Finite strain elasticity based cohesive zone model for mechanoluminescent composite interface: Part II. Interface damage characteristics

The need to estimate the micromechanical properties of elastico-mechanoluminescent (EML) composites was established in Part A of this paper. The particle-matrix interface was identified to be poorly understood towards building accurate EML models and to predict functional life estimates of the EML devices. Towards this, Part A of this paper defined the mechanical behavior of the interface as a softening spring through a bilinear cohesive zone model (CZM). Macroscale stress measurements were combined with material properties to estimate undamaged stiffness of the interface spring (k(sigma)(int)). In Part B of this paper, the damage characteristics of the interface spring are estimated through an experimental approach to complete the CZM. This is achieved by first establishing the finite strain behavior of the macroscopic EML-PDMS composite from uniaxial tensile testing. Secondly, a controlled tear is induced in the composite and the microscale displacement fields around the tear tip are captured using digital image correlation technique. Tear tip displacements and finite strain behavior are combined to estimate cohesive stresses in the tear-tip region of the composite. The contribution of particle-matrix interfaces towards resisting propagation of the tear is isolated from experimental results to obtain interface-CZM damage parameters. The interface CZM parameters are subsequently utilized in an FEM model to simulate macroscopic composite behavior to find good correlation. The experimental framework established in this paper can be utilized to estimate interface parameters of any particulate-elastomer composites that exhibit finite strain behavior.