Uniaxial creep and stress relaxation behavior of modified 9Cr-1Mo steel

2017 ◽  
Vol 684 ◽  
pp. 683-696 ◽  
Author(s):  
Krishna Guguloth ◽  
J. Swaminathan ◽  
Nilima Roy ◽  
R.N. Ghosh
Keyword(s):  
Stress Relaxation ◽  
Relaxation Behavior ◽  
Stress Relaxation Behavior ◽  
Uniaxial Creep ◽  
Creep And Stress Relaxation

Comparative Study of Creep and Stress Relaxation Behavior for 7055 Aluminum Alloy

2011 ◽  
Vol 314-316 ◽  
pp. 772-777 ◽  
Author(s):  
Li Hua Zhan ◽  
Yan Guang Li ◽  
Ming Hui Huang ◽  
Jian Guo Lin
Keyword(s):  
Aluminum Alloy ◽  
Creep Rate ◽  
Stress Relaxation ◽  
Relaxation Rate ◽  
Constitutive Equations ◽  
Relaxation Behavior ◽  
Experimental Results ◽  
Stress Relaxation Behavior ◽  
Creep And Stress Relaxation ◽  
7055 Aluminum Alloy

In order to study the similarities and dissimilarities between creep and stress relaxation behavior of age formed aluminum alloys, both creep ageing and stress relaxation ageing experiments have been conducted with plate shaped 7055 aluminum alloy specimens on the 100 KN tensile testing machine performed at 120 °C for 20 h, under different stress levels from 190.0 to 357.8 MPa. The experimental results show that similar variation trends for creep and stress relaxation behavior were observed. Both creep and stress relaxation curves can be divided into two stages. During the first stage, higher creep rate and stress relaxation rate occur, which increase with stress levels but decrease with ageing time. While during the second stage, both the creep rate and the stress relaxation rate reach its lowest value and keep constant. A set of unified creep ageing constitutive equations has been developed and calibrated from creep experimental data, which can be used to predict the creep strain under age forming conditions perfectly. But the experimental results from stress relaxation ageing tests cannot be predicted with the established creep ageing constitutive equations, which shows that there is not a one-to-one correspondence between creep and stress relaxation, creep deformation is the most important but not the only reason for stress relaxation under age forming condition.

Effects of accelerator type on stress relaxation behavior and network structure of aged natural rubber/chloroprene rubber vulcanizates

2016 ◽  
Vol 49 (5) ◽  
pp. 381-396 ◽  
Author(s):  
Farzad A Nobari Azar ◽  
Murat Şen
Keyword(s):  
Stress Relaxation ◽  
Natural Rubber ◽  
Network Structure ◽  
Structural Changes ◽  
Relaxation Behavior ◽  
Stress Relaxation Behavior ◽  
Rubber Blends ◽  
Chloroprene Rubber ◽  
Weather Changes ◽  
Behavior Network

Natural rubber/chloroprene rubber (NR/CR) blends are among the commonly used rubber blends in industry and continuously are exposed to severe weather changes. To investigate the effects of accelerator type on the network structure and stress relaxation of unaged and aged NR/CE vulcanizates, tetramethyl thiuram disulfide, 2-mercaptobenzothiazole, and diphenyl guanidine accelerators have been chosen to represent fast, moderate, and slow accelerator groups, respectively. Three batches have been prepared with exactly the same components and mixing conditions differing only in accelerator type. Temperatures scanning stress relaxation and pulse nuclear magnetic resonance techniques have been used to reveal the structural changes of differently accelerated rubber blends before and after weathering. Nonoxidative thermal decomposition analyses have been carried out using a thermogravimetric analyzer. Results indicate that there is a strong interdependence between accelerator type and stress relaxation behavior, network structure, cross-linking density, and aging behavior of the blends. Accelerator type also affects decomposition energy of the blends.

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