Variation of Stresses Ahead of The Internal Cracks in ReNI5 Powders During Hydrogen Charging and Discharging Cycles

1997 ◽  
Vol 496 ◽  
Author(s):  
S. B. Biner
Keyword(s):  
Modulus Of Elasticity ◽  
Spherical Particles ◽  
Tensile Stresses ◽  
Hydrogen Charging ◽  
Coupled Diffusion ◽  
Stress States

ABSTRACTIn this study, the evolution of the stress-states ahead of the penny shaped internal cracks in both spherical and disk shaped ReNi5 particles during hydrogen charging and discharging cycles were investigated using coupled diffusion/deformation FEM analyses. The results indicate that large tensile stresses, on the order of 20–50% of the modulus of elasticity, develop in the particles. The disk shaped particles, in addition to having faster charging/discharging cycles, may offer better resistance to fracture than the spherical particles.

scholarly journals Deformability in Unsaturated Polyester Resin-Based Concrete: Effects of the Concentration of Shrinkage-Reducing Agent and Type of Filler

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 727 ◽  
Author(s):  
Jung Heum Yeon ◽  
Hee Jun Lee ◽  
Jaeheum Yeon
Keyword(s):  
Thermal Expansion ◽  
Modulus Of Elasticity ◽  
Polyester Resin ◽  
Unsaturated Polyester ◽  
Compressive Strain ◽  
Spherical Particles ◽  
Polymer Concrete ◽  
Mix Proportion ◽  
Uniform Dispersion ◽  
Shrinkage Reducing Agent

In this study, the effects of shrinkage reduction agent (SRA) content and filler type on the deformability characteristics of unsaturated polyester (UP) resin-based polymer concrete were experimentally investigated. Specifically, the setting shrinkage, thermal expansion, maximum compressive strain and the modulus of elasticity of UP polymer concrete were all analyzed. Setting shrinkage was found to be influenced by the UP resin, the SRA and filler. The thermal expansion, maximum compressive strain and modulus of elasticity were also affected by the aggregate. The effect of SRA content on deformability was found to be greater than that of the filler type. To put UP polymer concrete to efficient use, it is essential to secure proper deformability according to the intended purpose. At that time, it is desirable that the deformation characteristics resulting from the SRA content and filler type sufficiently reflect when the mix proportion is determined. The effects of filler type on the deformability of UP polymer concrete are such that: A uniform dispersion of filler particles impacts the setting shrinkage; the thermal expansion is influenced by the filler’s various thermal expansion properties; the compressive strain is related to the nature of the small spherical particles that tend to fill porosity, producing better packing of the aggregate materials; and the modulus of elasticity is influenced by the density, which is related to the strength of the filler. However, additional in-depth studies are required on all of these elements.

A contact free measurement method to determine internal stress states in glulam

Holzforschung ◽  
2004 ◽  
Vol 58 (2) ◽  
pp. 148-153 ◽  
Author(s):  
J. Jönsson ◽  
S. Svensson
Keyword(s):  
Stress State ◽  
Internal Stress ◽  
Modulus Of Elasticity ◽  
Digital Camera ◽  
End Effects ◽  
Static Modulus ◽  
Stress States ◽  
Static Modulus Of Elasticity ◽  
Contact Free ◽  
Destructive Measurement

Abstract A method to determine the internal stress state across the grain of glued laminated wood (glulam), as well as the experimental equipment for measuring released deformation are described in this paper. The internal stress state is calculated from measured released deformations, which are measured by a contact free method based on a digital camera technique. Non-destructive measurement of the modulus of elasticity in the cross-grain direction is presented and the correlation between dynamic and static modulus of elasticity is shown. Results for a single specimen with induced moisture gradient show that the largest stress found in the tests was about 0.57 MPa, which is higher than the characteristic value of tensile strength perpendicular to the grain. This stress is based on released strain over the total length of the slices cut from the specimens. FEM-simulations evaluating the stress distribution within the specimen to account for end effects indicate that the maximum stress is about 30% higher.

Internal stresses in glulam due to moisture gradients in the grain direction

Holzforschung ◽  
2005 ◽  
Vol 59 (1) ◽  
pp. 18-22 ◽  
Author(s):  
Johan Hans Jönsson
Keyword(s):  
Climate Change ◽  
Experimental Study ◽  
Stress State ◽  
Modulus Of Elasticity ◽  
Internal Stresses ◽  
Test Results ◽  
Tensile Stresses ◽  
Glued Laminated Timber ◽  
Average Maximum ◽  
Different Types

Abstract An experimental study on the internal stress state perpendicular to grain in glued laminated timber induced by moisture variations along the grain is presented. The stress is evaluated by using measured modulus of elasticity and strain. Different types of tests are performed, in which specimens are exposed to artificial climate change when the specimens are in either a wetting or a drying state, and specimens are exposed to a cyclic climate change. Test results from the specimens that were in a drying state show that the tensile stresses near the end of the specimens at some point exceeds the strength of the wood and cracks. In the opposite test, when the specimens are in a moistening phase, the maximum tensile stresses are lower and in the order of 0.2 MPa during the tested period. The cyclic test, which continued during 20 weeks, showed that there were no accumulated effects regarding strain and stress values. In this test, the average maximum tensile and compression stresses were of the order 0.20 and 0.10 MPa, respectively.

Comparison of Substructures Between Uniaxial and Biaxial Deformation in 1100-0 Aluminum

1981 ◽  
Vol 39 ◽  
pp. 52-53
Author(s):  
D. L. Rohr ◽  
S. S. Hecker
Keyword(s):  
Plastic Strain ◽  
Cell Walls ◽  
Room Temperature ◽  
Mechanical Response ◽  
Biaxial Tension ◽  
Initial Deformation ◽  
Uniaxial Deformation ◽  
Biaxial Deformation ◽  
Stress States ◽  
Comprehensive Study

As part of a comprehensive study of microstructural and mechanical response of metals to uniaxial and biaxial deformations, the development of substructure in 1100 A1 has been studied over a range of plastic strain for two stress states.Specimens of 1100 aluminum annealed at 350 C were tested in uniaxial (UT) and balanced biaxial tension (BBT) at room temperature to different strain levels. The biaxial specimens were produced by the in-plane punch stretching technique. Areas of known strain levels were prepared for TEM by lapping followed by jet electropolishing. All specimens were examined in a JEOL 200B run at 150 and 200 kV within 24 to 36 hours after testing.The development of the substructure with deformation is shown in Fig. 1 for both stress states. Initial deformation produces dislocation tangles, which form cell walls by 10% uniaxial deformation, and start to recover to form subgrains by 25%. The results of several hundred measurements of cell/subgrain sizes by a linear intercept technique are presented in Table I.

STEM Study of Surface Plasmon Excitation in Small Spherical Particles

1990 ◽  
Vol 48 (2) ◽  
pp. 42-43
Author(s):  
Daniel UGARTE
Keyword(s):  
Energy Loss ◽  
Spherical Particles ◽  
Small Particles ◽  
Bulk Materials ◽  
Low Loss ◽  
Plasmon Excitation ◽  
Surface Modes ◽  
Surface Plasmon Excitation ◽  
Analytical Electron ◽  
Analytical Electron Microscope

Small particles exhibit chemical and physical behaviors substantially different from bulk materials. This is due to the fact that boundary conditions can induce specific constraints on the observed properties. As an example, energy loss experiments carried out in an analytical electron microscope, constitute a powerful technique to investigate the excitation of collective surface modes (plasmons), which are modified in a limited size medium. In this work a STEM VG HB501 has been used to study the low energy loss spectrum (1-40 eV) of silicon spherical particles [1], and the spatial localization of the different modes has been analyzed through digitally acquired energy filtered images. This material and its oxides have been extensively studied and are very well characterized, because of their applications in microelectronics. These particles are thus ideal objects to test the validity of theories developed up to now.Typical EELS spectra in the low loss region are shown in fig. 2 and energy filtered images for the main spectral features in fig. 3.

Short Stress State Questionnaire

2015 ◽  
Vol 31 (1) ◽  
pp. 20-30 ◽  
Author(s):  
William S. Helton ◽  
Katharina Näswall
Keyword(s):  
Stress State ◽  
Factor Structure ◽  
Human Performance ◽  
Self Report ◽  
Confirmatory Factor ◽  
Stress States ◽  
Related Stress ◽  
Using Data ◽  
Task Conditions ◽  
Multiple Samples

Conscious appraisals of stress, or stress states, are an important aspect of human performance. This article presents evidence supporting the validity and measurement characteristics of a short multidimensional self-report measure of stress state, the Short Stress State Questionnaire (SSSQ; Helton, 2004 ). The SSSQ measures task engagement, distress, and worry. A confirmatory factor analysis of the SSSQ using data pooled from multiple samples suggests the SSSQ does have a three factor structure and post-task changes are not due to changes in factor structure, but to mean level changes (state changes). In addition, the SSSQ demonstrates sensitivity to task stressors in line with hypotheses. Different task conditions elicited unique patterns of stress state on the three factors of the SSSQ in line with prior predictions. The 24-item SSSQ is a valid measure of stress state which may be useful to researchers interested in conscious appraisals of task-related stress.

Sign in / Sign up

Export Citation Format

Share Document