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高玉魁 《机械工人(热加工)》2008,(17):26-28
对于航空航天零部件而言,随着结构设计不断使用高强度结构材料来制造承力构件,越来越多的零件以疲劳断裂的方式发生失效事故。因此,总结疲劳断裂的失效特征,分析其影响因素,探讨疲劳失效的预防措施一直是材料和力学等学科的研究工作者和工程师们所关心的课题。 相似文献
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膨胀干燥机螺杆轴断裂失效分析 总被引:2,自引:2,他引:0
膨胀干燥机螺杆轴是一种呈悬臂状态工作的旋转轴,实际使用中常发生断裂事故。对该轴的断裂原因进行了失效分析。结果表明:螺杆轴断裂的主要原因是由于35CrMo材料承受介质的腐蚀和交变载荷作用而引起的腐蚀疲劳,而轴材料中的缺陷及其热处理工艺不当也是造成轴断裂的原因之一。在失效分析的基础上提出了解决问题的方法,经实际验证该方法可使轴的工作寿命得到大幅度提高。 相似文献
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在航天、核动力发电等工业中,小管道(直径小于2 in(约50 mm))的疲劳断裂失效已成为影响设备安全运行的主要因素之一.然而,在现有的设计与评估规范中,尚缺乏小管道疲劳断裂详细的评价方法与准则.采用管道疲劳性能测试和有限元数值仿真方法,对某焊接小管道进行了疲劳与断裂性能分析.研究结果表明,疲劳性能测试和有限元数值仿真方法获得的疲劳裂纹扩展寿命基本一致,分析案例中,裂纹的疲劳扩展寿命仅占整个疲劳断裂寿命的3%左右;管道的临界失效模式为塑性失稳失效,提高材料的屈服与抗拉强度可有效提高部件的临界裂纹尺寸. 相似文献
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齿轮因工作环境不同而失效形式也复杂多变。针对齿轮齿根疲劳断裂这一最主要的失效方式理论及预测进行研究,重点分析了直圆柱齿轮的弯曲疲劳强度、疲劳寿命、疲劳裂纹萌生和扩展的理论及计算。在此基础上通过计算机辅助计算,分析证实了理论计算的科学性和与实际情况的一致性。研究齿轮的疲劳强度和疲劳寿命在工业应用上有重要的意义和价值,疲劳试验成本较高,使用此理论计算方法对疲劳寿命和裂纹扩展进行模拟为实际应用和工业生产提供了重要参考。 相似文献
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采用宏观检验、化学成分分析、力学性能试验、金相检验、能谱分析和断口分析方法,对压缩机十字头断裂失效原因进行了分析。结果表明:结构设计不合理,铸造组织疏松,材料脆性严重等缺陷导致了此次压缩机十字头的疲劳断裂失效。 相似文献
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根据Φ700mm轧机用H11轧辊的工况,采用化学成分分析、力学性能检测、显微组织和断口观察等方法对其断裂失效原因进行了分析。结果表明:轧辊断裂性质是弯曲-扭转疲劳断裂;其断口上有多个疲劳源,疲劳源位于轧辊的表面或次表面;由于轧辊材料部分元素含量超标,轧辊表面硬度比标准规定的低,而且材料中存在较多弥散分布的Al2O3、MnS等氧化物和硫化物夹杂,这些都是产生疲劳裂纹的内因;在扭转和弯曲应力共同作用下,疲劳裂纹从轧辊轴径过渡圆角处等应力集中区域开始萌生,并沿与轴径呈约45°的方向扩展,最终导致轧辊断裂失效。 相似文献
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对某离心泵轴承的失效进行了分析,结果表明:在内、外温差较大的环境下长年使用,带冷却装置的中空轴承座会产生较大的变形,使轴承工作时外圈受到较大的异常载荷,导致沟道局部的实际载荷远远大于所能承受的设计载荷,引起轴承过早失效. 相似文献
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针对承受热应力和结构应力共同作用下的角接触球轴承,利用ANSYS Workbench软件对其进行疲劳寿命分析。在三维软件Pro/E中建立轴承模型,导入有限元软件ANSYS Workbench中得到轴承的有限元模型,进行热-应力耦合分析,得到轴承温度分布和应力分布;根据零件的材料属性,利用ANSYS Workbench的Fatigue模块分析了轴承的疲劳寿命。根据软件模拟计算得到轴承寿命情况,为机床主轴轴承寿命的预测奠定基础。 相似文献
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Ilya I. Kudish 《摩擦学汇刊》2013,56(4):711-721
A detailed derivation of a new statistical model of contact fatigue life followed by its qualitative and quantitative analysis are presented. The model is based on contact and fracture mechanics and statistical treatment of the initial distribution of material defect. The model assumptions and their validation as well as the model properties are discussed. A parametric study of the model is performed. A generalization of the model for the case of stochastic residual stress or other contact parameters is proposed. Some analytical formulas for calculation of contact fatigue are proposed and analyzed. The validation of the model and its applicability to calculation of bearing fatigue life and some particular data are considered. A reflection of the quality of bearing manufacturing process on the contact fatigue model is discussed. 相似文献
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R.D. Evans H.P. Nixon C.V. Darragh J.Y. Howe D.W. Coffey 《Tribology International》2007,40(10-12):1649
Lubricant additives have been known to affect rolling element bearing surface durability for many years. Tapered roller bearings were used in fatigue testing of lubricants formulated with gear oil type additive systems. These systems have sulfur- and phosphorus-containing compounds used for gear protection as well as bearing lubrication. Several variations of a commercially available base additive formulation were tested having modified sulfur components. The variations represent a range of “active” extreme pressure (EP) chemistries. The bearing fatigue test results were compared with respect to EP formulation and test conditions. Inner ring near-surface material in selected test bearings was evaluated on two scales: the micrometer scale using optical metallography and the nanometer scale using transmission electron microscopy (TEM). Focused-ion beam (FIB) techniques were used for TEM specimen preparation. Imaging and chemical analysis of the bearing samples revealed near-surface material and tribofilm characteristics. These results are discussed with respect to the relative fatigue lives. 相似文献
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D. Scott 《Tribology International》1976,9(6):261-264
Hollow rolling elements produced by electrodeposition on a removable substrate compared favourably in rolling contact fatigue resistance with conventional ball bearing material. They appear potentially attractive as lightweight rolling elements to reduce centrifugal forces and increase the fatigue life of high speed bearings. The background of the problem is briefly reviewed and the results of preliminary development work reported. 相似文献
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基于线性疲劳累计损伤橡胶悬置疲劳寿命预测研究 总被引:7,自引:0,他引:7
橡胶元件疲劳寿命的有效预测是其设计开发过程中的重要环节。引入橡胶元件线性疲劳累计损伤原理,提出张量形式橡胶疲劳寿命公式,且根据橡胶材料的实际承载工况提出其失效标准。依据橡胶材料的承载变形可简化为单轴拉伸及简单切应变,设计用于承载拉伸载荷的哑铃型橡胶试柱和承载剪切载荷的环形橡胶试柱,并实测疲劳寿命数据,以最小二乘法原理拟合拉伸与剪切的疲劳寿命函数公式。以车用变速箱悬置与发动机后悬置为疲劳寿命预测研究对象,通过分析其承载位移载荷时的应变张量,利用张量形式的疲劳寿命预测公式预测两种悬置在两种典型工况下的疲劳寿命。结果发现,橡胶材料的拉伸疲劳寿命曲线与简单剪切疲劳寿命曲线的变化趋势一致、形状类似、拟合函数幂指数十分接近;张量形式的疲劳寿命预测公式可有效地预测橡胶悬置的疲劳寿命。 相似文献
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Mostafa Yakout A. Elkhatib M. G. A. Nassef 《Journal of Mechanical Science and Technology》2018,32(1):91-99
In this paper, the authors introduce an experimental procedure for predicting the fatigue life of each individual rolling element bearing separately using vibration modal analysis. The experimental procedure was developed based on a statistical analysis. A statistical analysis was performed to find an empirical model that correlates the dynamic load capacity of rolling bearings to their dynamic characteristics (Natural frequencies and damping). These dynamic characteristics are obtained from the frequency response function of each individual bearing that results from vibration modal analysis. A modified formula to the already known Lundberg-Palmgren life formula is proposed for rolling element bearings. Given the modified formula, one can predict the fatigue life of each individual rolling element bearing based on its dynamic characteristics. The paper compares the results from the modified formula with those from Lundberg-Palmgren formula. The modified formula provides an accurate prediction for the fatigue life of each individual bearing based on its dynamic characteristics. The experimental validation of the modified formula is considered for future work. Therefore, it can be used in various applications of rolling element bearings in machinery systems. 相似文献
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It has been known for decades that high contact load in bearings leads to fatigue alterations of subsurface material, which can be optically visualized on etched samples. In the literature, these alterations are termed dark etching regions and white etching bands, due to their peculiar patterns and contrast. In the current work, it is proposed to study these alterations by the magnetooptical Kerr effect, expecting that the material changes associated with rolling contact fatigue also affect the magnetic properties of bearing steel. The advantage of this method is that it has good spatial resolution, allowing recording of magnetic properties on microscopic scales. Samples containing dark etching regions and white etching bands were compared in the magnetooptical test with the reference sample containing no optically visible changes. It was found that the coercive force of material reduces as result of microstructural changes caused by rolling contact fatigue. 相似文献