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关键词： 叶片式泵   叶片磨损   尺寸链  

摘要： 柴油机燃油输送泵是柴油机主油箱与日用油箱之间连接的叶片式泵,在某柴油机系统中该类燃油输送泵发生了叶片两侧严重磨损与叶片弯曲现象。本文通过对该类型叶片式泵现场运行及图纸分析,发现该故障原因为厂家出厂对叶轮两侧端盖与叶轮的间隙设置过小、尺寸链与实际使用状况不匹配,导致叶轮在运行期间由于轴的少量窜动而与两侧端盖发生磨擦,并提出了该类型叶片式泵的合理尺寸链,从而解决了柴油机燃油输送泵的叶片故障。

关键词： 组合密封圈   磨损   网格重构   密封性能   台架试验  

摘要： 针对橡塑组合密封圈的磨损和密封性能仿真方法开展研究,基于有限单元法开展接触压力的求解和磨损过程的仿真分析,采用有限差分法开展流-固耦合仿真分析获得密封间隙的压力和膜厚分布,提出了一种可用于组合密封圈磨损过程仿真和密封性能预测的方法。仿真过程中考虑了摩擦热对接触压力和磨损的影响,解决了塑料材质密封圈大体积磨损仿真时网格重构的难题,实现了磨损仿真过程中强度分析和流体力学分析的迭代求解,并实现了程序化。基于材料的摩擦磨损试验对模型参数进行了修正,通过旋转密封台架试验对仿真模型进行了验证。

关键词： 大气等离子喷涂   Al_(2)O_(3)-Cr_(2)O_(3)复合涂层   摩擦因数   耐磨损性能  

摘要： Cr_(2)O_(3)对Al_(2)O_(3)-Cr_(2)O_(3)复合涂层与高硬度陶瓷接触时的摩擦磨损行为及磨损机制的影响尚未揭示。采用大气等离子喷涂的方法制备Cr_(2)O_(3)含量不同的Al_(2)O_(3)-Cr_(2)O_(3)复合涂层以研究Cr_(2)O_(3)的影响机制。试验结果表明:Cr_(2)O_(3)明显减少了涂层的微观孔隙;复合涂层中α-Al_(2)O_(3)/γ-Al_(2)O_(3)的相对含量比明显高于Al_(2)O_(3)涂层中的37%;Al_(2)O_(3)-40%Cr_(2)O_(3)涂层的硬度与Al_(2)O_(3)涂层相比提高了48%,断裂韧性是Al_(2)O_(3)涂层的2倍多;当载荷为5 N、10 N和15 N时,Al_(2)O_(3)-40%Cr_(2)O_(3)复合涂层的摩擦因数最低,磨损率依次降低60%、85%和79%。但是当载荷为20 N时,Al_(2)O_(3)-20%Cr_(2)O_(3)复合涂层的摩擦因数最低,磨损率降低了50%。微观脆性断裂是涂层的主要磨损机制。复合涂层耐滑动磨损性能与Cr_(2)O_(3)含量及磨损条件是密切相关的。微观结构、硬度、断裂韧性、导热系数等是影响Al_(2)O_(3)-Cr_(2)O_(3)复合涂层耐磨损性能的重要因素。研究结果可为高耐磨性Al_(2)O_(3)基涂层的设计和应用提供指导。

关键词： ZrO_(2)颗粒   镁基复合材料   粉末冶金   热压烧结   微观组织   耐磨性  

摘要： 采用粉末冶金法制备了不同质量分数氧化锆(ZrO_(2))颗粒增强的AZ91镁基复合材料,并采用扫描电子显微镜(SEM)、能量色散谱仪(EDS)、X射线衍射仪(XRD)和硬度仪等手段研究了该复合材料的微观组织、硬度、密度和耐磨性。结果表明:ZrO_(2)颗粒在一般条件下都可能发生凝聚。除ZrO_(2)外,复合材料的结构内还包含Mg和Mg_(17)Al_(12)。加入ZrO_(2)颗粒能够有效的提高ZrO_(2)/AZ91复合材料的硬度和耐磨性;30wt%ZrO_(2)/AZ91复合材料的硬度为108.7 HV,相比基体AZ91合金,硬度提高了约22%。在20N载荷下,30 wt%ZrO_(2)/AZ91复合材料的磨损率为176.2 mm^(3)/(N·m),相比基体AZ91合金,磨损率降低了约28%。复合材料主要的磨损机制为磨粒磨损和氧化磨损。

关键词： 循环流化床   磨损量   磨损机理   冲蚀  

摘要： 本文通过探讨分析循环流化床锅炉的磨损机理和特点,总结了磨损发生的主要部位及磨损原因,提出了防磨措施,对使用单位具有指导意义。

关键词： Mechanical design   Stress recovery   Contact mechanics   Friction damping   Harmonic balance method   Cyclic symmetry  

摘要： Nonlinear forced response analyses of mechanical systems in the presence of contact interfaces are usually performed in built-in numerical codes on reduced order models (ROM). Most of the cases these derive from complex finite element (FE) models, resulting from the high accuracy the designers require in modeling and meshing the components in commercial FE software. In the technical literature several numerical methods are proposed for the identification of the nonlinear forced response in terms of a kinematic quantity (i.e. displacement, velocity and acceleration) associated either to the master degrees-of-freedom retained in the ROM, or to the slave ones after having expanded the reduced response through the reduction matrix. In fact, the displacement is the quantity usually adopted to monitor the nonlinear response, and to evaluate the effectiveness of a partially loose friction interface in damping vibrations, with respect to a linear case where no friction interfaces exist and no energy dissipation can take place. However, when a ROM is used the engineering quantities directly involved in the mechanical design, i.e. the strains and stresses, cannot be retrieved without a further data processing. Moreover, in the case of a strong nonlinear behavior of the mechanical joints, the distributions of the nonlinear strains and stresses over the structure is likely different than the one obtained as a superposition of linear mode shapes whose definition require a-priori assumptions on the boundary conditions at the contact interface. This means that the mentioned approximation cannot be used to predict the safety margins of a structure working in real (nonlinear) operative conditions. This paper addresses this topic and presents a novel stress recovery algorithm for the identification of the strains and stresses resulting from a nonlinear forced response analysis on a ROM. The algorithm is applied to a bladed disk with friction contacts at the shroud joint, which make t

关键词： Polyphenylene sulfide   Carbon fiber   Graphene oxide   Tribology  

摘要： The aim of this study was the improvement of the thermal conductivity and tribological properties of polyphenylene sulfide (PPS) with carbon fiber (CF) and graphene oxide (GO) fillers. Whereas CF reduce the mechanical strength of PPS, 3-mercaptopropyltrimethoxysilane (MPTMS)-treated CF improve the interfacial adhesion properties of fillers and PPS matrices, which increase the mechanical properties of composites. The improved thermal and mechanical properties of composites were confirmed via diffraction scanning calorimetry, dynamic mechanical analyzer, and wear test. The silane-modified PPS/20M-CF/5M-GO composite has a thermal conductivity of 0.323 W/m.K, which is 175% greater than that of the neat PPS composite. The friction coefficient has decreased from 0.236 to 0.176 and the specific wear rate has decreased from 1200 to 300 E-07 mm(3)/N.m.

关键词： 柔性机械系统   分布参数建模   控制策略   控制方法   振动抑制  

摘要： 近年来，柔性机械系统以其轻量化、低耗能、操作灵活等优势在航空航天、海底勘探、机器人、机械制造等领域得到了广泛应用，其建模和控制问题也成为了当今国内外学者研究的热点问题。在本文中，首先介绍了柔性机械系统的部分应用实例，紧接着汇总了柔性机械系统常见的分布参数建模方法、控制策略、控制方法以及实际工程中常见问题。最后，对柔性机械系统分布参数建模与控制问题进行了总结，并对未来的研究方向进行了展望。