The competition between transverse surface and sub-surface cracks in a thin, hard coating bonded to polycarbonate substrate due to spherical indentation is investigated in real-time as a function of coating thickness and indenter radius. Fine grain (Y-TZP) and medium grain (alumina) ceramics and pre-abraded amorphous glass are used for the coating. As the coating thickness is reduced, the famil...

Fracture toughness anisotropy of AA2139 (Al-Cu-Mg) in T351 and T8 conditions has been investigated via mechanical testing of smooth and notched specimens of different geometries, loaded in the rolling direction (L) or in the transverse direction (T). Fracture mechanisms were investigated via SEM and synchrotron radiation computed tomography (SRCT). Contributions to failure anisotropy are identi...

In this paper we address the issue of a creeping wave by investigating a twodimensional configuration which involves a surface-braking crack in a traction free planar backwall. We assume that this back-wall is irradiated by a shear Gaussian beam which is incident at a critical angle and hits the wall away from the crack edge. We show that the generated wave known in the engineering literature a...

Mode I steady crack growth is analyzed to determine the toughening due to domain switching in ferroelectric ceramics with electric field applied parallel to the crack front. A multi-axial, electromechanically coupled, incremental constitutive theory is applied to model the material behavior of the ferroelectric ceramic. The constitutive law is then implemented within the finite element method t...

Rotating shafts are important and responsible components of many machines, such as power generation plants, aircraft engines, machine tool spindles, etc. A transverse shaft crack can occur due to cyclic loading, creep, stress corrosion, and other mechanisms to which rotating machines are subjected. If not detected early, the developing shaft crack can lead to a serious machine damage resulting ...

A layer structure consisting of two glass plates bonded with polymer-based adhesives and loaded at the upper surface with a linewedge indenter is used to evaluate crack containment. Two adhesives are used, a low-modulus epoxy resin and a particle-filled composite. The adhesives arrest indentation-induced transverse cracks at the first interface. A substantially higher load is required to resume...

Plate-type structural members are commonly used in engineering applications like aircraft, ships nuclear reactors etc. These structural members often have cracks arising from manufacture or from material defects or stress concentrations. Designing a structure against fracture in service involves consideration of strength of the structure as a function of crack size, dimension and the applied lo...

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...

Resistance to tearing plays a major role when evaluating the reliability of textiles used for example in protective clothing [1] and in composite materials [2]. Tearing in textile structures proceeds through the formation and propagation of a Del zone ahead of the crack. It arises from the stretching and slippage of longitudinal yarns along transverse yarns followed by the stretching and alignm...