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These notes belong to a course on fracture mechanics

Decouple elastic deformation of the body and inelastic process of separation. Up to this point we have been dealing with the following situation. When a load causes a crack to extend in a body, a large part of the body is elastic, and the inelastic process of separation occurs in a zone around the front of the crack. Inelastic process of separation includes, for example, breaking of atomic bonds, growth of voids, and hysteresis in deformation.

The Engineering Science and Mechanics (ESM) Department at Virginia Tech is seeking a non-tenure track Instructor that will begin on August 10, 2010. The successful candidate will have a Ph.D. or a M.S. in Engineering Mechanics or a related discipline. Candidates with an M.S. degree must have taken a minimum of 18 graduate semester hours of courses related to engineering mechanics. Teaching experience in a university or college is preferred.

Postdoctoral Research Associate - Johns Hopkins University - April
2010:

In this paper that was published a few months ago, we reported the size effects on the elastic modulus and fracture strength of silicon nanowires. In addition, we observed that the silicon nanowires are linear elastic until fracture with a very large fracture strain up to 12%.



Y. Zhu, F. Xu, Q. Qin, W. Y. Fung, and W. Lu, Nano Letters 9, 3934-3939, 2009



Abstract:

Hi everybody,

I have done some experiments on the fracture toughness in mode II of wood specimens using attached geometry;so using

formula KIIc= 5.11P(3.1415*a)^0.5 /(2BW) I was able to calculate the frcature toughness of wood, but I am quite suprised

why this equation does not iclude depth of the specimens and moreover, I think that I have obtained higher values for the

fracture toughnes values. Is there any other formulation for obtaining the fracture toughness in mode II for this specimen?

P.s. dimension of my specimens is 100*100*63mm

In this paper we first obtain the order of stress singularity for a dynamically propagating self-affine fractal crack. We then show that there is always an upper bound to roughness, i.e. a propagating fractal crack reaches a terminal roughness. We then study the phenomenon of reaching a terminal velocity. Assuming that propagation of a fractal crack is discrete, we predict its terminal velocity using an asymptotic energy balance argument. In particular, we show that the limiting crack speed is a material-dependent fraction of the corresponding Rayleigh wave speed.