A novel method for preparing and testing bending specimens in-situ the TEM has been developed. This method provides high visibility of the crack front and its associated plastic zone. This is significant because energy release rates can now be calculated at many points throughout the test based on crack tip opening displacement (CTOD), crack opening angle (COA), and crack advance. Further refin...

Fatigue crack growth rate depends not only on the load amplitude, but also on the morphology of crack path. The strain energy density theory has the ability to analyze crack growth rate. A strain energy density crack growth model is proposed. It can predict the lifetime of fatigue crack growth for mixed mode cracks while an equation for mode I crack is also obtained. The validity of the model i...

Ultrasonic methods have been implemented for in situ sizing of fatigue cracks near fastener holes. These techniques, however, only provide an estimate at the time of the measurement and cannot predict the remaining life of the structure. In contrast, statistical crack propagation approaches model the expected fatigue life based on worst-case fatigue process assumptions. The authors have recentl...

The present study investigated the local arrestability of intergranular crack in high-strength martensitic steel through multi-scale three-dimensional (3D) analysis using X-ray computed tomography and focused ion beam machining (FIB)-scanning electron microscopy (SEM) serial sectioning combined with backscattering diffraction (3D EBSD). Macroscopic demonstrated discontinuous propagation cracks,...

in this paper the effects of transmittance, dispersion angle and diffusion length on the quantum efficiency of solar cells (qesc) have been simulated and investigated. optical path technic is used for simulation. the results show that base thickness, diffusion length, dispersion angle, number of optical confinement path and transmission angles have an extremely effects on the qesc. simulation r...

In this paper we consider the quasistatic crack growth in brittle materials in the particular case of a preassigned crack path Γ, and propose a new notion of irreversible quasistatic evolution which is based on a local stability criterion for the energy functional, rather than on a global one. To better focus on this aspect we present our approach in the simplest model case of a homogeneous iso...

This article discusses results obtained from a parametric study to analytically evaluate the impingement of a crack at the interface of an environmental barrier coating (EBC) and a monolithic Silicon nitride (Si 3 N 4) layered ceramics substrate. The study establishes a correlation that leads to determine if the crack is arrested or advanced by either penetrating or deflecting along the EBC/sub...

In robotics and video games, one often discretizes continuous terrain into a grid with blocked and unblocked grid cells and then uses path-planning algorithms to find a shortest path on the resulting grid graph. This path, however, is typically not a shortest path in the continuous terrain. In this overview article, we discuss a path-planning methodology for quickly finding paths in continuous ...

In this article, we report irregular cleavage front transmission at grain boundaries in free-standing polysilicon thin films. When the orientations of two adjacent grains are correlated, the crack may bypass the boundary via a ‘‘tunneling’’ process. Similar behavior can also be achieved if the crack path curves in the grain-boundary-affected zone. Moreover, the separation of crack flanks can be...

In order to investigate the properties of Y-shaped cracks of brittle materials under compression, compression tests by using square cement mortar specimens with Y-shaped crack were conducted. A true triaxial loading device was applied in the tests, and the major principle stresses or the critical stresses were measured. The results show that as the branch angle θ between the branch crack and th...