The Mori–Tanaka method for composite materials with nonlinear interface debonding

We have used the Mori–Tanaka method to study the effect of nonlinear interface debonding on the constitutive behavior of composite material with high particle volume fraction. The interface debonding is characterized by a nonlinear cohesive law determined from the fracture test of the high explosive PBX 9501. Using the example of the composite material with spherical particles subject to hydrostatic tension, we show that the particle size has an important effect on the behavior of the composite material, namely hardening for small particles and softening for large particles. The critical particle size that separates the hardening and softening behavior of the composite material is determined. For the composite material with large particles, the particle/matrix interface may undergo catastrophic debonding, i.e., sudden, dynamic debonding even under static load. The energy release during catastrophic debonding can be very large, thus may trigger the reaction or detonation of high explosives. For the high explosive PBX 9501, the energy release due to catastrophic debonding of coarse (large) particles is equivalent to the free drop of the high explosive from a height of 110 m. This value become much higher, 455 m, once the debonding of fine (small) particle is accounted for.