Discretization induced oscillations in the load-displacement curve are a well known problem for simulations of cohesive crack growth with finite elements. The problem results from an insufficient resolution of the complex stress state within the cohesive zone ahead of the crack tip. This work demonstrates that the hp-version of the finite element method is ideally suited to resolve this complex...

The Coherent Gradient Sensor (CGS) is extended to the optical differentiation of specular, diffracted wave fronts leading to the combined measurement of inand outof-plane displacement field gradients. A derivation of the underlying optical interference principles is presented along with an analysis of the effective instrument sensitivity. In order to demonstrate the capabilities of the techniqu...

In this paper, the extended finite element method (XFEM) is employed to investigate the statics and vibration problems of cracked isotropic bars and beams. Three kinds of elements namely the standard, the blended and the enriched elements are utilized to discretize the structure and model cracks. Two techniques referred as the increase of the number of Gauss integration points and the rectangle...

Newly developed stress increment measurement technique is presented. Based on stress inversion theory proposed by authors, spontaneous stress increment field can be obtained even if the material is under plastic deformation. We present here an application example of this technique by means of the stress increment field measurement at the crack tip of an aluminum plate under the monotonic loadin...

The boundary element formulation for analysing interaction between a hole and multiple cracks in piezoelectric materials is presented. Using Green’s function for hole problems and variational principle, a boundary element model (BEM) for a 2-D thermopiezoelectric solid with cracks and holes has been developed and used to calculate stress intensity factors of the crack-hole problem. In BEM, the ...

Numerical methods such as boundary element and finite element methods are widely used for the stress analysis in solid mechanics. This study presents boundary element method based on the displacement discontinuity formulation to solve general problems of interaction between hydraulic fracturing and discontinuities. The crack tip element and a higher order boundary displacement collocation techn...

In order to improve upon continuum models for understanding the origins of ductile versus brittle response in materials, an accurate assessment of the stress fields near a crack tip must be developed. Existing continuum models have considered the crack tip to be perfectly sharp in order to use convenient analytical solutions for the stress fields around the crack tip. Numerous experimental obse...

This paper deals with a procedure to calculate the elastic stress intensity factors for arbitrary-shaped cracks in plane stress and plane strain problems. An assumed displacement.hybrid finite element model is employed wherein the unknowns in the final algebraic system of equations are the nodal displacements and the elastic stress intensity factors. Special elements, which contain proper singu...