共查询到19条相似文献,搜索用时 265 毫秒
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应力在裂纹尖端会出现无限大的奇异性,但应力强度因子K则为有限值,是表征裂尖应力场强弱的物理参量。采用J积分法,位移外推法和相互作用积分法等3种不同的方法计算断裂模型裂尖的K值,并研究了受力、裂纹长度、含裂纹构件的几何参数等对裂纹尖端应力强度因子的影响。结果表明3种方法模拟出的K值结果一致性较好,与应力强度因子手册值相比都能达到较高精度。对照3种方法,分析出各种方法的优胜劣汰,对应用数值法计算应力强度因子方法的选择具有借鉴和参照作用。 相似文献
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纯Ⅱ型载荷作用下裂纹的三维厚度效应研究 总被引:1,自引:0,他引:1
采用修正的边界层模型,利用有限元计算方法对纯Ⅱ型裂纹的厚度效应进行分析和研究,通过比较三维裂纹纯Ⅰ型和纯Ⅱ型裂纹尖端的应力、应变以及J积分和裂尖张开位移等参数,得到纯Ⅱ型载荷作用下厚度效应影响弱的认识。与Ⅰ型结果相比可以看出,在Ⅱ型载荷作用下裂尖的应力、应变场的厚度效应不明显,但三维影响区的大小与Ⅰ型基本相同,在裂尖前方半厚度以内存在着很强的三维效应区,从半厚度到1.5倍厚度范围应力在不同的厚度位置有显著的变化,在1.5倍厚度以外的区域表现为平面应力场的特性。在纯Ⅱ型载荷的作用下,三维J积分J^local沿厚度分布不随载荷变化,且基本没有厚度效应,裂尖滑动位移(crack tip sliding displacement,CTSD)也没有厚度效应;沿不同厚度截面,J^local积分和CTSD存在线性关系。 相似文献
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双材料界面裂纹应力强度因子计算 总被引:1,自引:0,他引:1
建立不同裂纹长度的双材料界面裂纹模型,用有限元软件计算和分析界面裂纹尖端附近的应力场和位移场.利用裂尖前沿应力和裂纹面相对位移分别计算了界面裂纹尖端的应力强度因子K,两种方法计算的K值完全吻合.通过数值分析,给出一种计算双材料界面裂纹应力强度因子K的经验公式. 相似文献
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Finite element analysis (FEA) is the most popular numerical method to simulate plasticity-induced fatigue crack closure and
can predict fatigue crack closure behavior. Finite element analysis under plane stress state using 4-node isoparametric elements
is performed to investigate the detailed closure behavior of fatigue cracks and the numerical results are compared with experimental
results. The mesh of constant size elements on the crack surface can not correctly predict the opening level for fatigue crack
as shown in the previous works. The crack opening behavior for the size mesh with a linear change shows almost flat stress
level after a crack tip has passed by the monotonic plastic zone. The prediction of crack opening level presents a good agreement
with published experimental data regardless of stress ratios, which are using the mesh of the elements that are in proportion
to the reversed plastic zone size considering the opening stress intensity factors. Numerical interpolation results of finite
element analysis can precisely predict the crack opening level. This method shows a good agreement with the experimental data
regardless of the stress ratios and kinds of materials. 相似文献
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The singular stress field and stress intensity factors of a crack terminating at a bimaterial interface 总被引:1,自引:0,他引:1
For the fracture evaluation of inclined cracks terminating at the dissimilar material interface, not only the singularities, but also the detailed stress field and its stress intensity factors are necessary. However, though there are many researches reported on the singularity analysis, the stress field and its stress intensity factors are still not clear. This paper has deduced theoretically the singular stress and displacement fields near the tip of a crack terminating at the interface between bonded dissimilar materials, for both cases of real and oscillatory singularities. From the deduced singular stress field, the stress intensity factors are defined for such a crack, and the corresponding numerical extrapolation methods are also proposed. Through the numerical examinations, it is found that the theoretical stress distributions agree well with the numerical results obtained by the finite element method. Moreover, the proposed extrapolation method shows a good linearity, thus it can be used as an efficient way to determine the characteristics of the stress and displacement fields near the tip of a crack terminating at interface. 相似文献
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当齿轮发生故障时,时变啮合刚度的变化能够反映齿轮故障特征大小。因此,时变啮合刚度在齿轮传动过程中是一个重要的动力学参数。提出一种新的齿根裂纹啮合刚度计算方法,即解析有限元法(Analytical-finite element method,A-FM)。考虑到齿轮发生故障时,啮合刚度解析模型计算精度较低,将应力强度因子引入裂纹齿轮的啮合刚度计算过程。首先定义应力强度因子与啮合刚度之间的关系,通过建立齿轮接触模型计算裂纹尖端附近的应力强度因子,然后将计算结果替代解析模型中故障刚度部分。由于应力强度因子能够敏感地识别齿根裂纹的局部微小变化,故该方法相比于解析法具有更高的计算精度,相比于有限元法具备更快的计算效率。同时,建立6自由度动力学模型,通过对其振动响应进行分析,仿真结果验证了所提方法的可行性。 相似文献
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高精度求解应力强度因子的数值外插法 总被引:7,自引:3,他引:4
首先介绍求解应力强度因子的传统蜕化奇异等参元法和一种新型的数值外插法,两种方法均在裂尖使用精度较高的蜕化奇异二次等参元,考虑到传统方法受裂尖单元尺寸大小,结构物类型,材料泊松比影响较大等缺陷,新方法使用了不同的插值手段。其次,讨论了两种方法插值基础的显著区别,结合空间Ⅰ型裂纹问题论证了新型数值外插法的插值基础,研究了两种方法的理论插值误差,发现本文提出的数值外插法比传统的蜕化奇异等参元法的理论精度高一阶,最后,对两种方法的计算误差进行了探讨。数值外插法考虑到有限元计算断裂问题的误差,能以一定的方式决定不同裂纹问题的优化裂尖单元尺寸。 相似文献
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Hyeon Chang Choi 《Journal of Mechanical Science and Technology》2000,14(4):401-407
An elastic-plastic finite element analysis is performed to investigate detailed closure behavior of fatigue cracks and the numerical results are compared with experimental results. The finite element analysis performed under plane stress using 4-node isoparametric elements can predict fatigue crack closure behavior. The mesh of constant element size along crack surface can not predict the opening level of fatigue crack. The crack opening level for the constant mesh size increases linearly from initial crack growth. The crack opening level for variable mesh size, is almost flat after crack tip has passed the monotonic plastic zone. The prediction of crack opening level using the variable mesh size proportioning the reversed plastic zone size with the opening stress intensity factors presents a good agreement with the experimental data regardless of stress ratios. 相似文献
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