考虑齿圈柔性的风电行星轮系动态啮合特性研究

针对集中参数法难以考虑齿圈柔性而有限元法计算量大的问题,以风电行星轮系为研究对象在集中参数/有限元混合法基础上提出一种揭示内啮合齿轮副延长啮合现象的分析方法。首先采用集中参数法建立风电行星轮系的动力学模型,并求解获得动态啮合力;随后,运用有限元法建立行星轮系内啮合齿轮副的有限元模型,并开展静态接触分析从而获得内啮合齿轮副各啮合位置发生多齿啮合时的变形阈值;最后,将集中参数模型获得的动态啮合力施加在内齿圈有限元模型上计算出内齿圈的动态响应,并结合发生多齿啮合时的变形阈值,从而揭示在不同负载和支撑数量下内齿圈上多齿啮合的分布区域,获得接触应力和齿根应力,分析啮合齿对数量改变前后对应力的影响。结果表明：考虑齿轮柔性后,内啮合齿轮副会出现除理论啮合齿对外其他齿对相接触的现象;随着负载扭矩的增大,内齿圈上三齿啮合首先发生在支撑两侧,随后三齿啮合发生区域不断增加;当行星轮与内齿圈间的啮合由理论两齿啮合变为三齿啮合时,其齿面接触应力和齿根应力小于其在相同时刻只计入两齿啮合时的应力值。     

发动机主轴承座结构强度分析研究

建立了包括缸体、框架、轴瓦、曲轴及连接螺栓的发动机主轴承座网格模型,通过指定不同的接触区域、接触条件、载荷、约束边界条件及多点约束,分别建立了螺栓预紧、轴瓦过盈、曲轴动压力及热负荷四种工况主轴承座强度分析有限元模型。采用二阶修正单元并通过接触主从面上单元的对应性来保证计算精度和收敛性,采用小滑移接触算法计算出各工况下主轴承座的应力和变形情况,根据计算结果,对主轴承座的强度、变形、滑移表面的滑动以及轴瓦背面的压力分布进行了评价,对主轴承座结构提出了改进意见,改进方案满足结构设计要求。     

重载齿轮的最佳轮齿修形

本文给出了计算多对齿同时啮合轮齿接触线载荷分布的方法．并根据轮齿的啮合状态确定轮齿的最佳修形参数。利用作者编制的计算机程序研究了最佳轮齿修形参数对载荷分布系数的影响．     

齿轮和曲轴配合轴段间过盈联结的有限元分析

通过建立以结构强度限制确定的过盈量为上限和以承受最大扭矩不打滑原则确定的过盈配合量为下限的有限元模型，对齿轮和曲轴配合轴段间的过盈联结进行分析研究，从中找出影响过盈联结接触状态的主要因素，以及过盈量与各影响因素之间的关系。     

某低速柴油机曲轴齿轮过盈装配分析

根据某低速柴油机曲轴齿轮装配的实际工况,建立齿轮及过盈轴的三维有限元模型,对曲轴齿轮过盈装配进行分析。研究了不同装配过盈量下齿轮的应力分布情况,得出齿轮装配过盈量对齿轮受力影响的规律;并通过与增加凹槽模型的计算结果的对比,得到改善齿轮应力分布的方法。     

Parabolic Heat Conduction Specialized Applications Involving Imperfect Contact Surfaces: Local Discontinuous Galerkin Finite Element Method—Part 2

Parabolic heat conduction specialized applications involving imperfect thermal contact surfaces are analyzed via the Local Discontinuous Galerkin (LDG) finite element method. In this paper, we describe the advantages of the LDG finite element formulation over the traditional continuous Galerkin (CG) finite element method for modeling imperfect thermal contact between surfaces. To-date, mostly interface/gap elements have been primarily used to model the imperfect contact between two surfaces to solve thermal contact resistance problems. The LDG method eliminates the use of such interface/gap elements and provides a higher degree of accuracy. Several illustrative 2-D applications highlight the effectiveness of the present LDG finite element formulations for this class of problems.     

汽轮机套装叶轮接触问题的三维有限元分析

运用有限元分析软件SAMCEF,对某型号汽轮机套装叶轮与轴的过盈配合问题作三维模型计算分析,计算中采用接触单元处理过盈配合边界,得到了转子位移和应力分布,并对原来的过盈量设计进行了优化改进,在保证安全性的前提下减小了轮盘的接触应力。     

汽车紧急制动时钢板弹簧有限元分析

汽车紧急制动时,前钢板弹簧承受载荷最大,在最大载荷的情况下,前钢板弹簧出现最大应力。本文在分析软件中建立模型,并计算出在紧急制动的情况下前钢板弹簧两端受到的最大载荷,通过建立接触对分析出在此载荷下的最大应力。将有限元分析结果与理论公式计算结果相对比,为钢板弹簧提供改进依据和建议。     

Design of packing cup interference fit value of hypercompressors for low density polyethylene production

The hypercompressor is one of the core facilities in low density polyethylene production, with a discharge pressure of approximately 300 MPa. A packing cup is the basic unit of cylinder packing, assembled by the interference fit between an inner cup and an outer cup. Because the shrink-fitting prestresses the packing cup, serious design is needed to gain a favorable stress state, for example, a tri-axial compressive stress state. The traditional method of designing the interference fit value for packing cups depends on the shrink-fit theory for thick-walled cylinder subject to internal and external pressure. According to the traditional method, critical points are at the inner radii of the inner and external cup. In this study, the finite element method (FEM) has been implemented to determine a more accurate stress level of packing cups. Different critical points have been found at the edge of lapped sealing surfaces between two adjacent packing cups. The maximum Von Mises equivalent stress in a packing cup increases after a decline with the rise of the interference fit value. The maximum equivalent stress initially occurs at the bore of the inner cup, then at the edge of lapped mating surfaces, and finally at the bore of the outer cup, as the interference radius increases. The traditional method neglects the influence of axial preloading on the interference mating pressure. As a result, it predicts a lower equivalent stress at the bore of the external cup. A higher interference fit value accepted by the traditional method may not be feasible as it might already make packing cups yield at the edge of mating surfaces or the bore of the external cup. Along with fatigue analysis, the feasible range of interference fit value has been modified by utilizing FEM. The modified range tends to be narrower and safer than the one derived from the traditional method, after getting rid of shrink-fit values that could result in yielding in a real packing cup.     

用间隙元求解枞树形叶根轮缘的接触问题

就汽轮机枞树形叶根齿面与轮缘的接触状态进行了研究.通过在接触面上施加间隙元来解决叶根轮缘的接触问题,计算结果表明每一对叶根齿面的承载比直接取决于叶根齿与轮缘的初始接触情况,而每一对齿的内弧齿面的承载比与背弧齿面的承载比的变化则还与叶型相对叶根的位置有关.     

基于静力子结构技术对轮轴接触下车轮的强度分析

利用有限元分析中的静力子结构技术,在考虑轮轴过盈配合接触非线性情况下,利用有限计算资源,应用有限元方法快速完成车轮的强度分析。计算结果表明,采用此方法可以更加真实而准确地反映车轮在多载荷工况下的应力分布。     

Studies on gasketed flange joints under bending with anisotropic Hill plasticity model for gasket

The behavior of a gasketed flange joint under bending loads has been studied by three dimensional finite element analysis (FEA) and experiments. The in-plane and bending stiffness of spiral wound gaskets are considered using anisotropic Hill plasticity material model. The variation in bolt axial force of joints under bending load predicted by the finite element analysis compares well with the experimental results. The contact stress distribution obtained have significant variation in the pattern from the previous material models and consistent with the results of Bouzid [1] regarding flange rotation.     

Moment resistance of steel pipes subjected to combined loads

The first part of this paper provides a review of recent investigations on steel pipes subjected to combined loads. Attention is given to studies involving both numerical and experimental components aimed at quantifying the modified moment resistance of pipes subjected to internal pressure and axial force. The comparison of experimental and finite element results indicate that the nonlinear shell finite element analysis is a reliable tool for predicting moment capacities of pipes. The second part of the paper reports two additional full-scale tests recently conducted at the University of Ottawa aimed at expanding the existing experimental database to pipes subjected to more complex load combinations involving twisting moment and shear (in addition to axial force, internal pressure, and bending). The finite element analysis for both tests is shown to provide excellent predictions of pipe moment capacity. The third part of the paper is a systematic parametric study based on the FEA model verified in previous and present investigations, aimed to assess the ability of pipe sections to attain their modified elastic and/or plastic moment resistance as predicted by analytically derived interaction equations. The parameters investigated are the applied torsion, internal pressure, axial force, and the diameter-to-thickness ratio of the pipe.     

端齿盘在高速转向架空心轴传动中的应用

介绍了端齿联接机构在六轴交流高速转向架空心轴传动中的应用情况,对其主要参数选择原则、最小预紧力的确定、齿形强度计算和齿副接触应力等进行了阐述。指出梯形收缩齿形是端齿盘的首选齿形。建立了端齿盘的三维有限元模型。通过对接触应力的变化曲线进行分析,得出内齿尖处的接触应力最大的结论。     

发动机曲轴齿轮过盈接触有限元分析研究

结合某发动机曲轴齿轮过盈装配的实际参数,建立了三维实体模型,采用有限元分析方法,对曲轴齿轮过盈装配进行计算分析,探讨了曲轴齿轮过盈装配时最大主应力、等效应力、接触压力等随过盈量的变化关系,为后续的曲轴齿轮过盈装配设计分析提供参考依据。     

大功率柴油机曲轴飞轮圆锥过盈联结设计方法

针对某型柴油机螺栓端面压紧联结方式在发动机功率进一步强化时发生了部分螺栓松脱、甚至螺栓和定位销被剪断的情况,对该联结方式做了改进,将原先的端面压紧联结改为圆锥过盈联结。通过经典弹性力学方法计算出合理的过盈量以保证联结的可靠性;同时采用有限元仿真软件ABAQUS得到了连接面接触应力的分布情况,验证了过盈量的合理性;分析了危险区域的应力集中现象,提出了降低应力集中的优化方案。     

汽轮机末级钛合金长叶片围带接触力分析

大型汽轮机末级钛合金叶片的自锁阻尼围带在运行中会发生接触面磨损的现象,减小了接触面之间的接触紧力,导致叶栅整体性和刚性削弱,对叶栅的阻尼减振效应产生了负面影响.为更好地分析和了解这一问题,建立了末级长叶片整圈阻尼围带的接触力分析模型,可对不同结构、不同磨损状态的长叶片围带接触紧力进行定量分析.用有限元方法对该模型进行了...     

General static load‐carrying capacity of four‐contact‐point slewing bearings for wind turbine generator actuation systems

Four‐contact‐point slewing bearings are widely used in wind turbine generators (WTGs) to adjust the orientation of the blades and the nacelle to fully exploit wind resources. These bearings must withstand static and fatigue loads; however, at the first stages of the design process, the bearings are commonly selected by considering only static loads. This paper presents a further step of a previous theoretical work published by the authors in the field of the static load‐carrying capacity of four‐contact‐point slewing bearings under axial, radial and tilting‐moment loads. In that work, a generalization of the works by Sjoväll and Rumbarger was presented, providing an acceptance surface of the bearing in the load space. The contact angle of the balls was assumed to be load independent. The present work improves that development by considering the influence of the variability of the contact angle with the applied load, and as a result, the acceptance surface has been redefined. By comparing the results with those of the finite element model published by the authors, it is proven that the new model presented in this work is more realistic than the previous one. Thus, it is believed that this methodology can be easily applied for the initial selection of blade and yaw bearings in WTGs. Copyright © 2012 John Wiley & Sons, Ltd.     

1.5MW风力发电齿轮箱箱体的有限元分析

建立了一套针对该类箱体的有限单元计算方法,获得了在重力载荷、轴承载荷、内齿圈轮齿啃合载荷单独作用下,齿轮箱体的应力分布规律和位移变化情况.该方法充分考虑了外界支承,将轴承径向力等效成余弦分布压力,箱体变形与刚度通过提取轴承座中截面位移曲线来观察.分析结果表明:重力引起的应力可以忽略;箱体支承没计应考虑内齿圈啮合引起的旋转效应;采用侧面支承的增速齿轮箱的输出侧轴承凸缘附近应采取局部补强措施,以抵抗弯曲变形;轴承载荷的大小和方向都对箱体的应力分布有重要影响.     

Quenching residual stresses in 7060 aluminium alloy gas cylinder necks

A destructive technique under development to determine residual stresses in thick-walled pressure vessels has been employed to determine quenching residual stresses in 7060 aluminium alloy gas cylinder necks. The gas cylinders were supplied with interference fit collars attached to the apex of the gas cylinder neck. The effect the elastic interference fit stresses have on the quenching residual stresses in the gas cylinder neck was also investigated. Maximum tensile circumferential quenching residual stresses were detected in the gas cylinder neck below the threaded region of the bore. The magnitude of the maximum tensile circumferential quenching residual stress was in the order of half the yield strength of the aluminium alloy. The interference fit stresses only altered the quenching residual stresses in the immediate vicinity of the threaded bore. It was concluded that the interference fit collar provided no significant effect on the magnitude of the maximum tensile circumferential quenching residual stress in the gas cylinder neck.