Date of Award
Summer 2020
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Mechanical Engineering
First Advisor
Roy, Somesh Prasad
Second Advisor
Moore, John A.
Third Advisor
Borg, John
Abstract
Understanding the response of energetic materials to dynamic loading is critical for the design and safety of energetic systems. Energetic materials may contain heterogeneous microstructures, and hotspots can form at microstructural interfaces. The hotspots in these microstructures can determine if a material is safe to use. This study presents an analysis of the effect of material interfaces on the dynamic behavior of a heterogeneous sandwich structure subjected to high-velocity impacts using the cohesive zone model. The current work explores the sensitivity of a sugar-PMMA heterogeneous system to interface properties like stiffness, strength, and fracture energy both for normal and oblique impacts. Cohesive zone modeling is common for quasi-static fracture problems but is less common for modeling interfaces in dynamics problems. The dynamic impact simulation is carried out using a three-dimensional finite element framework using the finite element software ABAQUS. These results show that the stiffness of the cohesive zone element significantly affects the reflection of the normal waves at the material interfaces. Furthermore, for both normal and oblique impacts, interface properties are found to have a first-order effect on velocity response. It is also found that the velocity response is more sensitive to the interface strength (normal strength/ shear strength) than fracture energy under high impact dynamic loading.