Automated system for investigating the short-time stress relaxation of viscoelastic materials

1977 ◽  
Vol 12 (1) ◽  
pp. 126-130
Author(s):  
M. R. Kilevits ◽  
Ya. Ya. Indulevich ◽  
P. N. Adavich
Keyword(s):  
Stress Relaxation ◽  
Automated System ◽  
Viscoelastic Materials ◽  
Time Stress ◽  
Short Time

Stress Relaxation Testing For Analysis of 12Cr1MoVG Steel for Creep Strength Evaluation

2007 ◽  
Vol 353-358 ◽  
pp. 408-411 ◽  
Author(s):  
Wei Ming Sun ◽  
Bing Bing Chen ◽  
Wei Ya Jin ◽  
Zeng Liang Gao
Keyword(s):  
Elevated Temperature ◽  
Stress Relaxation ◽  
Constant Load ◽  
Tensile Creep ◽  
Stress Relaxation Test ◽  
New Approach ◽  
Creep Properties ◽  
Time Stress ◽  
Creep Analysis ◽  
Short Time

The design of pressurized components at elevated temperature is limited by available mechanical properties that often do not span appropriate range of stress, time, strain and temperature. To improve the design process, a new approach based on short-time stress relaxation test (SRT) is introduced in steel tensile creep analysis. The experiments are implemented using SRT and tested for creep properties of 12Cr1MoVG steel at 560 °C. The results of creep curves agree well with the traditional constant load creep test data. The possibility to apply SRT approach is shown promising in the design of the pressurized component at elevated temperature.

Short‐Time Stress Relaxation Behavior of Plastics

1955 ◽  
Vol 26 (6) ◽  
pp. 701-705 ◽  
Author(s):  
M. T. Watson ◽  
W. D. Kennedy ◽  
G. M. Armstrong
Keyword(s):  
Stress Relaxation ◽  
Relaxation Behavior ◽  
Stress Relaxation Behavior ◽  
Time Stress ◽  
Short Time

Disc Mechanics With Trans-Endplate Partial Nucleotomy are not Fully Restored Following Cyclic Compressive Loading and Unloaded Recovery

2006 ◽  
Vol 128 (6) ◽  
pp. 823-829 ◽  
Author(s):  
Edward J. Vresilovic ◽  
Wade Johannessen ◽  
Dawn M. Elliott
Keyword(s):  
Cyclic Loading ◽  
Stress Relaxation ◽  
Nucleus Pulposus ◽  
Time Constant ◽  
Annulus Fibrosus ◽  
Compressive Loading ◽  
Magnetic Resonance Images ◽  
Mechanical Behaviors ◽  
Short Time

Mechanical function of the intervertebral disc is maintained through the interaction between the hydrated nucleus pulposus, the surrounding annulus fibrosus, and the superior and inferior endplates. In disc degeneration the normal transfer of load between disc substructures is compromised. The objective of this study was to explore the mechanical role of the nucleus pulposus in support of axial compressive loads over time. This was achieved by measuring the elastic slow ramp and viscoelastic stress-relaxation mechanical behaviors of cadaveric sheep motion segments before and after partial nucleotomy through the endplate (keeping the annulus fibrosus intact). Mechanics were evaluated at five conditions: Intact, intact after 10,000cycles of compression, acutely after nucleotomy, following nucleotomy and 10,000cycles of compression, and following unloaded recovery. Radiographs and magnetic resonance images were obtained to examine structure. Only the short time constant of the stress relaxation was altered due to nucleotomy. In contrast, cyclic loading resulted in significant and large changes to both the stiffness and stress relaxation behaviors. Moreover, the nucleotomy had little to no effect on the disc mechanics after cyclic loading, as there were no significant differences comparing mechanics after cyclic loading with or without the nucleotomy. Following unloaded recovery the mechanical changes that had occurred as a consequence of cyclic loading were restored, leaving only a sustained change in the short time constant due to the trans-endplate nucleotomy. Thus the swelling and redistribution of the remaining nucleus pulposus was not able to fully restore mechanical behaviors. This study reveals insights into the role of the nucleus pulposus in disc function, and provides new information toward the potential role of altered nucleus pulpous function in the degenerative cascade.

Stress Relaxation Near the Tip of a Stationary Mode I Crack in a Poroelastic Solid

2013 ◽  
Vol 80 (2) ◽  
Author(s):  
Chung-Yuen Hui ◽  
Rong Long ◽  
Jing Ning
Keyword(s):  
Stress Relaxation ◽  
Pore Pressure ◽  
Crack Tip ◽  
Small Region ◽  
Small Scale ◽  
Stationary Mode ◽  
Elastic Solids ◽  
Approximate Analytical Solutions ◽  
Scale Yielding ◽  
Short Time

We study the short time transient stress and pore pressure fields near the tip of a stationary crack when a sudden load is applied to a poroelastic solid. These fields are determined using a small scale “yielding” (SSY) analysis where the stress relaxation due to fluid flow is confined to a small region near the crack tip. They are found to exhibit the usual inverse square root singularity characteristic of cracks in linear elastic solids. Analysis shows that these fields are self-similar; the region of stress relaxation that propagates outward from the crack tip is proportional to Dct, where Dc is the cooperative diffusion coefficient and t is time. The pore pressure at the crack tip vanishes immediately after loading. The stress intensity factor at the crack tip is found to be reduced by a factor of 1/[2(1-v)], where v is the Poisson's ratio of the drained solid. Closed form approximations are found for the pore pressure and the trace of the effective stress. These approximate analytical solutions compare well with finite element results.

Tensile Stress—Strain and Stress Relaxation Behavior of Raw Elastomers Using a High Speed Tester

1974 ◽  
Vol 47 (2) ◽  
pp. 307-317 ◽  
Author(s):  
H. H. Bowerman ◽  
E. A. Collins ◽  
N. Nakajima
Keyword(s):  
Stress Relaxation ◽  
High Speed ◽  
Strain Rates ◽  
Time Behavior ◽  
Stress Strain ◽  
Strain Behavior ◽  
Relaxation Measurements ◽  
Ultimate Properties ◽  
Short Time ◽  
Acrylonitrile Copolymers

Abstract A high-speed, tensile-testing device was used to determine the stress—strain behavior of uncompounded butadiene—acrylonitrile copolymers over a range of temperatures and deformation rates. The strain rates were varied from 267 to 26,700 per cent/sec and the temperature was varied from 25 to 97° C. The high-speed tester was also used for stress—relaxation measurements by applying the strain nearly instantly in conformity with theoretical requirements in order to obtain the short time behavior. The WLF equation was obtained from the stress—relaxation data and then used to reduce the ultimate properties to one temperature over four decades of the strain rates. The ultimate properties could be represented by a failure envelope similar to those obtained for vulcanizates.

Modeling the Effects of Mixed Flowing Gas (MFG) Corrosion and Stress Relaxation on Contact Interface Resistance

1993 ◽  
Vol 115 (4) ◽  
pp. 404-409 ◽  
Author(s):  
Shrikar Bhagath ◽  
Michael G. Pecht
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Stress Relaxation ◽  
Contact Resistance ◽  
Time Dependence ◽  
Normal Force ◽  
Operating Temperature ◽  
Contact Interface ◽  
Time Stress ◽  
Over Time

This paper presents the development of an initial, “first-cut”, mathematical model for the prediction of electrical interface reliability trends. The model pertains to gold plated contacts subject to loss of normal force and environmental corrosion with time. Stress relaxation over time and temperature in the base metal of the contact is accounted for. Utilizing the results of Mixed Flowing Gas (MFG) tests, the model can be used to estimate the statistical contact resistance at a particular load (normal force), aging and operating temperature in the class II and III environments. An attempt is made to correlate experimental data with the classical Holm’s equation and to introduce time dependence into the equation. Further work is proposed to correlate results with experimental connector performance data.

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