MS Research

THESIS TITLE:	A Model for Predicting the Evolution of Damage in the Plastic Bonded Explosive LX17
THESIS COMMITTEE:	Dr. David Allen - Advisor
	Dr. Dimitris Lagoudas
	Dr. J.N. Reddy
THESIS ABSTRACT:	Viscoelastic cohesive zones are employed within the framework of a finite element code to model a two-phase particle-reinforced composite material consisting of a relatively stiff aggregate embedded in a copolymer binder. The composite of interest, LX17, is noted to have a very large aggregate volume fraction and as such, Voronoi tessellation has been used to generate aggregate grain boundaries within finite element meshes along which viscoelastic cohesive zones have been embedded to model the binder. It has been observed experimentally that the majority of damage in LX17 occurs within the binder, and thus, a damage evolution law has been applied to the viscoelastic cohesive zones that is phenomenological in nature. The responses obtained for the composite from the FEM analysis are then compared to the experimental data compiled by Lawrence Livermore National Labs for various constant strain rate tests conducted by Groves and Cunningham (2000). In addition, comparisons are made to a previous effort at modeling LX17 in an endeavor to demonstrate the improved effectiveness in the modeling of granular composites using viscoelastic cohesive zones with damage. Finally, results for several test cases, some with analytic solutions, are provided as validation of the FEM code employed.

Selection of Results from Thesis:
Simple Geometry Animations w/ Magnification of 15x on Displacements
	SimpleAnim1:	12 Grain w/ Damage
	SimpleAnim2:	30 Grain w/ Damage
	SimpleAnim3:	100 Grain w/ Damage (Actually...Mag. is 1x on this one)
Real Geometry PBX Animations w/ Magnification of 15x on Displacements
	RealAnim1:	5 Grain w/ Damage
	RealAnim2:	10 Grain w/ Damage (note: misapplied bc at bottom right..oops)
	RealAnim3:	12 Grain w/ Damage
	RealAnim4:	30 Grain w/ Damage
	RealAnim5:	100 Grain w/ Damage
	RealAnim6:	506 Grain w/out Damage
	RealAnim7:	506 Grain w/ Damage
Cyclic Loading Results:	Excel Format
	1.	Strain vs. Time Imposed
	2.	Stress vs. Strain Response
	3.	Damage vs. Strain Response
	4.	Stress vs. Time Response
	5.	Damage vs. Time Response