共查询到19条相似文献,搜索用时 78 毫秒
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疲劳裂纹工程评定方法的新进展 总被引:4,自引:0,他引:4
本文首先简单回顾了一些评定疲劳裂纹的工程方法,随后主要介绍了一种新的应用三维有限元直接模拟疲劳裂纹扩展方法的研究进展;最后着重描述了本文作者最近发展的,能自动模拟面形疲劳裂纹形状扩展的计算软件DUCK的基本原理及一些技术细节,并给出了一些裂纹在疲劳载荷作用下形状扩展的数值模拟结果。 相似文献
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疲劳裂纹的萌生以及扩展对于零构件的安全使用存在着巨大的潜在隐患,对于广大从事材料研发工作的技术人员来说,掌握疲劳裂纹扩展的基本规律,了解国内外疲劳裂纹扩展的最新研究进展是非常必要的。本文概括了疲劳裂纹在近门槛扩展阶段和高速扩展阶段(Paris区)的扩展规律,总结了近年来国内外学者在这2个扩展阶段的最新研究进展,结合近年来飞速发展的计算机技术,概述了计算机模拟技术在疲劳裂纹扩展研究领域中的广泛应用。 相似文献
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为了研究20CrMnTi齿轮钢的疲劳裂纹扩展问题,首先,将材料20CrMnTi制成紧凑拉伸试样,在疲劳拉伸试验机上进行载荷比R=0.3的疲劳裂纹扩展试验;然后,应用数值模拟软件Abaqus对疲劳裂纹扩展过程进行数值模拟.结果表明,数值模拟结果和试验结果具有相同的变化趋势,二者的差别在误差允许范围内;数值模拟方法能够很好地描述紧凑拉伸试样疲劳裂纹扩展过程.为20CrMnTi齿轮钢疲劳裂纹扩展过程及疲劳寿命的研究提供了一种有效的试验和模拟分析方法. 相似文献
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采用直流电压降法测试了F690超高强钢在模拟海水中的疲劳裂纹扩展速率,研究了应力比(0.1,0.2,0.3)和加载频率(0.15,0.30,0.60 Hz)对疲劳裂纹扩展行为的影响;采用基于能量释放率Paris法则的扩展有限元方法对腐蚀疲劳过程进行了模拟,并与试验结果进行对比.结果表明:F690钢在模拟海水中的腐蚀疲劳裂纹扩展速率随着应力比或频率的增大而减小;腐蚀疲劳断裂形式为穿晶断裂,且随着频率增加,二次裂纹的宽度变小;模拟得到F690钢的腐蚀疲劳裂纹扩展长度与试验结果相吻合,相对误差小于0.6%,说明采用该扩展有限元方法可有效模拟和预测F690钢的腐蚀疲劳裂纹扩展行为. 相似文献
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16MnR钢在不同应力比下的疲劳裂纹扩展的试验研究及模拟 总被引:1,自引:0,他引:1
采用3.8 mm厚带有圆形缺口的CT试样,研究了16MnR钢在不同应力比的恒幅循环载荷作用下的疲劳裂纹扩展。开发了一种基于疲劳损伤的方法来模拟疲劳裂纹扩展速率。将16MnR钢的循环塑性本构模型通过用户材料子程序UMAT嵌入到ABAQUS中。把有限元计算得到的疲劳裂纹尖端附近区域的弹塑性循环应力应变结果,代入到疲劳损伤模型中,得到每个加载循环在裂尖各点产生的疲劳损伤值。通过疲劳损伤准则,导出疲劳裂纹稳定扩展速率的计算公式。疲劳裂纹扩展试验验证了模拟结果。实验结果和模拟结果都表明,该试样厚度下,应力比对裂纹扩展速率几乎没有影响。 相似文献
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基于动态响应有限元模拟的点焊接头疲劳寿命预测 总被引:6,自引:1,他引:5
利用三维有限元模拟和动态响应试验对点焊接头疲劳裂纹萌生和扩展特性进行了研究。利用所模拟的裂纹长度和固有频率的关系,定义了点焊疲劳裂纹扩展的三个阶段。根据所定义的裂纹萌生阶段的定义,利用局部应力应变法预测了点焊接头的疲劳裂纹萌生寿命。结果表明,所预测的疲劳萌生寿命与试验结果相吻合。 相似文献
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基于循环J积分的压力容器疲劳寿命预测的数值模拟 总被引:3,自引:0,他引:3
开发出一种基于三维弹塑性循环J积分(△J)的压力容器疲劳寿命预测的数值模拟技术.对1台含内壁纵向表面裂纹的实物压力容器进行有限元数值模拟计算和试验测试,结果显示:初始椭圆形表面裂纹在疲劳扩展过程中形状逐渐趋圆并保持圆形继续扩展.裂纹疲劳扩展过程是一个非等速的扩展过程,扩展速度呈现越来越快的趋势.基于△J的疲劳寿命预测的数值模拟结果较之基于应力强度因子幅△K的结果具有更高的精度,满足工程要求.该技术对于在役含缺陷压力容器的疲劳寿命预测具有重要的应用价值. 相似文献
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Fatigue crack growth for various cracks in both unnotched and notched round bars is directly modelled by using an automated numerical technique, which calculates the stress intensity factors at a set of points on the crack front through the three-dimensional finite element method and then applies an appropriate fatigue crack growth law to this set of points to obtain a new crack front. This technique also has the capability of automatic remeshing so that the crack propagation can conveniently be followed. The crack geometries modelled in the present paper include a small internal crack near the free boundary and several initially part-elliptical or irregular surface cracks in a smooth round bar under tension, a surface crack in different semi-circularly notched bars under both tension and bending, a surface crack initiated from the root of a V-notched bar and an initially twin crack configuration within a smooth tension bar. Some fatigue growth characteristics relevant to each type of cracks are also revealed. It is demonstrated that the fatigue growth analyses of various cracks commonly occurring in bars can reliably be made by using the automated finite element technique proposed. 相似文献
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In this article, a UIC60 rail with accurate geometry is studied by employing the finite element method. For this purpose, a three-dimensional elastic-plastic finite element model is conducted using model. In addition, the stress distribution of wheel-rail operation is acquired, and its effects on fatigue life are specified by damage mechanic methods. In the finite element model, the displacements and stress intensity factors (SIFs) are computed on the crack near the leading edge to calculate crack propagation trajectories and crack growth rate. The modified Paris model is used to estimate fatigue crack growth rates. 相似文献
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提升机主轴疲劳仿真研究 总被引:5,自引:1,他引:4
介绍了基于有限元分析结果进行疲劳分析的基本理论,思路及方法,运用ANSYS程序对假定无缺陷和含横向裂纹KJ型双筒提升机主轴进行有限元数值模拟,得到交变应力最大部位,预测了提升机主轴疲劳裂纹萌生寿命和裂纹扩展阶段的疲劳寿命。并得到不同裂纹深度的主轴疲劳寿命。 相似文献
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随机因素对疲劳裂纹扩展分散性影响的探讨 总被引:4,自引:2,他引:2
采用概率有限元和可靠性分析相结合的方法,将影响裂纹扩展的主要随机因素作为随机变量处理,研究裂纹扩展失效概率的计算问题。文中采用梯度投影方法,对各种主要随机因素作为随机变量时用于失效概率计算的可靠性指标进行了计算,在此基础上用一阶可靠性方法计算了疲劳裂纹扩展的失效概率。 相似文献
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Hadi Taghizadeh Tajbakhsh Navid Chakherlou Afshin Babaei Aghdam 《Journal of Mechanical Science and Technology》2013,27(5):1415-1425
To predict fatigue crack initiation and fatigue crack growth lives in cold expanded double shear lap joints a numerical method has been employed. The total estimated fatigue lives were compared with available experimental fatigue test results for plain hole and cold expanded hole specimens of Al 2024-T3 in double shear lap joints. Three-dimensional finite element simulations have been performed in order to obtain the created residual stresses field due to cold expansion and subsequent far field longitudinal loading in the double shear lap joint. The obtained stress and strain distributions from the finite element analyses were employed to predict stress concentration factors to calculate fatigue crack initiation and fatigue crack growth lives using AFGROW computer code. The predicted fatigue lives demonstrate that there is a good agreement between the proposed method and experimental fatigue test results. 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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