硬齿面齿轮齿根裂纹扩展特性与剩余寿命研究

为了研究齿根裂纹对硬齿面齿轮疲劳寿命的影响,以某渐开线硬齿面齿轮为研究对象,基于断裂力学方法和疲劳裂纹扩展理论,分析研究了齿轮齿根疲劳裂纹扩展机制;建立了考虑载荷大小、初始裂纹大小以及初始裂纹位置等因素影响的硬齿面齿轮齿根裂纹扩展剩余寿命分析模型,研究了齿根裂纹不同扩展阶段的应力强度因子演变规律与裂纹扩展机制;根据某渐开线硬齿面齿轮副弯曲疲劳试验数据,对所建计算模型进行了分析与验证,证明了模型的准确性。结果表明,与Ⅱ型裂纹、Ⅲ型裂纹相比,Ⅰ型裂纹应力强度因子最大,从齿面到裂纹深度方向,其值逐渐减小;随载荷、裂纹长度、裂纹宽度以及初始裂纹距齿宽中心位置的距离等因素的增大,裂纹扩展剩余寿命都随之减小。     

含双裂纹齿轮副轮齿裂纹扩展寿命分析

裂纹扩展是齿轮传动的主要故障,而且裂纹所处位置对裂纹扩展行为作用明显。为探讨齿轮副轮齿裂纹位置与裂纹扩展寿命的关系,提出几种相邻轮齿含分度圆裂纹和齿根裂纹的双裂纹齿轮副模型,基于ABAQUS建立齿轮副的三齿啮合有限元分析模型,分析不同载荷作用下分度圆裂纹和齿根裂纹尖端的主应力值和应力强度因子值;结合Pairs方程探讨分度圆裂纹扩展和齿根裂纹扩展寿命之间的关系。结果表明:齿轮副单齿啮合时的裂纹尖端应力比齿轮副双齿啮合时的裂纹尖端应力大,而且裂纹尖端的弯曲应力明显大于剪切应力;同一载荷同一裂纹深度时,齿根裂纹尖端的应力强度因子值大于分度圆裂纹尖端的应力强度因子值;相同加载时,含齿根裂纹齿轮的裂纹扩展寿命小于含分度圆裂纹齿轮的裂纹扩展寿命;裂纹扩展过程中,齿根裂纹深度和分度圆裂纹深度之比非定值,而且深度之比与载荷无关。     

直齿轮弯曲疲劳裂纹的扩展行为预测与分析

以渐开线圆柱齿轮为研究对象,在其齿根部存在初始裂纹的前提下,研究齿根疲劳裂纹扩展特性及其寿命;将齿轮啮合过程的动力学计算等效为多个啮合位置的静力分析,得到不同位置的应力强度因子;根据线弹性断裂力学,将裂纹扩展过程线性等效,以K判据分析裂纹是否发生扩展,根据Paris准则计算裂纹扩展量,采用最大周向应力准则确定裂纹扩展角度,得到整个计算周期的应力强度因子、疲劳裂纹扩展路径及疲劳寿命;采用高频试验台对齿轮进行疲劳试验,得到齿轮的疲劳扩展路径,与有限元计算结果进行对比验证;最后分别分析了初始裂纹的尺度、位置和载荷的不同对疲劳裂纹的扩展及疲劳寿命的影响。     

高速列车齿轮副裂纹扩展寿命研究

为研究高速列车齿轮的齿根裂纹扩展特性,在有限元软件ABAQUS中建立齿轮副模型并通过静力学分析,以确定裂纹萌生位置。基于线弹性断裂力学理论,在软件ABAQUS中建立含齿根初始裂纹的斜齿轮模型,计算裂纹前缘不同节点处的应力强度因子;研究齿根裂纹自动扩展的方式及轨迹,通过计算得到齿根裂纹的扩展寿命。在此研究的基础上,探讨了载荷大小等因素对裂纹扩展寿命及轨迹的影响规律。研究表明,裂纹扩展速率先慢后快,载荷对裂纹扩展寿命的影响十分明显。     

基于ABAQUS的圆柱直齿轮齿根裂纹扩展与寿命估计

以渐开线直齿轮为研究对象,通过齿轮应力分析确定轮齿裂纹易萌生位置,利用ABAQUS软件建立齿轮裂纹扩展有限元模型,获取齿根裂纹扩展路径,计算不同阶段裂纹尖端应力强度因子。通过多种曲线拟合方式的对比,选取指数函数建立的裂纹长度与裂纹尖端应力强度因子幅之间的函数关系。运用Paris公式构建裂纹扩展速率模型,实现含齿根裂纹齿轮的寿命估计。     

能量法计算齿根具有裂纹的齿轮啮合刚度

计算齿根具有裂纹的齿轮啮合刚度是求解含裂纹的齿轮传动系统动力学问题的基础.提出一种计及齿根裂纹表面自由能的计算齿轮啮合刚度的能量方法,该法将法向力作用下裂纹齿轮的弹性势能视为无裂纹齿轮的弹性势能与裂纹产生过程中释放的裂纹表面自由能之和.裂纹表面自由能通过裂纹应力强度因子与能量释放率之间的关系获得,齿根裂纹应力强度因子用权函数法求解.计算结果表明:齿根裂纹对齿轮啮合刚度影响很大;随着裂纹长度增加,裂纹齿轮啮合刚度减小,其求解结果与ANSYS软件计算结果一致.     

某地铁齿轮箱齿轮弯曲疲劳裂纹分析

结合动力学仿真和扩展有限单元法(XFEM),对某城轨车辆齿轮箱齿轮进行裂纹扩展分析。通过动力学分析,确定扩展有限元模型初始裂纹的位置及载荷加载位置;建立扩展有限元模型,对计算结果进行分析,总结齿轮齿根裂纹扩展规律。结果表明,齿根处最大弯曲应力位置不随齿轮啮合过程而改变,裂纹起裂位置应在此位置附近;裂纹尖端应力值在量化一裂纹长度到达0. 61前低速率稳定增加,0. 61后裂纹进入瞬断区,裂纹尖端应力值变化明显;结合有限元动力学及扩展有限元分析发现,裂纹扩展初期属于Ⅰ型裂纹,在裂纹扩展的中后期属于Ⅰ、Ⅱ混合型裂纹;不同加载位置结果显示,扩展初期裂纹偏转角度随着加载位置的下移而减小,扩展后期裂纹整体沿着齿厚方向进行扩展。     

齿轮齿根疲劳裂纹扩展特性和剩余寿命研究

以某渐开线圆柱齿轮为对象,基于有限元法对其齿根疲劳裂纹的扩展进行了数值模拟。首先通过对一对健康齿的啮合分析确定其啮合过程中齿根部位弯曲应力最大点,并将其作为裂纹起始点。据此将其分割为裂纹块和非裂纹块。在裂纹块预制初始裂纹并重生网格,裂纹块网格采用等参奇异单元,裂纹块和非裂纹块之间通过多点约束连接不匹配节点。利用有限元分析得到裂纹扩展过程中应力强度因子变化情况,并根据最大周向应力准则计算疲劳裂纹扩展角度,模拟齿根裂纹扩展轨迹,依据Paris公式对齿根疲劳裂纹剩余寿命进行预估。分析了载荷大小和初始裂纹长度对剩余寿命的影响。     

高速动车组齿轮副齿根裂纹应力强度因子数值计算

为研究高速动车组齿轮的齿根裂纹的应力强度因子,结合有限元法和作图法确定了裂纹萌生位置。基于线弹性断裂力学理论,以Abaqus为工具,研究了齿根初始裂纹前缘不同节点处的应力强度因子大小及变化规律,通过对比,确定Ⅰ型应力强度因子在裂纹扩展中占主导地位;在此研究的基础上,探讨了Ⅰ型应力强度因子随载荷、裂纹半径、裂纹形状等因素的变化规律。结果表明,载荷对Ⅰ型应力强度因子大小影响最为显著且呈线性关系;裂纹形状对Ⅰ型应力强度因子在裂纹前缘的分布规律影响十分明显。     

基于Abaqus的直齿圆柱齿轮疲劳裂纹应力强度因子研究

应力强度因子是研究断裂问题的重要参量,可以度量和控制裂纹的发生发展,对研究裂纹的疲劳损伤及预估寿命具有重要意义。为了研究直齿圆柱齿轮三维裂纹应力强度因子的变化规律,利用Abaqus建立了含半椭圆形初始裂纹的三维有限元模型,计算了半椭圆形裂纹前缘应力强度因子,分析了裂纹大小、形状以及载荷变化对裂纹前缘应力强度因子的影响规律。结果表明,齿根裂纹在扩展过程中主要表现为张开型裂纹;随着载荷的增大,应力强度因子K_I不断增大,但其分布规律保持不变;在载荷不变的情况下,K_I随着裂纹尺寸的增大而增大;在建立的半椭圆形裂纹中,随着长轴的增加,裂纹前缘上的K_I波动逐渐变小。     

Application of similarity theory to load capacity of gearboxes

This study suggests the theoretical methodology to construct a small-sized similarity model having the same load capacity as a large gearbox. The prototype gearbox was a 2-MW wind turbine gearbox consisting of two planetary gear stages and one parallel shaft gear stage, and the specifications of its 1/4 scale similarity model were determined by applying similarity theory. The constructed similarity model was validated by comparing load capacity parameters with those of the prototype gearbox using analysis tool. The validation results showed that the nominal tooth root and contact stresses of the similarity model and prototype gearbox were identical, whereas the tooth root and contact stresses satisfied the similarity condition within 2% difference. Furthermore, most factors that influenced the tooth root and pitting stress limits were identical. Thus, information related to load capacity, one of the major design evaluation criteria for gears, of large-size gearbox can be replicated by its similarity model. Although this is a theoretical methodology and still has many difficulties to apply to practical situations, these results have opened up the possibility of applying similarity theory to load capacity of gearboxes. Because the load capacity is the primary cause of commercial gearbox failure, this result also shows the possibility of life similarity in the gearbox application, although some further study is needed.     

基于解析有限元的齿根裂纹时变啮合刚度计算方法

当齿轮发生故障时,时变啮合刚度的变化能够反映齿轮故障特征大小。因此,时变啮合刚度在齿轮传动过程中是一个重要的动力学参数。提出一种新的齿根裂纹啮合刚度计算方法,即解析有限元法（Analytical-finite element method,A-FM）。考虑到齿轮发生故障时,啮合刚度解析模型计算精度较低,将应力强度因子引入裂纹齿轮的啮合刚度计算过程。首先定义应力强度因子与啮合刚度之间的关系,通过建立齿轮接触模型计算裂纹尖端附近的应力强度因子,然后将计算结果替代解析模型中故障刚度部分。由于应力强度因子能够敏感地识别齿根裂纹的局部微小变化,故该方法相比于解析法具有更高的计算精度,相比于有限元法具备更快的计算效率。同时,建立6自由度动力学模型,通过对其振动响应进行分析,仿真结果验证了所提方法的可行性。     

Finite element structural analysis of wind turbine gearbox considering tooth contact of internal gear system

Gearbox for wind turbine must be designed to have the sufficient structural strength to sustain the extreme torque and forces transferred from rotor blades. Traditionally, the structural analysis of gearbox has been made using the simplified FEM models in which the contacts between gear teeth are replaced with the equivalent forces acting on the gear shafts, because the consideration of the detailed internal gear transmission system requires a huge number of degrees of freedom. But, the traditional method can neither accurately reflect the gear transmission forces, nor is it preferable for the dynamic analysis. In order to solve these problems, a structural analysis method considering the tooth contact of internal gear system is introduced in this paper. The actual tooth contact between a pair of gears is modeled with spring elements and the spring constants are determined through the stiffness analysis of gear teeth. The current analysis technique is justified through the comparison with the simplified gear system model and applied to the structural analysis of a 2-stage differentialtype gearbox for wind turbine.     

太重Ⅲ型风力发电增速齿轮箱有限元分析

风电增速齿轮箱在兆瓦级风力发电机中属易过载和损坏率较高的部件,对其性能进行分析,预测其性能并进行优化是十分必要的.本文中利用ANSYS软件对太重Ⅲ型两级行星一级平行轴1.5MW风力发电增速齿轮箱进行有限元分析,对太重Ⅲ型风力发电增速齿轮箱各级齿轮强度进行校核,得到了各级齿轮副的齿廓和齿向修形数据;对行星轮系载荷均载特性、主箱体组件、行星架、花键联接等进行分析,得到了风力发电增速齿轮箱各级零部件强度和刚度等相关数据,为风电增速齿轮箱的可靠性评估及优化设计奠定基础.     

Effects of gear modifications on the dynamic characteristics of wind turbine gearbox considering elastic support of the gearbox

The reliability and service life of wind turbines are directly influenced by the dynamic performance of the gearbox under the time-varying wind loads. The control of vibration behavior is essential for the achievement of a 20-year service life. We developed a rigid-flexible coupled dynamic model for a wind turbine gearbox. The planet carrier, the housing, and the bedplate are modelled as flexibilities while other components are assumed as rigid bodies. The actual three points elastic supporting are considered and a strip based mesh model is used to represent the engagement of the gear pairs. The effects of gear tooth modifications on the dynamics were investigated. Finally, we conducted a dynamic test for the wind turbine gearbox in the wind field. Results showed that the contact characteristics of gear pairs were improved significantly; the peak-to-peak value of transmission error of each gear pair was reduced; the amplitudes of the vibration acceleration and the structural noise of the wind turbine gearbox were lowered after suitable tooth modification.     

Research on load sharing performance of wind turbine gearbox involving multiple-errors and tooth crack

The current research on wind turbine gearboxes (WTG) considering multiple-factors influence mainly focuses on dynamic response. However, load sharing performance (LSP) is also extremely important for gear transmission system reliability. In this paper, considering the comprehensive effects of manufacturing errors, assembly errors, clearance floating between stages, mesh stiffness and time-varying load, a coupled translation-torsion dynamic model for WTG was developed to study the LSP. Based on the amplitude variations of time-varying mesh stiffness caused by tooth crack, an approach is provided to introduce the tooth crack into the dynamic model. The results indicate the LSP is mostly sensitive to multiple-errors and severe tooth crack, followed by the time-varying load. The LSP of a system is periodically affected by tooth crack, and the fluctuation ranges increase with the crack growth. Furthermore, the crack of sun gear has greater influence on LSP than that of planet and ring gear.

     

风电行星齿轮系统变载荷激励动力学模型及其响应特性

针对风电行星齿轮系统变载变速的运行特点,通过分析系统构件为刚体和弹性体时的受力情况,应用运动合成原理,提出了变载荷激励下行星齿轮系统动力学模型的建立方法,并推导出系统的运动微分方程。在此基础上,分析了行星齿轮系统的内外部激励因素及其对系统动载荷和动载系数的影响机理。计算并分析了某MW级风电行星齿轮系统的动态响应,结果表明：系统的时变啮合刚度和时变轴承刚度主要影响响应频率的数值大小和系统的振动能量;外部变载荷使响应频率中存在明显的低频成分,并影响各阶振动间的能量分配;齿轮啮合力的动载系数主要受到外部变载荷的影响,而轴承力的动载系数同时受到系统内部激励和外部激励的影响。研究结果为风电齿轮箱的疲劳寿命分析和动态优化设计奠定了基础。     

圆柱齿轮的齿根应力及其影响因素分析

利用二维有限元分析方法，考虑齿轮变位及刀具圆角等因素，建立了参数化轮齿通用二维有限元分析模型及其前后处理程序。对圆柱齿轮的齿根应力进行了大量的计算和详细的分析，并且与按国标渐开线圆柱齿轮承载能力计算方法（ＧＢ３４８０－８３）计算的结果进行了对比。分析了外载荷作用点的变化及刀具圆角的变化对轮齿齿根应力的影响。