Cohesive zone model for mode-I fracture with viscoelastic-sensitivity

Abstract

A viscoelastic cohesive zone model (CZM) is formulated herein to model the time- and temperature-dependent fracture process of the interface between the solid propellant and insulation. The model is suitable for the simulation of a wide range of problems especially for the relaxation response of the fracture process. Independent control parameters of the Park-Paulino-Roesler (PPR) models are deduced first. By introducing the relaxed critical displacement, cohesive strength and initial slope parameter into the static PPR model, a viscoelastic CZM is established. Numerical time integration about obtaining the reduced time is described considering the change of the temperature. The properties of the proposed model are discussed in detail through the stretch and relaxation test of the double cantilever beam (DCB). Stretch test of the double cantilever sandwich beam (DCSB) under different loading rates and loading temperatures are designed to inverse the time-dependent and temperature-dependent model parameters respectively. To check the effectiveness of the proposed model and the accuracy of the inversed model parameters, three different tests including stretch test, multiple stretch-relaxation test, and creep test are conducted. The agreement is achieved between the numerical and experimental results.