Abst rac t -The continuum constitutive modeling for rate-dependent fracture of brittle microcracking solids, which was described in Part 1 of this paper, is applied to the finite element analysis of stationary and nonstationary macrocracks in a single-edge-notched three-point bend specimen under a static loading. The microcrack damage zones near the macro-crack-tip can be classified as being "l...

A transient _nite element analysis is carried out to provide insight into the low temperature dynamic material toughness versus crack tip relationship for high strength structural steels under intense stress pulse loading[ The problem analyzed here is plane strain fracture of an edge cracked specimen under plane wave loading conditions[ The _nite element formulation employed accounts for the e}...

We study thermal crack shielding and thermal shock damage in a double-edge cracked metal-particlereinforced ceramic matrix composite subjected to sudden cooling at the cracked surfaces. Under severe thermal shocks, the crack will grow but will be bridged by the plastically stretched metal particles. A linear softening bridging law is used to describe the metal particle bridging behavior. An int...

Fracture-induced mechanochemical activation is achieved for the first time in a structural engineering polymer. Rubber toughened PMMA is lightly cross-linked (1.0 mol%) with the mechanophore spiropyran by free radical polymerization. Single Edge Notch Tension tests are performed on the spiropyran-linked material and a distinct change in color and fluorescence is detected at the crack tip, indic...

Vibrothermogrphy is a promising technique that uses ultrasonic elastic waves to locally stimulate defects on solids specimens and is typically applied in the aerospace and automotive industries. This technique allows for defect selective imaging using thermal waves that are generated by ultrasound waves. The mechanism involved is frictional heating or hysteresis that turns a dynamically loaded ...

The effects of loading conditions, specimen size and metal particle size on the crack growth resistance curve (R-curve) and residual strength of a ceramic-metal functionally graded material (FGM) are studied based on the crack-bridging concept. It is found that the FGM exhibits strong R-curve behavior when a crack grows from the ceramic-rich region toward the metal-rich region and the residual ...

-Properties of elastic solutions to interface crack problems are discussed in both the open formulation, in which the crack faces are assumed to be traction-free and interpenetration is permitted, and the unilateral formulation, where a contact zone is generally established adjacent to the crack tips. It is shown that if the contact zone is sufficiently small compared with the other dimensions ...

An exact dynamic 2D solution for a concentrated force near a stationary semi-infinite crack in an unbounded plane can be used in the transient analysis of wave-scattering problems. Direct approaches to obtaining the solution, however, are complicated by the existence of a characteristic length. A less direct approach is used here which circumvents these complications. As an example, the dynamic...

introduction: supplies of illegal drugs play determinant roles in developing new cases, relapse after treatment and some health criteria. recently, iran has encountered an illicit new coming drug which belongs to opioids. this article presents the crack supply in retail market in tehran.   method: this qualitative study was conducted in 2009 in tehran. in-depth interviews with drug dealers, dru...

Abstract: In this research, at first, the natural frequencies of a cracked beam are obtained analytically, then, location and depth of a crack in beam is identified by neural network method. The research is applied on a beam with an open crack for three different boundary conditions. For this purpose, at first, the natural frequencies of the cracked beam are obtained analytically, to get the ex...