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柴油机缸套在激光处理中采用不同的扫描排布方式,在磨损试验中其磨损量差异很大,本文从应力角度证实了激光处理网纹排布方式的不合理性。 相似文献
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为提高金属陶瓷涂层与基体的结合性能,通过对Ni-WC金属陶瓷涂层实施电阻加热和超声深滚耦合处理,探究高温环境下不同超声深滚静压力对Ni-WC金属陶瓷涂层微观组织结构的影响。通过扫描电镜、X射线衍射仪和JADE软件对改性金属陶瓷涂层进行测试,通过分析改性金属陶瓷涂层的表面微观形貌、晶粒尺寸和表面残余应力,探讨改性金属陶瓷涂层结合强度,用ImageJ软件评价改性金属陶瓷涂层孔隙率。结果表明:高温下超声深滚提高了涂层表面光洁度,细化了晶粒,引入了残余压应力,提高了涂层综合性能;随静压力的增大,改性金属陶瓷涂层的表面微观形貌得到明显改善,表面残余压应力逐渐增大,涂层与基体之间形成了部分冶金结合,结合强度大大提高;静压力较大时出现了物相的转变,且随静压力的增大,其孔隙率也逐渐减小。 相似文献
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针对铁路列车制动闸片摩擦块排布方式对制动盘热机耦合响应状态影响显著的问题,提出了一种考虑接触压力分布和非均匀热流密度的热机耦合仿真分析方法。通过在轨道车辆制动性能试验台上进行的制动台架试验,从温度的角度验证了所提方法的正确性。在此基础上,建立了列车全尺寸盘型制动系统有限元仿真分析模型,对现有铁路列车制动闸片摩擦块的排布方式进行了优化分析。结果表明,合理的制动闸片摩擦块排布方式可以显著降低制动盘面的温度和应力峰值,在改善制动盘面温度和应力分布的同时,提供较为优异的制动性能。研究成果可为铁路列车盘型制动系统热机耦合分析提供一种快速有效的仿真分析方法,同时可为铁路列车制动闸片摩擦块的排布优化提供指导方向。 相似文献
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多孔生物镁的制备及其表面改性 总被引:3,自引:0,他引:3
采用粉末冶金方法制备多孔镁,其孔隙率为20%~55%。通过碱热处理法对孔隙率为35%的多孔镁进行表面改性,以提高多孔镁在仿生体液中的耐腐蚀能力,并对碱处理和碱热处理后试样表面的沉积成分进行了测定。结果表明:多孔镁的孔隙率和孔径可以通过造孔剂的颗粒和含量来控制;通过碱热处理对多孔镁进行表面改性,未处理的多孔镁试样在仿生体液中浸泡7天后完全腐蚀,碱处理后的试样在仿生体液中浸泡10天后完全腐蚀,而经过碱热处理后的试样在仿生体液中浸泡14天后仍然保持原状,证明碱热处理可以显著提高多孔镁表面在仿生环境下的耐腐蚀性能。 相似文献
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考虑磨粒排布方式对砂轮磨削效率和性能有重要影响,设计制备磨粒无序和有序排布的加压内冷却砂轮,利用砂轮表面形貌检测和图像识别技术,建立砂轮磨削GH4169高温合金的三维有限元模型。采用不同磨粒排布的砂轮开展磨削GH4169高温合金的实验研究,对比分析磨削力、磨削温度、加工表面粗糙度以及表面微观形貌,研究磨粒无序和有序两种排布方式对砂轮磨削性能的影响。结果表明:对于加压内冷却砂轮而言,相对磨粒无序排布,磨粒有序排布方式能获得更优良的加工表面质量,磨削力、磨削温度和表面粗糙度均降低,且工件表面形貌更加规则完整。 相似文献
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钎焊单层金刚石砂轮关键问题的研究 总被引:8,自引:1,他引:8
概述了用活性钎料将金刚石磨料钎焊到钢基体表面制作单层金刚石砂轮,比传统的单层电镀金刚石钞轮具有明显的工艺优势。分析指出了钎焊工艺用现存的关键问题,即如何实现金刚石磨料与合金钎料层高的结合强度,钎料层厚度的均匀性和金刚石磨料的有序排布。给出了可行的解决方案,即利用Ag-Cu-Cr或Ni-Cr等活性钎料与金刚石界面化学反应生成的Cr7C3和Cr23C7,实现钎料层与金刚石间的高强度结合;通过化地貌优化,优化出磨粒排布方式,然后按优化的结果排布磨料。 相似文献
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内曲线柱塞马达中柱塞受力导致滚柱与柱塞接触面之间发生硬性接触,造成摩擦磨损,降低了马达工作性能与使用寿命。为减小内曲线柱塞马达柱塞的磨损,在柱塞上开应力变形孔释放应力能量,达到减小变形的目的。利用ANSYS-Workbench进行仿真,得到柱塞滚柱面的变形分布,并分析了应力变形孔的宽度和位置对变形的影响。结果表明:应力变形孔可以改变柱塞应力分布,从而减小滚柱面关键部位的变形,并且随着应力变形孔宽度和位置的变化,滚柱面上不同位置的变形变化规律也有差异,因此存在着相对最优的宽度与位置。 相似文献
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A perturbation technique is used to determine the stress concentration around reinforced curvilinear holes in thin pressurized spherical shells. Starting from the governing differential equations for thin shallow spherical shells, a solution is first obtained for a circular hole. The solution for an arbitrary shaped curvilinear hole is then obtained as a first-order perturbation over the circular hole solution using the conformal mapping technique. The effects of a large number of parameters involved in the design of a reinforcement around cutouts in shells are studied. The problems of symmetric and eccentric reinforcements are also considered. The results obtained would be very helpful in the design of an efficient reinforcement for elliptical and square holes in thin shallow spherical shells. 相似文献
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The areas around predrilled holes are highly stressed regions where cracks can easily form, which decreases the resistance of metal components to fatigue and causes serious problems in industry, such as aerospace, automobile, and ship building. In this paper, a novel method utilizing the effects of a strong pulsed electromagnetic field is introduced to effectively produce residual compressive stress into the surface of a predrilled hole. Basic principles of electromagnetic peening (EMP) are investigated using a multiphysics simulation approach. Simulations of EMP process on the surface of a work piece with predrilled blind hole are carried out by COMSOL Multiphysics 3.4. The distributions of stress and strain are presented and discussed, which demonstrate the feasibility of EMP on inducing compressive residual stress into the interior surface around a hole. In addition, the distribution of residual stress varies with various hole depth and work piece thickness is investigated. Finally, the influence of process parameters is also studied. The results of this work will help design process of strengthening 3D surfaces in metal components in manufacturing industry. 相似文献
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堵孔板外围的封闭焊缝由于受到较大的约束,因此会在焊缝和堵孔板内产生很大的内应力。研究了结构补强中的由堵孔板封闭焊缝引起的应力的分布规律,并对在堵孔板中开设应力释放孔以减小焊缝处应力的规律进行了研究。 相似文献
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基于有限元软件,分析了铝塑复合管承压条件下增强体铝表面应力场。结果表明,表面的应力状态为张应力。通过对增强体铝进行等离子体渗氮,在铝的表面得到了A1N层,其厚度随时间延长而增加。A1N层的存在,提高了复合管的平均弹性模量,改变了表面应力分布状态,使铝塑复合管的总承载能力进一步增加。 相似文献
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研究了纳米尺度圆孔孔边裂纹在远场反平面剪切载荷作用下的断裂性能。基于Gurtin-Murdoch表面弹性理论和保角映射技术,利用复变弹性理论获得了该类非均匀材料应力场的解析解,给出了裂尖Ⅲ型应力强度因子的闭合解。基于所得解答,研究了孔边的应力场分布规律,讨论了裂尖应力强度因子的尺寸依赖效应以及圆孔相对尺寸对应力强度因子的影响。研究结果表明:孔边应力场呈现非单调分布,表面效应对孔边不同位置应力的影响程度不同;当圆孔裂纹的尺寸在纳米量级时,裂尖应力强度因子具有显著的尺寸依赖效应;圆孔相对裂纹尺寸对裂尖应力强度因子的影响规律受表面性能的制约,同时表面性能对应力强度因子的影响也取决于圆孔的相对尺寸。 相似文献
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The stress state of a unilaterally reinforced hole in a plate under axial extension is analyzed. Such reinforcement does not effectively reduce the maximum stress. 相似文献
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Two-dimensional photoelastic stress analyses were conducted for epoxy resin models containing a hole defect under the conditions of Hertzian contact. Stress concentrations around the defect were determined as a function of several parameters. These were hole diameter, its vertical distance from the contact surface, and the horizontal distance from the Hertzian contact area. Also determined was the effect of tangential traction (generated by a friction coefficient of 0.1) on the stress concentration. Sharp stress concentrations occur in the vicinity of both the left and the right side of the hole. The stress concentration becomes more distinct the larger the hole diameter and the smaller the distance between the hole and the contact surface. The stress concentration is greatest when the disk imposing a normal load is located at the contact surface directly over the hole. The magnitude and the location of stress concentration varies with the distance between the Hertzian contact area and the hole. Taking into account the stress amplitude, the area which can be involved in a process of rolling contact fatigue seems to be confined to a shallow region at both sides of the hole. The effect of tangential traction is comparatively small on the stress concentration around tile hole. 相似文献