We demonstrate the microscopic equivalent of a step-stress rheological measurement. An optical torque is applied to a birefringent wax microdisk embedded in gelatin, a highly entangled viscoelastic biopolymer, using circularly polarized laser tweezers. By increasing the laser power and measuring the angular displacement of the disk, we explore the microscopic rheological response of presheared ...

The plane-strain bulge test is a powerful new technique for measuring the mechanical properties of thin films. In this technique, the stress–strain curve of a thin film is determined from the pressure-deflection behavior of a long rectangular membrane made of the film of interest. For a thin membrane in a state of plane strain, film stress and stain are distributed uniformly across the membrane...

This paper mainly studies the behavior of axisymmetric radial interaction between soil and structure under stress. Considering possible factors in interaction, such as arching effect caused by finite curvature, a simplified model is established. The influence curvature change on stress field, strain displacement field stress-strain relationship analyzed. Finally, status various their changes ar...

A model of the left ventricle which combines a spheroidal geometry with a spatial fiber angle distribution is presented. The mechanics of each muscle fiber is described by its passive stress-strain relationship, active stress-strain relationship, and an activation function (half a sinusoid) which represents the time-dependent degree of activation of the fiber. A stress-strain rate relationship ...

Once plaques intrude into the lumen, the shear stress they are exposed to alters with hitherto unknown consequences for plaque composition. We investigated the relationship between shear stress and strain, a marker for plaque composition, in human coronary arteries. We imaged 31 plaques in coronary arteries with angiography and intravascular ultrasound. Computational fluid dynamics was used to ...

In a recent letter, Govaert et al. examined the relationship between strain hardening modulus Gr and flow stress σflow for five different glassy polymers. In each case, results forGr at different strain rates or different temperatures are linearly related to the flow stress. They noted that this linear relation is different than a simple proportionality between Gr and σflow, which they claimed ...

Extraction of the material stress-strain curve from a dynamic tensile or shear experiment is not straightforward. Indeed, stress and strain are not homogeneously distributed in the specimen, and consequently no one-one relation exists between the measured elongation and strain on one hand, and the measured force and stress on the other hand. This work aims at improving the accuracy of the stres...

determination of critical points on hot stress-strain curve of metals is crucial in thermo-mechanical processes design. in this investigation a mathematical modeling is given to illustrate the behavior of metal during hot deformation processes such as hot rolling. the critical strain for the onset of dynamic recrystallization has been obtained as a function of strain at the maximum stress. in a...

We performed simultaneous high-fidelity left ventricular pressure and echocardiographic dimension measurements in 30 patients with normal left ventricular function (group 1; n = 6), moderate-tosevere aortic regurgitation (group 2; n = 14) or congestive cardiomyopathy (group 3; n = 10). We determined diastolic stress, strain and strain rate in all 30 patients and fitted the data to a simple elas...