Applications of the EndoFEM with node-released methods had been used successfully to simulate the plastic wakes left behind the advancing fatigue crack. In this paper, employing the plastic zone size estimated by LEFM as a guideline, four strategies with various plans of node-released rates and two plans of finite element discretization near crack tip, are proposed to generate various fatigue cracked lengths of A12024-T3 CCT specimen under all tensile-cyclic loading. Evaluations based on the mechanical responses near crack tip and the crack opened/closure behaviors, it can be concluded that the EndoFEM with the rc dominant node-released strategy can lead to not only economical but also reliable results.

The problem of two circular inclusions of arbitrary radii and of different elastic moduli, which are perfectly bonded to an infinite matrix subjected to arbitrary loading, is solved by the heterogenization technique. This implies that the solution of the heterogeneous problem can be readily obtained from that of the corresponding homogeneous problem by a simple algebraic substitution. Based on the method of successive approximations and the technique of analytical continuation, the solution is formulated in a manner which leads to an approximate, but arbitrary accuracy, result. The present derived solution can be also applied to the problem with straight boundaries. Both the problem of two circular inclusions embedded in an infinite matrix and the problem of a circular inclusion embedded in a half-plane matrix are considered as our examples to demonstrate the use of the present approach.

Active control of noise radiation from vibrating plate excited by a harmonic line moment is analytically investigated. This study model of simple supported rectangular plate with a line moment excitation is used to simulate the vibration of ship hull or fuselage from the flutter of ship deck or aircraft wing respectively. The control is achieved by various configurations of piezoelectric actuators. The strategy of radiated power minimization is used to obtain the optimal control input unit voltage. The numerical results show that the significant attenuation of noise radiated power for volumetric modes in the low frequency range can be achieved with one control actuator located at the center of plate, irrespective of whether the excitation is on or off resonance. The efficiency of the active control is dependent on the location of the line moment and the actuators. It is also shown that the modal suppression and modal restructuring are two physical mechanisms of radiated power attenuation.

In this paper, the problem of a debonding crack at the interface between a circular fiber and an infinite matrix opened by internal pressure is discussed. We concentrated on the effect of contact near the crack tips within the content of linear elastic fracture mechanics. The Muskhelishvili complex variable method is used in this analysis. The frictionless contact crack tip condition is adopted in this study in order to avoid the oscillatory stress singularity at the crack tip as shown in the classical solution. By using the crack opening displacement gradient as the primary variable, the problem is then reduced to two coupled singular integral equations, and the final discretization of the equations employs the method given by Erdogan and Gupta (1972). The comprehensive numerical results of stress fields and the mode II SIF at the closed crack tip will be given in the paper. It is also found from the numerical evidences that the contact length at the crack tip is independent of one of the Dundurs parameters, α.

In this study, a computer program DBFWD is developed for data analysis of Falling Weight Deflectometer (FWD) test on flexible pavements. To backcalculate the layer moduli of the pavement, a number of iterative backcalculation schemes were employed with the forward analysis of the Green's flexibility influence functions. The temperature and the moisture influences on material moduli of the asphalt surface and the subgrade soils were considered in the analysis. As the result, the iterative scheme based on the peak deflection ratios was selected to backcalculate the layer moduli of local pavements. Owing to the correction procedure used in the program, interpretations with four original deflections were found more accurate than those with equivalent number of modified deflections. Comparisons of program DBFWD with other static backcalculation programs on theoretical and experimental deflections indicated that dynamic interpretation is more effective in providing the layer modulus information. Despite of the requirements of accurate inputs of the layer thickness and the testing load for the analysis, a generalized application of the program needs to be clarified with model road test in demand.

The purpose of this research is to study the effect of motion curves on the curvature of variable pitch lead screw (hereinafter VPLS) transmission mechanisms with different meshing elements. The surfaces of VPLS are generated based on various meshing elements with different specified motion curves. There are three kinds of ruled- and one involute-revolution surface meshing elements, and four types of motion curves are studied, which including modified trapezoidal (MT) curve, modified sine (MS) curve, modified constant velocity (MCV) curve, and polynomial (PL) curve. The curvature analyses include the determination of direction of contact line, induced principal radii of curvature, and lubrication angles between the surfaces of VPLS and various meshing elements. The results of this work provide a comparison between the effect of motion curve on the curvature of VPLS transmission mechanisms with different meshing elements.