Low Strain Rate Measurements on Explosives Using DIC

Digital Image Correlation (DIC) is a technique that has a wide range of applications. At the High Explosives Applications Facility (HEAF), Lawrence Livermore National Laboratory, we are using DIC to perform a variety of strain measurements on plastic bonded explosives (PBXs). Because of the nature of these highly filled polymer composite materials, some conventional strain measurement devices, for example strain gages, cannot be used to measure strain reliably. While there are some drawbacks to DIC, there are also many advantages to this non-contact, optically based measurement system.

We have been successful in using DIC to measure strain in high strain rate experiments involving explosively driven plates. However, in this paper we will focus on our application of DIC to low strain rate measurements. Included in the work to be discussed will be DIC measurements of thermal expansion, Poisson’s ratio, strain derived from axial-torsion loading, and tensile creep. For each measurement type we provide some details on the additional hardware required and on the requisite modifications to our existing equipment. Also, in each case we will assess the effectiveness of our approach and, where applicable, compare results to those obtained using more traditional measurement techniques.