Professor Vikram S. Deshpande
Micro-mechanics of ultra-high molecular weight polyethylene fibre composites
Fibre composites comprising Ultra High Molecular Weight Polyethylene (UHMWPE) fibres in a polyurethane or polyethylene matrix are now extensively used for ballistic protection applications. This interest arises from a recognition that the ballistic limit of fibre composites scales linearly with the so-called Cunniff velocity. Based on this parameter the UHMWPE fibres outperform most known materials as the UHMWPE fibres have a tensile strength exceeding 3.5 GPa at a density less than water. However, a detailed experimental investigation reveals that the Cunniff model fails to rationalise two key observations: (i) the ballistic performance of fibre based composites is strongly dependent on the shear strength of matrix and (ii) penetration of the UHMWPE composites does not occur in a membrane mode but rather in progressive manner, such that the number of failed plies increases with increasing impact velocity.
In this presentation, we report a comprehensive experimental and numerical investigation of the mechanics of these composites under both static and dynamic loading conditions. The understanding of the range of deformation/failure mechanisms gained from this combined numerical/experimental investigation will be used to motivate a discussion on a new class of UHMWPE composites that have the potential to further enhance performance.
Bio: Prof. Vikram Deshpande joined the faculty of Engineering at the University of Cambridge as a lecturer in October 2001 and was promoted to a professorship in Materials Engineering in 2010. He holds a Visiting Professorship at Eindhoven University Mechanical Engineering Department, The Netherlands. He was a tenured Associate Professor at the University of California, Santa Barbara (UCSB) in 2007-2008, and has written in excess of 200 journal articles in the experimental and theoretical mechanics solid mechanics with an h-index of 57. He serves on the editorial boards of a number of journals in mechanics and biomechanics including Journal of the Mechanics and Physics of Solids, Molecular and Cellular Biomechanics and Modelling and Simulation in Materials Science and Engineering.