Multi‐Relaxation Test to Characterize PE Pipe Performance

2019 ◽  
Vol 75 (8) ◽  
pp. 40-45
Author(s):  
Na Tan ◽  
P‐Y Ben Jar
Keyword(s):  
Relaxation Test

Analysis on the Creep Mechanism of 12Cr-Mo-W-0.25V Steel Based on Long-Term Stress Relaxation Test Data

2016 ◽  
Vol 853 ◽  
pp. 158-162
Author(s):  
Jie Zhao ◽  
Tie Shan Cao ◽  
Cong Qian Cheng ◽  
Hui Fang Li
Keyword(s):  
Stress Relaxation ◽  
Test Data ◽  
Activation Volume ◽  
High Stress ◽  
Relaxation Curve ◽  
Relaxation Test ◽  
Dislocation Slip ◽  
Stress Relaxation Test ◽  
Steel Base

The current paper investigates on the creep behavior of 12Cr-Mo-W-0.25V heat resistant steel base on the long-term stress relaxation test data. It is shows that the stress relaxation curve can be divided into 2 stages: the high stress stage has higher apparent activation volume of 79~350 b3 and the low stress stage is 35~78 b3. Besides, the Helmholtz free energy at the high stress stage is 827~1034 kJ/mol which is higher than 210~252 kJ/mol of the low stress stage. Taking both apparent activation volume and activation energy into account, it is assumed that the high stress stage is mainly controlled by dislocation slip and the low stress stage is more related to diffusion.

Prediction of creep life of X10CrMoVNbN-91 (P-91) steel through short term stress relaxation test methodology

2004 ◽  
Vol 20 (10) ◽  
pp. 1290-1296 ◽  
Author(s):  
S.C. Bose ◽  
Kulvir Singh ◽  
J. Swaminathan ◽  
D.S. Sarma
Keyword(s):  
Stress Relaxation ◽  
Relaxation Test ◽  
Stress Relaxation Test ◽  
Creep Life ◽  
Short Term ◽  
Test Methodology

Tracing of stresses and pore water pressure changes during a multistage modified relaxation test model on organic soil

2021 ◽  
Vol 14 (19) ◽  
Author(s):  
Mohammed Y. Fattah ◽  
Raid R. Al-Omari ◽  
Mudhafar K. Hameedi
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Organic Soil ◽  
Relaxation Test ◽  
Test Model ◽  
Pressure Changes

Comparison of the Trueness of Fits of the Biphasic Transverse Isotropic and Kelvin Models to the Tensile Behavior of Temporomandibular Joint Disc

2021 ◽  
Vol 143 (6) ◽  
Author(s):  
Wuyang Li ◽  
Sara Trbojevic ◽  
Alejandro J. Almarza
Keyword(s):  
Experimental Data ◽  
Stress Relaxation ◽  
Temporomandibular Joint ◽  
Second Order ◽  
Relaxation Test ◽  
Stress Relaxation Test ◽  
Kelvin Model ◽  
Biphasic Model ◽  
Tmj Disc ◽  
Transverse Isotropic

Abstract This technical brief explores the validity and trueness of fit for using the transverse isotropic biphasic and Kelvin models (first and second order generalized) for characterization of the viscoelastic tensile properties of the temporomandibular joint (TMJ) discs from pigs and goats at a strain rate of 10 mm/min. We performed incremental stress-relaxation tests from 0 to 12% strain, in 4% strain steps on pig TMJ disc samples. In addition, to compare the outcomes of these models between species, we also performed a single-step stress-relaxation test of 10% strain. The transverse isotropic biphasic model yielded reliable fits in reference to the least root mean squared error method only at low strain, while the Kelvin models yielded good fits at both low and high strain, with the second order generalized Kelvin model yielding the best fit. When comparing pig to goat TMJ disc in 10% strain stress-relaxation test, unlike the other two Kelvin models, the transverse isotropic model did not fit well for this larger step. In conclusion, the second order Kelvin model showed the best fits to the experimental data of both species. The transverse isotropic biphasic model did not fit well with the experimental data, although better at low strain, suggesting that the assumption of water flow only applies while uncrimping the collagen fibers. Thus, it is likely that the permeability from the biphasic model is not truly representative, and other biphasic models, such as the poroviscoelastic model, would likely yield more meaningful outputs and should be explored in future works.

scholarly journals A Wireless Body Sensor Network for Clinical Assessment of the Flexion-Relaxation Phenomenon

Electronics ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 1044 ◽  
Author(s):  
Michele Paoletti ◽  
Alberto Belli ◽  
Lorenzo Palma ◽  
Massimo Vallasciani ◽  
Paola Pierleoni
Keyword(s):  
Sensor Network ◽  
Clinical Assessment ◽  
Activity Patterns ◽  
Relaxation Test ◽  
Relaxation Phenomenon ◽  
Myoelectric Activity ◽  
Back Muscles ◽  
Body Sensor Network ◽  
Flexion Relaxation Phenomenon ◽  
Flexion Relaxation

An accurate clinical assessment of the flexion-relaxation phenomenon on back muscles requires objective tools for the analysis of surface electromyography signals correlated with the real movement performed by the subject during the flexion-relaxation test. This paper deepens the evaluation of the flexion-relaxation phenomenon using a wireless body sensor network consisting of sEMG sensors in association with a wearable device that integrates accelerometer, gyroscope, and magnetometer. The raw data collected from the sensors during the flexion relaxation test are processed by an algorithm able to identify the phases of which the test is composed, provide an evaluation of the myoelectric activity and automatically detect the phenomenon presence/absence. The developed algorithm was used to process the data collected in an acquisition campaign conducted to evaluate the flexion-relaxation phenomenon on back muscles of subjects with and without Low Back Pain. The results have shown that the proposed method is significant for myoelectric silence detection and for clinical assessment of electromyography activity patterns.

scholarly journals A Method of Discerning Frictional Stress and Internal Stress by the Stress Relaxation Test

1976 ◽  
Vol 40 (4) ◽  
pp. 393-399 ◽  
Author(s):  
Katunori Abe ◽  
Hideo Yoshinaga ◽  
Shotaro Morozumi
Keyword(s):  
Stress Relaxation ◽  
Internal Stress ◽  
Relaxation Test ◽  
Frictional Stress ◽  
Stress Relaxation Test

Study on Nonlinear Viscoelastic Properties of Asphalt Mixture Based on Stress Relaxation Test

2014 ◽  
Vol 563 ◽  
pp. 48-52
Author(s):  
Lei Chen ◽  
Zhi Xin Yu ◽  
Wei Ping Cui ◽  
Li Juan Qin
Keyword(s):  
Stress Relaxation ◽  
Asphalt Mixture ◽  
Viscoelastic Behavior ◽  
Exponential Model ◽  
Relaxation Test ◽  
Asphalt Binders ◽  
Stress Relaxation Test ◽  
Nonlinear Viscoelastic ◽  
Low Temperature Cracking ◽  
Relaxation Experiments

Development of normal stress in the direction perpendicular to the asphalt mixture is an important feature of the nonlinear viscoelastic behavior of asphalt binders. In this paper, this phenomenon was studied with the help of stress-relaxation experiments in torsion.  Results indicate that stress relaxation test by controlling strain could be used to evaluate the stress relaxation ability of asphalt mixture. With the aging degree of asphalt mixtures increased, the low temperature cracking resistance got worse; the higher the temperature is, the faster the stress relaxed; the smaller the initial strain, the worse the stress relaxation ability also. The viscoelasticity of asphalt mixture could be simulated by exponential model fractional and the experiments well supported the modeling results.

Application of Stress Relaxation Test Methodology for Predicting Creep Life of a Large Steam Turbine Rotor Steel (1CrMoV)

2003 ◽  
Vol 31 (3) ◽  
pp. 19074 ◽  
Author(s):  
DR Petersen ◽  
RE Link ◽  
SC Bose ◽  
K Singh ◽  
G Jayaraman
Keyword(s):  
Stress Relaxation ◽  
Steam Turbine ◽  
Turbine Rotor ◽  
Relaxation Test ◽  
Rotor Steel ◽  
Stress Relaxation Test ◽  
Creep Life ◽  
Steam Turbine Rotor ◽  
Test Methodology
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