Crack Initiation and Propagation in Laminated Composite Materials

Abstract

PVB laminated glass is a kind of typical laminated composite material and its crack characteristics are of great interest to vehicle manufacturers, safety engineers, and accident investigators. Because crack morphology on laminated windshield contains important information on energy mitigation, pedestrian protection, and accident reconstruction. In this chapter, we investigated the propagation characteristics for both radial and circular cracks in PVB laminated glasses by theoretical constitutive equations analysis, numerical simulation, experiments, and tests of impact. A damage-modified nonlinear viscoelastic constitutive relations model of PVB laminated glass were developed and implemented into FEA software to simulate the pedestrian head impact with vehicle windshield. Results showed that shear stress, compressive stress, and tensile stress were main causes of plastic deformation, radial cracks, and circumferential cracks for the laminated glass subject to impactor. In addition, the extended finite element method (XFEM) was adopted to study the multiple crack propagation in brittle plates. The effects of various impact conditions and sensitivity to initial flaw were discussed. For experiment analysis, crack branching was investigated and an explicit expression describing the crack velocity and number of crack branching is proposed under quasi-static Split Hopkinson Pressure Bar (SHPB)