Foam core sandwich composites are finding a wider breadth of use in aerospace, automotive, and construction applications. These structures present unique challenges in terms of material failure and interaction and are highly sensitive to damage and imperfections introduced during manufacturing. An emerging class of 3D Fiber Reinforced Foam Core (3DFRFC) aims to replace monolithic foams used in ...

Mechanisms for fatigue crack closure under plane strain conditions have recently been identified at very low (near-threshold) stress intensities in terms of effects of excess corrosion deposits or fracture surface roughness in promoting premature closure of the crack. In the present paper, a geometric model is presented for crack closure induced by fracture surface roughness. This model specifi...

‘Curving’ could occur in Mode I brittle fracture and it can be attributed to the constraint. The variation of the apparent fracture toughness with constraint with or without crack curving is investigated. Using a critical opening or hoop stress as the fracture criterion, it is demonstrated that a fracture event can be quantified by two mechanics parameters, i.e. K and A3 for fracture without cu...

Finite element analysis of the delamination crack propagation in laminated composites is presented. Fracture mechanics based Virtual Crack Closure Technique (VCCT), and the cohesive element technique, have been used to simulate the delamination initiation and propagation under Mode-I type loading. Detailed description of the parameter selection process for these two techniques with ABAQUS®/Stan...

Stable ductile crack growth in 3 mm thick AISI 304 stainless steel specimens has been investigated experimentally and numerically. Multi-linear Isotropic Hardening method coupled with the Von-Mises yield criterion was adopted for modeling elasto-plastic behavior of the material. Mode-I CT fracture specimens have been tested to generate experimental load-displacement-crack growth data during sta...

Prior detailed microscopic observations have revealed the essential mechanisms of damage in through-thickness reinforcing tows when a delamination crack passes. As expected, the damage sequence depends quite strongly on whether the crack is loaded in Mode I or Mode II and, if loading is mixed mode, the order of loading. Here, micromechanical models are presented that show how geometry and const...

We consider the buckle-driven delamination of compressed thin lms. For a wide class of patterns of delamination, it is shown that the loading on the delamination front progressively goes from mode I to mode II during growth of the blister. As a result, the mode dependence of the lm/substrate interface excludes widespread delamination. This explains the observations of blisters of nite extent, w...

Abstract In this study, mode I fracture tests on cracked straight-through Brazilian disc (CSTBD) and notched semi-circular bend (NSCB) shale specimens with different sizes were conducted to investigate the difference between maximum tangential stress criterion size effect law (SEL) model in predicting apparent toughness ( K a ) of shale. addition, effects specimen geometry selection prediction ...