共查询到19条相似文献,搜索用时 62 毫秒
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为了在较真实地模拟接触状态的同时节省计算耗费,采用自适应无网格法求解粗糙表面热弹塑性接触问题。计算中考虑了屈服强度温度相关因素,将基于应变能梯度的自适应无网格法与线性规划-增量初应力法相结合,构建了热弹塑性接触自适应无网格分析模型,并给出相应的程序流程。通过粗糙表面与弹塑性平面热弹塑性接触算例进行验证,分别对两种不同工程材料考虑切向摩擦力、材料应变硬化和材料屈服强度温度相关等情况进行了讨论。结果表明,采用自适应无网格法能有效求解粗糙表面热弹塑性接触问题,在保证计算精度与整体加密相当的情况下,自适应加密的计算耗费约为整体加密计算耗费的10%。 相似文献
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目前表面模型主要以统计数学方法和分形方法居多,不能真实的反应表面特征.通过Wyko NT1100形貌测量仪获得车削表面的形貌数据,利用最小二乘法对Bad点和噪声点进行拟合插值处理,然后通过逆向建模得到真实粗糙表面模型,运用有限元方法,研究了弹性阶段和弹塑性阶段无量纲化接触面积和位移随无量纲化载荷的变化关系.结果表明:利用测量数据格式与CATIA V5之间联系,可以建立真实粗糙表面的模型;在弹性接触阶段,无量纲化接触面积和位移与无量纲化载荷之间近似成线性关系;而在弹塑性接触阶段,当弹塑性切向模量Et较大时,无量纲化接触面积和位移与无量纲化载荷之间才近似成线性关系.当载荷一定时,Et越小,接触面积和位移越大,对于一定接触面积和位移的载荷也越大. 相似文献
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新的粗糙表面弹塑性接触模型 总被引:15,自引:3,他引:15
提出一种新型的粗糙表面弹塑性微观接触模型.该模型的建立基于接触力学理论和接触微凸体由弹性变形向弹塑性变形及最终向完全塑性变形的转化皆是连续和光滑的假设.研究单个微凸体在载荷逐渐增加时的变形规律,并重点推出弹塑性变形区间的接触方程.在此基础上应用概率统计理论导出了粗糙表面的接触载荷、平均分离和实际接触面积之间的数学关系式.在不同的塑性指数和载荷条件下,该模型与GW弹性模型和CEB弹塑性模型就实际接触面积和法向距离的预测结果进行了对比.结果表明,在同样塑性指数和载荷条件下比GW模型预测的实际接触面积大但法向距离小,且两者的差距随塑性指数和载荷的增加而增大.因此该模型的预测结果更加符合人们的试验观察和直觉,能够更加科学和合理地描述两个粗糙表面的微观和宏观接触状态. 相似文献
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运用有限元法、线性规划法和塑性增量理论对含涂层真实粗糙表面的弹塑性接触问题进行了分析。通过改变涂层材料的弹性模量、屈服极限及涂层厚度,研究了不同条件下接触面积与接触压力、平均间隙与接触压力的关系及变化规律,给出了3种数值方法的解与弹性解的比较,分析了各主要因素对接触压力、接触面积及平均间隙的影响。 相似文献
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利用弹塑性有限元和单纯形法求解弹塑性接触模型,分别模拟了屈服强度呈梯度变化的渗氮钢、未经处理的匀质材料和硬涂层材料粗糙表面的弹塑性接触行为。与未经处理的匀质材料相比,渗氮钢可承受更大接触载荷。在相同载荷作用下,渗氮钢表面粗糙峰接触面积较小,平均间距较大,接触体内材料不易发生屈服,从而显著提高接触性能。和硬涂层材料相比,渗氮钢接触体内等效von Mises应力分布平缓,没有应力突变。最后讨论了渗氮层和硬涂层的厚度对粗糙表面接触特性的影响。 相似文献
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对近年国内外工程粗糙表面微观热力学的数值模拟的进展作了综述,介绍了工程粗糙表面的表征、接触模型、表面温升的计算模型与方法的研究现状,并提出了当前相关研究中所遇到的问题及今后研究发展方向. 相似文献
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A numerical method is presented for evaluating the elastic-elastic contact of real rough surface contacts during running-in. For the surface contact, an elastic-plastic model based on the variational method is applied to analyze the pressure distribution and contact area of worn surfaces during running-in. In conjunction with the classical statistic model of Greenwood and Williamson, the numerical result showed that the plasticity index Ψ was decreased to one in the elastic range as running-in proceeded. In comparison with the Hertzian solution, the influence of the asperities is very significant on the pressure distribution, thereafter causing a higher peak value of contact pressure. For the subsurface, the interior stress from the von Mises criterion was calculated to evaluate the subsurface stress field subject to both normal and tangential forces. In the calculated of the interior stress, the total stress is decomposed into a fluctuating component and a smooth component. The fluctuating part is solved by using FFT from the concept of the convolution theorem while the smooth part is obtained directly by analytical solution. Calculations of contact area and subsurface stress on experimentally produced surfaces whose topography has been determined using an atomic force microscope and friction coefficient front sliding have been carried out. The results showed that asperities and friction coefficient gave rise to stress increase in the near-surface stress field and produced a high stress zone towards the surface. As a result, transverse asperity cracking was produced. The calculations and supporting experimental evidence clearly confirmed that the reduction of peak pressure during running-in decreased the plastic deformation of contact. 相似文献
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为研究真实管道连接件在拧紧力矩作用下的接触状态和密封机制,从而有效控制管路密封性能,以真实管路连接件为研究对象,对粗糙接触表面真实接触形貌数据进行实测,通过逆向建模工程建立粗糙接触表面有限元模型,利用有限元仿真分析方法得出真实接触面积比与平均接触应力的关系。结果表明,在开始施加位移载荷时同时发生弹性与塑性变形,随着载荷的增加,发生塑性变形区域越来越大,形成真实接触区域部分也逐渐增加。基于逾渗理论对接触界面进行栅格化模型模拟,通过寻径算法得出接触界面达到密封时所需要的最小真实接触面积比,结合仿真结果得到管路连接件接触表面达到密封时所需要的最小接触应力值。研究结果为管路连接件密封性能仿真分析提供重要密封评判指标,也进一步通过仿真分析得到管接头密封条件下的最小拧紧力矩提供参考。 相似文献
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不同真空度气体对粗糙表面接触摩擦的影响 总被引:1,自引:0,他引:1
在大气压作用下,通过对不同真空度下接触物体表面摩擦力的测量,研究气体对粗糙接触物体表面摩擦的影响,该实验采用的摩擦副材料是铝合金/有机玻璃、45钢/有机玻璃。实验结果显示:随着真空度的增大,2种摩擦副的摩擦力近似呈现线性变化,静摩擦因数则先减小而后趋于稳定,再有回增的趋势;45钢/有机玻璃摩擦副静摩擦因数取得最小值所对应的真空度比铝合金/有机玻璃摩擦副的更大。通过分析得出静摩擦因数变化的原因:随着真空度的增大,摩擦副接触间隙间的气体密度减小,当固体刚开始运动时,产生摩擦的气体分子与固体表面的分子减少;随着真空度的增大,正压力增大,材料的变形程度增大。 相似文献
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In this work, the statistical asperity microcontact models in combination with the acoustic spring model and the load sharing concept are utilized to study the interfacial normal contact stiffness for a rough surface in line contact elastohydrodynamic lubrication (EHL). Two different statistical microcontact models of Greenwood and Williamson (GW) and Kogut and Etsion (KE) are employed to derive the normal contact stiffness expressions for a dry rough line contact considering the purely elastic contact and the multiple regimes elastic–elastoplastic–fully plastic contact, respectively. The liquid film stiffness is calculated based on the relationship between film thickness and bulk modulus of the lubricant. The lubricant film thickness equations are employed in conjunction with the load sharing concept and the empirical formulas for the maximum contact pressure in a dry rough contact are fitted for the GW model and the KE model, to evaluate the relationship between film thickness and motion velocity for the purely elastic GW microcontact model and the multiregime KE microcontact model, respectively. The comparison with experimental results shows that the KE model predicts closer total contact stiffness results than the GW model. The stiffness contributions from the solid asperity contact and lubricant film are obtained and effects of surface roughness, applied load, motion velocity, and type of lubricant on the normal contact stiffness are analyzed. 相似文献