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.
Highlights
The split Hopkinson bar technique is well known for characterizing the high strain rate behaviour of materials
A combined experimental-numerical method to improve the extraction of the material behaviour from dynamic tensile and shear experiments was presented
The Johnson-Cook model is used in the FEM to describe the material behaviour
Summary
The split Hopkinson bar technique is well known for characterizing the high strain rate behaviour of materials. An alternative iterative experimental-numerical method is presented to extract the local high strain rate material behaviour (effective stress and strain) of Ti6Al4V in the centre of the specimen. The Johnson-Cook parameters that are obtained during this procedure are more realistic than with methods that only use the average stress-strain curves because local adiabatic temperature, strain rate and stress triaxiality are taken into account during the parameter fitting process. The information from the FE simulations is applied to determine parameters from damage initiation criteria such as the Johnson-Cook failure criterion The use of both tensile and shear experiments for fitting of the constitutive model, leads to model parameters that are applicable for a wider range of loading paths. The second part of the paper focuses on the material behaviour extraction method and identification of the parameters from the constitutive and damage initiation model
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
