Determination of stress–strain curves of materials at high strain rates using dynamic indentation technique

Abstract

Determination of dynamic behaviour of materials is a serious challenge in mechanics of materials. In this investigation, a new approach is proposed to obtain stress–strain curves of metals from dynamic indentation test. This approach is based on a combined experiment, simulation, and optimization techniques. In the experiment side, a conical penetrator is shot against the material as the target. The load–indentation depth curve is obtained from the dynamic indentation test. The indentation test is simulated using Ls-dyna and the numerical load–indentation depth is obtained from the simulation. The stress–strain curves are defined by Johnson–Cook material model. From optimization of the difference between the experimental and numerical load–indentation depth curves, the constants of the material model are identified. The material model is validated also by stress–strain curves obtained from quasi-static test conducted using Instron and dynamic tests conducted using Split Hopkinson Bar. The results show a close agreement between the model prediction and the experimental stress–strain curves for different strain rates.

Determination of the parameters of material models using dynamic indentation test and artificial neural network

“…Split Hopkinson pressure bar (SHPB) apparatus was developed to obtain the stress-strain curve of materials at high strain rates. 24,25 The stress, strain rate, and strain can then be calculated using the relations defined by 26 :…”

Determination of mechanical properties from sharp dynamic indentation

“…In this study, finite element software ABAQUS is used for numerical simulations, and a two-dimensional axisymmetric dynamic indentation finite element model is built, 14 as shown in Figure 1. The dynamic indentation device based on the split Hopkinson pressure bar mainly consists of striker, incident bar, indenter and transmission bar, which are used to test the dynamic mechanical properties of the target material.…”

“…Wang 13 investigated the dynamic indentation mechanical properties of metallic glasses, and found that the dynamic indentation hardness is significantly different from the static indentation hardness and the related mechanical parameters are also significantly different, which also indicates the need for dynamic indentation studies. Pourolajal and Majzoobi 14 showed that the dynamic indentation study mainly focuses on the comparison of the relevant responses under different impact velocities through dynamic compression tests to obtain the relevant constitutive parameters; the relevant response data are obtained by measurements using load sensors and laser high-speed cameras, which may generate uncertainty errors. Overall, the current research work is mainly focused on the research and development of experimental equipment, simple static and dynamic hardness tests, and others.…”