Monday  |  Salon 13  |  09:00 AM–09:20 AM

#15727, Full-field Local Deformation Measurements Around a Collapsing Pore in Shock-loaded Solids

Pore collapse—the rapid closure of pores contained in a material subjected to dynamic compression—has been the focus of investigation for various engineering disciplines. The presence of pores has been shown to cause accidental detonation of energetic materials, change in shock absorption and spall behaviors of engineered porous materials, and jetting in lattice structures. To use these porous materials most effectively in engineering designs, one must understand the extreme, local deformations which cause or accompany the aforementioned phenomena of detonation, shock absorption, spall, and jetting. Much work has been accomplished to study and model the behavior of porous materials in an averaged, continuum sense, and to qualitatively investigate the local mechanical behavior. However, to further our fundamental understanding of the pore collapse phenomenon and its physical relation to observed behaviors on the continuum scale, local deformation measurements are necessary. This work develops an experimental framework to characterize the mechanical deformation field surrounding a collapsing pore. A quantitative visualization technique which performs ultra-high speed digital image correlation (DIC) internally is termed “inner-plane DIC”. The technique is developed for plate impact experiments and applied to the shock compression of polymethyl methacrylate (PMMA) with a single spherical pore. Quantitative, full-field displacement and strain measurements are taken for the region immediately surrounding the pore during its collapse at pressures ranging from 0.5-2GPa, and results are discussed in light of strain localization and failure mechanisms.

Barry Lawlor   California Institute of Technology
Vatsa Gandhi   California Institute of Technology
Guruswami Ravichandran   California Institute of Technology