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异质双材料界面端部应力奇异性的实验分析 总被引:8,自引:0,他引:8
用高灵敏度的云纹干涉实验方法测量了弯曲载荷作用下异质结构的位移场,并采用局部混合法对实验结果进行处理,根据结果对界面端部区域的应力分布规律进行了讨论;求出了应力奇异性阶数λ和应力强度因子K,并将这一结果与Bogy ̄[1]等人用理论分析的方法所预期的结果和有限元计算结果进行了比较。本文的工作从实验的角度证实了异质双材料结构界面端部区域的应力状态可以用表达式:σ_(ij)(r,θ)=k·r ̄(-λ)f_(ij)(θ)来描述。 相似文献
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本文从分析弹塑性力学的基本方程人手,探讨了幂硬化材料I型裂纹端三维应力应变场的结构,结果表明,按其应力特征,裂纹端沿厚度方向可划分为三个区域:ZⅠ,ZⅡ和ZⅢ,在区域ZⅠ,垂直于Z轴(厚度方向)的平面内应力分量可首先用平面应变条件下的基本方程求解,在区域ZⅢ,这些分量可首先用平面应力条件下的基本方程求解.本文定义区域ZⅡ为弹塑性Ⅰ型裂纹的过渡层,指出,过渡层是弹塑性Ⅰ型裂纹三维应力应变场的特性所在.对揭示其本质有特殊重要的意义.本文选择裂纹端张开位移(CTOD)作为描述局部解幅值系数的参数,并探讨了三维变形状态下,CTOD的分布规律. 相似文献
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提出了一种分析双材料轴对称界面端的应力奇异行为的特征值法.基于弹性力学空间轴对称问题的基本方程和一阶近似假设,利用分离变量形式的位移函数和无网格算法,导出了关于应力奇异性指数的离散形式的奇异性特征方程.由奇异性特征方程的特征值和特征向量,即可确定应力奇异性指数、位移角函数和应力角函数.数值求解了纤维/基体轴对称界面端模型的奇异性特征方程, 结果表明:尺寸效应参数δ(奇异点与轴对称轴的距离和应力奇异性支配区域大小的比值)影响着应力奇异性的强弱与阶次, 准一阶近似解析解只是δ>>1时的一个特例. 相似文献
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直角结合异材界面端应力强度系数的经验公式 总被引:1,自引:0,他引:1
由不同材料结合而成的材料(简称异材或双材料)的力学性能及其可靠性评价是工程中亟待解决的问题。表征界面端奇异应力场大小的应力强度系数是结合异材强度评价的依据,本文针对工程中最常见的直角结合异材,通过对大量不同材料组合的异材的边界元数值分析,提出了界面端应力强度系数的近似计算公式,无量纲化后的应力强度系数的值只与异材Dundurs参数a,卢有关,该公式具有较高的精度,可以作为一般工程上的应力强度系数的计算以及异材结构设计的依据。 相似文献
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影响双材料界面端三维应力奇异性的几何因素研究 总被引:1,自引:0,他引:1
应用常规有限单元分析技术,对几种典型接头形式的三维双材料结构界面端点附近应力奇异性进行了研究,重点分析了棱角(两自由平面的夹角)大小对界面端点附近应力奇异性指数的影响。数值分析结果表明:棱角大小对界面端应力奇异性指数有明显影响,棱角越大,奇异性指数越小;当棱角趋于180°时,端点附近的应力奇异性指数收敛于界面端线上的值(等于平面应变条件下的理论值)。研究发现,如果采用圆弧对三维双材料结构的棱边进行倒角,使相应的界面端线变成光滑连续曲线,则原界面端点附近的应力奇异性会完全退化为界面端线附近的应力奇异性,即界面端点独特的应力奇异性现象消失。 相似文献
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残余应力分析方法主要有衍射法、应力释放法和声、光、磁等方法。其中,X射线衍射法与应力释放中的钻孔技术与理论最为成熟,应用最广。在应力均匀且数值较小时,两者可以给出相互接近的结果。然而当样品微小且微观结构复杂时,两者给出的结果会有明显的差异。本文利用上述两种方法对同一纯铜样品表面的残余应力进行分析,对比分析结果并讨论了相关的影响因素。我们对X射线衍射法与环芯法的适用性进行了讨论:前者适用于晶体材料的无损检测,而后者更能反映当前应力水平。此外,对方法的选用需要考虑应力测试的目的。 相似文献
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对各向异性双材料自由边界面端部奇异性场问题进行了研究,利用有限元分析法所得到的各向异性双材料自由边界面端部的应力奇异性指数以及角分布函数,构造了一个自由边界面端部单元,据此建立了自由边界面端部奇异性场的杂交应力模型,并结合Hellinger-Reissner变分原理导出应力杂交元方程,建立了求解平面各向异性材料裂纹尖端问题的杂交元计算模型.与四节点单元相结合,提出一种求解自由边界面端部广义应力强度因子的杂交元法.考核例结果表明:本文方法的数值解精度高,可应用于各向异性材料双材料自由边界面端部问题. 相似文献
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瓷修复体界面断裂行为的模拟实验研究 总被引:1,自引:0,他引:1
本文利用云纹干涉法和云纹干涉--有限元混合法,对瓷修复体的模拟双材料模型界面断裂问题进行了实验研究。用云纹干涉和数字错位云纹干涉法测量带边裂纹的双材料四点简支梁在剪切作用下界面表面的剪应变分布及界面两侧局部表面的位移场,实验表明,由于界面两两侧材料力学性质不同,表现出界面剪切断裂问题的非称性和裂尖附近复合型断裂的特点;用云纹干涉法和有限元法相结合的混合法对粘接界面角点应力奇异性进行研究,并对角点附近应力应变场作了分析,得到了应力奇异指数与边界楔角,载荷的关系,证明了用界面应力强度因子Kf来描述界面端部区域应力分布的公式,并得到了双材料界面端部区域的应力应变分布情况。本文的实验结果为进一步研究口腔金瓷修复体界面的优化设计提供了基础,同时也说明云纹干涉法对于双材料界面断裂行为的研究是有效的。 相似文献
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Paul E.W. Labossiere Martin L. DunnShawn J. Cunningham 《Journal of the mechanics and physics of solids》2002,50(3):405-433
Motivated by the existence of a universal singular stress field at bimaterial interface corners, a fair amount of work has been performed to support the use of the corresponding critical stress intensities to correlate fracture initiation. The approach is in the spirit of interface fracture mechanics but applicable to a different class of problems, specifically, when a crack does not previously exist (or cannot be detected, at least economically), and when subsequent crack propagation does not necessarily occur along the interface. Here we further progress toward the development, understanding, and application of the approach, both experimentally and theoretically, for a series of silicon/glass anodically bonded structures. To this end we designed and fabricated two series of silicon/glass anodically bonded bimaterial specimens with different interface corner geometries that commonly arise from different silicon etching technologies. Offset three-point flexure tests were performed that resulted in brittle fracture that initiated at the interface corner. From a rigorous stress analysis at the interface corner, we determined the order of the stress singularities and the angular variation of the stress fields. We computed the corresponding stress intensities via full-field finite element analyses of the silicon/glass specimens loaded in offset three-point flexure. Measured fracture data show that although the failure stress varies significantly with bond size, the corresponding critical stress intensity of the dominant mode is constant, thus providing support for its use as a fracture initiation criterion. In the light of both the stress analysis and the measured fracture data, we discuss the effect of mode mixity (loosely shearing versus opening) and show that it has little influence on the results for the specimens and loading considered in this study. Via an idealized model of a small crack, either interfacial or extending into one of the adherends, we study the effects of geometrical perturbations at the interface corner on the stress state, and discuss implications for fracture analysis and interpretation of fracture data. We also explore the prediction of the crack initiation angle and achieve reasonable success with a simple criterion based on the maximum circumferential stress near the uncracked interface corner. 相似文献
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The three-dimensional weight function method recently developed by the authors is used to determine stress intensity factors
for two symmetric quarter-elliptical corner cracks at a hole in a wide finite-thickness plate subjected to remote tensile
loading. The geometry parameters considered arer/t=0.5, 1, 2;a/c=0.2, 0.5, 1, 2;a/t=0.2, 0.5 withinc/r=2. The results are compared, where possible, with other solutions available in the literature. Generally good agreement is
observed. The effect of an approximation of the two-dimensional unflawed stress distribution on the accuracy of stress intensity
factors by the weight function method is discussed. 相似文献
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A contour integral, based on Betti’s reciprocal theorem, is used in conjunction with the finite element method to evaluate the magnitude of the wedge corner stress intensities associated with the higher order terms of the singular stress field near the interface corner of a bi-material joint. It is shown that using a different auxiliary field can eliminate the dependence of the wedge corner stress intensity on the integration path observed by [W.C. Carpenter, Int. J. Fracture 73 (1995) 93–108]. Finite element analysis of a typical joint geometry is used to demonstrate the path-independence of the magnitude of the stress intensities evaluated using the proposed method, and to show the effects of higher order terms on the stress state near the interface corner. 相似文献
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论文对半平面双材料角受集中力问题的界面应力场作了深入的探究,特别着重于双材料角端点附近的界面应力的奇异性分布规律.论文通过对界面应力的严格解和渐近解[16]的比较,发现在双材料角界面端点邻近,严格解和渐近解的差是一个向端点衰减的微幅震荡分布的应力.这个向端点衰减的微幅震荡应力的起始点,称为转换点.自界面端点到转换点,严... 相似文献
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《International Journal of Solids and Structures》1999,36(29):4425-4445
The spatial axisymmetric problem of an isotropic, elastic, homogeneous body containing an inclusion of a different material with an interface corner point (along a circular contour) and arbitrary joining angles is considered in this paper. It is found that the order of the stress singularity at the interface corner coincides with that of the corresponding plane strain problem, but the dependence of the singular stress field on the material properties depends on both the Poisson ratios (of the two isotropic materials) as well as on the ratio of their shear moduli. The theoretical results have been confirmed by numerical, finite-element-based results in a special bimaterial case. 相似文献
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QUASI-FLOWCORNERTHEORYONLARGEPLASTICDEFORMATIONOFDUCTILEMETALSANDITSAPPLICATIONSHuPing(胡平)LiuYuqi(柳玉启)GuoWei(郭威)TaiFeng(台风)(R... 相似文献