Elastic-plastic analysis of a rolling disk by finite elements

An elastic-plastic finite element method is employed to determine the stress distribution in a circular disk rolling on a rigid track and subjected to hub loads. This model can be assumed to represent a railroad wheel. Of particular interest are the stresses that exceed the initial yield limit near the point of contact. The material constitutive laws considered herein represent elastic-perfectly plastic and strain hardening materials that obey Mises' yield condition. It is shown that unloading of the previously yielded elements due to rotation can be easily handled by the direct stiffness tangent modulus approach. Total and plastic strains, and the plastic work in the disk model are given for the entire rolling history of the disk. It is also demonstrated that the disk will shake down to a purely elastic steady state for load values beyond the initial yield if the material of the disk exhibits even a small amount of strain hardening.     

基于GAP单元的滚动轴承应力分析

利用有限元分析软件MSC.Marc/Mentat对某一滚动轴承进行有限元分析,采用GAP单元代替滚动体模拟轴承内外圈间的接触,在某组载荷工况下,计算该简化模型的应力结果;在同组工况下,对比实体轴承模型与GAP单元简化模型的有限元分析结果,对比各自的最大应力值;同时用理论计算方法计算轴承在相同工况下的最大应力值,来验证有限元结果的正确性.结果表明:GAP单元可以有效的模拟滚动轴承内外圈之间的接触,从而为滚动轴承建模及与轴承连接的组合件之间的建模提供了一种简便且有效的方法.     

Friction machine for accelerated wear tests of frictional rolling elements

The construction of a friction machine for accelerated tests of friction rolling elements for frictional torque and wear. A study of the influence of rolling resistance force, rotational speed, and external load on the wear of samples has been carried out. A regression mathematical model that makes it possible to predict the amount of wear on the components of the friction pair under loading conditions has been obtained.     

Investigation of abrasive wear in a pair of elements of rolling friction

A physical and mathematical model of abrasive wear of heavily loaded rolling and sliding elements such as gears and rolling bearings is developed on the basis of a previously proposed fatigue theory. The various mechanisms of wear, their controlling factors and the criteria for the transition from one type to another are discussed. Comparison of the theoretical results is made with experimental results and experimental results from the literature.     

Ribbed strip rolling by three-dimensional finite element method combining extremely thin array of elements

In this paper, a three-dimensional finite element modelling of the ribbed strip rolling is carried out, coupling the use of an extremely thin array of elements that is equivalent to the calculation of the additional shear deformation work rate occurred by the velocity discontinuity in the roll bite. The formulation of the finite element modelling by adding a rib inclined contact surface boundary condition is derived, and the performance of the proposed method is conducted. The simulated rib height, forward slip, and the pulling down of rib height have been compared with the measured values and are in good agreement. The equivalent strain rate of the rib was obtained in the simulation. The effect of the rib inclined angle on pulling down of rib height has also been discussed, which is helpful in optimizing the design of the rib inclined angle.     

Dynamic analysis of a linear motion guide having rolling elements for precision positioning devices

Linear motion (LM) guides supported by rolling elements can be used to ultra-accurately position precision machines. For accurate positioning, the micro and macro dynamic behavior of the LM guide must be understood, but the research on this subject is rather limited. In this investigation, experiments to reveal the dynamic characteristics of the LM guide were performed and a simplified model to predict the observed dynamics of the LM guide was developed. Several experiments conducted in the present research demonstrated the hysteretic behavior as well as frequency-and force-dependent phenomena of the LM guide. The validity of the proposed modeling method was checked with theoretical and numerical analyses.     

Ribbed strip rolling by three-dimensional finite element method combining extremely thin array of elements

In this paper, a three-dimensional finite element modelling of the ribbed strip rolling is carried out, coupling the use of an extremely thin array of elements that is equivalent to the calculation of the additional shear deformation work rate occurred by the velocity discontinuity in the roll bite. The formulation of the finite element modelling by adding a rib inclined contact surface boundary condition is derived, and the performance of the proposed method is conducted. The simulated rib height, forward slip, and the pulling down of rib height have been compared with the measured values and are in good agreement. The equivalent strain rate of the rib was obtained in the simulation. The effect of the rib inclined angle on pulling down of rib height has also been discussed, which is helpful in optimizing the design of the rib inclined angle.     

基于应变的柴油机滚动轴承故障诊断方法研究

从简单的悬臂梁入手,建立了柴油机上滚动轴承的动力学模型,从理论上推导了梁上各点位移、速度、加速度和应变的响应解析表达式。通过仿真计算,发现上述四种参数对激振力都很敏感,而相对于其它三种响应而言,应变响应对其它激振源的加速度信号不敏感,得出了利用应变信号可以有效地避免柴油机上其它振动源的干扰的结论。并通过试验研究,验证了上述结论。     

Increase in the coefficient of friction of the rolling stock disc brake via fluid cooling of its friction elements

The paper presents the results of theoretical and experimental investigations in the effect of a partial heat energy removal in the friction contact zone upon the disc brake coefficient of friction during braking. A fluid cooling system for the disc brake friction elements has been proposed based on a recuperative liquidpneumatic heat-exchange apparatus.     

The rotordynamic analysis of the vibration considering the hydro-electric force supported by rolling elements in 500 kW Francis turbine

A Francis turbine which is one of the reaction water turbine types is mainly used in the multipurpose dam. The purpose of this research is to explain the vibration characteristics due to the various causes generated in Francis-turbines generator system. The hydrodynamic force was determined to use the fluid dynamics analysis considering the exciting force that is transmitted to the shaft from the runner part. Besides, in the generator parts electromagnetic forces can have a severe influence on the rotor dynamics in some situations. Because, the hydro turbine-generator system supported by various types of bearing, mechanical vibration analysis is also necessary. Based on a real small-scale Francis-turbine generators parameter, several analysis were performed the stability at the operating speed of the rotor such as natural frequency analysis and forced response analysis. Through this analysis, aside from the mechanical factor, electromagnetic and hydrodynamic factors have also been found to affect vibration.     

Effect of rolling ratio on groove-section profile ring rolling

Ring rolling is an advanced plastic forming technique which is used to manufacture precise seamless rings. Rolling ratio is regarded as a decisive parameter for the ring rolling process because it decides the blank dimension, reflects the ring deformation degree and influences the forming results. However, its importance for the ring rolling process is always neglected. In this paper, the effect of rolling ratio on the groove-section profile ring rolling is firstly investigated. The relationships between rolling ratio and blank dimension, rolling ratio and ring deformation degree are theoretically studied and a theoretical value range of rolling ratio is proposed. Then, with FE simulation, the influences of rolling ratio on the forming results are revealed. Based on comparison and experimental verification, a reasonable value range of rolling ratio is determined.     

冷轧渐开线齿形零件滚轧轮的设计

在分析冷轧加工原理的基础上,提出渐开线(直齿、螺旋齿)零件冷滚轧的设计原理.介绍了毛坯零件工艺参数的选定及滚轧轮的设计参数的计算.     

Multipass rolling systems

Russian Engineering Research -     

加工滚丝轮重点工序浅析

针对滚牙滚丝轮重点工序加工时出现的问题，提出解决问题的具体方法，提高了生产效率和产品质量。     

自行车空心轴脚蹬

以"仿生学"原理和"材料力学"方法,从理论上确定了"空心轴脚蹬"创新的可行性.脚蹬的转动副采用纳米塑料薄层,减小了摩擦系数,提高了效率.分析了构件的强度和刚度.     

激光拼焊碾压机构碾压力研究

间隙是影响激光拼焊焊缝质量的主要因素之一,碾压预成型技术是解决间隙问题的有效方法.基于碾压机构的工作原理,通过微积分的方法建立了碾压机构碾压力计算的数学模型,并用有限元方法对碾压过程进行了仿真分析.搭建了碾压试验平台,对碾压力等参数进行了试验研究.结果表明碾压力的教学模型是准确的.该模型可为碾压机构设计和碾压工艺参数设计提供重要依据.     

紧随数字化制造技术与装备同步发展的滚动功能部件产品

CIM T2005展示了当今全球数字化制造技术与装备以及相关功能部件的最新科技成果。从事滚动功能部件生产的企业,国内有22家,海外有12家参展,云集了这个产业一流企业的产品。中国机床工具工业协会滚动功能部件分会组织行业资深专家在展会上对上述企业的展品进行了考察,现作如下评