基于CAE的QX1060车轮结构性能分析

以轻型车QX1060铝合金车轮为研究对象,详细叙述了车轮的设计过程。首先确定了车轮零件的类型和相关基本参数,然后运用UG软件对车轮零件进行三维建模。在ANSYS软件中,利用92号单元建立其有限元模型,分别就车轮承受胎压载荷、径向载荷、周向载荷、侧向载荷的工况进行模拟计算,得出了不同工况下车轮的应力和变形的大小和分布。计算结果表明,对车轮的有限元仿真分析是实现其设计的有效手段。     

Analysis of railway wheel rolling process based on three-dimensional simulation

Rolling is one of the key stages of railway wheel hot forming process. In this work, a three-dimensional finite element analysis on wheel vertical rolling process based on some strategies proposed has been carried out by using FE code SuperForm. In modeling, a virtual mandrel is exploited in the hub hole to keep the wheel central instead of the guide rolls and centering rolls. Some features of the wheel forming are deeply investigated such as the rim diameter expanding, the rim lateral spreading, the metal flow in the circumferential direction, and the stresses distribution. The results show that (1) the rim radius expanding mainly occurs in the two affected zones before and after the back roll deformation zone; (2) the rim metal has flow trend in the circumferential direction during rolling, the metal of the intersection area, between the tread and the rim external side surface has the largest relative angular displacement; and (3) the tensile stresses of the web both in radial and circumferential directions during rolling result in the web thickness decreasing by about 3 mm for the investigated wheel. The simulations results reveal the forming mechanisms of wheel rolling, laying the basis for designing and optimizing railway wheel forming process.     

60t履带起重机四轮一带结构有限元分析

阐述了60t履带起重机中四轮一带结构的组成和受力特点,对结构进行了有限元计算与分析,适应了履带起重机发展的需求,可以更好地指导实际生产。     

电镀CBN锥砂轮磨齿热状态的研究

通过对磨齿过程中砂轮与工件系统的分析 ,建立了锥砂轮磨齿热状态分析模型 ,并分别运用一维传热杆模型及有限单元法分析、计算了磨削所引起的齿面表层的温度场 ;同时 ,用电镀CBN、陶瓷CBN和刚玉砂轮做模拟磨齿试验 ,考察了不同的砂轮及工艺参数对齿面温度的影响。结果表明 ,试验结果与计算结果基本吻合 ,电镀CBN锥砂轮磨削所引起的齿面温升仅是刚玉砂轮的 5 0 % ,比陶瓷CBN砂轮亦低。     

Thermo-mechanical finite element analysis of a rail wheel

The rail wheel, which is acted upon by mechanical forces also experiences thermal stresses due to braking, during service. The coupled nature of these forces is analysed using a three-dimensional elasto-plastic finite element model. Contact stresses at the rail–wheel interaction location are analysed using a global–local approach on a three-dimensional elasto-plastic finite element model. The paper also brings out the size and shape of the plastic zone at the contact region. Commercial finite element code ABAQUS has been used for the analysis and SDRC’s I-DEAS has been used for modelling. American Association of Railroad’s standards, available for the purpose of analytical evaluation of the rail wheel, has also been critically evaluated in this work.     

汽车车架严重载荷工况下的应力分析

车架的受力十分复杂,首先对某四驱越野车的车架结构进行了分析,对车架模型中不影响整体力学性能的结构部分进行了简化.然后利用Algor软件,建立了该四驱越野车车架的有限元模型.并将紧急制动载荷等效添加到车架模型上.在该车架有限元模型的基础上,对车架在紧急制动和对角线轮上台阶两种严重载荷工况下分别进行了应力分析,得出了整个车架结构的应力分布云图.指出了两种工况下其局部应力较大的部位,并提出了相应的改进措施.     

Analysis of internal cracks in railway wheels under experimentally determined pressure distributions

In recent years much effort has been devoted to the definition of design approaches of railway systems based on the analysis of the system itself and on accurate knowledge of its effective working conditions. In this paper, the attention is focused on railway wheels. This latter component is subjected to different types of damage: sub-surface crack propagation is considered. The prediction of the evolution of this process depends on the knowledge of the stress intensity factors concerning modes I, II and III, which are dependant both on the total load acting on the wheel and on how the load is transmitted through the wheel/rail interface. However, until now the solutions commonly used consider a theoretical (Hertzian) pressure distribution, even if, due to wear or to the dynamic phenomena, the actual contact patch can be strongly different for most of the lifespan of the wheel. An approach is developed with the aim to solve the case of an internally cracked wheel subjected to an arbitrary contact patch and pressure distribution. It is based on Boussinesq's formulae and utilises a three-dimensional finite element model of the part of the wheel close to the crack to calculate the stress intensity factors along a curvilinear crack front. Pressure distributions experimentally determined by means of a technique based on the reflection of high-frequency ultrasonic waves from the wheel–rail interface were applied to internal cracks in wheels: the results were critically compared with the those obtained by considering Hertzian pressure distributions, the aim being the assessment of the influence of the contact conditions in respect of damage cause by internal crack propagation.     

Numerical analysis for predicting the rolling contact fatigue crack initiation in a railway wheel steel

This paper concerns the modelling of the rolling contact fatigue of a railway wheel steel, which is simulated with moving Hertzian contact pressure. Parametric studies are carried out with a two-dimensional elastic-plastic finite element model of a part of a wheel containing defects. Several parameters, namely the size and shape of material defects, the load magnitude and the friction coefficient are varied to investigate their effect on the railway wheel fatigue damage. Defects or small friction coefficient are a plausible explanation to the initiation of deep subsurface fatigue cracks.     

气压砂轮抛光工具振动稳动性分析

针对气压砂轮光整加工过程中的振动问题,对气压砂轮抛光工具进行了振动稳动性研究;通过确定抛光工具结合面的等效动力特性参数,建立结合面的动力学模型,进行了有限元模态分析,得出了气压砂轮抛光工具在不同工况下的固有频率,发现抛光工具的主要振动部件为保持架和连接板;在有限元模态分析基础上搭建了模态测试平台,进行了实验模态验证;对比有限元分析结果和实验验证结果,分析了误差产生的原因;根据有限元分析和实验测试结果,对振动部件连接板进行了局部增强,优化了抛光工具结构;研究结果表明优化后的抛光工具能有效提高其振动稳定性,满足光整加工需求。     

接触分析在车轮弯曲疲劳有限元分析中的应用

利用有限元接触分析方法,建立车轮、试验轴、螺栓连接件的有限元模型,施加合理的载荷与边界条件,模拟车轮弯曲疲劳试验。通过有限元分析软件ANSYS,建立模型、设置接触对与相关参数,得出车轮高应力区域与各应力值。运用疲劳寿命计算理论中的名义应力法及ANSYS软件估算车轮疲劳寿命,且两数据基本一致。与车轮弯曲疲劳试验结果比较表明:在疲劳寿命计算理论与ANSYS软件估算的疲劳寿命内车轮均没有破坏。从而验证了运用接触分析有限元法预估车轮寿命的有效性,为以后的结构改进起到了指导作用。     

A study on the effect of rectangular cut out on laser forming of AISI 304 plates

Laser bending of a rectangular AISI 304 plate with a rectangular cut out is investigated in the present work. In particular, effects of process parameters: laser power, scanning speed, and geometric parameters: dimensions of the cut out of sheet metal on temperature distribution and bending angle are explored with the help of numerical simulation. Analyses are carried out through a coupled thermo-mechanical formulation with finite element method using COMSOL MULTIPHYSICS. The temperature distribution and deformation of sheet metal have been obtained from numerical simulations. The bending angle is affected by process parameters, namely, laser power, scanning speed, and width of the cut out of the sheet metal. Position of the cut out vis-à-vis the scanning path and length of the cut out have very little effect on the bending angle.     

Thermo-mechanical forming of a large sling shackle

A 3D finite element analysis has been carried out of the whole manufacturing process of a shackle involving the steps of closed-die forging and de-flashing of the extremity jaws, the open-die forging of the central body, and the ram bending of the crown. Thermal effects related to the transportation from the gas furnace to the mechanical press and from convective/radiative cooling were also taken into consideration. An elastic-plastic law with viscous effects was used to describe the thermo-mechanical behavior of the 34CrNiMo6 low alloy steel used for the shackle. Based on a fully coupled thermo-mechanical approach, the evolution of thermal and mechanical parameters was studied in details and compared with experimental measurements. A good agreement between the predicted and the experimental data for the die load, process energy, and the dimensions of the flash and the shackle was obtained. This study showed that design, optimization, and analysis of parameters for the manufacturing of shackles can be done efficiently with the use of the numerical simulation; such a numerical design could enhance the productivity.     

金刚石砂轮电解修整参数对工具阴极形状的影响

在金属结合剂成形金刚石砂轮电解修整过程中,电解参数对工具阴极的形状有显著影响。通过有限元法计算出阴极曲线形状,并与砂轮廓形比较,分析了砂轮廓形、修整电压、电解液电导率、电流效率和阳极砂轮表面的电流密度等参数对工具阴极形状的影响。     

Effect of parameters on grinding forces and energy while grinding Al (A356)/SiC composites

Abstract

Grinding processes require a high energy input per unit volume of material removed, which is converted to heat at the grinding zone, resulting in increased force and wear. In the present study, the influence of grinding parameters like work speed and depth of cut on grinding forces and energy was studied. An attempt has been made to study the forces and energy involved while grinding aluminium alloy (A356)/silicon carbide (SiC) composite material with different grinding wheels. Experiments were carried out on a surface grinding machine. Three different types of wheels like SiC, cubic boron nitride (CBN) and diamond wheels were used. The grinding forces increased with increase in depth of cut and work speed. SiC exhibited high grinding force compared to the CBN wheel. In the case of the diamond wheel, it was even less. The specific grinding energy was highest for the diamond wheel followed by CBN and SiC wheels. The specific grinding energy decreased with increase in depth of cut and work speed.     

航空发动机转速传感器的音轮优化方法研究

航空发动机转速信号中存在高次谐波,信号在传感器与线缆组成的回路中谐振而发生畸变。基于低频电磁场有限元软件Ansys Maxwell,该文对某型转速传感器匹配不同参数音轮进行数值模拟分析,获得转速传感器感应电动势曲线。然后对仿真数据进行分析,识别音轮参数对转速信号的影响,并梳理出音轮优化设计流程。结果表明:通过设计合适的音轮参数,可以明显减少转速信号中高次谐波分量,增强信号抗干扰能力。     

基于控制的自由摆激光追踪系统

分析了自由摆激光笔控制系统设计的要点与难点,建立了激光笔转角与自由摆转角之间的数学关系。利用单片机根据一定的控制方法与策略,采用步进电机控制位于摆杆末端与激光笔固连的平板转动,使得自由摆在任意摆动过程中激光笔光斑始终能够瞄准照射在靶纸的中心。最后在该自动控制系统的基础上提出了两种改进方案。拓宽其应用范围,并且对其未来的发展方向做出了展望。     

钢制薄壁车轮弯曲疲劳模拟精度探讨

介绍了如何用有限元法准确模拟钢制薄壁车轮弯曲疲劳试验的方法,着重讲述如何合理选择有限元网格类型、单元积分形式、单元尺寸大小,强调分析应采用材料"真应力-应变"曲线,给出旋转作用力、螺栓预紧力、加载时间步的设置方法和注意事项,以及判断有限元应力分析结果是否合理的方法.论文随后以车轮疲劳试验结果为参照,结合S-N曲线数学表...     

Application of Moiré interferometry to reconstruction of residual stress in cut railroad car wheels

Railroad car wheels develop residual stresses both in their manufacture and while in service. Knowledge of the residual stress distribution and its variation over time is necessary for the prediction of wheel service life and possible catastrophic failure. It is also vital for the safety of railway transportation. Although a theoretical solution is possible, it remains complex. Alternatively, the solution may be also obtained by using experimental measurements assisted by the theory of mechanics. An approach known as “physically-based enhancement of experimental data” formulated and subsequently developed and tested is the best available experimental-numerical tool for the reconstruction of acquired residual hoop stress component in railroad car wheels. This paper presents the formulation, approach and results of the analysis performed on experimental data obtained from investigations of the passenger and freight wheels during a saw cutting process. A discussion on the precision of the results has been included.     

Simulation and assessment of diamond mill grinding wheel topography

The topography of grinding wheel has a remarkable effect on grinding process. In this paper, the topographies of two mill grinding wheels with different grain sizes were measured by using an Olympus confocal scanning laser microscope. Kolmogorov–Smirnov normality tests were carried out to obtain distribution characteristics of abrasive grains. The test results indicate that the surface of grind wheel is of non-Gaussian nature. Consequently, a non-Gaussian statistical model was proposed to simulate the mill grinding wheel topography. Simultaneously, some parameters of “Birmingham 14” were introduced to assess the grinding wheel surface quantitatively. Simulated profile of the grinding wheel is found to correspond well in appearance with that of the actual grinding wheel.