共查询到19条相似文献,搜索用时 36 毫秒
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复杂应力状态应力坐标点的简单界定薛福林(哈尔滨工业大学哈尔滨150006)在材料力学中,为了导出复杂应力状态正应力和剪应力的最大值,需要说明在应力坐标平面中,主单元体的任意斜截面的应力坐标点必在图1的阴影区域内。为此,现在的材料力学书中的办法是推导出... 相似文献
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接合残余应力对异种接合材料强度的影响很大,正确地分析接合残余应力在界面端附近的分布及其奇异特性,是研究异材强度评价方法的关键问题之一,本文利用弹性学中的Goursat公式和有关微分方程解的理论,求得了平面近似下的界面端附近的残余应力场及其应力奇异性,与单纯的外力作用时的情况不同,残余应力在界面端有可能出现对数型的应力奇异性,并且不能仅用Dunders的异材参数来描述。 相似文献
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15万立米气柜残余应力及工作应力测试分析 总被引:4,自引:2,他引:4
报导了15万立米大型煤气气柜挂圈走台的残余应力及气柜升降时工作应力的测试结果。该气柜服役十余年后发生煤气泄漏,为分析其原因,进行了残余应力及气柜修复前后的工作应力测试,结果表明:修复前残余应力及工作应力均达到很高水平,气柜升起时伴有严重侧偏现象,修复后应力状态有明显好转。 相似文献
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杂交元本征应力模式和应力子空间的性质研究 总被引:3,自引:0,他引:3
详细讨论了有限元本征应力模式和应力子空间的性质,并着重讨论和进一步完善了与杂交应力有限元应力子空间有关的一些定理,为提出新方法提供了理论基础,主要包括:(1)证明了杂交元特征值不大于对应位移元的特征值;(2)证明了矩阵H非奇异的充分必要条件是假设应力模式线性无关;(3)证明了杂交元所对应位移元的本征应力模式形成的杂交元与该位移元相同;(4)证明了等价假设应力模式形成相同的杂交元;(5)证明了确定杂交元本征应力模式的充分必要条件是其范数平方等于所形成杂交元的变形模态特征值;(6)证明了杂交元假设应力模式与变形模态的能量一一对应的充分必要条件是假设应力模式彼此正交且与所对应位移元的本征应力模式除了一一对应者之外都正交。 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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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 systematic study utilizing the experimental method of reflected photoelasticity was undertaken to determine the effects of assembly stress on the stresses around circular holes under uniaxial tension. The assembly stresses are the result of the contact and bearing stresses between the bolts and the member. It has been concluded that assembly stress contributes to reducing the stresses around the hole. 相似文献
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《Acta Mechanica Solida Sinica》2017,(4)
In this paper, a 3-node triangular element for couple stress theory is proposed based on the assumed stress quasi-conforming method. The formulation starts from polynomial approximation of stresses. Then the stress-function matrix is treated as the weighted function to weaken the strain-displacement equations. Finally, the string-net functions are introduced to calculate strain integration and the stress smooth technique is adopted to improve the stress accuracy. Numerical results show that the proposed new model can pass the C~(0-1) patch test with excellent precision, does not exhibit extra zero energy modes and can capture the scale effects of microstructure. 相似文献
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A method for the resolution of all stress components from the first invariant J1 measured by thermoelastic stress analyzer is described. This method may be used to determine, not only surface stress, but also internal stress and stress on the underside.The method is based on the following procedure:
- 1. (1) Pick an arbitrary domain Ω, within the structure, for which the stresses are required.
- 2. (2) Measure J1 on the surface of Ω.
- 3. (3) Determine the optimum traction along the boundary Γ, which is a part of Ω, by the least squares method such that the difference between the measured J1 and the calculated J1 is at a minimum. Either FEM or BEM may be used for this calculation.
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The acoustoelastic stress analysis is based on the fact that an initially isotropic material becomes anisotropic under stress. The birefringent effect for polarized ultrasonic shear waves in the stressed material will then be similar to the photoelastic effect in which a light wave and a transparent model specimen are used. In this paper, the velocity differences of acoustical, perpendicularly polarized waves are measured directly by a ‘sing-around’ method using a 5-MHz shear-type transducer. The residual-stress distribution in a mild-steel circular plate with a concentrically patch-welded joint is measured by this method. The acoustoelastic coefficient is obtained separately by uniaxial testing of the base material. The results show that the acoustical stress measurement, carried out nondestructively, agrees well with those obtained by conventional destructive methods as well as with theoretical predictions. 相似文献
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Applying two identities for divergence-free non-symmetric and symmetric second-order tensors, novel type of first- and second-order stress functions are proposed for three-dimensional elasticity problems. It is shown that self-equilibrated but non-symmetric 3D stress fields can be generated by one first-order stress function vector, whereas a self-equilibrated and symmetric 3D stress field can be generated by one Airy-type second-order stress function. Assuming linearly elastic materials, the zero-energy modes of the stress functions introduced are derived and investigated. It is pointed out that the structure of the zero-energy modes of the proposed first-order stress function vector is the same as that of the rigid-body displacements in the linear theory of elasticity. 相似文献
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Using Beltrami-Schaefer stress function in the theory of elasticity in this paper, we derive the stress functions of torsion, plane problem, axisymmetric deformation in solid of revolution and torsion on solid of revolution. 相似文献
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