Strain Rate

Types 304L and 316L austenitic Stainless Steels (SS) are widely used in PWR environment. These past few years, a limited number of cases of intergranular stress corrosion cracking (IGSCC) have been detected in cold worked areas of non sensitized austenitic stainless steel components. A first study has been initiated at EDF to assess the conditions of the cracking. The main results include cold work thresholds of 240 HV0,1 for initiation cracking, and of 310 HV0,1 for crack propagation, and propose that a dynamic loading is necessary for SCC. The aim of the present paper is to provide a basis of a crack propagation model by investigating the effect of loading, material and cold-work. In order to try to approach a static loading, a trapezoidal cyclic loading is applied on high cold-worked (by rolling or by tensile loading) materials. It is shown that, for the most severe loading, the rolling cold-worked (RCW) materials undergo TGSCC whereas IGSCC is observed after tensile cold-working...

The stiffness of articular cartilage is a nonlinear function of the strain amplitude and strain rate as well as the loading history, as a consequence of the flow of interstitial water and the stiffening of the collagen fibril network. This paper presents a full investigation of the interplay between the fluid kinetics and fibril stiffening of unconfined cartilage disks by analyzing over 200 cases with diverse material properties. The lower and upper elastic limits of the stress (under a given strain) are uniquely established by the instantaneous and equilibrium stiffness (obtained numerically for finite deformations and analytically for small deformations). These limits could be used to determine safe loading protocols in order that the stress in each solid constituent remains within its own elastic limit. For a given compressive strain applied at a low rate, the loading is close to the lower limit and is mostly borne directly by the solid constituents (with little contribution from...

This paper investigates the performance of self-piercing riveted joints in aluminium sheet (A5754) at typical automotive crash speeds. Tension, shear and peel joint specimens have been tested over the speed range from low rate (10−3m/s) to high rate (5m/s), using a high rate servo-hydraulic machine. A heat treatment was applied to some of the material and joint specimens to simulate