共查询到19条相似文献,搜索用时 234 毫秒
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脆性材料内部含有大量裂纹,当某一裂纹扩展时,其他裂纹会对扩展裂纹产生影响。为了研究冲击载荷下,脆性材料内两裂纹的相互影响、连通规律及裂纹尖端应力强度因子的变化规律,利用有机玻璃板制作了含非平行双裂纹的实验试件,利用落板冲击设备进行了中低速冲击实验,结合有限元分析软件ABAQUS计算出裂纹尖端应力强度因子,利用有限差分软件AUTODYN进行了动态数值模拟研究,并将其模拟结果与实验结果进行对比分析。实验及模拟结果表明:裂纹破坏形态与AUTODYN数值模拟破坏形态基本一致;试件的断裂形态随着两裂纹间距不同而不同;裂纹间的相互影响程度随着裂纹间间距增大而减小;裂纹尖端应力强度因子KI随着裂纹间距的增大而减小,而KII随着裂纹间距增大而增大。 相似文献
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估算裂纹应力强度因子的新方法 总被引:1,自引:0,他引:1
根据裂纹形状与裂纹尖端应力强度因子分布之间的固有关系,在线弹性断
裂力学条件下,提出了一种按已知I型裂纹应力强度因子分布规律求裂纹形状及相应应力强
度因子的无梯度迭代法. 通过有限厚度、有限宽度板穿透裂纹和表面裂纹的数值模拟实例验
证了所提出方法的有效性和实用性,并对不同应力强度因子分布规律对裂纹形状以及相应的
应力强度因子大小的影响进行了分析和讨论. 所提出的方法有助于提高实际扩展裂纹应
力强度因子的估算精度以及更合理地预测疲劳裂纹形状演化. 相似文献
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《应用力学学报》2016,(1)
运用广义复变函数方法,通过构造适当的广义保角映射研究了含有共线双半无限裂纹的正交异性复合材料板的平面弹性问题,得出了部分裂纹面上受均匀面内载荷时应力场与两裂纹尖端处应力强度因子的解析解。结果表明:应力场的大小不仅与材料的几何构型及外载荷有关,还与材料的弹性常数有关,这是正交异性复合材料不同于各向同性材料的显著特征;两裂纹尖端处应力强度因子的大小只与材料的几何构型及外载荷有关;当两裂纹尖端的距离趋于无穷大时,所得到的解析解可退化为已有的正交异性复合材料板中半无限裂纹问题的解,通过将其与已有文献中的结果进行对比,验证了本文解析解的正确性。并通过数值算例分析了裂纹面上的受载长度、两裂纹尖端的距离对应力强度因子的影响规律以及两裂纹之间的相互作用。 相似文献
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为研究叶片裂纹尖端的应力奇异性,以某型航空发动机压气机叶片为例,利用有限元方法研究了叶片裂纹尖端应力强度因子的计算方法,并研究了旋转叶片振动状态下裂尖应力强度因子随裂纹长度的变化规律。建立计算模型时,在裂纹尖端划分了三维奇异单元,在裂尖外围划分了过渡单元。计算结果表明:研究旋转叶片振动状态下的裂尖应力奇异性,仅利用I型应力强度因子就具有足够的精度;对于同一裂纹,绝大多数情况下叶盆面应力强度因子大于叶背面应力强度因子,故研究叶片应力强度因子时只需研究叶盆应力强度因子即可;随着裂纹扩展,叶盆面I型应力强度因子不断增大。本文的研究方法及结论为进一步研究叶片的裂纹扩展规律及损伤容限奠定了基础。 相似文献
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研究双周期裂纹和刚性线夹杂非均匀材料的反平面剪切问题。基于保角变换技术和椭圆函数理论,获得了问题应力场的全场精确解,给出了裂纹和刚性线尖端应力强度因子的封闭形式解答,讨论了裂纹和刚性线尖端场的干涉效应。数值结果表明:改变水平和垂直分布周期对裂纹和刚性线尖端场影响明显不同;裂纹长度2a逐渐增大时(0≤a/ω1≤0.5),裂纹尖端应力强度因子从1逐渐增大到无限大,而刚性线的尖端场变化不大;刚性线长度2d逐渐增大时(0≤d/ω2≤1),刚性线尖端应力强度因子逐渐减小,而裂纹的尖端场仅略微增大。 相似文献
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采用权函数法确定了含裂纹飞轮在离心力和接触压力作用下的应力强度因子,计算了在同步转速工况下裂纹尖端应力强度因子的值,并与解析法和有限元法计算结果进行了对比。结果表明:权函数法与解析法的误差在3%以内,与有限元法的误差在1%以内,验证了权函数法计算应力强度因子的准确性高;在结构不变的情况下,权函数法可以快速求解不同载荷条件、不同长度裂纹的应力强度因子。通过控制变量法研究了不同参数对应力强度因子的影响,结果表明,飞轮裂纹尖端总应力强度因子随着裂纹尺寸、旋转转速、飞轮尺寸外径与内径比值的增大而增大。 相似文献
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断裂力学研究有裂纹构件的强度。因此,必须研究裂纹尖端附近的应力场。对于线弹性材料,裂纹尖端附近的应力场主要由应力强度因子所控制。当应力强度因子K_I到达临界值——材料的断裂韧度K_(Ic)时,裂纹就迅速扩展,构件发生脆性破坏。所以,应力强度因子是线弹性断裂力学中的一个主要参数,确定任意构件的应力强度因子也就成为断 相似文献
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界面裂纹问题中的权函数方法 总被引:2,自引:0,他引:2
本文将Paris等确定均匀材料中裂纹尖端应力强度因子的权函数方法推广应用到界面裂纹问题,给出了界面裂纹尖端附近或无限大体半无限界面裂纹问题的权函数的显式表达式。利用此权函数表达式可以很简便地求解界面裂纹尖端附近一些外来作用引起的应力强度因子,比如任意分布力、相变应变、位错和热等。作为一个算例,本文计算了界面一侧一个刃型位错引起的应力强度因子。 相似文献
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应用随机边界元法分析材料弹性常数的随机性和裂纹面随机性对应力强度因子的影响。文中首先简介了随机边界元法,给出了具有随机材料或几何参数的弹性体的边界位移或面力的协方差,进而给出了材料参数和裂纹面随机时应力强度因子均值和方差的计算公式。算例中详细讨论了杨氏模量、泊松比及裂纹面的随机性对应力强度因子的影响。 相似文献
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Muhammad Treifi S. Olutunde Oyadiji Derek K.L. Tsang 《International Journal of Solids and Structures》2008,45(25-26):6468-6484
The fractal-like finite element method (FFEM) is used to compute the stress intensity factors (SIFs) for different configurations of cracked/notched plates subject to in-plane shear and bending loading conditions. In the FFEM, the large number of unknown variables in the singular region around a notch tip is reduced to a small set of generalised co-ordinates by performing a fractal transformation using global interpolation functions. The use of exact analytical solutions of the displacement field around a notch tip as the global interpolation functions reduces the computational cost significantly and neither post-processing technique to extract SIFs nor special singular elements to model the singular region are required. The results of numerical examples of various configurations of cracked/notched plates are presented and validated via published data. Also, new results for cracked/notched plate problems are presented. These results demonstrate the accuracy and efficiency of the FFEM to compute the SIFs for notch problems under in-plane shear and bending loading conditions. 相似文献
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Ravitej Kommana Venkitanarayanan Parameswaran 《International Journal of Solids and Structures》2009,46(11-12):2420-2428
The variation of stress intensity factor along the thickness in a cracked transversely graded plate subjected to in plane bending is investigated in this study. A transversely graded plate having elastic modulus varying continuously along the thickness was prepared by embedding glass beads in epoxy resin. An edge crack in this plate was subjected to in plane bending and the crack tip displacement field on the surfaces of the plate was measured using digital image correlation (DIC). Using the recently reported asymptotic displacement fields for cracked transversely graded plates (Wadgaonkar, S.C., Parameswaran, V., 2009. Structure of near tip stress field and variation of stress intensity factor for a crack in a transversely graded material, Journal of Applied Mechanics 76 (1), 011014), the stress intensity factor (SIF) on the surfaces of the plate was calculated from the experimental data. The results of this part of the study indicated that the extent of variation of the SIF across the plate thickness is nearly the same as that of the elastic modulus. An expression to calculate the variation of the SIF through the plate thickness was developed assuming simple bending of the plate. The predicted variation of SIF was verified through finite element calculations. Further, the behavior of the SIF near the intersection of the crack front and the plate surfaces, the extent of dominance of the corner singular field and the exponent of the corner singularity were also investigated in detail. Finally, the effect of gradation strength and gradation type on the SIF was also studied. 相似文献
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An effective boundary element method for analysis of crack problems in a plane elastic plate 总被引:3,自引:0,他引:3
闫相桥 《应用数学和力学(英文版)》2005,26(6):814-822
A simple and effective boundary element method for stress intensity factor calculation for crack problems in a plane elastic plate is presented. The boundary element method consists of the constant displacement discontinuity element presented by Crouch and Starfield and the crack-tip displacement discontinuity elements proposed by YAN Xiangqiao. In the boundary element implementation the left or the right crack-tip displacement discontinuity element was placed locally at the corresponding left or right each crack tip on top of the constant displacement discontinuity elements that cover the entire crack surface and the other boundaries. Test examples (i. e. , a center crack in an infinite plate under tension, a circular hole and a crack in an infinite plate under tension) are included to illustrate that the numerical approach is very simple and accurate for stress intensity factor calculation of plane elasticity crack problems. In addition, specifically, the stress intensity factors of branching cracks emanating from a square hole in a rectangular plate under biaxial loads were analysed. These numerical results indicate the present numerical approach is very effective for calculating stress intensity factors of complex cracks in a 2-D finite body, and are used to reveal the effect of the biaxial loads and the cracked body geometry on stress intensity factors. 相似文献
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A novel singular finite element is presented to study cracked plates with arbitrary traction acting on crack surfaces. Firstly, the analytical solution around crack tips is determined using the symplectic dual approach. Subsequently, the solution is used to develop a novel singular finite element, which depicts accurately the characteristic of singular stresses field near crack tips. And the novel element can be applied to solve cracked plates, and both Mode I and Mode II stress intensity factors can be determined directly and accurately. Lastly, two numerical examples are given to illustrate the present method. 相似文献
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The formulation and implementation of a singular finite element for analyzing homogeneous anistropic materials is presented in this paper. Lekhnitskii's stress function method is used to formulate the boundary value problem with the stress function expressed as a Laurent series. The development of the element stiffness matrix and the method of integrating the element to conventional displacement based finite element programs is shown. The stiffness matrix generation is based on a least squates collocation technique to satisfy displacement continuity boundary conditions at the element interface. Implementation of the element is demonstrated for cracked anisotropic materials subjected to inplane loading. Center cracked, on and off-axis coupons under tensile loading are analyzed using the element. It is shown that the stress distributions and intensity factors compare well with those obtained using other methods. 相似文献