We present an experimental study of the dynamics of rapid tensile fracture in brittle amorphous materials. We first compare the dynamic behavior of “standard” brittle materials (e.g. glass) with the corresponding features observed in “model” materials, polyacrylamide gels, in which the relevant sound speeds can be reduced by 2-3 orders of magnitude. The results of this comparison indicate unive...

The very high cycle fatigue behavior (10-10 cycles) of Ti-6246 has been investigated using ultrasonic fatigue techniques. In this regime of fatigue (0.4-0.6σYS), only certain microstructural regions are susceptible to fatigue damage accumulation, and lifetimes are related to the distribution of fatigue critical microstructural neighborhoods. Three distinct categories of crystallographic crack i...

The fracture property of amorphous metal was studied by a large scale molecular dynamics (MD) simulation. The Finnis-Sinclair potential for α-iron was used as an inter-atomic potential. At first, we made a model amorphous metal by melting-rapid quenching simulation. And then a crystal growth simulation in the amorphous was performed. We used circular model, and the cracktip is assumed to be at ...

Recent experimental and computational work by Link and associates has demonstrated that relatively small (W = 150 mm) single edge notched tension specimens (SE(T)) can be used to obtain crack arrest data high in the ductile-to-brittle transition of ferritic structural steel using dynamic computational techniques if a thermal gradient is utilized to aid in the crack arrest. Testing has been repo...

There are few experimental results to date describing the crack-propagation threshold behavior of short fatigue cracks under multiaxial loading conditions. To address this need, in the present study, the variation in mixed-mode, high-cycle fatigue-crack growth thresholds with crack size and shape are reported for a Ti-6Al-4V turbine blade alloy, heat treated to two widely different microstructu...

There are few experimental results to date describing the crack-propagation threshold behavior of short fatigue cracks under multiaxial loading conditions. To address this need, in the present study, the variation in mixed-mode, high-cycle fatigue-crack growth thresholds with crack size and shape are reported for a Ti-6Al-4V turbine blade alloy, heat treated to two widely different microstructu...

A newly developed computational approach is proposed in the paper for the analysis of multiple crack problems based on the eigen crack opening displacement (COD) boundary integral equations. The eigen COD particularly refers to a crack in an infinite domain under fictitious traction acting on the crack surface. With the concept of eigen COD, the multiple cracks in great number can be solved by ...

Three-dimensional dislocation dynamics simulations are used to study micro-crack interaction with the first micro-structural barrier in face-centred cubic bi-crystals loaded in high cycle fatigue conditions. In the examined configuration, we assumed that micro-crack transmission occurs due to surface relief growth in the secondary grain ahead of the primary crack. This indirect transmission mec...

A nonlinear acoustic effect is a sensitive tool to detect a micro-scale crack or early stage of cracking during the fatigue process. The damage produces a nonlinear stress-strain relationship, and the nonlinearity can be measured by a higher harmonic component in the frequency domain. The greater the damage, the larger the level of a nonlinearity, which can be used for the diagnosis of micro-cr...