Abstract
The paper aims at the numerical simulation of the wave propagation in compressive Split Hopkinson Pressure Bar (SHPB) experiment. The paper deals with principles of SHPB measurement, optimisation of a numerical model and techniques of pulse shaping. The parametric model of the typical SHPB configuration developed for LS-DYNA environment is introduced and optimised (in terms of element size and distribution) using the sensitivity study. Then, a parametric analysis of a geometric properties of the pulse shaper is carried out to reveal their influence on a shape of the incident pulse. The analysis is algorithmized including the pre- and post-processing routines to enable automated processing of numerical results and comparison with the experimental data. Results of the parametric analysis and the influence of geometric properties of the pulse shaper (diameter, length) on the incident wave are demonstrated.
Highlights
Since material parameters are dependent on strain rate, many experimental methodologies allowing to investigate material behavior during dynamic loading like fast impacts and explosions were developed
First experiments were performed by Hopkinson [1], while an important improvement was proposed by Kolsky [2] introducing the common Split Hopkinson Pressure Bar (SHPB) apparatus [3]
SHPB is an experimental device, which allows to measure the stress-strain diagram in dynamic compression, where the strain-rate and maximum compressive strain can be regulated within physical boundaries given by performance of the SHPB apparatus and the investigated samples
Summary
Since material parameters are dependent on strain rate, many experimental methodologies allowing to investigate material behavior during dynamic loading like fast impacts and explosions were developed. Yield strength of most of metals (e.g. copper) and alloys (including aluminium based alloys, steel, etc.) tends to increase with higher strain rates The physics of this phenomena can be explained, for example, in a way that particles of material are affected by micro-inertia effects and do not have enough time to move and to cause yielding during high strain rates. Incident, reflected and transmitted pulses are recorded with strain-gauges (see Figure 2). The recorded strain-gauge signals and known properties of the experimental setup (e.g. bar dimensions, Young’s modulus, density, wave propagation velocity etc.) are used for the evaluation of the stress-strain diagram of the specimen for the given strain-rate. Diameter and impacting velocity were varied parameters and evaluation of their influence on shape of stress pulse was analyzed
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