Constitutive models for the dynamic behaviour of direct metal laser sintered AlSi10Mg_200C under high strain rate shock loading

The microstructural and mechanical response of materials to shock loading is of the utmost importance in the development of constitutive models for high strain-rate applications. However, unlike a purely mechanical response, to ensure that the microstructure has been generated under conditions of pure one dimensional strain, the target assembly requires both a complex array of momentum traps to prevent lateral releases entering the specimen location from the edges and spall plates to prevent tensile interactions (spall) affecting the microstructure. In this paper, we examine these effects by performing microhardness profiles of shock loaded copper and tantalum samples. In general, variations in hardness both parallel and perpendicular to the shock direction were small indicating successful momentum trapping. Variations in hardness at different locations relative to the impact face are discussed in terms of the initial degree of cold work and the ability to generate and move dislocations in the samples.

Download Full-text

Dynamic Fracture Feature in Metals under Very High Strain Rate Induced by Shock Loading

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.145-149.273 ◽

1997 ◽

Vol 145-149 ◽

pp. 273-278 ◽

Cited By ~ 1

Author(s):

C.W. Sun ◽

S.P. Feng ◽

S.M. Zhuang ◽

X.P. Long

Keyword(s):

High Strain Rate ◽

Strain Rate ◽

Dynamic Fracture ◽

Shock Loading ◽

High Strain ◽

Fracture Feature ◽

Very High

Download Full-text

Experimental and Numerical Study of Soft Tissue Surrogate Behavior Under Ballistic Loading

Volume 2: Biomedical and Biotechnology ◽

10.1115/imece2012-85724 ◽

2012 ◽

Author(s):

Ericka K. Amborn ◽

Karim H. Muci-Küchler ◽

Brandon J. Hinz

Keyword(s):

Soft Tissue ◽

Constitutive Model ◽

High Strain Rate ◽

Strain Rate ◽

High Strain ◽

Split Hopkinson Pressure Bar ◽

Numerical Study ◽

Constitutive Models ◽

Material Behavior ◽

Good Representation

Studying the high strain rate behavior of soft tissues and soft tissue surrogates is of interest to improve the understanding of injury mechanisms during blast and impact events. Tests such as the split Hopkinson pressure bar have been successfully used to characterize material behavior at high strain rates under simple loading conditions. However, experiments involving more complex stress states are needed for the validation of constitutive models and numerical simulation techniques for fast transient events. In particular, for the case of ballistic injuries, controlled tests that can better reflect the effects induced by a penetrating projectile are of interest. This paper presents an experiment that tries to achieve that goal. The experimental setup involves a cylindrical test sample made of a translucent soft tissue surrogate that has a small pre-made cylindrical channel along its axis. A small caliber projectile is fired through the pre-made channel at representative speeds using an air rifle. High speed video is used in conjunction with specialized software to generate data for model validation. A Lagrangian Finite Element Method (FEM) model was prepared in ABAQUS/Explicit to simulate the experiments. Different hyperelastic constitutive models were explored to represent the behavior of the soft tissue surrogate and the required material properties were obtained from high strain rate test data reported in the open literature. The simulation results corresponding to each constitutive model considered were qualitatively compared against the experimental data for a single projectile speed. The constitutive model that provided the closest match was then used to perform an additional simulation at a different projectile velocity and quantitative comparisons between numerical and experimental results were made. The comparisons showed that the Marlow hyperelastic model available in ABAQUS/Explicit was able to produce a good representation of the soft tissue surrogate behavior observed experimentally at the two projectile speeds considered.

Download Full-text