Combined experimental and numerical approach for identification of dynamic material model parameters

Abstract

Abstract. Extraction of the material stress-strain curve from a dynamic tensile or shear experiment is not straightforward. Indeed, stress and strain are not homogeneously distributed in the specimen, and consequently no one-one relation exists between the measured elongation and strain on one hand, and the measured force and stress on the other hand. This work aims at improving the accuracy of the stress-strain curves calculated from high strain rate experiments and the modelling of the material behaviour. Therefore numerical simulations are used to determine the relationship between the average stress-strain and local effective stress-strain. The material model parameters used in these simulations are improved during an iterative procedure which combines the experimental results and the simulated stress and strain distribution. Stress triaxiality, local temperature and strain rate are taken into account. The method is applied to dynamic tensile and shear experiments on a Ti6Al4V alloy carried out on a split Hopkinson bar set up. The Johnson-Cook model is used to describe the strain rate and temperature dependent material behaviour. The two types of tests are used separately or simultaneously to extract and model the material behaviour. It is found that using tensile and shear experiments simultaneously has clear advantages. The same approach is used to identify parameters for the Johnson-Cook damage initiation criteria.

Novel Technique for Static and Dynamic Shear Testing of Ti6Al4V Sheet

“…To determine the local strain either a numerical-experimental approach [27] or a local strain measurement technique should be used. Also for the simple shear test a local optical strain measurement technique is recommended [6].…”

Experimental Study of the High Strain Rate Shear Behaviour of Ti6Al4V

“…The strain rate and temperature dependent constitutive behaviour of Ti6Al4V is modelled with the Johnson-Cook model. The same parameters are used for the three experiments and were obtained in a previous study through tensile and planar shear tests (A=951MPa, B=892MPa, C=0.015, n=0.7, m=0.71, =0.00008s -1 ) [3]. ALE adaptive meshing is used in the simulation of the hat-shaped specimen test to avoid problems due to excessive mesh distortion.…”

Analysis of Friction Vibration in Sliding Model of Double Rough Surfaces

“…Table 1 The mechanical properties of the material name The JC failure parameters (d1=0.242,d2=0.183 and d3=0.452) were obtained from characterization work carried out by Peirs et al [8].A plot of true stress versus true strain for the chosen material model is shown in Fig. 4.…”