The time dependence of fracture has two sources: (1) the viscoelasticity of material behavior in the bulk of the structure, and (2) the rate process of the breakage of bonds in the fracture process zone which causes the softening law for the crack opening to be rate-dependent. The objective of this study is to clarify the differences between these two influences and their role in the size effec...

Cohesive laws are stress-strain curves used in finite element calculations to describe the debonding of interfaces such as grain boundaries. It would be convenient to describe grain boundary cohesive laws as a function of the parameters needed to describe the grain boundary geometry; two parameters in two dimensions and five parameters in three dimensions. However, we find that the cohesive law...

A well-controlled and minimal experimental scheme for dynamic fracture along weak planes is specifically designed for the validation of large-scale simulations using cohesive finite elements. The role of the experiments in the integrated approach is two-fold. On the one hand, careful measurements provide accurate boundary conditions and material parameters for a complete setup of the simulation...

We develop a three-dimensional nite-deformation cohesive element and a class of irreversible cohesive laws which enable the accurate and e cient tracking of dynamically growing cracks. The cohesive element governs the separation of the crack anks in accordance with an irreversible cohesive law, eventually leading to the formation of free surfaces, and is compatible with a conventional nite elem...

Recent disagreements on the mathematical modeling of fracture and size effect in concrete and other quasi-brittle materials are obstacles to improvements in design practice, and especially in design codes for concrete structures. In an attempt to overcome this impediment to progress, this paper compares the Hu-Duan boundary effect model BEM expounded since 2000 to the size-shape effect law SEL ...

The application of peel tests for the measurement of adhesive fracture toughness of metal-polymer laminates is reviewed and the merits of a mandrel peel method are highlighted. The mandrel method enables a direct experimental determination of both adhesive fracture toughness (GA) and the plastic bending energy (GP) during peel, whilst other approaches require a complex calculation for GP. In th...

The present study aimed at morphological and chemical characterization of the coating-substrate interface of a commercially available dental implant coated with plasma-sprayed hydroxyapatite (HA). For this purpose, elements in the chemically and mechanically exposed substrate surfaces were analyzed by EPMA and XPS. A thin titanium oxide film containing Ca and P was found at the interface. When ...

The present paper is concerned with modelling damage and fracture in notched woven fabric composites. Previous experimental work has shown that damage at a notch in a variety of GFRP and CFRP composites based on woven fabric reinforcement comprises matrix damage and fibre tow fracture along the plane of maximum stress. It is these experimental observations that inform the failure modelling deve...

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...