The formation of discrete water clusters in polymer electrolyte fuel cell gas diffusion layers (GDL) can lead to increased resistance for oxygen transport the catalyst layer. This study investigates effect MPL crack propagation on cluster development a X-ray computed tomography (CT) microstructure using volume-of-fluid method (VoF). VoF calculation was compared operando CT data by voxel matchin...

The effect of Si doping on the strain and microstructure in GaN films grown on sapphire by metalorganic chemical vapor deposition was investigated. Strain was measured quantitatively by x-ray diffraction, Raman spectroscopy, and wafer curvature techniques. It was found that for a Si concentration of 2310 cm, the threshold for crack formation during film growth was 2.0 mm. Transmission electron ...

We present electrical conductivity measurements (at a fixed frequency of 1kHz) performed on three directions on limestone samples from the quarry of Meriel, during uniaxial tests of deformation up to failure. Samples were saturated from 100% to 80% by drainage. The samples showed brittle fracture with Young’s modulus in the range 10-13 MPa. Formation factor (sample resistivity divided by water ...

Joints and fissures in natural rocks have a significant influence on the stability of the rock mass, and it is often necessary to evaluate strength failure and crack evolution behavior. In this paper, based on experimental tests and numerical simulation (PFC2D), the macro-mechanical behavior and energy mechanism of jointed rock-like specimens with cross non-persistent joints under uniaxial load...

The failure time of samples of heterogeneous materials (wood, fiberglass) is studied as a function of the applied stress. It is shown that in these materials the failure time is predicted with a good accuracy by a model of microcrack nucleation proposed by Pomeau. It is also shown that the crack growth process presents critical features when the failure time is approached. It is very well known...

Abstract A framework for damage modelling based on the fast Fourier transform (FFT) method is proposed to combine variational phase-field approach with a cohesive zone model. This combination enables application of FFT methodology in composite materials interfaces. The voxel technique laminate model adopted this purpose. frictional incorporated describe fracture behaviour interface including sl...

This contribution introduces a multiscale fracture model that aims to take the microstructural length scale effects into account in brittle failure. is formulated framework of Cosserat continuum theory and coupled with phase field approach failure describe complex crack paths. The effectiveness proposed method demonstrated using two cases: shear propagation problem interaction problem. first be...

Very high cycle fatigue (VHCF) properties and damage mechanisms were investigated for a Ti-6Al-4V alloy with needle-like ? phase. It was revealed that the is dominated by interior crack initiation fish-eye pattern. The center of area covered peaks, dimples, microvoids grooves, exhibiting micro-ductile characteristics instead commonly reported brittle ones. found formation this particular appear...

A strain gradient void-driven ductile fracture model of single crystals is proposed and applied to simulate crack propagation in oligo-crystal specimens. The based on a thermodynamical framework for homogenized porous solids unifying generalizing existing formulations. This crystal relies multi-surface representation plasticity which the standard Schmid law enhanced account porosity, including ...

Rock masses generally contain many fissures filled with weak materials. At present, the interaction mechanisms of crack coalescence and seepage in rock are still poorly understood. Therefore, this study conducts systematic laboratory tests on sandstone samples two under hydromechanical coupling conditions. The influences fissures, filling, ligament length, bridge angle strength, fracture patter...