共查询到20条相似文献,搜索用时 78 毫秒
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夹杂将导致结构应力集中,是降低结构承载能力重要影响因素,尤其是动载作用情况下,弹性波衍射和叠加将加剧应力集中程度.弹性波衍射方程建立和求解非常复杂,目前主要研究对象集中在二维模型情况,三维有限域内夹杂引起的动应力集中现象在大型结构中比较常见,有界域边界不仅作为边界条件,同时也是散射波波源,提高了求解难度.一般通过近似方... 相似文献
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1 引言在纵向冲击载荷作用下,圆柱体及圆板内产生的应力波经传播及在其自由表面上的反射,将使其某些局部产生动应力集中,进而导致脆性破坏.Kolsky 曾通过冲击实验对此问题进行了较为系统的研究.笔者曾通过数值计算分析了Kolsky 的试验中圆柱内产生的各应力成分的变化情况及动应力集中现象.求得的动应力集中的发生位置同Kolsky的试验结果基本一致.本文采用同样的数值计算方法,以立体图形表示了受冲击弹性圆板中发生动应力集中的部位,并研究了不同的冲击载荷及其作用范围,圆板的尺寸及材料特性等因素对动应力集中的发生及其发生部位的影响. 相似文献
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本文利用自制的光粘弹性材料,用光弹性法研究了在轴向拉伸荷载作用下带有圆孔的杆件中的粘弹性应力集中系数。文中提供了杆件在荷载作用后6秒内每间隔1秒的等差线照片,叙述了有关实验及计算结果,並讨论了确定粘弹性应力集中系数的实用方法的途径。 相似文献
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本文提供了用电阻应变片方法测量一组不同厚度的带有对称圆槽的拉伸平板在应力集中部位的应力分布情况。实验结果表明,应力集中系数不仅与板平面的几何尺寸有关,而且与板的厚度有关。 相似文献
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本文介绍了用应变电测法测试起重机上M30螺栓应力集中的一种方案.在现场实测时得到一系列测试数据和曲线,为分析该螺栓的疲劳破坏提供了依据. 相似文献
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The stress relaxation function after steady shear flow and the stress growth function at inception of steady flow are derived for several constitutive equations of the integral and differential types. Relationships between these functions are deduced and discussed. 相似文献
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A new continuum model is developed to study the influence of surface stress on the behaviors of piezoelectric nanobeams. Different from existing piezoelectric surface models which only consider the surface properties, the proposed model takes surfaceinduced initial fields into consideration. Due to the fact that the surface-induced initial fields are totally different under various boundary conditions, two kinds of beams, the doubly-clamped beam and the cantilever beam, are analyzed. Furthermore, boundary conditions can affect not only the initial state of the piezoelectric nanobeam but also the forms of the governing equations. Based on the Euler-Bernoulli beam theory, the nonlinear Green-Lagrangian strain-displacement relationship is applied. In addition, the surface area change is also considered in the proposed model. The governing equations of the doubly-clamped and cantilever beams are derived by the energy variation principle. Compared with existing Young-Laplace models, the proposed model for the doubly-clamped beam is similar to the Young-Laplace models. However, the governing equation of the cantilever beam derived by the proposed model is very different from that derived by the Young-Laplace models. The behaviors of piezoelectric nanobeams predicted by these two models also have significant discrepancies, which is owing to the surface-induced initial fields in the bulk beam. 相似文献
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不久前,王振东给朱照宣写信说道: "我那本<诗情画意谈力学>在出版时,曾对‘无量纲数'一事与出版社有过讨论.""我指出:某页某行,将‘无量纲化'、‘无量纲的'错为‘量纲一化'、‘量纲一的'.这已经是概念性错误了."回函称: "根据现在的‘物理量和单位'的标准,凡是‘无量纲'的说法现在都改为‘量纲为1,这种说法了,就是说无量纲的量并不是没有量纲,而是它的量纲是单位1.这是现在法制推行的国家标准,遇到时必须要改." 相似文献
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《International Journal of Solids and Structures》2006,43(20):6208-6219
Effect of surface stress on stress concentration near a spherical void in an elastic medium is examined in the framework of continuum surface elasticity. It is assumed that the void is of spherical shape, and the elastic medium is elastically isotropic and infinitely extended. By using the Papkovitch–Neuber displacement potentials, the elastic field caused by a unidirectional remote load is obtained explicitly. Numerical results show that the influence of surface stress becomes remarkable when the size of the void is reduced to nanometer scale, leading to that stress concentration near the void depends not only on the void size but also on the remote load. 相似文献
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Residual stress field and reduction of stress intensity factors in cold-worked holes 总被引:1,自引:0,他引:1
S.T. Pinho H.B. Martins P.P. Camanho M.H. Santare P.M.S.T. de Castro 《Theoretical and Applied Fracture Mechanics》2005,44(2):168-177
Closed-form and semi-analytical solutions are obtained for the residual stress distributions in a plate caused by pressure acting on a central circular hole, representing the cold-work process. The material is elastic–perfectly plastic. Both Tresca and von Mises yield criteria are used and the corresponding residual stress distributions are compared. The relation between the dimension of the plastic zone and the value of internal pressure is presented. The relation between the magnitude of the residual stresses and the remote uniform tensile stress required to open symmetrical radial cracks is also presented. The reduction of the stress intensity factors of cracked open and riveted holes as a function of the internal pressure applied (or mandrel radial displacement) is investigated using numerical models for both an elastic–perfectly plastic material and for an Al 2024-T3 Alclad aluminum alloy. 相似文献
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