SIMULATION OF THE FRACTURE-BEHAVIOR OF ELASTOMERIC COMPOSITES - MECHANICAL INTERACTIONS AT MATERIAL INTERFACES

The fracture mechanics of multilayered elastomeric composites was simu lated by the Blister Test using a polyurethane (PU)/Al base plate inte rfacial assembly. In the various systems studied, a hard or soft inter posed layer (approximately 50 mum) separated the bulk matrix (approxim ately 1000 mum) from the metal counterface, with a hard-to-soft modulu s ratio of 1.70. Debonding was performed at a constant pressurization rate (1 X 10(-8) m3/S) corresponding to an average delamination rate o f 0.025 m/s. Lateral hardening of the composite modulus (negative tran sversal gradient of modulus) improved the fracture resistance (by 35%) at the material interface, in conformance with analytical predictions . Particle-dispersed and liquid-doped systems exhibited a sharp attenu ation (40 to 90%) in the debond pressure. The latter results were subs tantiated by subjective assessment using optical microscopy, and were found consistent with stress concentration and weak cohesive fracture at the resin-substrate interface, respectively.