Feasibility of introducing compositional gradients to the core of a sandwich structure and the resulting fracture behavior under impact loading conditions is the primary focus of the study. Model sandwich structures comprising of graded core with bilinear variation of volume fraction of hollow microballoons are considered for experimental and numerical simulations. Conventional sandwiches with ...

Cohesive-zone models have been used to study the effects of strength and toughness on the delamination of beam-like geometries. The conditions under which linear-elastic interfacial mechanics provide a good frame-work for predicting failure of such systems have been studied. It has been determined that the phase angle derived from LEFM calculations provides an excellent description of the parti...

The dynamic propagation of a bifurcated crack under arbitrary loading is studied. Under plane loading con2gurations, it is shown that the model problem of the determination of the dynamic stress intensity factors after branching is similar to the anti-plane crack branching problem. By analogy with the exact results of the mode III case, the energy release rate immediately after branching under ...

The dynamic fracture behavior of layered architectures is experimentally studied. Specifically, crack penetration, trapping, and branching at an interface are examined. A newly introduced optical technique called Digital Gradient Sensing (DGS) that quantifies elasto-optic effects due to a non-uniform state of stress is extended to perform full-field measurements during the fracture event using ...

The addition of liquid-filled urea-formaldehyde (UF) microcapsules to an epoxy matrix leads to significant reduction in fatigue crack growth rate and corresponding increase in fatigue life. Mode-I fatigue crack propagation is measured using a tapered doublecantilever beam (TDCB) specimen for a range of microcapsule concentrations and sizes: 0, 5, 10, and 20% by weight and 50, 180, and 460 lm di...