Phase field damage simulations of debonding between matrix and spherical inclusions

Johanna B Palsdottir, Purdue University

Abstract

Polymer-bonded explosives (PBX) are complicated composites, and it is important for practical applications to know how they deform and fracture. PBX consists of large volume fraction of energetic particles and experiments show that the interface is a critical region for structural stability since particles are often weakly bonded to the polymer and cracks initiate there and the composite fractures. This study focuses on the interface between a particle and a binder and how the particle inclusion starts to debond from the polymer binder in compressive and tensile loading. A phase field damage model is used to model the response of a glass bead particle in a Sylgard 184 binder under compressive loading, and the model is validated with a Kolsky bar experiment of the same set-up. The comparison between the simulations and the experiment reveals that the damage model should be described with positive volumetric strain only, and deviatoric strain does not contribute to damage in compressive loading of Sylgard 184. In tensile loading, the phase field damage model is used to study cavitation and debonding, as compared with results from literature. In cavitation the interface is perfectly bonded and the fracture initiates slightly away from the interface. In debonding the interface is weaker than the matrix, and fracture initiates at the interface. Analytic solution of the critical stress needed for debonding shows good agreement with the simulations from the model.

Degree

M.S.M.E.

Advisors

Koslowski, Purdue University.

Subject Area

Mechanical engineering

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