Papers by Keyword: Strain Rate Effects

Abstract: This paper focuses on progressive damage investigation and failure analysis of carbon fiber reinforced laminates under varying strain rates in tensile mode. Samples specimen prepared for experiments were made from unidirectional ply with 70/30 fiber-matrix volume fraction and cross-ply (0°-90°) balanced stacking. These laminates were subjected to uniaxial longitudinal tensile loading in a Universal Testing Machine (UTM) with varying strain rates. Results acquired from the experiments were used to plot stress versus strain curves for different strain rates. These plots were subsequently analyzed to investigate the effect of varying loading rates on the mechanical properties and failure behavior of these composites. Experimental data revealed a considerable increase in the tensile strength with increasing strain rate. The tensile modulus and strain to failure were also found to exhibit slight increase with the increasing strain rate.

Abstract: Both quasi-static compressive tests and dynamic loading tests on the open-cell aluminum foam made of 6061 aluminum alloy were firstly conducted. The Split Hopkinson Pressure Bar (SHPB) apparatus was used to perform the dynamic loading tests. The rate-dependent constitutive model for the open-cell aluminum foam was then studied. Based on the empirical constitutive model proposed by Sherwood for polyurethane foam, a new function was found to analyze the three-stage characteristic of quasi-static stress-strain curve of the aluminum foam. Moreover, the temperature softening was also modified. Thus a new strain rate hardening constitutive model coupled with temperature softening for the open-cell aluminum foam was obtained. Finally, both Taylor impact tests and finite element analysis (FEA) were conducted to verify the new constitutive model and the results show that the model was reliable.

Abstract: Underwater explosion is a complex discussion because it has two phase environment including shock waves, bubble effects, cavitation, high strain rate, geometric and material non linearity. Results of underwater explosion tests on the circular steel plates have been discussd. Test results compared with numerical analysis results which it is done by LS-DYNA code. LS-DYNA is the software which is used to analyze large dynamic deflections by use of explicit method. We found that this code has good accuracy to predict the maximum deflections. Strain rate effects included in the program by use of Cowper-Symonds relation.