Slow strain rate testing

About: Slow strain rate testing is a research topic. Over the lifetime, 1228 publications have been published within this topic receiving 24018 citations.

Plastic deformation and fracture behaviour of Ti–6Al–4V alloy loaded with high strain rate under various temperatures

Abstract: This study investigates the plastic deformation and fracture behaviour of titanium alloy (Ti–6Al–4V) under high strain rates and various temperature conditions. Mechanical tests are performed at constant strain rates ranging from 5×102 to 3×103 s−1 at temperatures ranging from room temperature to 1100°C by means of the compressive split-Hopkinson bar technique. The material's dynamic stress–strain response, strain rate, temperature effects and possible deformation mechanisms are discussed. Furthermore, the plastic flow response of this material is described by a deformation constitutive equation incorporating the effects of temperature, strain rate, strain and work hardening rate. The simulated results based on this constitutive equation are verified. The fracture behaviour and variations of adiabatic shear band produced by deformation at each test condition are investigated with optical microscopy and scanning electron microscopy. The results show that the flow stress of Ti–6Al–4V alloy is sensitive to both temperature and strain rate. Nevertheless, the effect on flow stress of temperature is greater than that of strain rate. Fracture observations reveal that adiabatic shear banding turns out to be the major fracture mode when the material is deformed to large plastic strain at high temperature and high strain rate.

A tensile testing technique for fibre-reinforced composites at impact rates of strain

Abstract: A brief review is given of techniques which have been employed in attempts to determine the mechanical properties of composite materials under tensile impact loading. The difficulties encountered in the design of a satisfactory tensile impact testing machine for composite materials are discussed and a new method, using a modified version of the standard tensile split Hopkinson's pressure bar (SHPB), is described. Dynamic stress-strain curves for unidirectionally-reinforced carbon/epoxy composite, in which failure occurs in less than 30 μsec at a mean strain rate of about 400 sec−1, are presented and their validity is established. An extension of the technique to allow the testing of wovenroving reinforced glass/epoxy composites is described and dynamic stress-strain curves obtained for which the times to failure approach 100 μsec and the average strain rate is of the order of 1000 sec−. Comparative stress-strain curves at low and intermediate rates of strain are obtained and the effect of strain rate, over about 7 orders of magnitude, on the tensile modulus, and strength, fracture strain and energy absorbed in fracturing is determined. The limitations of the technique are discussed.