Author Type

Graduate Student

Date of Award

1996

Document Type

Thesis

Publication Status

Version of Record

Submission Date

October 2026

Thesis/Dissertation Advisor [Chair]

Wille, Luc T.

Abstract

We developed code in MasPar Fortran (an extension of Fortran 90) to conduct molecular dynamics simulations on a MasPar MP-1 massively parallel computer. The code is portable to other Single-Instruction Multiple-Data (SIMD) platforms with minor modifications. We used a two dimensional grid containing over 220,000 atoms to simulate a high strain-rate fracture growth in Cu-Ni alloys. The atoms are arranged in a triangular lattice corresponding to an fcc (111) surface and a Lennard-Jones (LJ) potential with a spline cutoff is used for the inter-atomic potential. The location of the spline cutoff can be adjusted to simulate either brittle or ductile fracture. The atomic positions are spatially decomposed on each Processor Element, the data are shared with adjacent PEs, and atoms are transferred as they move. Free boundary conditions are used, and the appropriate techniques for applying strain and damping unwanted reflections are developed. We report variations in the critical applied strain with increasing temperature, and propose a novel method for characterizing the location of a crack tip. This method lends itself to algorithmic calculation and reporting by the fracture code. Our results represent the first microscopic analysis of fracture in an alloy system and extend recent work on pure metals. During the investigation, we introduced a Sigma 5 grain boundary (36.9) into the sample, with appropriate grain-boundary segregation. We developed a technique for rapidly quenching the high-energy particles at an artificially constructed grain boundary. We demonstrate crack blunting at the grain boundary. We also report on flyer/target impact simulations in an alloy with an LJ inter-atomic potential.

Extent

151 p.

Comments

FAU Electronic Theses and Dissertations Collection|Thesis (Ph.D.)--Florida Atlantic University, 1996.|FAU Electronic Theses and Dissertations Collection

Identifier

FADT12445

Format

pdf

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