaviour of these materials. (C.A.K.) [es

Design of a cruciform bend specimen for determination of out-of- plane biaxial tensile stress effects on fracture toughness for shallow cracks

International Nuclear Information System (INIS)

Bass, B.R.; Bryson, J.W.; Mcafee, W.J.; Pennell, W.E.; Theiss, T.J.

1993-01-01

Pressurized-thermal-shock loading in a reactor pressure vessel produces significant positive out-of-plane stresses along the crack front for both circumferential and axial cracks. Experimental evidence, while very limited, seems to indicate that a reduction in toughness is associated with out-of-plane biaxial loading when compared with toughness values obtained under uniaxial conditions. A testing program is described that seeks to determine the effects of out-of-plane biaxial tensile loading on fracture toughness of RPV steels. A cruciform bend specimen that meets specified criteria for the testing pregam is analyzed using three-dimensional elastic-plastic finite-element techniques. These analysis results provide the basis for proposed test conditions that are judged likely to produce a biaxial loading effect in the cruciform bend specimen

Study of the tensile properties of individual multicellular fibres generated by Bacillus subtilis

Science.gov (United States)

Ye, Xuan; Zhao, Liang; Liang, Jiecun; Li, Xide; Chen, Guo-Qiang

2017-04-01

Multicellular fibres formed by Bacillus subtilis (B. subtilis) are attracting interest because of their potential application as degradable biomaterials. However, mechanical properties of individual fibres remain unknown because of their small dimensions. Herein, a new approach is developed to investigate the tensile properties of individual fibres with an average diameter of 0.7 μm and a length range of 25.7-254.3 μm. Variations in the tensile strengths of fibres are found to be the result of variable interactions among pairs of microbial cells known as septa. Using Weibull weakest-link model to study this mechanical variability, we predict the length effect of the sample. Moreover, the mechanical properties of fibres are found to depend highly on relative humidity (RH), with a brittle-ductile transition occurring around RH = 45%. The elastic modulus is 5.8 GPa in the brittle state, while decreases to 62.2 MPa in the ductile state. The properties of fibres are investigated by using a spring model (RH  45%) for the time-dependent response. Loading-unloading experiments and numerical calculations demonstrate that necking instability comes from structural changes (septa) and viscoelasticity dominates the deformation of fibres at high RH.

Residual stresses determination in an 8 mm Incoloy 800H weld via neutron diffraction

International Nuclear Information System (INIS)

Chen, Xizhang; Zhang, Shu Yan; Wang, Jingjun; Kelleher, Joe F.

2015-01-01

Highlights: • Stress through thickness at 5 mm from weld centerline indicates a “U” distribution. • Declining of tensile stress through thickness occurred at weld centerline. • Residual stress between layers is the lowest. - Abstract: To investigate the distribution of residual stresses, the 8 mm 800H alloy was joined by multi-layer butt TIG process. Residual stresses in the longitudinal, transverse and normal directions were measured via neutron diffraction. These residual stress measurements were taken at a series of points 2 mm below the top surface, covering the fusion zone, heat affected zone (HAZ) and base metal. In addition, two lines of longitudinal residual stress values at the weld centerline and 5 mm from weld centerline through thickness were measured. Results show that both the longitudinal and transverse stresses from the weld centerline to base metal are mainly tensile stresses. The longitudinal residual stress is the largest, with a maximum value of 330 MPa. As for the normal residual stress, the weld zone shows tensile stress, while the HAZ shows compressive stress. The middle of the thickness shows compressive residual stress along the thickness direction. The longitudinal stress at weld centerline through thickness reveals the interlayer heat treat effects leads to a declining of tensile stress. While the stress at 5 mm from weld centerline indicates a “U” distribution due to the mixed microstructure close to fusion line. With the increasing distance from weld seam, the residual stress decreases gradually

Ancestral Exposure to Stress Generates New Behavioral Traits and a Functional Hemispheric Dominance Shift.

Science.gov (United States)

Ambeskovic, Mirela; Soltanpour, Nasrin; Falkenberg, Erin A; Zucchi, Fabiola C R; Kolb, Bryan; Metz, Gerlinde A S

2017-03-01

In a continuously stressful environment, the effects of recurrent prenatal stress (PS) accumulate across generations and generate new behavioral traits in the absence of genetic variation. Here, we investigated if PS or multigenerational PS across 4 generations differentially affect behavioral traits, laterality, and hemispheric dominance in male and female rats. Using skilled reaching and skilled walking tasks, 3 findings support the formation of new behavioral traits and shifted laterality by multigenerational stress. First, while PS in the F1 generation did not alter paw preference, multigenerational stress in the F4 generation shifted paw preference to favor left-handedness only in males. Second, multigenerational stress impaired skilled reaching and skilled walking movement abilities in males, while improving these abilities in females beyond the levels of controls. Third, the shift toward left-handedness in multigenerationally stressed males was accompanied by increased dendritic complexity and greater spine density in the right parietal cortex. Thus, cumulative multigenerational stress generates sexually dimorphic left-handedness and dominance shift toward the right hemisphere in males. These findings explain the origins of apparently heritable behavioral traits and handedness in the absence of DNA sequence variations while proposing epigenetic mechanisms. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Structure-dependent behavior of stress-induced voiding in Cu interconnects

International Nuclear Information System (INIS)

Wu Zhenyu; Yang Yintang; Chai Changchun; Li Yuejin; Wang Jiayou; Li Bin; Liu Jing

2010-01-01

Stress modeling and cross-section failure analysis by focused-ion-beam have been used to investigate stress-induced voiding phenomena in Cu interconnects. The voiding mechanism and the effect of the interconnect structure on the stress migration have been studied. The results show that the most concentrated tensile stress appears and voids form at corners of vias on top surfaces of Cu M1 lines. A simple model of stress induced voiding in which vacancies arise due to the increase of the chemical potential under tensile stress and diffuse under the force of stress gradient along the main diffusing path indicates that stress gradient rather than stress itself determines the voiding rate. Cu interconnects with larger vias show less resistance to stress-induced voiding due to larger stress gradient at corners of vias.

Fused deposition modeling (FDM) fabricated part behavior under tensile stress, thermal cycling, and fluid pressure

Science.gov (United States)

Hossain, Mohammad Shojib

Material extrusion based additive manufacturing (AM) technology, such as fused deposition modeling (FDM), is gaining popularity with the numerous 3D printers available worldwide. FDM technology is advancing from exclusively prototype construction to achieving production-grade quality. Today, FDM-fabricated parts are widely used in the aerospace industries, biomedical applications, and other industries that may require custom fabricated, low volume parts. These applications are and were possible because of the different production grade material options (e.g., acrylonitrile butadiene styrene (ABS), polycarbonate (PC), polyphenylsulfone (PPSF), etc.) available to use in FDM systems. Recent researchers are exploring other material options including polycaprolactone (PCL), polymethylmethacrylate (PMMA), composites containing ceramic, glass and metal fillers, and even metals which depict the diversified materials and possibility of new material options using FDM technology. The understanding of the behavior and mechanical properties of the finished FDM-fabricated parts is of utmost importance in the advancement of this technology. The processing parameters, e.g., build orientation, raster width (RW), contour width (CW), raster angle (RA), and raster to raster air gap (RRAG) are important factors in determining the mechanical properties of FDM fabricated parts. The work presented here focused on the mechanical properties improvement by modifying those build parameters. The main concentration is on how modifying those parameters can improve ultimate tensile stress (UTS), Young's modulus, and tensile strain of the final product. In this research, PC parts were fabricated using three build methods: 1) default method, 2) Insight revision method, and 3) visual feedback method. By modifying build parameters, the highest average UTS obtained for PC was 63.96 MPa which was 7% higher than that of 59.73 MPa obtained using the default build parameters. The parameter modification

Status of automated tensile machine

International Nuclear Information System (INIS)

Satou, M.; Hamilton, M.L.; Sato, S.; Kohyama, A.

1992-01-01

The objective of this work is to develop the Monbusho Automated Tensile machine (MATRON) and install and operate it at the Pacific Northwest Laboratory (PNL). The machine is designed to provide rapid, automated testing of irradiated miniature tensile specimen in a vacuum at elevated temperatures. The MATRON was successfully developed and shipped to PNL for installation in a hot facility. The original installation plan was modified to simplify the current and subsequent installations, and the installation was completed. Detailed procedures governing the operation of the system were written. Testing on irradiated miniature tensile specimen should begin in the near future

Effect of Applied Stress and Temperature on Residual Stresses Induced by Peening Surface Treatments in Alloy 600

Science.gov (United States)

Telang, A.; Gnäupel-Herold, T.; Gill, A.; Vasudevan, V. K.

2018-04-01

In this study, the effects of applied tensile stress and temperature on laser shock peening (LSP) and cavitation shotless peening (CSP)-induced compressive residual stresses were investigated using neutron and x-ray diffraction. Residual stresses on the surface, measured in situ, were lower than the applied stress in LSP- and CSP-treated Alloy 600 samples (2 mm thick). The residual stress averaged over the volume was similar to the applied stress. Compressive residual stresses on the surface and balancing tensile stresses in the interior relax differently due to hardening induced by LSP. Ex situ residual stress measurements, using XRD, show that residual stresses relaxed as the applied stress exceeded the yield strength of the LSP- and CSP-treated Alloy 600. Compressive residual stresses induced by CSP and LSP decreased by 15-25% in magnitude, respectively, on exposure to 250-450 °C for more than 500 h with 10-11% of relaxation occurring in the first few hours. Further, 80% of the compressive residual stresses induced by LSP and CSP treatments in Alloy 600 were retained even after long-term aging at 350 °C for 2400 h.

Layer specific tensile testing of human arteries at the Austrian SAXS beamline at ELETTRA

International Nuclear Information System (INIS)

Schmid, F.; Rappolt, M.; Amenitsch, H.; Laggner, P.; Schulze-Bauer, C.A.; Sommer, G.; Holzapfel, G.A.; Regitnig, P.

2005-01-01

Full text: The collagen diffraction patterns of human aortas under uniaxial tensile test conditions have been investigated by synchrotron small angle x-ray diffraction. Using a recently designed tensile testing device, the orientation and d-spacing of the collagen fibers in the major arterial layers have been measured in situ under physiological conditions, together with the macroscopic force and sample stretching. The results show a direct relation between the orientation/extension of the collagen fibers on the nanoscopic level and the macroscopic stress and strain. This is attributed first to a straightening, second to a reorientation of the collagen fibers, and third to an uptaKEX of the increasing loads by the collagen fibers. (author)

Residual stress state in an induction hardened steel bar determined by synchrotron- and neutron diffraction compared to results from lab-XRD

International Nuclear Information System (INIS)

Holmberg, Jonas; Steuwer, Axel; Stormvinter, Albin; Kristoffersen, Hans; Haakanen, Merja; Berglund, Johan

2016-01-01

Induction hardening is a relatively rapid heat treatment method to increase mechanical properties of steel components. However, results from FE-simulation of the induction hardening process show that a tensile stress peak will build up in the transition zone in order to balance the high compressive stresses close to the surface. This tensile stress peak is located in the transition zone between the hardened zone and the core material. The main objective with this investigation has been to non-destructively validate the residual stress state throughout an induction hardened component. Thereby, allowing to experimentally confirming the existence and magnitude of the tensile stress peak arising from rapid heat treatment. For this purpose a cylindrical steel bar of grade C45 was induction hardened and characterised regarding the microstructure, hardness, hardening depth and residual stresses. This investigation shows that a combined measurement with synchrotron/neutron diffraction is well suited to non-destructively measure the strains through the steel bar of a diameter of 20 mm and thereby making it possible to calculate the residual stress profile. The result verified the high compressive stresses at the surface which rapidly changes to tensile stresses in the transition zone resulting in a large tensile stress peak. Measured stresses by conventional lab-XRD showed however that at depths below 1.5 mm the stresses were lower compared to the synchrotron and neutron data. This is believed to be an effect of stress relaxation from the layer removal. The FE-simulation predicts the depth of the tensile stress peak well but exaggerates the magnitude compared to the measured results by synchrotron/neutron measurements. This is an important knowledge when designing the component and the heat treatment process since this tensile stress peak will have great impact on the mechanical properties of the final component.

Residual stress state in an induction hardened steel bar determined by synchrotron- and neutron diffraction compared to results from lab-XRD

Energy Technology Data Exchange (ETDEWEB)

Holmberg, Jonas, E-mail: jonas.holmberg@swerea.se [Swerea IVF AB, Argongatan 30, 431 22 Mölndal (Sweden); University West, 461 86 Trollhättan (Sweden); Steuwer, Axel [Nelson Mandela Metropolitan University, Gardham Avenue, 6031 Port Elizabeth (South Africa); Stormvinter, Albin; Kristoffersen, Hans [Swerea IVF AB, Argongatan 30, 431 22 Mölndal (Sweden); Haakanen, Merja [Stresstech OY, Tikkutehtaantie 1, 40 800 Vaajakoski (Finland); Berglund, Johan [Swerea IVF AB, Argongatan 30, 431 22 Mölndal (Sweden)

2016-06-14

Induction hardening is a relatively rapid heat treatment method to increase mechanical properties of steel components. However, results from FE-simulation of the induction hardening process show that a tensile stress peak will build up in the transition zone in order to balance the high compressive stresses close to the surface. This tensile stress peak is located in the transition zone between the hardened zone and the core material. The main objective with this investigation has been to non-destructively validate the residual stress state throughout an induction hardened component. Thereby, allowing to experimentally confirming the existence and magnitude of the tensile stress peak arising from rapid heat treatment. For this purpose a cylindrical steel bar of grade C45 was induction hardened and characterised regarding the microstructure, hardness, hardening depth and residual stresses. This investigation shows that a combined measurement with synchrotron/neutron diffraction is well suited to non-destructively measure the strains through the steel bar of a diameter of 20 mm and thereby making it possible to calculate the residual stress profile. The result verified the high compressive stresses at the surface which rapidly changes to tensile stresses in the transition zone resulting in a large tensile stress peak. Measured stresses by conventional lab-XRD showed however that at depths below 1.5 mm the stresses were lower compared to the synchrotron and neutron data. This is believed to be an effect of stress relaxation from the layer removal. The FE-simulation predicts the depth of the tensile stress peak well but exaggerates the magnitude compared to the measured results by synchrotron/neutron measurements. This is an important knowledge when designing the component and the heat treatment process since this tensile stress peak will have great impact on the mechanical properties of the final component.

A Simplified Micromechanical Modeling Approach to Predict the Tensile Flow Curve Behavior of Dual-Phase Steels

Science.gov (United States)

Nanda, Tarun; Kumar, B. Ravi; Singh, Vishal

2017-11-01

Micromechanical modeling is used to predict material's tensile flow curve behavior based on microstructural characteristics. This research develops a simplified micromechanical modeling approach for predicting flow curve behavior of dual-phase steels. The existing literature reports on two broad approaches for determining tensile flow curve of these steels. The modeling approach developed in this work attempts to overcome specific limitations of the existing two approaches. This approach combines dislocation-based strain-hardening method with rule of mixtures. In the first step of modeling, `dislocation-based strain-hardening method' was employed to predict tensile behavior of individual phases of ferrite and martensite. In the second step, the individual flow curves were combined using `rule of mixtures,' to obtain the composite dual-phase flow behavior. To check accuracy of proposed model, four distinct dual-phase microstructures comprising of different ferrite grain size, martensite fraction, and carbon content in martensite were processed by annealing experiments. The true stress-strain curves for various microstructures were predicted with the newly developed micromechanical model. The results of micromechanical model matched closely with those of actual tensile tests. Thus, this micromechanical modeling approach can be used to predict and optimize the tensile flow behavior of dual-phase steels.

Finite element analysis of maxillary bone stress caused by Aramany Class IV obturator prostheses.

Science.gov (United States)

Miyashita, Elcio Ricardo; Mattos, Beatriz Silva Câmara; Noritomi, Pedro Yoshito; Navarro, Hamilton

2012-05-01

The retention of an Aramany Class IV removable partial dental prosthesis can be compromised by a lack of support. The biomechanics of this obturator prosthesis result in an unusual stress distribution on the residual maxillary bone. This study evaluated the biomechanics of an Aramany Class IV obturator prosthesis with finite element analysis and a digital 3-dimensional (3-D) model developed from a computed tomography scan; bone stress was evaluated according to the load placed on the prosthesis. A 3-D model of an Aramany Class IV maxillary resection and prosthesis was constructed. This model was used to develop a finite element mesh. A 120 N load was applied to the occlusal and incisal platforms corresponding to the prosthetic teeth. Qualitative analysis was based on the scale of maximum principal stress; values obtained through quantitative analysis were expressed in MPa. Under posterior load, tensile and compressive stresses were observed; the tensile stress was greater than the compressive stress, regardless of the bone region, and the greatest compressive stress was observed on the anterior palate near the midline. Under an anterior load, tensile stress was observed in all of the evaluated bone regions; the tensile stress was greater than the compressive stress, regardless of the bone region. The Aramany Class IV obturator prosthesis tended to rotate toward the surgical resection when subjected to posterior or anterior loads. The amount of tensile and compressive stress caused by the Aramany Class IV obturator prosthesis did not exceed the physiological limits of the maxillary bone tissue. (J Prosthet Dent 2012;107:336-342). Copyright © 2012 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

Tensile behavior of orthorhombic alpha ''-titanium alloy studied by in situ X-ray diffraction

DEFF Research Database (Denmark)

Wang, X.D.; Lou, H.B.; Ståhl, Kenny

2010-01-01

are indeed due to a low stress yielding (similar to 400 MPa) followed with a significant work-hardening before necking and fracture. In this process, the [0 2 2] orientation of grains more approaches the tensile direction and the [2 0 0] moves to the transverse, causing the lattice parameter a to be shrunk...

NUMERICAL MODELING OF STRESSES NEAR THE SURFACE IN THE INGOT OF CIRCULAR SECTION, CRYSTALLIZABLE AT CIRCULAR TORCH SECONDARY COOLING

Directory of Open Access Journals (Sweden)

A. N. Chichko

2004-01-01

Full Text Available The results of computer calculations of the stresses, generated in outside layer of ingot of steel 20 of circular section with diameter 300 mm, in application to one of the industrial technological schemas of RUP “BMZ”, are presented. The segments of compressive and tensile stresses formation along the length of ingot are determined and the principal possibility of production of continuously cast slug of circular section at circular-torch spray cooling is shown.

Effect of cryogenic treatment on tensile behavior of case carburized steel-815M17

International Nuclear Information System (INIS)

Bensely, A.; Senthilkumar, D.; Mohan Lal, D.; Nagarajan, G.; Rajadurai, A.

2007-01-01

The crown wheel and pinion represent the most highly stressed parts of a heavy vehicle; these are typically made of 815M17 steel. The reasons for the frequent failure of these components are due to tooth bending impact, wear and fatigue. The modern processes employed to produce these as high, durable components include cryogenic treatment as well as conventional heat treatment. It helps to convert retained austenite into martensite as well as promote carbide precipitation. This paper deals with the influence of cryogenic treatment on the tensile behavior of case carburized steel 815M17. The impetus for studying the tensile properties of gear steels is to ensure that steels used in gears have sufficient tensile strength to prevent failure when gears are subjected to tensile or fatigue loads, and to provide basic design information on the strength of 815M17 steel. A comparative study on the effects of deep cryogenic treatment (DCT), shallow cryogenic treatment (SCT) and conventional heat treatment (CHT) was made by means of tension testing. This test was conducted as per ASTM standard designation E 8M. The present results confirm that the tensile behavior is marginally reduced after cryogenic treatment (i.e. both shallow and deep cryogenic treatment) for 815M17 when compared with conventional heat treatment. Scanning electron microscopic (SEM) analysis of the fracture surface indicates the presence of dimples and flat fracture regions are more common in SCT specimens than for CHT and DCT-processed material

Tensile properties of V-Cr-Ti alloys after exposure in hydrogen-containing environments

International Nuclear Information System (INIS)

Natesan, K.; Soppet, W.K.

1998-01-01

A systematic study has been initiated at Argonne National Laboratory to evaluate the performance of several V-Cr-Ti alloys after exposure to environments containing hydrogen at various partial pressures. The goal is to correlate the chemistry of the exposure environment with hydrogen uptake in the samples and its influence on the microstructure and tensile properties of the alloys. At present, the principal effort has focused on the V-4Cr-4Ti alloy of heat identified as BL-71; however other alloys (V-5Cr-5Ti alloy of heats BL-63, and T87, plus V-4Cr-4Ti alloy from General Atomics [GA]) are also being evaluated. Other variables of interest are the effect of initial grain size on the tensile behavior of the alloys. Experiments conducted on specimens of various V-Cr-Ti alloys exposed to pH 2 levels of 0.01 and 3 x 10 -6 torr showed negligible effect of H 2 on either maximum engineering stress or uniform and total elongation. However, uniform and total elongation decreased substantially when the alloys were exposed to 1.0 torr H 2 pressure. Preliminary data from sequential exposures of the materials to low-pO 2 and several low-pH 2 environments did not reveal an adverse effect on the maximum engineering stress or on uniform and total elongation. Further, tests in H 2 environments on specimens annealed at different temperatures showed that grain-size variation by a factor of ∼2 had little or no effect on tensile properties

Residual Stress Analysis Based on Acoustic and Optical Methods

Directory of Open Access Journals (Sweden)

Sanichiro Yoshida

2016-02-01

Full Text Available Co-application of acoustoelasticity and optical interferometry to residual stress analysis is discussed. The underlying idea is to combine the advantages of both methods. Acoustoelasticity is capable of evaluating a residual stress absolutely but it is a single point measurement. Optical interferometry is able to measure deformation yielding two-dimensional, full-field data, but it is not suitable for absolute evaluation of residual stresses. By theoretically relating the deformation data to residual stresses, and calibrating it with absolute residual stress evaluated at a reference point, it is possible to measure residual stresses quantitatively, nondestructively and two-dimensionally. The feasibility of the idea has been tested with a butt-jointed dissimilar plate specimen. A steel plate 18.5 mm wide, 50 mm long and 3.37 mm thick is braze-jointed to a cemented carbide plate of the same dimension along the 18.5 mm-side. Acoustoelasticity evaluates the elastic modulus at reference points via acoustic velocity measurement. A tensile load is applied to the specimen at a constant pulling rate in a stress range substantially lower than the yield stress. Optical interferometry measures the resulting acceleration field. Based on the theory of harmonic oscillation, the acceleration field is correlated to compressive and tensile residual stresses qualitatively. The acoustic and optical results show reasonable agreement in the compressive and tensile residual stresses, indicating the feasibility of the idea.

Mechanical stability of individual austenite grains in TRIP steel studied by synchrotron X-ray diffraction during tensile loading

Energy Technology Data Exchange (ETDEWEB)

Blondé, R. [Fundamental Aspects of Materials and Energy, Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, 2629 JB Delft (Netherlands); Materials Innovation Institute, Mekelweg 2, 2628 CD Delft (Netherlands); Jimenez-Melero, E. [Dalton Cumbrian Facility, The University of Manchester, Westlakes Science and Technology Park, Moor Row, Cumbria, CA24 3HA (United Kingdom); Zhao, L. [Materials Innovation Institute, Mekelweg 2, 2628 CD Delft (Netherlands); Department of Materials Science and Engineering, Delft University of Technology, Mekelweg 2, 2628 CD Delft (Netherlands); Wright, J.P. [European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, BP 220, 38043 Grenoble Cedex (France); Brück, E. [Fundamental Aspects of Materials and Energy, Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, 2629 JB Delft (Netherlands); Zwaag, S. van der [Novel Aerospace Materials Group, Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629 HS, Delft (Netherlands); Dijk, N.H. van, E-mail: N.H.vanDijk@tudelft.nl [Fundamental Aspects of Materials and Energy, Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, 2629 JB Delft (Netherlands)

2014-11-17

The stability of individual metastable austenite grains in low-alloyed TRIP steels has been studied during tensile loading using high-energy X-ray diffraction. The carbon concentration, grain volume and grain orientation with respect to the loading direction was monitored for a large number of individual grains in the bulk microstructure. Most austenite grains transform into martensite in a single transformation step once a critical load is reached. The orientation-dependent stability of austenite grains was found to depend on their Schmid factor with respect to the loading direction. Under the applied tensile stress the average Schmid factor decreased from an initial value of 0.44 to 0.41 at 243 MPa. The present study reveals the complex interplay of microstructural parameters on the mechanical stability of individual austenite grains, where the largest grains with the lowest carbon content tend to transform first. Under the applied tensile stress the average carbon concentration of the austenite grains increased from an initial value of 0.90 to 1.00 wt% C at 243 MPa, while the average grain volume of the austenite grains decreased from an initial value of 19 to 15 µm{sup 3} at 243 MPa.

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)

The medial tibial stress syndrome score: Item generation for a new ...

African Journals Online (AJOL)

The medial tibial stress syndrome score: Item generation for a new patient reported outcome measure. ... instrument that evaluates injury severity and treatment effects for medial tibial stress syndrome (MTSS) patients. ... from 32 Countries:.

Combined spectrophotometry and tensile measurements of human connective tissues: potentials and limitations.

Science.gov (United States)

Ernstberger, Markus; Sichting, Freddy; Baselt, Tobias; Hartmann, Peter; Aust, Gabriela; Hammer, Niels

2013-06-01

Strain-dependent transmission data of nine iliotibial tract specimens are determined using a custom-built optical setup with a halogen light source and an industrial norm material testing machine. Polarized light microscopy and hematoxylin-eosin staining indicated that lateral contraction of collagen structures is responsible for total intensity variations during a 20-cycle preconditioning and a 5-cycle tensile test. Tensile force progress is opposite to total transmission progress. Due to dehydration, wavelength-specific radiation intensity shifting is determined during the test, primarily noticeable in a water absorption band between 1400 and 1500 nm. The results show the capability of integrating spectrophotometry technology into biomechanics for determining structural alterations of human collagen due to applied strain. Being more sensitive to drying, spectrophotometry may likely serve as a quality control in stress-strain testing of biological structures.

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)

Microstructure and Strain Rate-Dependent Tensile Deformation Behavior of Fiber Laser-Welded Butt Joints of Dual-Phase Steels

Science.gov (United States)

Liu, Yang; Dong, Danyang; Han, Zhiqiang; Yang, Zhibin; Wang, Lu; Dong, Qingwei

2018-05-01

The microstructure and tensile deformation behavior of the fiber laser-welded similar and dissimilar dual-phase (DP) steel joints over a wide range of strain rates from 10-3 to 103 s-1 were investigated for the further applications on the lightweight design of vehicles. The high strain rate dynamic tensile deformation process and full-field strain distribution of the base metals and welded joints were examined using the digital image correlation method and high-speed photography. The strain rate effects on the stress-strain responses, tensile properties, deformation, and fracture behavior of the investigated materials were analyzed. The yield stress (YS) and ultimate tensile strength (UTS) of the dissimilar DP780/DP980 welded joints were lying in-between those of the DP780 and DP980 base metals, and all materials exhibited positive strain rate dependence on the YS and UTS. Owing to the microstructure heterogeneity, the welded joints showed relatively lower ductility in terms of total elongation (TE) than those of the corresponding base metals. The strain localization started before the maximum load was reached, and the strain localization occurred earlier during the whole deformation process with increasing strain rate. As for the dissimilar welded joint, the strain localization tended to occur in the vicinity of the lowest hardness value across the welded joint, which was in the subcritical HAZ at the DP780 side. As the strain rate increased, the typical ductile failure characteristic of the investigated materials did not change.

Microstructure and Strain Rate-Dependent Tensile Deformation Behavior of Fiber Laser-Welded Butt Joints of Dual-Phase Steels

Science.gov (United States)

Liu, Yang; Dong, Danyang; Han, Zhiqiang; Yang, Zhibin; Wang, Lu; Dong, Qingwei

2018-04-01

The microstructure and tensile deformation behavior of the fiber laser-welded similar and dissimilar dual-phase (DP) steel joints over a wide range of strain rates from 10-3 to 103 s-1 were investigated for the further applications on the lightweight design of vehicles. The high strain rate dynamic tensile deformation process and full-field strain distribution of the base metals and welded joints were examined using the digital image correlation method and high-speed photography. The strain rate effects on the stress-strain responses, tensile properties, deformation, and fracture behavior of the investigated materials were analyzed. The yield stress (YS) and ultimate tensile strength (UTS) of the dissimilar DP780/DP980 welded joints were lying in-between those of the DP780 and DP980 base metals, and all materials exhibited positive strain rate dependence on the YS and UTS. Owing to the microstructure heterogeneity, the welded joints showed relatively lower ductility in terms of total elongation (TE) than those of the corresponding base metals. The strain localization started before the maximum load was reached, and the strain localization occurred earlier during the whole deformation process with increasing strain rate. As for the dissimilar welded joint, the strain localization tended to occur in the vicinity of the lowest hardness value across the welded joint, which was in the subcritical HAZ at the DP780 side. As the strain rate increased, the typical ductile failure characteristic of the investigated materials did not change.

Statistical characterization of tensile strengths for a nuclear-type core graphite

International Nuclear Information System (INIS)

Kennedy, C.R.; Eatherly, W.P.

1986-09-01

A data set of tensile strengths comprising over 1200 experimental points has been analyzed statistically in conformance with the observed phenomenon of background and disparate flaws. The data are consistent with a bimodal normal distribution. If corrections are made for strength dependence on density, the background mode is Weibull. It is proposed the disparate mode can be represented by a combination of binomial and order statistics. The resultant bimodal model would show a strong dependence on stress volume

Stress Transmission and Failure in Disordered Porous Media

Science.gov (United States)

Laubie, Hadrien; Radjai, Farhang; Pellenq, Roland; Ulm, Franz-Josef

2017-08-01

By means of extensive lattice-element simulations, we investigate stress transmission and its relation with failure properties in increasingly disordered porous systems. We observe a non-Gaussian broadening of stress probability density functions under tensile loading with increasing porosity and disorder, revealing a gradual transition from a state governed by single-pore stress concentration to a state controlled by multipore interactions and metric disorder. This effect is captured by the excess kurtosis of stress distributions and shown to be nicely correlated with the second moment of local porosity fluctuations, which appears thus as a (dis)order parameter for the system. By generating statistical ensembles of porous textures with varying porosity and disorder, we derive a general expression for the fracture stress as a decreasing function of porosity and disorder. Focusing on critical sites where the local stress is above the global fracture threshold, we also analyze the transition to failure in terms of a coarse-graining length. These findings provide a general framework which can also be more generally applied to multiphase and structural heterogeneous materials.

Dynamic strain aging of twinning-induced plasticity (TWIP) steel in tensile testing and deep drawing

International Nuclear Information System (INIS)

Kim, J.G.; Hong, S.; Anjabin, N.; Park, B.H.; Kim, S.K.; Chin, K.-G.; Lee, S.; Kim, H.S.

2015-01-01

The dynamic strain aging (DSA) of metallic materials due to solute atom diffusion to mobile dislocations induce deformation instability with load fluctuations and deformation localizations, hence reducing their sheet formability. In this paper, DSA behaviors of twinning induced plasticity (TWIP) steel with and without Al during tensile testing and deep drawing are investigated in terms of strain localization and the Portevin-Le Chatelier (PLC) band. A theoretical DSA model with internal variables of dislocation density and twin volume fraction is presented for an estimation of strain localization and strain hardening behavior of TWIP steels. The simulation results of the load history and PLC bands during tensile testing and deep drawing are in good agreement with the experimental values. A serration behavior is observed in high-Mn TWIP steels and its tensile residual stress is higher than that in the Al-added TWIP steels, which results in a deformation crack or delayed fracture of deep drawn specimens

Tensile Fracture Behavior of Progressively-Drawn Pearlitic Steels