A Constitutive Model for the Dynamic Response of Brittle Materials (Submitted to J. Appl. Phys., August 1989); LA-UR-89-2651 (Preprint)
Los Alamos, NM: Los Alamos National Laboratory, 1989. Preprint. Wraps. [2], 28. plus covers (rear cover is plain paper). Tables. Figures. References. Appendix. This was prepared for the DARPA Armor-Antiarmor Program, Joint DoD/DOE Munitions Technology Development Program which is a cooperative, jointly funded effort of research and development to improve nonnuclear munitions technology across all service mission areas. This program is enabled under a Memorandum of Understanding that tasks the DOE to solve problems in conventional defense. The technical areas investigated are based on their importance to the services, the needs that are common to the conventional and nuclear weapons programs, and the perceived benefit to the overall national defense efforts. Technology Coordination Groups (TCGs) serve as technology liaisons between the DoD and DOE. The members are technical experts who coordinate multiagency requirements, establish project plans, monitor technical activity, and develop classification guidance. A microphysically based material model for the dynamic inelastic response of a brittle material is developed. The progressive loss of strength as well as the post failure response of a granular material with friction are included. Crack instability conditions (an inelastic surface in stress space) and inelastic strains are obtained by considering the response of individual microcracks to an applied stress field. The assumptions of material isotropy and an exponential distribution for the crack radius are invoked to provide a tractable formulation. The constitutive model requires a minimal number of physical parameters, is compatible with a previously developed ductile fracture model [J. Appl. Phys. 64, 6699 (1988)] that utilizes inelastic surfaces, and can be formulated as an efficient, robust numerical algorithm for use in three dimensional computer codes. The material model is implemented into a Lagrangian computer formulation for the demonstration of material response to dynamic loading conditions. Comparisons with one dimensional, uniaxial impact experiments are provided. Condition: Very good.
Keywords: Armor, Antiarmor, Conventional Weapons, Conventional Munitions, Joint Munitions Program, Brittle Materials, Constitutive Model, Dynamic Response, Damage Surfaces, Pressure-Volume Material Response, Crack Growth, Silicon Carbide, Boron Carbide, Titani
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