This study introduces the free vibration analysis of multilayered symmetric sandwich Timoshenko beams, made of functionally graded materials with two edge cracked, using the finite element method and linear elastic fracture mechanic theory. The FG beam consists of 50 layers, located symmetrically to the neutral plane, whose material properties distribution change along the beam thickness, accor...

Mixed-mode dynamic crack growth behavior in a compositionally graded particle filled polymer is studied experimentally and computationally. Beams with single edge cracks initially aligned in the direction of the compositional gradient and subjected to one-point eccentric impact loading are examined. Optical interferometry along with high-speed photography is used to measure surface deformations...

This report presents a simple and convenient method to generate nanoscale fractures (cracks) in smooth, single-crystalline Si substrates. The cracks propagated as approximately straight lines along the {100} crystal planes with controllable length defined by a stabilizing backlayer. Close to its tip, the crack presented a vertical offset of the two planes as step of smoothly decreasing height, ...

The miniaturization and three dimensional die stacking in advanced microelectronic packages poses a big challenge to their non-destructive evaluation by acoustic micro imaging. In particular, their complicated structures and multiple interfaces make the interpretation of acoustic data even more difficult. A common phenomenon observed in acoustic micro imaging of microelectronic packages is the ...

A methodology for the detection and removal of cracks on digitized paintings. The objective of this research is to develop an automatic crack detection system. The algorithm is composed of two parts; image processing and image classification. In the first step, cracks are distinguished from background image easily using the filtering, the improved subtraction method, and the morphological opera...

In this paper, an analytical model based on the modified couple stress theory and Timoshenko beam is developed to study vibrational power flow of a microbeam with crack. The open edge crack modeled as rotational spring, which connects two segments separated by location. governing equations cracked are derived from Hamilton's principle. By introducing differential operator method, transformed in...

The analytical approach used to develop a novel fatigue crack growth coupon for highly plastic stress field condition is presented in this paper. The flight hardware investigated is a large separation bolt that has a deep notch, which produces a large plastic zone at the notch root when highly loaded. Four test specimen configurations are analyzed in an attempt to match the elastic-plastic stre...

Micromechanical methods to predict the fracture behavior and estimate the fracture toughness of cellular solids and foams are presented in this paper. The microstructure of the foam is modeled using finite elements. The struts of foam are modeled using either structural elements such as beams or three-dimensional solid elements. A portion of the foam containing an edge crack is modeled. Displac...

We present an experimental study of the dynamics of rapid tensile fracture in brittle amorphous materials. We first compare the dynamic behavior of “standard” brittle materials (e.g. glass) with the corresponding features observed in “model” materials, polyacrylamide gels, in which the relevant sound speeds can be reduced by 2-3 orders of magnitude. The results of this comparison indicate unive...

The presented work introduces a numerical parametric study on the crack propagation direction under mixed-mode conditions (mode I + II). It is conducted for the geometry of an eccentric asymmetric fourpoint bending of a single edge notched beam specimen; various levels of mode-mixity are ensured by modifications in the crack length and crack eccentricity. The direction of crack propagation is e...