Full-Field Deformation Observation of Polymer Foam Subjected to Shock Loading

Abstract

Dynamic material response of polymer foam subjected to shock loading has been investigated, and the effects of density and loading rate have been studied. Cubic specimens 20 and 30 lb/ft³ nominal densities were subjected to shock loading using a single diaphragm shock tube apparatus. Full field displacements and strain fields are obtained with the use of stereo high speed cameras in conjunction with the 3D digital image correlation technique. Simultaneously, load data is obtained with the use of piezotronic load cells. Material responses of the two different mass densities of polymer foam have been examined, while the effect of loading rate is also examined by comparisons with results from quasi-static compression testing. The material response as a function of loading rate was recovered using load cell data and digital image correlation strain fields. Failure mechanisms are observed to differ in specimens of different density. Failure stress is seen to increase significantly with increasing foam density. Both 20 and 30 lb/ft³ density foams exhibit substantial strain rate dependence, with large increases in stress at failure observed at an elevated strain rate.