Improved analytical model for residual stress prediction in orthogonal cutting

The analytical model of residual stress in orthogonal cutting proposed by Jiann is an important tool for residual stress prediction in orthogonal cutting. In application of the model, a problem of low precision of the surface residual stress prediction is found. By theoretical analysis, several shortages of Jiann’s model are picked out, including: inappropriate boundary conditions, unreasonable calculation method of thermal stress, ignorance of stress constraint and cyclic loading algorithm. These shortages may directly lead to the low precision of the surface residual stress prediction. To eliminate these shortages and make the prediction more accurate, an improved model is proposed. In this model, a new contact boundary condition between tool and workpiece is used to make it in accord with the real cutting process; an improved calculation method of thermal stress is adopted; a stress constraint is added according to the volume-constancy of plastic deformation; and the accumulative effect of the stresses during cyclic loading is considered. At last, an experiment for measuring residual stress in cutting AISI 1045 steel is conducted. Also, Jiann’s model and the improved model are simulated under the same conditions with cutting experiment. The comparisons show that the surface residual stresses predicted by the improved model is closer to the experimental results than the results predicted by Jiann’s model.     

弧齿锥齿轮准静态啮合仿真分析

利用大型有限元软件MSC.Marc,建立了弧齿锥齿轮副三齿啮合的三维有限元非线性接触模型.该模型可以实现转速和转矩的传递,基于该模型对齿轮副进行了准静态啮合仿真分析,并对啮合过程中的齿面接触应力及齿根弯曲应力变化规律进行了研究.数值计算结果符合弧齿锥齿轮的实际啮合规律,为进一步分析高速情况下弧齿锥齿轮的啮合状态提供了基础和依据.     

航空减速器弧齿锥齿轮啮合仿真模型

利用大型有限元分析软件Msc．Marc的直接约束法,建立了某航空减速器弧齿锥齿轮副多齿啮合的三维有限元非线性接触分析模型,该模型可同时实现转矩和运动的传递。基于该模型,对齿轮副进行了一个啮合周期的准静态啮合仿真分析,给出了准静态啮合时轮齿的接触状态、接触应力、齿根弯曲应力及主从动齿轮的转矩和转速随啮合位置变化的规律。分析表明,本文得到的结果非常符合实际啮合规律,也验证了模型的正确性。     

渐开线直齿轮啮合过程中载荷及应力的计算机模拟

基于有限元法,提出了一种渐开线直齿轮在啮合过程中参数化模型的表达方法,建立了能随啮合过程变化自动调整接触区和整体模型的啮合轮齿有限元分析模型,采用有限元弹性接触分析方法对轮齿从啮入至啮出整个啮合周期的接触载荷分配及分布、应力分布的变化等进行了研究。采用该方法可实现用计算机模拟齿轮在啮合过程中载荷及应力的变化。     

航空减速器弧齿锥齿轮动态啮合仿真分析

利用大型有限元分析软件MSC.Marc,建立了某航空减速器弧齿锥齿轮副多齿对啮合的三维有限元非线性接触分析模型。基于该模型,在一个啮合周期内,对齿轮副进行了在一定转矩和转速下的动态啮合仿真分析,给出了动态啮合时轮齿的接触状态、接触应力、齿根弯曲应力及主从动齿轮的转矩、转速和加速度随啮合位置变化的规律。分析表明,本文得到的结果非常符合实际啮合规律,并对进一步的疲劳寿命分析提供了依据。     

基于有限元方法的不同长径比柔轮受力分析研究

通过UGNX5.0建立不同长径比柔轮和波发生器的三维实体模型,并用parasolid格式导入ANSYS。采用SOLID185六面体单元用sweep方式对柔轮进行网格化,建立有限元模型。在波发生器外柱面与柔轮内柱面之间建立两对面-面接触,更真实地模拟出柔轮的边界条件,然后在波发生器长轴方向对称位置的两个轮齿的节点上施加等效于扭矩的切向力,从而研究出柔轮的应力分布和变形与长径比的关系。     

基于ANSYS的谐波减速器柔轮受力分析

通过UGNX4．0建立柔轮和波发生器的三维实体模型,并用parasolid格式导入ANSYS。采用SOL—ID185六面体单元用sweep方式对柔轮进行网格化,而波发生器无需网格化,建立有限元模型。在波发生器外柱面与柔轮内柱面之间建立两对面-面接触,更真实地模拟出柔轮的边界条件,然后在波发生器长轴方向对称位置的两个轮齿的节点上施加等效于扭矩的切向力,从而研究出柔轮的应力分布和变形与载荷的关系。     

宽斜齿轮啮合过程三维接触有限元分析

针对宽斜齿轮，提出了轮齿在不同位置啮合时有限元网格及模型的自动生成方法，并开发出相应的三维前后处理及接触分析程序，进行了轮齿啮合过程中应力应变的数值分析。本文程序使用方便，只需输入齿轮基本参数，即可得到轮齿不同啮合位置的网格、应力分布、位移场、应力场、接触状态及接触线载荷分布。     

Contact problems of a trochoidal-gear pump

The aim of the approach of this paper is to characterise contact stress of a trochoidal-gear set when it works as part of the hydraulic machine. It is important to know that the contact stress forces in a trochoidal-type machine is important because the machine cannot be adjusted for wear. The main difficulty in calculating the contact forces is to determine the forces that are transmitted through each contact point. Since there are many points of contact, at any instant, the problem is statically indeterminate. The first part of this paper presents a simplified analytical model of a trochoidal-type machine when friction at the contact points is neglected. From this study, the performance of the gear set is evaluated through the calculation of the normal maximum contact stress in the gear teeth. Then the second part of the paper presents a finite element model of the same machine. The analysis of both models is for quasi-static conditions. An experimental approach using a prototype model of the gear set provides the maximum contact stress on a pair of teeth through photoelasticity measurement techniques of the same machine. The results from the two models and the experimental work are compared and important conclusions are drawn and discussed.     

Stress calculation for plastic helical gears under a real transverse contact ratio

Calculation methods of plastic helical gears with a real transverse contact ratio have never been studied in depth. The methods used in some references assume a uniform load distribution along the line of contact or don’t take into consideration the effect of premature mesh between one or more pair of teeth during engagement, which is not in good agreement with numerical results. This paper is focused on analysis of plastic helical gears. The nonuniform load distribution obtained from the proposed mathematical model is based on the calculation of the real contact ratio representing the real number of pairs of teeth in contact. This model also leads to the distribution of the tooth bending stress and the contact stress along the area of contact.     

Ring crack propagation in silicon nitride under rolling contact

Silicon nitride has been found to have the optimum combination of properties which are suitable for rolling element bearing applications to withstand high loads, severe environments, and high speeds. Surface ring cracks are difficult to detect but are found on the surface of silicon nitride balls. These ring crack defects decrease the rolling contact fatigue life considerably. This paper presents an experimental study and numerical analysis of ring crack propagation in rolling contact. The contribution of this study is to provide understanding of ring crack propagation behaviour and life prediction in rolling contact. Rolling contact tests are performed on the silicon nitride/steel elements. Silicon nitride ball surfaces are examined before testing using a dye-penetrant technique and optical microscopy. The surfaces are examined using optical microscopy and scanning electron microscopy during testing and after failure. The numerical calculations are based on a 3D model of ring crack growth. The rolling contact loading is simulated by a repeated Hertzian surface load with normal pressure and tangential traction. Fracture mechanics analysis is utilised to determine the stress intensity along the crack front and the stress intensity factors are analysed using a 3D boundary element model. Life predictions from the present calculations are in line with the experimental observations.     

基于ANSYS的新型人字齿同步带受力分析

人字齿同步带传动是同步带传动在结构上的新突破,它兼有直齿和斜齿同步带的优点,有承载能力强、噪声低等特点,在传动领域得到重视.通过Pro/E建立了一对人字齿带与带轮完全啮合的三维模型,利用ANSYS有限元软件对其进行了静态非线性接触分析,结果表明:随着螺旋角的增大,带齿根最大等效应力和强力层最大等效应力减小.通过对带齿加载过程的动态过程分析,带齿顶与带轮齿槽接触,减缓带齿根应力集中,表明新型人字齿同步带带齿与轮齿间齿形设计更合理.     

鼓式制动器的有限元模拟与接触分析

运用ANSYS Workbench平台建立了某鼓式制动器的三维有限元模型,对摩擦衬片与制动鼓之间的摩擦接触进行模拟。通过改变边界条件的施加方式及不同的接触对设置参数,确定了模拟鼓式制动器制动过程的接触分析边界条件及接触对的设置方法。采用三个载荷步加载,分析了制动力矩在制动过程中的变化规律,得出摩擦力矩达到平稳时接触压强的分布特性及制动器的等效应力与变形。为优化制动器结构参数、改善鼓式制动器磨损均匀性和制动效能提供了参考依据。     

蹄-鼓式制动器热弹性耦合有限元分析

首先探讨蹄—鼓式汽车制动器的摩擦接触热弹性耦合非线性动力学问题及其分析方法,包括摩擦生热模型、多物理场中的弹性体有限元模型、接触问题模型的建立方法以及相应的数值分析方法。然后,利用有限元分析软件ADI-NA建立一种新型蹄—鼓式制动器热弹性耦合动力学分析的三维有限元模型,确定对模型求解的位移边界条件和热边界条件,设定材料物性参数、加载过程及模拟工况,探讨进行制动器热弹性耦合有限元分析的过程,通过仿真计算得到制动器工作过程中摩擦副间接触力分布、制动鼓瞬态温度场、应力场、变形场等重要信息。     

Comparison of three teeth and whole body models in spur gear analysis

The gear teeth deflections and stresses are estimated by the boundary element method with two types of gear models, three teeth and whole body, respectively. The models are developed by considering profile modifications, contact deformations, frictional effects, hub boundary conditions, keyway effects, load sharing of the teeth, etc. The results are shown to compare favourably with analogous results obtained by strain gage experiments. Consequently, whole body model gives more realistic results from the modeling point of view in spur gear analysis.     

基于ANSYS的齿轮接触问题研究

通过齿轮接触分析应用实例,分析了齿轮接触应力的分布和最大应力,介绍了CAXA电子图板齿轮建模和ANSYS接触分析的方法,对接触问题进行探讨,对在计算过程中可能影响收敛的因素：处理界面约束方法、摩擦模型、接触刚度、初始接触条件等的选择和模拟提出建议,通过算例说明了有限元分析在齿轮接触问题上的有效性,提出了齿轮接触的最大应力是在单齿接触时。     

油膜轴承锥套过盈装配过程中的压力分布及损伤

针对1580 PC热板带连轧机油膜轴承在装拆与使用过程中的锥套损伤问题,建立锥套装配的边界元力学模型及边界条件。利用三维弹塑性接触问题边界元法定量分析轧机油膜轴承锥套与轧辊辊颈过盈装配过程中的变形和载荷特性,通过设定不同加载模型的参数,对锥套装拆过程进行数值模拟。讨论油膜轴承偏载时锥套接触应力和变形对锥套与辊颈损伤的影响,得出装拆过程中不同胀型压力和轴向推力条件下的应力和应变变化规律,找出导致锥套损伤的根本原因,给出防止锥套与辊颈装配过程损伤的具体改进措施。利用制造出的两台轧机油膜轴承样机试验验证理论分析结果的正确性,并且找到油膜轴承损伤的根本原因。     

点蚀与剥落对齿轮扭转啮合刚度影响的分析

为了模拟齿面点蚀和剥落对齿轮扭转啮合刚度的影响,提出了利用ANSYS软件对齿轮传动扭转啮合刚度有限元模型的建模和计算方法。根据扭转啮合刚度定义,分别建立了无齿面缺陷和有齿面缺陷的齿轮三维接触仿真分析模型。计算了两种运行状态下,不同接触位置上的扭转啮合刚度,并利用MATLAB比较了有点蚀剥落与无点蚀剥落齿轮的扭转啮合刚度的变化情况。模拟结果表明,点蚀和剥落的存在使齿轮的扭转啮合刚度减小,特别是在轮齿的单啮合区时,对扭转啮合刚度的影响剧烈。     

Some Optimum Conditions for the Lubrication of Gear Teeth

The percentage of boundary operation, or metal-to-metal contact between gear teeth, was measured to determine optimum running conditions for a pair of gears. A nondestructive test method was used. The effects of load, speed, lubricant viscosity, and lubricant additive were investigated.     

Modal and stress analysis of gear train design in portal axle using finite element modeling and simulation

The portal axle is a gearbox that is specially designed for off-road driving conditions. It is installed between the wheel and the axle shaft to give higher ground clearance to the vehicle. The modeling and simulation of spur gears in portal axle is important to predict the actual motion behavior. However, gear train design in portal axle is difficult to study comprehensively due to their relatively low cost and short product life cycle. In this study, modal analysis of portal axle is simulated using finite element method (FEM). Modal analysis is simulated on three different combinations of gear train system commonly designed for portal axle. The three gear trains being analyzed are gear train without idler gear, one idler gear and two idler gears. FEM static stress analysis is also simulated on three different gear trains to study the gear teeth bending stress and contact stress behavior of the gear trains in different angular positions from 0° to 18°. The single and double pair gear teeth contact are also considered. This methodology serves as a novel approach for gear train design evaluation, and the study of gear stress behavior in gear train which is needed in the small workshop scale industries.