CMP逆的表示及其应用

给出了复矩阵CMP逆的多种表示,分裂计算以及在求解约束矩阵方程中的应用.

Computational Fracture Analysis of an AFM-Specimen under Mixed Mode Loading Conditions

Fracture processes in ship-building structures are in many cases of a 3-D character. A finite element （FE） model of an all fracture mode （AFM） specimen was built for the study of 3-D mixed mode crack fracture behavior including modes Ⅰ,Ⅱ, and Ⅲ. The stress intensity factors （SIFs） were calculated by the modified virtual crack closure integral （MVCCI） method, and the crack initiation angle assessment was based on a recently developed 3-D fracture criterion--the Richard criterion. It was shown that the FE model of the AFM-specimen is applicable for investigations under general mixed mode loading conditions, and the computational results of crack initiation angles are in agreement with some available experimental findings. Thus, the applicability of the FE model of the AFM-specimen for mixed mode loading conditions and the validity of the Richard criterion can be demonstrated.

Light intensification effect of trailing indent crack in fused silica subsurface

A finite-difference time-domain algorithm was applied to solve Maxwell＇s equations to obtain the redistribution of an electro- magnetic plane wave in the vicinity of a trailing indent crack （TIC）. The roles of five geometrical parameters playing in light intensification were calculated numerically under the irradiation of a 355-nm normal incidence laser. The results show that the light intensity enhancements between the nearest neighbor pits were remarkable, which may lead to damage, The calculated results reveal that the light intensity enhancement factor （LIEF） can be up to 11.2 when TIC is on the rear-surface. With the increase of the length as well as the depth of pits, LIEF increased. Conversely, with the increase of the axis of pits, LIEF grad- ually declined to a stable status. It was observed that there exists an optima width or gap, which enables LIEF to be increased dramatically and then decreased gently. By comparison, results suggest that the worst cases occur when the depth and the length are both very large, especially if the width equals to 22 and the gap equals the width. This work provides a recom- mended theoretical criterion for defect inspection and classification.

Sufficient Conditions for Heegaard Splittings with Disjoint Curve Property

In the paper,we give two conditions that the Heegaard splitting admits the disjoint curve property.The main result is that for a genus g(g■2)strongly irreducible Heegaard splitting(C_1,C_2;F),let D_i be an essential disk in C_i,i=1,2,satisfying(1)at least one of ■D_1 and ■D_2 is separating in F and|■D_1∩■D_2|■2g-1;or(2)both ■D_1 and ■D_2 are non-separating in F and|■D_1∩■D_2|■2g-2,then(C_1,C_2;F)has the disjoint curve property.

Determination of T-stress using finite element analysis

A method that uses finite element analysis to determine the non-singular stress （T-stress） at a crack tip is proposed in this study. T-stress includes two components： the Tx-stress parallel to the tangent of the crack at its tip and the Ty-stress perpendicular to this tangent. The effects of contact and friction on both the Tx- and Ty-stresses on the crack flanks are considered in the method. Because the method uses a single standard elastic finite element analysis derived directly from the equation of the stress fields around the crack tip and does not require any assumptions or simplification, it can be used to determine the T-stress for any given geometry and loading condition. Theoretical results are used to calibrate the results, which exhibited good agreement and to discuss the T-stress computational methodology. Furthermore, the Tx- and Ty-stresses in center-cracked Brazilian disc （CCBD） specimens subjected to diametrical or partially distributed compression were numerically computed, and the effects of contact and friction on the Tx- and Ty-stresses are discussed.