Modeling the progressive damage of the microdroplet test using contact surfaces with cohesive behavior

A quarter-symmetric, three-dimensional finite element model is used to determine the stress state and progressive failure of the fiber-matrix interface during a microdroplet pull-out test of a glass fiber/epoxy matrix system. The microdroplet system interphase region is modeled using contact with cohesive behavior and is able to undergo progressive damage. The cohesive model strength and toughness are varied to determine their influence on the macro-behavior of the system and the simulations are compared to experimental results from the literature. Additionally, geometric test parameters including the blade opening, fiber free length, and fiber diameter are varied to assess their relative influence on the macro-response of the system.