T. De Vuyst

Effects of orientation on the strength of the aluminum alloy 7010-T6 during shock loading: Experiment and simulation

The shock response of the aluminum alloy 7010-T6, induced by the technique of plate impact, has been investigated as a function of orientation to the loading axis to the rolling direction. Measurements of the Hugoniot elastic limit (HEL) and spall strength show that the material is stronger in the longitudinal orientation than the short transverse, in keeping with the mechanical properties measured at quasistatic strain rates. Furthermore, a comparison of the HELs to the 0.2% proof stresses suggests that there is a degree of strain-rate sensitivity in the longitudinal orientation, whilst the short transverse appears strain-rate insensitive. Thus, there exists the possibility that strain-rate sensitivity itself is orientation dependent in this alloy. Comparison of the ratios of spall strength according to orientation, to the equivalent quasistatic yield strengths provides further evidence of this hypothesis. A simulation using finite-element modeling has shown that while the model can reproduce the depende...

Total Lagrangian SPH modelling of necking and fracture in electromagnetically driven rings

This paper describes research on the prediction of necking and failure in metals at very high strain rates. The model developed in this paper uses a total Lagrangian SPH formulation with a normalised kernel. The detailed data from electromagnetically driven ring experiments by Zhang and Ravi-Chandar (Int J Fract 142:183–217, 2006) is used to evaluate the accuracy of the model predictions. In order to correctly model fracture in the total Lagrangian SPH formulation a visibility criterion based on a truncated cone has been implemented to remove particles obscured by a failed particle. A Johnson-Cook plasticity model is used in combination with a Lemaitredamage model to describe the plastic deformation and fracture of the rings. The effect of Joule heating due to the current induced in the ring is taken into account in the constitutive model. The acceleration due to the ring currents was implemented in the SPH code as a body force. The results demonstrate that this type of model is capable of predicting the number of fragments as well as the time of fracture. In agreement with experimental data, the model also predicts arrested necks and bending in the fragments.

Numerical modelling of the effect of using multi-explosives on the explosive forming of steel cones

Modelling and analysis of underwater explosive forming process by using FEM and SPH formulation is presented in this work. The explosive forming of a steel cone is studied. The model setup includes a low carbon steel plate, plate holder, forming die as well as water and C4 explosive. The effect of multiple explosives on rate of targets deformation has been studied. Four different multi-explosives models have been developed and compared to the single explosive model. The formability of the steel plate based on forming limit failure criteria has been investigated. Aspects such as shape of plates deformation and thickness of the plate during the forming process have been examined. The model results indicate that a multi-explosives model does not always guarantee a faster rate of target deformation without central explosive. On the other hand the model results indicate that the multi-explosives setup is capable of preventing crack failure of the steel plate during the forming process which would occur if a single explosive model was used.

Prediction of the ballistic limit of an aluminium sandwich panel

This work was funded by the European Space Agency under a contract with Airbus Defence and Space.