基于疲劳寿命的角接触球轴承结构参数优化分析

基于滚动轴承微区接触的疲劳寿命计算方法,建立了角接触球轴承的结构参数优化计算模型。以某燃气涡轮发动机转子系统前支点角接触球轴承为例,分析了角接触球轴承结构参数对轴承承载区最大接触应力、轴承疲劳寿命和保持架滑动率的影响规律,并基于轴承延寿的目标进一步提出了结构参数优化方案。分析结果可为角接触球轴承的结构设计提供参考。     

风力发电机主轴的非线性接触有限元分析

使用非线性接触有限元方法对风力发电机主轴零件进行结构分析.模型模拟了轴承和轴套对主轴的非线性支承条件以及轴承的调心转动,给出静强度和疲劳寿命计算结果.分析结果表明,该主轴的强度、刚度和疲劳寿命满足设计要求.     

基于接触载荷等效的角接触球轴承疲劳寿命计算方法

针对滚动轴承疲劳寿命计算方法未考虑轴承元件不断变化的载荷和速度、预测精度还有待进一步提升的现实,结合轴承拟动力学分析方法、轴承元件接触载荷及速度等效计算模型,建立了基于轴承接触载荷等效的疲劳寿命计算方法。该方法可为轴承寿命预测、工程选型提供更准确的计算模型和分析工具。     

滚动轴承接触疲劳内部裂纹扩展有限元分析

滚动轴承滚道在工作过程中承受较大的接触应力,接触疲劳是滚动轴承失效的主要形式。为了探究轴承的接触疲劳以及接触疲劳引起的内部裂纹,将损伤力学带入Voronoi有限元方法中,仿真轴承材料拓扑随机性和材料的劣化过程。建立轴承接触疲劳裂纹扩展模型,有效仿真出轴承内部裂纹的萌生、生长、相交、扩展至表面的过程,得到轴承表面裂纹出现的寿命和内部裂纹扩展路径。计算了裂纹扩展过程中所释放的能量,研究内容能够为轴承接触疲劳损伤研究提供新的思路和工具。     

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。     

双列角接触球轴承疲劳寿命分析与研究

双列角接触球轴承在汽车前轮轮毂等场合有较为广泛的应用,然而其疲劳寿命的计算和影响因素分析却很少有研究涉及。通过分析双列角接触球轴承的寿命计算方法,采用ROMAX软件对自行设计加工的双列角接触球轴承试验台原型进行建模仿真,分析得出了模型中试验型号为SKF3216的双列角接触球轴承的外圈预紧量、接触角、内外圈沟道系数对轴承疲劳寿命的影响大小。这不仅提供了一种快速估算双列角接触球轴承疲劳寿命的方法,也为轴承结构优化和工作条件改进以提高轴承工作寿命提供了有效的参考。     

滚动轴承接触问题的有限元分析

基于有限元分析软件ANSYS,建立了滚动轴承接触分析的三维有限元模型,对轴承的接触问题进行了数值模拟,得到了轴承承载过程中的应力和变形分布趋势.通过与Hertz理论计算结果对比分析,两者结果比较接近,说明该方法分析是可行的,也为轴承动力学仿真分析提供了理论基础.     

考虑温度影响的角接触球轴承疲劳寿命仿真研究

针对承受热应力和结构应力共同作用下的角接触球轴承,利用ANSYS Workbench软件对其进行疲劳寿命分析。在三维软件Pro/E中建立轴承模型,导入有限元软件ANSYS Workbench中得到轴承的有限元模型,进行热-应力耦合分析,得到轴承温度分布和应力分布;根据零件的材料属性,利用ANSYS Workbench的Fatigue模块分析了轴承的疲劳寿命。根据软件模拟计算得到轴承寿命情况,为机床主轴轴承寿命的预测奠定基础。     

滚动轴承接触问题的数学规划法

将滚动轴承的接触分析采用有限元弹性问题计算,可以获得一个与实验结果比较一致的解。本文通过讨论摩擦接触问题的本构模型,利用参变量分原理获得一个解有间隙带摩擦弹性接触问题的数学规划法。为使滚动轴承的接触分析更能符合实际情况,考虑轴承箱与外圈的摩擦,得到不同摩擦状况下轴承的接触区及接触力分布。从而为轴承接触问题分析提供了一个有效的数值方法。     

滚动轴承疲劳破坏机理和疲劳寿命模型综述

延长轴承疲劳寿命,尤其是滚动轴承的接触疲劳寿命.一直是轴承工作者十分重视的研究课题.本文概括了滚动轴承接触疲劳破坏机理的主要形式和形成原因,总结了不同阶段的滚动轴承接触疲劳寿命计算公式,分析了不同滚动轴承接触疲劳寿命模型的区别.介绍了表面涂层的摩擦学性能在滚动轴承中的应用.     

Static friction at high contact temperatures and low contact pressure

The problem of measuring static friction at high temperatures and low contact pressures is theoretically analyzed, as well as the instruments for the accurate determination of the coefficient of static friction at high temperatures for contact pairs made of steel and bronze. The results of experimental investigation show that at low contact pressure and temperature above 120°C coefficient of static friction dramatically increases. This increase in the coefficient of friction can be of great practical value with regard to the load capacity of contacts where external forces are balanced with friction forces.     

Glenohumeral contact forces

Glenohumeral contact forces have only been calculated previously either for simple abduction or for athletic activities. The objective of this study was to determine the glenohumeral contact forces for tasks which are demanding of the shoulder but which would commonly be performed by older people. The functional tasks chosen were using the arms to stand up from and sit down into a chair, walking with a cane, lifting a 5 kg box to shoulder height with both hands, and lifting a 10 kg suitcase. The trunk angles, arm angles and hand loads of six healthy subjects, average age 55 years, were recorded. This information was input into a biomechanical computer model which optimized the muscle force distribution by minimizing the sum of squared muscle stresses subject to constraints on the maximum muscle forces and maintaining the direction of the resultant force within the glenoid fossa. Average contact forces ranged from 1.3 to 2.4 times body weight (930-1720 N), the highest force being for lifting a suitcase. This latter value would be even higher if lifting either a greater load or to a greater height. Thus, contact forces at the shoulder should not be underestimated. This study provides functionally relevant contact forces which can be used for mechanical testing or finite element modelling of shoulder prostheses.     

Thermomechanical contact homogenization with random rough surfaces and microscopic contact resistance

We extend an earlier computational thermomechanical contact homogenization framework [Temizer ?, Wriggers P. International Journal for Numerical Methods in Engineering 2010; 83:27-58] to random rough surfaces generated through the random-field model based on the concepts of ensemble averaging and sample enlargement towards the effective limit. Additionally, the homogenization theory is revisited in order to incorporate thermal dissipation at the microscopic contact interface within a thermodynamically consistent approach that preserves dissipation across the scales. Large-scale three-dimensional computations were performed to demonstrate the effectiveness and feasibility of the computational framework for an accurate characterization of the macroscopic thermomechanical response of rough surfaces in contact.     

Edge contact effect on thermal elastohydrodynamic lubrication of finite contact lines

Minimum lubricant film thickness and maximum pressure every so often appear close to roller ends. This study combines the Boussinesq–Cerruti half-space equations with a free boundary correction procedure for precise modeling of edge contact conditions. The thermal EHL model developed associates this representation to a standard finite difference of the energy equation, and to a modified finite difference expansion of the Couette term of the Reynolds equation. To complete the model, the Carreau expression describes the shear-thinning response of the lubricant. The investigation includes different roller profile corrections. The results show that a large radius crowning modification combined with a rounding of the corners constitutes the most effective profile adjustment.     

Evaluation of the real contact areas, pressure distributions and contact temperatures during sliding contact between real metal surfaces

A three-dimensional elastic contact algorithm has been developed to analyse the normal contact problems of bodies having rough surfaces. The algorithm can evaluate the real contact areas and contact pressure distributions using measured surface roughness data.

Following an approximate elastic-plastic contact solution the analysis produces more realistic elastic and plastic contact areas; in addition results of contact pressure distributions can be predicted according to a given maximum plastic limit pressure.

The technique can simulate (in an approximate way) the elastic-plastic sliding contact behaviour in the vicinity of asperities or concentrated contact areas by ignoring the effect of the tangential forces on the vertical displacement.

Assuming a certain sliding speed and a particular coefficient of friction the local temperature distribution due to the heat generation over the real contact areas can also be calculated for 'slow sliding' problems.

The results show the moving real contact areas and the contact temperature fields for an electric spark mechanical steel surface moving over a planed bronze surface. Changes of the rigid body displacement, as well as the average and maximum pressures are also presented during sliding.

The micro-contact or asperity contact behaviour for bodies having large nominal contact area and the macro-contact behaviour for bodies being in 'concentrated contact' are also compared. In the latter case an ideal smooth steel ball was slid over the previously mentioned bronze surface.     

双列角接触球轴承的游隙与接触角

通过对双列角接触球轴承轴向游隙、径向游隙、接触角关系的推导换算,分析影响接触角的各因素,采取合理可行的方法保证接触角。     

Modeling the edge contact effect of finite contact lines on subsurface stresses

Finite contact line conditions lead to subsurface stress distributions determined by the free boundaries. Combined with a correction procedure, Semi-Analytical Methods (SAMs) accurately include the free boundary effects, and represent a rapid alternative to the Finite Element Method (FEM) for contact pressure calculation. This paper extends the free boundary correction procedure to the evaluation of surface and subsurface stresses from SAMs. The investigation integrates a validation based on a two-level factorial comparison confronting the stress distributions established with the developed procedure to results obtained from FEM models. The comparison examines three dimensionless factors, and shows that the stress distributions are evaluated with a high level of precision. The model also offers evaluation more than 125 times faster than FEM simulations.     

Self-levitating sliding air contact

A linear sliding contact with self-lifting capability due to squeeze film action was theoretically investigated. It was found that this type of contact can operate under a wide range of frequency and load conditions. Calculations for frequency of up to 4000 Hz and the mass of up to 800 g indicate that a air film with thickness of a few microns can be created.It is the unsymmetrical pressure distribution in a time period or positive mean film force that makes squeeze air film contact able of self-levitation. The mean film force is equal to the weight supported. A physical rationale for the load-carrying capacity of a squeeze air film is that because of the viscous resistance around contact boundary, the air is repeatedly compressed and expanded in the central part of the contact, which results in a positive mean film force.