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1.
SH波在正交各向异性功能梯度材料直裂纹处的散射 总被引：2，自引：0，他引：2
研究了正交各向异性功能梯度材料中直裂纹对SH波的散射问题,材料两个方向的剪切模量和密度假定为指数模型,通过积分变换-积分方程方法,建立数学模型,化为对偶积分方程,用Copson方法求解对偶积分方程,最后得到动应力强度因子,并且给出了数值算例,讨论了在SH波作用下,裂纹尖端的动应力强度因子与入射波的频率,入射角的关系． 相似文献
2.
黄上恒 《商丘师范学院学报》2000,16(4):36-38
研究了同时处于机械与电学载荷之下的压电陶瓷柱体表面裂纹前缘的应力场和电位移场。求得了应力及电位移的奇异性阶数和相应的两个强度因子。 相似文献
3.
研究弹性材料夹杂含裂纹功能梯度材料的接触问题．利用Fourier积分变换,将问题转化为关于未知位错密度函数的奇异积分方程,再用配点法对奇异积分方程进行数值求解．获得了裂纹尖端标准应力强度因子．数值结果显示了标准应力强度因子与梯度材料非均匀参数、摩擦系数、裂纹长度以及裂纹距刚性压头中心水平距离的关系． 相似文献
4.
ALSHOAIBI Abdulnaser M HADI M.S.A ARIFFIN A.K. 《浙江大学学报(A卷英文版)》2007,8(2):228-236
INTRODUCTION The finite element method (FEM) has proved to be very well suited for the study of fracture mechanics. Nevertheless, modelling the propagation of a crack through a finite element mesh turns out to be difficult because of the modification of the mesh topology. Use of crack propagation laws based on stress inten-sity factor range is the most successful engineering application of fracture mechanics. The stress intensity factors are a very important parameter in fracture analys… 相似文献
5.
The concept of eigen crack opening displacement (COD) can be defined as the COD of a crack in infinite plate under the tractions acting on the crack surface. By introducing this concept, the eigen COD formulation of boundary integral equation is proposed in this paper, together with the solution procedures for multiple crack problems in plane elasticity. With the proposed approach, the multiple crack problems can be solved with the conventional displacement discontinuity boundary integral equations in an it... 相似文献
6.
周春梅 《宁夏师范学院学报》2014,35(3):10-15
分析了SH波在功能梯度压电带拼接半无限大压电材料中共线双裂纹处的散射,基于功能梯度压电材料参数指数模型,在裂纹面电渗透性边界条件下,利用Fourier积分变换将问题转化成对偶积分方程,并利用Copson方法对问题进行了求解,最后通过数值算例表明了右裂纹尖端的动应力强度因子受波数和梯度参数的影响情况. 相似文献
7.
讨论了无限长功能梯度压电板中双裂纹尖端热响应分析,用Fourier积分变换把混合边值问题转化为以裂纹面上位移为未知量的对偶积分方程,利用Schmidt方法对其求解,最后通过数值算例考察了温度变化及材料系数对应力强度因子的重要影响. 相似文献
8.
1 Introduction a The crack problem has always been an important topic to researchers in engineering mechanism. Some initial defects, like microcrack for example, will exist in the manufacturing procedure of real materials, they will grow or coalesce gradu… 相似文献
9.
通过构造含有复奇异指数的新应力函数,利用复合材料断裂复变方法对正交异性双材料界面裂纹应力奇异性进行了研究.通过求解一类偏微分方程组的边值问题,推出了正交异性双材料界面裂纹尖端应力具有λ=-1/2的常数奇异性,λ=-1/2+ε的非常数奇异性,λ=-1/2+iε的常数振荡奇异性和λ=-1/2+c+iε的非常数振荡奇异性,并建立了四种奇异性下正交异性双材料Ⅱ型中心穿透界面裂纹尖端的应力强度因子的计算公式以及应力场和位移场的解析解. 相似文献
10.
讨论无限大一维六方压电准晶材料中一类裂纹中心位于矩形顶点且成双周期分布的反平面问题,利用周期对称性、保角变化、椭圆函数及施瓦兹公式,给出该问题场势函数的封闭解,进而得到了裂纹尖端的强度因子。 相似文献
11.
基于ANSYS的应力强度因子计算 总被引：1，自引：0，他引：1
利用大型有限元分析软件ANSYS并基于"位移外推"法进行应力强度因子的计算,其实现方法有两种:一种是采用1/4节点单元模拟裂纹尖端奇异性,由ANSYS直接给出应力强度因子值;另一种是先计算出靠近裂纹尖端处节点的位移或应力,再线性拟合,这种方法不一定要考虑奇异性,只需使网格足够精细即可。文章通过实例介绍了这两种方法求解应力强度因子的过程和技巧,并将计算结果与理论分析结果进行了比较,表明两种方法均可行。 相似文献
12.
Under tension and shear conditions related to unloading of rock mass, a jointed rock mass model of linear elastic fracture mechanics is established. According to the model, the equations of stresses, strains and displacements of the region influenced by the crack but relatively faraway the crack (the distance between the research point and the center of the crack is longer than the length of crack) are derived. They are important for evaluating the deformation of cracked rock. It is demonstrated by the comparison between computational results of these theoretical equations and the observed data from unloading test that they are applicable for actual engineering. 相似文献
13.
ALSHOAIBI Abdulnaser M. ARIFFIN Ahmad Kamal 《浙江大学学报(A卷英文版)》2006,7(8):1336-1342
INTRODUCTION The finite element method (FEM) has been widely employed for solving linear elastic and elas-tic-plastic fracture problems. The evaluation of stress intensity factors in 2D geometries by FEM is a tech-nique widely used for non-standard crack configura-tions. Basically, there are two groups of estimation methods, those based on field extrapolation near the crack tip (Chan et al., 1970; Shih et al., 1976) and those using the energy release when the crack propagates. However… 相似文献
14.
周春梅 《宁夏师范学院学报》2009,30(6):34-38,51
讨论了SH波在功能梯度压电带中共线双裂纹处的散射问题,假定裂纹面上边界条件是电渗透性的,通过建立数学模型并利用Copson方法对问题进行了求解,最后通过数值算例讨论了右裂纹尖端的动应力强度因子与材料梯度参数等因素的关系． 相似文献
15.
Pure bending of simply supported circular plate of transversely isotropic functionally graded material 总被引：3，自引：0，他引：3
LI Xiang-yu DING Hao-jiang CHEN Wei-qiu 《浙江大学学报(A卷英文版)》2006,7(8):1324-1328
INTRODUCTION In recent years, functionally graded materials (FGMs) have attracted more and more attention. Due to their continuously varying material properties in space on the macroscopic scale, FGMs, therefore, are usually superior to conventional fiber-matrix materi-als in mechanical behavior, especially for perform-ance under thermal loading. Now FGMs have been widely used in various fields including electronics, chemistry, optics, biomedicine, etc. Heretofore, volumes of literatu… 相似文献
16.
In this paper, a kind of singularly perturbed first-order differential equations with integral boundary condition are considered. With the method of boundary layer function and the Banach fixed-point theorem, the uniformly valid asymptotic solution of the original problem is obtained. 相似文献
17.
张立 《淮南职业技术学院学报》2008,8(1):15-16
针对采用爆破施工时确定参数大多是靠工程经验,而没有进行机理分析问题;通过引入有效应力强度因子,从岩石断裂力学和爆生气准静态理论角度分析了岩石裂纹的启裂、止裂判据和扩展规律,为爆破参数的合理设计提供了理论依据。 相似文献
18.
The fracture processes of concrete were described by a cohesive crack model based on initial toughness criterion. The corresponding analytical method to predict the instability state was proposed. In this model, the initial toughness was adopted as the crack propagation criterion and the weight function method was used to calculate the stress intensity factor and the crack opening displacement caused by the cohesive stress. The unstable toughness can be easily obtained using the proposed method without measuring parameters at the critical state that was necessary in traditional methods. The proposed method was verified by existing experimental data of wedge splitting specimens with different grades of concrete and the sensitivity of the results on the tensile softening curve was discussed. The results demonstrate that the proposed method can well predict the peak load, the critical effective crack length, and the unstable toughness of concrete specimens. Moreover, the calculated unstable toughness is not sensitive to the tensile softening curve. 相似文献
19.
Xian-kui Zhu 《浙江大学学报(A卷英文版)》2009,10(11):1541-1560
In this paper a critical review is presented ofthe history and current state of the art of J-integral resistance curve testing and experimental evaluation methods in conjunction with a discussion of the development of the plane strain fracture toughness test standard ASTM E 1820 developed by American Society for Testing and Materials （ASTM）. Early research efforts on this topic are reviewed first, These include the J-integral concept, experimental estimates of the J-integral for stationary cracks, load line displacement （LLD） and crack mouth opening displacement （CMOD） based ηfactor equations, different formulations of J-integral incremental equations for growing cracks, crack growth corrected .JR curve determination, and experimental test methods. Recent developments in J-R curve testing and evaluation are then described, with emphasis on accurate J-integral incremental equations, a normalization method, a modified basic method, a CMOD direct method with use of incremental equations, relationships of plastic geometry factors, constraint-dependent J-R curve testing and correction approaches. An overview of the present fracture toughness test standard ASTM E1820-08a is then presented. The review shows that after more than 40 years of investigation and development, the J-integral resistance curve test methods in ASTM E1820 have become simpler, more cost-effective and more accurate. 相似文献
20.
3-D scattering of obliquely incident plane p waves by alluvial valley embedded in layered half-space
The indirect boundary element method(IBEM) was established to solve the problem of 3-D seismic responses of 2-D topographies,by calculating the free-field responses with the direct-stiffness method and simulating the scattering wave fields with the dynamic Green’s functions of moving distributed loads.The proposed method yields accurate results,because the 3-D dynamic stiffness matrixes used are exact and the fictitious moving distributed loads can be acted directly on the interface between the alluvial valley and the layered half-space without singularity.The comparison with the published methods verifies the validity of the proposed method.And the numerical analyses are performed to give some beneficial conclusions.The study shows that 3-D scattering by an alluvial valley is essentially different from the 2-D case,and that the presence of soil layer affects not only the amplitude value of surface displacements but also the distribution of surface displacements. 相似文献