scholarly journals Experimental studies and constitutive modelling of AA6082 in stress-relaxation age forming conditions

2017 ◽  
Vol 207 ◽  
pp. 293-298 ◽  
Author(s):  
Q. Rong ◽  
Z. Shi ◽  
X. Li ◽  
X. Sun ◽  
Y. Li ◽  
...  
Polymers ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2967
Author(s):  
John Sweeney ◽  
Paul Spencer ◽  
Glen Thompson ◽  
David Barker ◽  
Phil Coates

Sheet specimens of a PLLA-based polymer have been extended at a temperature near to the glass transition in both uniaxial and planar tension, with stress relaxation observed for some time after reaching the final strain. Both axial and transverse stresses were recorded in the planar experiments. In all cases during loading, yielding at small strain was followed by a drop in true stress and then strain hardening. This was followed by stress relaxation at constant strain, during which stress dropped to reach an effectively constant level. Stresses were modelled as steady state and transient components. Steady-state components were identified with the long-term stress in stress relaxation and associated with an elastic component of the model. Transient stresses were modelled using Eyring mechanisms. The greater part of the stress during strain hardening was associated with dissipative Eyring processes. The model was successful in predicting stresses in both uniaxial and planar extension over a limited range of strain rate.


2021 ◽  
Vol 263 ◽  
pp. 02051
Author(s):  
Armen Ter-Martirosyan ◽  
Artur Manukyan ◽  
Lyubov Ermoshina

Rheological studies of soils were carried out by S.S. Vyalov, M.N. Gol’dshtejn, N.N. Maslov, G.I. Ter-Stepanyan, S.R. Meschyan, A.L. Gol’din, Z.G. Ter-Martirosyan and many others. On the basis of existing rheological soil models, a new universal rheological equation was proposed in Ter-Martirosyan’s dissertation, which allows describing kinematic shear, creep and stress relaxation at the same parameters. Experimental studies of the soil were carried out in a simple shear device in a kinematic loading mode at a shear displacement rate u̇= 0.05 mm/min and at two values of compaction loads (σ1 < σ2). Based on the results of the experimental studies, the parameters of the elastoviscoplastic model were determined and graphs of the dependence of shear stresses on time were plotted, which clearly show the high convergence of the experimental and theoretical curves.


2021 ◽  
Vol 57 (2) ◽  
pp. 161-170

Torsional deformations of cylindrical bodies with magnetizable elastomers in a uniform magnetic field are considered. During theoretical research, different models of viscoelastic materials are used. Experimental studies of stress relaxation in a magnetic field are carried out, and the models that consider stress relaxation are used to describe the experiment. Dependences of the shear moduli and viscosity coefficients of magnetizable elastomers on the magnetic field strength are found experimentally. Tables 1, Figs 10, Refs 9.


2019 ◽  
Vol 130 ◽  
pp. 105370 ◽  
Author(s):  
Simon Klinge Nielsen ◽  
Hamid Rezaei ◽  
Matthias Mandø ◽  
Shahab Sokhansanj

1978 ◽  
Vol 100 (2) ◽  
pp. 287-294 ◽  
Author(s):  
A. Harnoy

The hydrodynamic theory of lubrication in journal bearings is extended to elastico-viscous lubricants. The stress relaxation effect upon flow, pressure distribution, friction, and bearing load capacity is considered. This analysis deals with the case of a small relaxation time compared with the transit time required for the lubricant to pass through the bearing. A lubricant model is assumed with a constant relaxation time and without any cross stresses. It is found that the bearing load capacity of an elastic liquid lubrication film is higher than that of a Newtonian one, while the friction torque remains unchanged. Existing experimental studies have shown considerable improvement in journal bearing performance with elastico-viscous lubricants. This analysis suggests stress relaxation to be one of the factors giving rise to this improvement.


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