共查询到18条相似文献,搜索用时 125 毫秒
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用有限元法计算了X型焊缝接头处一种可能的三维焊接缺陷所导致的应力集中,定量分析了缺陷尺寸的变化对应力集中系数的影响,结果表明缺陷高度和宽度的增加将导致应力集中系数的增大,但其增大趋势逐渐变缓;而缺陷厚度的增加则使应力集中系数减小。 相似文献
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用有限元法计算了X型焊缝接头处一种可能的三维焊接缺陷所导致的应力集中,定量分析了缺陷尺寸的变化对应力集中系数的影响,结果表明缺陷高度和宽度的增加将导致应力集中系数的增大,但其增大趋势逐渐变缓;而缺陷厚度的增加则使应力集中系数减小。 相似文献
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用有限元法计算X型焊缝接头处一种可能的三维焊接缺陷所导致的应力集中,定量分析了缺陷尺寸的变化对应力集中系数的影响,结果表明缺陷高度和宽度的增加将导致应力集中系数的增大,但其增大趋势逐渐变缓;而缺陷厚度的增加则使就力集中系数减小。 相似文献
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非线性超声检测镁合金早期疲劳的试验研究 总被引:3,自引:0,他引:3
为利用基于二次谐波的非线性超声方法检测镁合金材料的早期疲劳损伤,建立超声非线性系数β的测试试验系统,设计制作预设应力集中区的厚板镁合金疲劳试件,并通过有限元法仿真应力集中区的有效性.对三个不同疲劳加载模式的镁合金试件进行非线性超声检测试验研究.结果表明,在疲劳寿命的早期,三个试件的超声非线性系数均随疲劳周数明显增加.同时,测量其中一个试件在非应力集中区的超声非线性系数,与应力集中区相比,超声非线性系数变化幅度只有应力集中区的27%,进一步表明超声非线性系数的变化来源于镁合金材料疲劳引起的微缺陷变化,也证实试验的可靠性.另外,波速和弹性常数的试验结果表明,这两个线性参数对于镁合金材料的早期疲劳损伤不如超声非线性系数敏感. 相似文献
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基于有限元法的桁架节点搭接接头应力集中分析 总被引:1,自引:0,他引:1
应力集中对桁架节点处疲劳寿命影响显著,焊缝处几何形状不规则,易产生应力集中,可能导致结构破坏。为了研究结构的几何尺寸和焊缝的几何形状对焊缝处应力集中系数的影响,将总应力集中系数分解为焊缝几何应力集中系数和热点应力集中系数的乘积形式。用有限元方法分析焊缝长度、焊缝熔深、弦杆厚度和焊脚尺寸对几何应力集中系数和热点应力集中系数的影响,并拟合经验公式。结果表明:弦杆厚度对应力集中影响不大,焊缝截面形状和焊缝长度对应力集中有一定影响。 相似文献
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用有限元的方法计算对接接头焊趾部位的应力集中系数,分析计算了焊趾倾角和焊趾过渡圆弧对应力集中系数的影响。结果表明,通过减小焊趾倾角或者增大过渡圆弧半径可以有效的缓和接头的应力集中。而焊趾过渡圆弧的引入从力学和焊接冶金两方面提高了接头的抗裂性能。同时也指出了双侧都有加强高的对接接头比单侧有加强高的接头有较大的应力集中系数。 相似文献
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Stress concentration factor due to a circular hole in functionally graded panels under uniaxial tension 总被引:2,自引:0,他引:2
The effect of the material property inhomogeneity on the stress concentration factor (SCF) due to a circular hole in functionally graded panels is numerically investigated. The multiple isoparametric finite element formulation is used to simulate the elastostatic boundary value problem. A parametric study is performed by varying the functional form and the direction of the material property gradation. The material property inhomogeneity is characterized by the intrinsic inhomogeneity length scale, modulus ratio and the power-law index. The results from our parametric study showed that the SCF is reduced when Young's modulus progressively increased away from the hole. The angular position of the maximum tensile stress on the surface of the hole remains unaffected by the material property inhomogeneity. The SCF is seen to be most influenced by the power-law index, followed by the variation of the inhomogeneity length scale. The SCF is least affected by the modulus ratio. 相似文献
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T. Ahmed R. S. Choudhry Atta Ur Rehman Shah Hasan Aftab Saeed 《Journal of Mechanical Science and Technology》2018,32(8):3653-3658
The study investigates the pre damaged stress concentration factor (SCF) for a composite laminate member (CLM) with central circular hole subjected to tensile loading. The presence of holes yields high stress concentrations in the structural members termed as stress raiser and often regarded as an important design deriver. The pre damaged SCF refers to the stress concentrations within elastic (undamaged) range of the CLM prior to the failure initiation. The traditional experimental and analytical methods for the estimation of SCF offer macro level behaviour which is not considered appropriate for CLM where lamina by lamina behaviour is more significant. A meso level finite element (FE) model is presented to capture the lamina by lamina influence on the overall SCF for a CLM using commercial software Abaqus. The paper deals with the fundamental influencing factors such as laminae orientation effect, stress distribution effect around periphery of the hole, decaying effect and ligament effect on SCF for CLM. Analytical models have been formulated to validate the FE models. The results of FE models have been found in close agreement with the analytical results. 相似文献
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研究了不同沉积方式和工艺参数对沉积在K 9基底上的单层ZnS、Y bF3薄膜和多层ZnS/Y bF3薄膜缺陷的影响,发现基底温度和蒸发速率等工艺参数对缺陷的产生有较大的影响,太高或太低的基底温度和蒸发速率都会导致缺陷增加,采用电子束蒸发和蒸发源形状不同的阻蒸蒸发方式,缺陷密度分布有较大的差异。通过比较不同蒸发方式和工艺参数所镀薄膜的缺陷密度,找到了现有工艺条件下缺陷密度最小的最佳蒸发方式和工艺参数。 相似文献
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本文利用红外光谱分析技术系统分析大直径LEC(Light Energy Converter光能转换器)Si—GaAs中深施主缺陷EL2的浓度分布。实验结果表明,大直径LECSi—GaAs深施主缺陷EL2浓度沿直径方向成W型分布,中心区域比较高,靠近中间区域最低,边缘区域最高。EL2是GaAs晶体中过量As存在的一种形式,其浓度强烈依赖过量As的浓度。晶体生长后的冷却过程中热应变场对过量As的分布会造成一定影响,同时位错密度的分布也会影响过量砷的分布,也就影响深施主缺陷EL2浓度的分布。 相似文献
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Optimum shape design of shoulder fillets in flat tension bars, round tension bars and at T-heads are considered by a mathematical programming method. The curved shape is defined by a general third degree function in the coordinates x and y which is completely determined by making use of boundary conditions and four design variables. To have a better shape control during optimization, the problem is formulated as minimization of volume with limitation on stress concentration factor. The successive optimum shapes are obtained by changing the limitation on the stress concentration factor (SCF), until minimum possible SCF limitation is reached. Design charts are presented for a few cases. It is observed that stress concentration factor can be reduced from 5 to 10% in comparison with circular fillets. 相似文献
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本文利用红外光谱分析技术系统分析大直径LEC (Light Energy Converter光能转换器)Si-GaAs中深施主缺陷EL2的浓度分布。实验结果表明,大直径LEC Si-GaAs深施主缺陷EL2浓度沿直径方向成w型分布,中心区域比较高,靠近中间区域最低,边缘区域最高。EL2是GaAs晶体中过量As存在的一种形式,其浓度强烈依赖过量As的浓度。晶体生长后的冷却过程中热应变场对过量As的分布会造成一定影响,同时位错密度的分布也会影响过量砷的分布,也就影响深施主缺陷EL2浓度的分布。 相似文献