Simulation of failure in polymers by crazing using a phase field micromechanical model
Abstract
In this study, a Phase Field Micromechanical Model (PFMM) is used to model failure by crazing in an amorphous polymer under an applied uniaxial tension. The primarily failure mechanism in tension in amorphous materials, such as Poly-Methyl-Methacrylate (PMMA) or PolyStyrene (PS), is through the crazing mechanism. Crazes are localized defects that are nucleated around material defects such as voids or solid inclusions. The evolution of a defect driven by the Time-Dependent Ginzburg-Landau equation is used to model the initiation, and subsequent widening and propagation of a craze under an external uniaxial stress field. The equivalent system approach is used to break the inhomogeneous system into an equivalent system where an effective eigenstrain field is used to minimize the elastic energy. Three geometries are used to compare the phase field model to experiments: the flat plate with a hole, a penny-shaped crack, and a spherical void. The phase field contours and the macroscopic stress-strain curves are used to determine the overall effect of the strain-rate on the material response for all three geometries.
Degree
M.S.M.E.
Advisors
Koslowski, Purdue University.
Subject Area
Mechanics|Mechanical engineering
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