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断裂失效是最主要,危害最大的一种零件失效模式。断裂失效分析是从断口的宏观、微观特征入手,研究断裂过程和形貌特征与材料的性能、显微组织、零件的受力状态及环境条件之间的关系,从而提出断裂的原因。 相似文献
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钟培道 《理化检验(物理分册)》2005,41(10):535-539
3.3疲劳断裂失效分析 疲劳断裂失效分析的内容包括:分析判断零件的断裂失效是否属于疲劳断裂与疲劳断裂的类别;引起疲劳断裂的载荷类型与大小以及疲劳断裂的起源等.疲劳断裂失效分析的目的则是找出引起疲劳断裂的确切原因,从而为防止同类疲劳断裂失效再次出现所要采取的措施提供依据. 相似文献
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座椅输送提升机投入使用3个月传动轴即发生断裂失效.用化学分析、硬度测试、金相检验、扫描电镜等方法对断轴进行了相应分析.结果表明,传动轴在进行表面加工时,加工刀具断裂产生切削缺陷,在该处形成较大缺口敏感和应力集中,导致传动轴断裂. 相似文献
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汽车悬置大批量生产中最常见失效模式为铝合金托臂断裂,断裂会造成车辆无法行走,断裂原因比较多,有设计强度安全系数不足的原因,也有铸件本身就存在缺陷,象裂纹和内部气孔,裂纹通过外观检查可以发现,而内部气孔除非100%采用X光检查,否则难以发现,该文以铸造过程中产生的缩孔而造成断裂为例进行了分析。 相似文献
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本文利用金相技术,电子探针等方法,对汽车零件后桥半轴套管断裂失效原因进行了分析,结果表明失效原因主要是疲劳断裂。 相似文献
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通过对失效的第八级压气机盘和叶片观察和金相分析,探讨了该失效件断裂的原因。结果表明,微动磨损引起疲劳断裂。 相似文献
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通过宏观分析、扫描电镜及能谱分析、金相分析、化学成分分析、力学性能试验及受力分析等方法对卡箍连接片断裂失效原因进行了分析。结果表明:该卡箍连接片失效模式为高温蠕变断裂;导致其断裂的主要原因是装配条件下连接片承受的应力水平较高,在实际工作温度中存在较大的高温蠕变断裂风险;建议根据实际工况选用抗高温蠕变性能良好的材料。 相似文献
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本文分析了TDJ型火车减速顶的受力状况,采用SEM及金相物理等手段观察减速项构件失效断口的微观形貌,对构件断裂失效原因进行了详细的研究,并得出应力集中造成的疲劳断裂是减速顶构件失效原因的结论 相似文献
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Hot rolling behaviors of whisker reinforced aluminum composites 总被引:1,自引:0,他引:1
Aluminium matrix composites reinforced by silicon carbide and aluminium borate whiskers were hot rolled at 550°C, and the hot rolling behaviors of the composites were studied by scanning electronic microscope and X-ray diffraction (anti-pole figure). The results indicated that the whiskers in composite were reorientated, and some whiskers were broken during hot rolling process. The cracks in hot rolled composites may be related to the interface slide which is dependent on the interface strength of the composites. The tensile properties of hot rolled composites were also investigated. 相似文献
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高殿荣|赵建华|张作超 《工程力学》2013,30(4):423-428
目前液体静压导轨的导轨面内一般设计成对称单行、若干列油腔。油腔的数目(即列数)是液体静压导轨设计中的关键,对导轨的动态、静态性能都有着较大的影响。以液体静压导轨的单一导轨面为研究对象,分别作用垂直和倾覆载荷,推导了导轨的承载能力、静刚度与油腔数目的数学关系式,并进行了相应的分析。以工程中的滑板系统为例,滑板导轨面内分别对称设计单行,2列~6列油腔的五种方案。以滑板的承载能力、静刚度为性能依据,对五种方案进行对比分析,结果发现设计成单行、3列油腔时滑板的性能最佳。 相似文献
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通过分析当前电力机车受电弓滑板存在的各种问题,用粉末冶金法研制出一种新型的受电弓滑板.该滑板由铜、碳纤维和石墨等构成.分析了成形压力、烧结温度对滑板性能的影响,对其导电性、摩擦、磨损性能及冲击韧性进行了检测,并与当前正在使用的受电弓滑板进行了对比.结果表明:该新型滑板的最佳制备工艺条件为(含量)铜78%,碳纤维2%,石墨15%,添加剂5%,成形压力为200MPa,烧结温度为880℃.该滑板不仅电阻率低,而且其摩擦、磨损及冲击韧性等性能也优越于当前正在使用的受电弓滑板.与国外浸金属碳滑板Rh82Mb相比,其摩擦系数降低20%,磨损量减少1.3%,冲击韧性提高1.7倍,导电性增强65倍. 相似文献
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采用显微激光拉曼光谱及X射线电子衍射测量,摘要选用进口和国产滑板材料作为对比材料,并进行高温烧结处理。分析了试样的形貌和结构,并表征了不同碳滑板材料在高温烧结前后的结构参数。结果表明,两种表征方法的结果存在一致性;进口碳滑板材料的石墨化度高于国产滑板,且两种滑板材料都有不同的石墨相组成,不同相的石墨化度也不同;经过高温烧结处理,滑板材料的石墨化度提高。 相似文献
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Daniel Fovargue Sorin Mitran Georgy Sankin Ying Zhang Pei Zhong 《International Journal of Fracture》2018,209(1-2):203-222
Instabilities in thermally-driven crack growth in thin glass plates have been observed in experiments that slowly immerse a hot, pre-notched glass slide into a cold bath. We show that a nonlocal model of thermomechanical brittle fracture with minimal input parameters can predict the entire phase diagram of fracture measured in experiments for the low immersion speed regime. Geometrical restrictions to crack growth commonly found in other approaches are absent here. We discuss a method for determining the appropriate size of the peridynamic horizon based on a data point around a separating line between crack-type zones in the experimental phase diagram. Once the nonlocal size is smaller than the length-scale introduced by the thermal gradient, the computational results show that no fracture criterion is needed beyond Griffith’s criterion to capture the observed instabilities. The combination of thermal gradients and competing contraction forces on the two sides of the crack are behind the observed crack path instabilities. Elastic (velocity) vortices of material points show how and why the cracks develop along the observed paths. Our results demonstrate that thermally-driven fracture in brittle materials can be predicted with accuracy. We anticipate that this model will lead to design protocols for controlled fracture in brittle materials relevant in materials science and advanced manufacturing. 相似文献
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索杆结构成形过程中,连续索在一些节点处能够相对滑移,索与节点间的连接不能按铰接简单处理,传统有限元对此类问题的求解多有不便。针对索在节点处的滑移问题,该文采用一种新型分析方法—有限质点法,将连续索离散成相互联系的质点集合,质点运动满足牛顿第二定律,索的滑移行为通过质点的运动来描述。该文推导了滑移索单元内力求解公式,提出了滑移索单元的判定方法,通过自编程序对算例进行计算分析,验证了滑移索单元的正确性和合理性。 相似文献
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Wenqing ChenZiwen Xing Hao TangHuagen Wu 《International Journal of Refrigeration》2011,34(4):1141-1150
Slide valve is normally employed in screw refrigeration compressor to meet the cooling capacity demanded by the load variation. A mathematical model describing the working process of screw refrigeration compressor with a slide valve assembly under part-load conditions is established based on the calculation of the effective by-pass area and radial discharge area. Experimental investigation on a screw refrigeration compressor under part-load conditions with several evaporation and condensation temperatures is also carried out. Simulation results are in good agreement with the experimental ones. With the validated model, effects of key design parameters, i.e. the installation angles of the slide valve relative to the cylinder and the slide stop length, on the working process and performance of screw refrigeration compressor have been analyzed. These results can be useful for optimum design of the slide valve assembly to improve the energy efficiency of refrigeration system with screw compressor under part-load conditions. 相似文献