Development of a constitutive model for DPX2 explosive

Philip Church,Peter Gould,David Williamson,E Buzaud,E Cadoni,A Cosculluela,H Couque

doi:10.1051/epjconf/201818301059

Philip Church, Peter Gould + Show 5 more

Open Access

https://doi.org/10.1051/epjconf/201818301059

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Abstract

There is a significant challenge in simulating the behaviour of PBXs under high strain rate impact loading. A Porter-Gould physically based constitutive model has been developed for the DPX2 explosive. A series of quasi-static compression and tensile tests over a range of temperatures were performed together with DMA tests to calibrate the model. In particular tests were performed for different L/D ratios to understand the complex localisation and damage behaviour of the material. High rate tests on the compression Split Hopkinson Pressure Bar (SHPB) for a range of temperatures were then used for validation of the model under idealised stress states. Some model development is still required, particularly at lower temperatures near the glass transition temperature. In addition a series of classical Taylor Tests were used to validate the model under impact loading conditions at room temperature. The DYNA3D simulations gave very good results compared to the experiments for these impact conditions.

Highlights

The UK Ministry of Defence has a desire to move to explosives that have both higher performance and lower sensitiveness than historic compositions and this has led them to consider DPX2 as a candidate.DPX2 is a pressed explosive which has a higher HMX content than the explosives that it is designed to replace and should have increased performance
Data that exist on PBXN5 – a similar composition – suggest that the mechanical response will be dominated by shear failure [1] and this is borne out by the observed fracture response, Figures 1 and 2. Such fracture behaviour is often seen in granular materials and highly loaded particulate composites
All tests apart from the Taylor tests were carried out at various temperatures; these temperatures were determined by analysis of the Dynamic Mechanical Analysis (DMA) output

Summary

Introduction

The UK Ministry of Defence has a desire to move to explosives that have both higher performance and lower sensitiveness than historic compositions and this has led them to consider DPX2 as a candidate.DPX2 is a pressed explosive which has a higher HMX content than the explosives that it is designed to replace and should have increased performance. Data that exist on PBXN5 – a similar composition – suggest that the mechanical response will be dominated by shear failure [1] and this is borne out by the observed fracture response, Figures 1 and 2. In order to address this lack a comprehensive test regime was proposed covering physical and mechanical properties of DPX2 over a range of strain rates and temperatures. These data would be used to generate a numerical simulation capability to allow design and assessment of warhead concepts

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