Advanced ceramics and semiconductors (i.e. SiC, Si, Quartz, etc.) are increasingly being used for industrial applications. These ceramics/semiconductors are hard, strong, inert, and light weight. This combination of properties makes them ideal candidates for tribological, semiconductor, MEMS and optoelectronic applications. Manufacturing these materials without causing surface and subsurface da...

This study presents a probabilistic, 3-D framework to describe brittle fracture in structural components which incorporates weakest link statistics and a micromechanics model reflecting local damage of material. The Weibull stress (a,) emerges as a fracture parameter to define conditions leading to local material failure. This parameter is correlated with the macroscopic loading and used to des...

The fracture initiation in ductile materials is governed by the damaging process along the plastic loading path. A new damage plasticity model for ductile fracture is proposed. Experimental results show that fracture initiation in uncracked ductile solids is sensitive to the hydrostatic pressure and is dependent on the Lode angle. The damage plasticity model is established on a "cylindrical dec...

We present a contribution on the risk of hydraulic fracturing in CO2 geological storage using an analytical model of hydraulic fracturing in weak formations. The work is based on a MohrCoulomb dislocation model that is extended to account for material with fracture toughness. The complete slip process that is distributed around the crack tip is replaced by superdislocations that are placed in t...

Mechanisms for interpreting anomalous decreases in radon in ground water prior to earthquakes are examined with the help of a case study to show that radon potentially is a sensitive tracer of strain changes in the crust preceding an earthquake. The 2003 Chengkung earthquake of magnitude (M) 6.8 on December 10, 2003, was the strongest earthquake near the Chengkung area in eastern Taiwan since 1...

forming limit curve (flc) is an important tool for evaluation of formability of sheet metals subjected to different loading. free bulge of aluminume tubes has been investigated numerically to obtain flc. to verify the numerical results one experimental setup has been manufactured which has the ability of controlling the internal pressure and axial feed. in this study, time and zone of bursting ...

The hardened alpha-case (alpha-case) layer inevitably forms on the surface of titanium castings when prepared by investment casting. Because the hardness of the alpha-case is incomparable to that of the interior structure, the perception exists that the alpha-case is difficult to remove during cutting, grinding and polishing. Grindability (ease of grinding) of cast cpTi and cast Ti-6Al-4V was e...

The ductile fracture arrest may present supplementary requirement for selection of base material for most demanding steel welded structures. The most representative one with such requirement are gas pipelines. Therefore to ensure that the pipeline materials has adequate toughness to arrest a ductile fracture, the pipe material must be designed and tested in accordance with the specific procedur...

In the present research, damage mechanisms during room temperature uniaxial tensile testing of two different modern high strength dual phase steels,DP780 and DP980, were studied. Detailed microstructural characterization of the strained and sectioned samples was performed by scanning electron microscopy (SEM). The results revealed that interface decohesion, especially at the triple junctions of...

two-layer metallic sheets have wide applications in aerospace, marine, automotive and domestic industries due to their superlative characteristics. in this paper, the formability of two-layer sheet is investigated through analytical, experimental and numerical approaches. an analytical model is developed based on marciniak-kuczynski method associated hill’s non-quadratic yield criterion. formin...