涡轮盘疲劳裂纹故障分析

火箭发动机涡轮盘工作在高温、高转速及恶劣的振动环境中，并承受着较大气动力作用，是发动机的关键组合件，涡轮盘的失效破坏将严重影响发动机的正常工作，甚至带来灾难性的后果。针对某火箭发动机涡轮盘在热试车中出现的裂纹故障，进行全面的分析，准确定位故障类型，以试验和计算分析给出合理的故障原因，重点是在疲劳分析方面所做的工作，包括振动模拟试验、疲劳强度计算，并根据疲劳强度分析结果提出改进方案。结果表明原结构圆角处应力集中明显，静态应力值水平高，在发生耦合振动后，涡轮盘出现疲劳裂纹，最终发生低周大应力破坏。试验和计算表明，采用改进方案可有效降低尺圆角处的应力集中，明显提高疲劳强度。对采用改进方案后的涡轮盘发动机进行了多次热试车，证实改进后的结构未发生耦合振动，未发现疲劳裂纹，改进方案是可行的。     

基于气热固耦合的涡轮模态分析

主要研究了气热固耦合场对涡轮模态参数的影响.采用基于k-ε湍流模型理论建立了涡轮的流场模型,进行网格划分和边界条件的加载.通过气热固耦合分析计算获得了流场内部温度和压力的分布,把气动力及温度载荷映射到涡轮结构上,并在此基础上进行了涡轮模态的计算.计算结果表明,气热固耦合场主要影响涡轮结构的模态固有频率,对模态振型的影响较小.     

基于ANSYS的故障涡轮振动性能分析

利用UG软件,模拟某型号航空发动机涡轮叶片在工作中出现的变形故障,对涡轮盘及叶片进行整体建模,然后利用有限元分析软件ANSYS对涡轮盘和叶片的模型进行分析,得到其前几阶模态的振动特性。     

基于ANSYS的航空发动机压气机盘模态分析

运用ANSYS软件对某航空涡轮发动机压气机盘进行了模态分析,得到了压气机盘的前10阶固有频率和振型,确定了压气机盘的振动特性,为压气机盘的结构优化和动力修改提供了参考依据.     

氢燃料电池空压机转速轴模态分析

转速轴是空压机的关键部件,用于联接涡轮盘、轴承座等零件.由于转速轴在高转速、高温度、变负荷条件下工作,工作条件恶劣,因此转速轴工作可靠与否直接影响空压机的寿命和安全.转速轴不仅传递扭矩还承受转子自身的重力、不平衡力等影响.将空压机转速轴模型分为携带涡轮和不携带涡轮两种结构分别进行自由模态分析.并将两种分析结果进行对比,为某空压机整机振动提供试验数据并进行详细分析,为后续相关研究奠定基础.     

涡轮增压器叶轮流固耦合模态分析

为了研究流固耦合场对涡轮增压器叶轮模态参数的影响,采用基于湍流模型理论建立了涡轮增压器压气机的流场模型.并进行了流场网格划分和边界条件的加载.通过计算获得了流场内部的流速、压力分布,把流场压力分布加载到叶轮固体表面上,并计算考虑流固耦合场的叶轮模态.计算结果表明,流固耦合场主要影响叶轮结构的模态固有频率,对模态振型的影响较小.     

航空发动机涡轮盘热-机械载荷耦合响应分析研究

发动机热端部件在工作过程中受热——机械载荷的耦合作用，其结构强度分析具有一定的难度，尤其是其热边界条件较难确定。这里针对发动机涡轮盘的换热边界条件进行了分析和简化，计算了涡轮盘的换热系数，并把获得的换热系数应用于涡轮盘的有限元应力分析。采用瞬态分析方法和热——机械耦合算法，计算了该盘在热——机械载荷耦合作用下的响应。     

航空发动机热态下不均匀叶尖间隙的热固耦合分析

涡轮叶尖间隙对发动机性能有很大影响。孔探图像显示高压涡轮叶片前缘与机匣衬套之间摩擦严重,且发动机排气温度裕度持续偏低。为了精确获得航空发动机在工作环境最恶劣工况下的叶尖间隙值,对涡轮盘与叶片进行热固耦合有限元分析。采用SolidWorks 2014建立高压涡轮盘与高压涡轮叶片模型,借助ANSYS Workbench获取工作状态下涡轮盘与叶片的温度场分布与结构变形量,得到高压涡轮叶尖前缘与后缘的实际间隙值,为改进高压涡轮单元体维修方案,提高发动机性能提供合理建议。     

弹性支承高速喷漆涡轮系统动态特性研究

将一类高速喷漆涡轮系统机架与转子间精密滚动球轴承用约束矩阵来描述,进而将涡轮系统考虑成柔性、耦合双弹性梁,运用模态综合法建立其动力学模型.考虑转子前后两端喷杯及底盘偏心,建立双面离心力作用下的转子子系统强迫力模型.据此,研究了耦合系统固有频率、主模态等动特性,分析了转子末端动态响应.     

地铁齿轮箱振动测点位置分析

以某地铁现役齿轮箱三维模型为例,通过有限元仿真的方法对其进行模态分析,寻找箱体结构的刚度薄弱部位,并以此初步作为振动测点位置,并导出含有模态信息的柔性箱体,构造传动系统为刚体的刚柔耦合模型,进行动力学仿真,通过三维模型的修改制造含有断齿故障齿轮箱与正常状态齿轮箱,对比各测点有无故障下的振动数据,选用合适振动测量点.通过...     

Modal identification of spindle-tool unit in high-speed machining

The accurate knowledge of high-speed motorised spindle dynamic behaviour during machining is important in order to ensure the reliability of machine tools in service and the quality of machined parts. More specifically, the prediction of stable cutting regions, which is a critical requirement for high-speed milling operations, requires the accurate estimation of tool/holder/spindle set dynamic modal parameters. These estimations are generally obtained through Frequency Response Function (FRF) measurements of the non-rotating spindle. However, significant changes in modal parameters are expected to occur during operation, due to high-speed spindle rotation.The spindle's modal variations are highlighted through an integrated finite element model of the dynamic high-speed spindle-bearing system, taking into account rotor dynamics effects. The dependency of dynamic behaviour on speed range is then investigated and determined with accuracy. The objective of the proposed paper is to validate these numerical results through an experiment-based approach. Hence, an experimental setup is elaborated to measure rotating tool vibration during the machining operation in order to determine the spindle's modal frequency variation with respect to spindle speed in an industrial environment. The identification of natural frequencies of the spindle under rotating conditions is challenging, due to the low number of sensors and the presence of many harmonics in the measured signals. In order to overcome these issues and to extract the characteristics of the system, the spindle modes are determined through a 3-step procedure. First, spindle modes are highlighted using the Frequency Domain Decomposition (FDD) technique, with a new formulation at the considered rotating speed. These extracted modes are then analysed through the value of their respective damping ratios in order to separate the harmonics component from structural spindle natural frequencies. Finally, the stochastic properties of the modes are also investigated by considering the probability density of the retained modes. Results show a good correlation between numerical and experiment-based identified frequencies. The identified spindle-tool modal properties during machining allow the numerical model to be considered as representative of the real dynamic properties of the system.     

Shape optimization of rotating cantilever beams considering their varied modal characteristics

The modal characteristics of rotating structures vary with the rotating speed. The material and the geometric properties of the structures as well as the rotating speed influence the variations of their modal characteristics. Very often, the modal characteristics of rotating structures need to be specified at some rotating speeds to meet their design requirements. In this paper, rotating cantilever beam is chosen as a design target structure. Optimization problems are formulated and solved to find the optimal shapes of rotating beams with rectangular cross section.     

基于ANSYS的复合材料飞轮系统模态分析

储能飞轮系统在工程中应用广泛,由于飞轮系统转速较高,因此对飞轮系统进行模态分析是非常必要的。利用有限元分析软件ANSYS对复合材料飞轮系统进行模态分析,得到了飞轮的固有频率与模态振型,为飞轮系统的结构设计与优化以及振动特性研究提供了有效的依据。     

高速龙门加工中心GMC3000动态特性的有限元分析

在大型高架桥式高速数控加工中心GMC3000的设计中,利用有限元分析方法对GMC3000各个主要部件及整机做静变形计算、模态分析和动力响应分析,找出影响整机动态性能的薄弱环节并提出结构设计修改方向,从而使机床具有更好的静态、动态特性.     

基于ANSYS的超细高速冲击磨结构刚度优化设计

为快速获得不同结构参数的模型,利用ANSYS的APDL语言对超细高速机械冲击磨的机架进行参数化建模,利用模态分析找到机架中影响轴承座支承刚度的薄弱环节并做相应优化设计,最后利用谐响应分析技术验证了机架结构刚度提高的有效性。分析结果表明,在保证结构刚度较大幅提高的条件下,优化后的机架结构重量可得到不同程度的减轻,这对在机械设计过程中从设计上保证高速机械的轴承工作条件、减少材料消耗以及降低机器的生产成本有一定的指导意义。     

非线性接触下直线电机悬架作动器模态分析

针对直线电机式悬架作动器模态分析误差较大的问题,提出影响分析结果的非线性因素--法向接触刚度,通过优化接触刚度因子实现对作动器模态的精确分析。利用ANSYS Workbench对其进行了有限元仿真,研究了作动器各部件在不同阶数下的固有频率变化值,获得了作动器固有频率与接触刚度因子的相互影响关系,得到了作动器在最优接触刚度因子下的固有频率与振型图,分析了运行速度与模态频率之间的关系曲线。结果表明:初级铁心对样机结构整体频率影响最大;接触刚度因子等于0.6时,固有频率最优以及形变位移值最小;在第2阶频率下,作动器整体变形量较小,最大变形集中在次级铁心两端量;模态频率随运行速度的增大而增大。最后对悬架作动器样机进行了模态试验,仿真值与试验值较好吻合,验证了分析结果的正确性。     

某轿车前副车架模态分析与优化

以“某车型前副车架”为研究对象,利用Hyper works 11.0软件对该副车架结构进行了自由模态分析、全约束模态分析和半刚性约束模态分析,针对分析结果与实际整车下的模态值比较,提出了较为合理的边界约束条件下的模态分析方法,以更加接近副车架在整车下的实际状态值。同时由于该副车架整车实测模态值偏低,与发动机常用转速下产生共振,实车在加速过程中当发动机转速在3000~4000 r/min之间,整车存在轰鸣声,对此问题进行了分析并进行了优化。结果表明:该优化方案解决了轰鸣问题,且节约了成本。     

Effectiveness of Impact-Synchronous Time Averaging in determination of dynamic characteristics of a rotor dynamic system

Dynamic characteristics of rotor dynamic systems, namely natural frequencies, damping and mode shape, vary with rotation speed due to gyroscopic effect. To consider such effect, modal analysis is required to be performed while in operation. However, to generate the frequency response functions, it is not viable to perform data reduction in frequency domain as noise and harmonics excited by rotating forces dominate the spectrum and hide the natural frequencies. The full set of dynamic characteristics is difficult to obtain. A novel technique, referred to as Impact-Synchronous Time Averaging (ISTA), is developed in this study to screen out the noise and harmonics.     

Mode localization of a component cooling water heat exchanger

In a nuclear power plant, the tubes of a component cooling water heat exchanger are frequently affected by cold and hot fluid shock waves. Thus, tubes are often found to be worn out. This wear may alter the dynamics of the tubes and introduce mode localization in the heat exchanger. This paper examines mode localization in a component cooling water heat exchanger. A heat exchanger, consisting of periodic cooling tubes is used to simulate as a coupled periodic structure system. Each tube is coupled to the adjacent one through the water, and so the system is weakly coupled. The Galerkin method is employed herein to derive the mode localization equations off the mistuned system, with reference to the fluid effect. Numerical results reveal that the wear may introduce mode localization into a mistuned heat exchanger with fluid.     

基于Gauss滤波和Hilbert变换的模态参数辨识算法

通过Gauss滤波和Hilbert变换相结合的方法,对柔性结构的模态参数进行了辨识。仿真计算结果表明,该方法可以十分有效地辨识出结构的相近模态参数,并具有较好的抗噪声性能。应用该方法,完成了空间柔性桁架结构的模态参数辨识,得到了比传统处理方法更接近理论计算结果的结构模态参数,能够有效地避免柔性结构参数辨识中的漏频现象,并具有高的辨识精度。