The effects of elastic constants mismatch on the interaction between a propagating crack and single or multiple inclusions in brittle matrix materials are investigated using numerical simulations. The simulations employ a quasi-static crack-growth prediction tool based upon the symmetric-Galerkin boundary element method (SGBEM) for multiregions, a modified quarter-point crack-tip element, the d...

Gas turbine operating cycles at high temperatures often consist of load reversals mixed with hold times; the latter occurring either as cruise for aero engines or at continuous power output for land based turbines, but also at low frequency loading conditions, e.g. slow “ramp up” of engine thrust. The hold time conditions cause the crack to grow by intergranular fracture due to material damage ...

This paper deals with the behavior of anti-plane shear crack in a piezoelectric layer bounded between two orthotropic half-planes within the framework of linear electroelasticity. The crack surfaces are assumed to be permeable or impermeable. The analysis is based on the stress fields caused by Volterra-type screw dislocation in the medium. Fourier transforms are used to reduce the dislocation ...

Turbine-generator shafts are often subjected to a complex transient torsional loading. Such transient torques may initiate and propagate a circumferential crack in the shafts. Mode III crack growth in turbo-generator shafts often results in a fracture surface morphology resembling a factory roof. The interaction of the mutual fracture surfaces results in a pressure and a frictional stress field...

Modelling Crack Propagation in Aluminium-Alloys 2524-T3 and 7050-T7452 Subjected to Fatigue Loading at Low Temperature M. D. Liu and J. J. Xiong * School of Transportation Science and Engineering, Beihang University, Beijing 100191, China; [email protected] * Correspondence: [email protected] Abstract: This paper seeks to model the crack propagation in of AAs (aluminum-alloys) 2524-T3 and 705...

Use of smart sensor technology along with intelligent signal processing plays a crucial role in the implementation and working of ultrasonic wave based damage detection system. In this work, the interaction of A0 Lamb mode with damages like crack and delamination are studied. Piezoelectric Wafer Active Sensors (PWAS) are used for generation of Lamb waves to detect damages in metal and composite...

The generation and the subsequent evolution of dynamic failure events in homogeneous layered materials that occur within microseconds after impact were investigated experimentally. Tested configurations include three-layer and two-layer, bonded Homalite specimens featuring different bonding strengths. High-speed photography and dynamic photoelasticity were utilized to study the nature, sequence...

A traction-displacement relationship that may be embedded into a cohesive zone model for microscale problems of intergranular fracture is extracted from atomistic molecular-dynamics simulations. A molecular-dynamics model for crack propagation under steady-state conditions is developed to analyze intergranular fracture along a flat Σ99 [1 1 0] symmetric tilt grain boundary in aluminum. Under hy...

In piping the defects play a key role for determining the life of component. Also the risk for pipe failure combined to the defects has to be taken into account. In this study thermal dynamic load has been applied to austenitic material (Aisi 304) in order to introduce dynamic behaviour into the crack. The studied crack (~20 mm ! 7 mm) has been produced by thermal fatigue in advance. Different ...

Since concrete is used for marine and hydraulic structures, pipe coatings and channel walls, its wear due to the attack of fast flowing water is a problem (1). The first systematic investigations on the resistance of concrete against wear in marine structures were carried out in the 1940s (2). Investigations carried out in the fields of water flow erosion, cavitation and abrasion have been revi...