Mixed-modes (I/III) fracture of aluminum foam based on micromechanics of damage

Abstract

Nowadays, foam structures have several applications in industries. Basically, discontinuities such as pores cause complications in evaluating the mechanical and fracture behavior. In other words, understanding the multi scale of porous cells in cracked foams can play a significant role in fracture prediction. The present research proposes an analytical approach based on the experimental concept of damage in which the behavior of cracked metal foam was investigated under mixed-mode I/III (tensile and out-of-plane) fracture. In this method, pores in foam are modeled as circular and elliptical defects. In this context, mechanical properties and crack inclination angle are obtained based on loading and configuration of pores. Dispersion of circular and elliptical discontinuities determines the overall modulus and crack inclination angle trajectory based on the experimental results, pure mode I SIF were occurred on (0°) and pure mode III were obtained at (62°) loading angle. The aluminum foams were produced and prepared according to the edge notch disc bend (ENDB) test method to obtain the onset of fracture initiation (K_Ic and K_IIIc) and trajectory of cracked foam body. The results demonstrated that analytical approach, based on circular pore distribution, had a good agreement with experimental results. Moreover, the results indicated that SIF in mode I and mode III had the most agreement with the experimental results at angles of 0° and 62°, respectively.