步兵战车车体结构有限元模型修正

针对某型步兵战车整车刚柔耦合发射动力学中柔性车体有限元模型精度低的问题,基于模态试验数据,应用支持向量机响应面模型修正理论对车体结构有限元模型进行了修正。应用ANSYS有限元分析软件对车体结构进行模态分析,提取前6阶模态的固有频率和振型。为验证模型,设计了模态试验方案,实测了车体结构的模态信息。基于有限元模型数据与实测数据的相对误差,采用支持向量机响应面模型修正方法对车体结构弹性模量和密度进行修正。模型确认结果和动力学模型应用结果表明,修正后的车体有限元模型精度有了大幅度提高,能更加真实地反映车体的结构特征,为射击精度分析提供了准确的模型基础。     

Modal testing of nanocomposite materials through an optimization algorithm

An efficient identification method for modal testing of viscoelastic composite materials is demonstrated in this paper, through the analytical–experimental transfer function method. The procedure for the identification of analytical–experimental transfer functions is carried out using a genetic algorithm (GA) by minimizing the difference between the measured response from tests and the calculated response, which is a function of the modal parameters. The analytical transfer functions provide a sub-structuring process to identify modes, as a function of damped natural frequencies and loss factors of a complex structure and it is insensitive to experimental noise as well as the modal coupling effect. The proposed method is verified with the calculation of the elastic modulus and modal properties of a cantilever steel beam with the FEM and compared with the identification results of the proposed algorithm. The effectiveness of the proposed method is demonstrated by investigating the static and dynamic behavior of epoxy cantilever beam specimens reinforced with silica nanoparticles. Analytical–experimental transfer functions accurately identified the viscoelastic and dynamic response of the studied specimens, while the results indicated that the inclusion of nanosilica particles increased the stiffness of the epoxy network and the damping response of the reinforced specimens is improved.     

数控机床动态特性测试与分析研究

应用试验模态分析方法对某型号数控机床进行了模态试验,得到其固有频率、阻尼比、模态振型、动刚度等参数。测试结果表明,主要薄弱环节集中在滑枕、滑板、立柱处。将现代测试手段和模态分析技术相结合,在综合分析实验结果的基础上,提出在滑枕处增加镶条来提高机床动刚度的方法,并用实验验证了改进措施的有效性。     

Finite element model updating of concrete-filled steel tubular arch bridge under operational condition using modal flexibility

This paper presents finite element (FE) model updating method for real bridge structure under operational condition using modal flexibility. The theoretical background of the updating procedure is presented. The case study of a simulated simply supported beam demonstrates an effectiveness of modal flexibility in objective function. This objective function is then implemented in case study of a real concrete-filled tubular arch bridge. The bridge was tested under operational condition. Followed by the three-dimensional FE modeling of the bridge, an eigenvalue sensitivity study is carried out to select the most sensitive parameters to the concerned modes. Guyan technique is used to the mass normalization of the mode shapes extracted from ambient modal test to calculate the modal flexibility. The updated FE model of the bridge is able to produce a sufficient improvement on modal parameters of the concerned modes, which is in close agreement with the experiment results and updated parameters still preserve the physical meaning in practice.     

某钻机车架有限元分析

应用Pro/E三维造型软件和HyperMesh有限元软件,建立了某钻机车架的实体模型和有限元网格模型,并用ANSYS软件对车架进行了模态分析和强度分析,得到了该车架自由状态下的振动模态以及工作状态下的应变和应力图。为该车架的结构改进提供了理论依据。     

空调翅片立式穿管机穿管支架有限元分析

采用AnsysWorkbench软件建立了穿管支架有限元模型并进行了静力和模态分析,得到了其结构变形图以及前6阶固有频率和模态振型。对计算结果的分析表明,穿管支架具有良好的静力特性和动态特性,能够满足设计要求。指出了穿管支架结构设计的薄弱环节,并为其结构优化设计提供了一些参考数据。     

基于实验模态分析的机床动态性能测试

根据实验模态分析理论,构建了实验模态分析系统.利用压电传感器和加速度传感器作为前端信号采集装置,通过7700Pulse软件采集激励信号和响应信号,然后应用ME’scope软件进行机床实验模态分析.以HMC630rp卧式加工中心整机及其立柱为研究对象开展模态试验,分析结果显示立柱是机床动态性能的薄弱部件,原因在于导轨滑块结合面动态性能较差.     

On the use of damped updated FE model for dynamic design

Model updating techniques are used to update the finite element model of a structure, so that updated model predicts the dynamics of a structure more accurately. The application of such an updated model in dynamic design demands that it also predicts the effects of structural modifications with a reasonable accuracy. Most of the model updating techniques neglect damping and so these updated models cannot be used for predicting amplitudes of vibration at resonance and antiresonance frequencies. This paper deals with updating of the finite element model using the FRF data with damping identification using complex modal data and its subsequent use for predicting the effects of structure modifications. The updated model is obtained in two steps. In the first step, mass and stiffness matrices are updated using FRF-based model updating method. In the second step, damping is identified using updated mass and stiffness matrices, which are obtained in first step. Structural modifications in terms of mass and beam modifications are then introduced to evaluate the updated model for its usefulness in dynamic design.     

加工中心关键部件的动态特性分析

可分度车削头是加工中心的关键部件,它的动态特性好坏直接影响到机床的加工精度和表面粗糙度.以车削头为研究对象,利用Solidworks实体建模,借助有限元分析软件ANSYS进行模态分析,并采用现有的高精度信号采集仪和测试分析软件进行模态试验.对比这两种不同的模态分析结果,找出了该关键部件的薄弱环节.结合对车削主轴动刚度的测试,为提高机床的动态性能和结构优化提供了有效依据.     

基于ANSYS的铣床工作台动态特性分析

基于ANSYS软件建立了数控铣床工作台的三维有限元模型,对工作台进行了无预紧力和有预紧力情况下的模态分析,分别得出了工作台前4阶的固有频率和振型。分析结果为评定数控铣床工作台的动态特性提供了依据,也为对铣床进行进一步动力学分析打下了理论基础。     

105g压阻效应阵列式加速度微传感器硅悬臂梁结构分析

在已有10^5g压阻效应阵列式加速度微传感器版图设计的基础上,应用有限元理论及相关软件,对版图中的硅微悬臂梁进行了模态分析和结构动态计算。将宏观理论应用到微观结构分析中;并对该种结构的加速度传感器的样品进行了冲击实验,得到实验曲线。对计算分析与实验结果进行了比较,指出并分析了误差可能出现的方面。     

Dynamic characteristics analysis and experimental research on a new type planetary gear apparatus with small tooth number difference

Aimed at an internal mesh planetary gear with small tooth number difference (PGSTD) reducer, this paper proposes dynamic characteristics analysis. First, static finite element (FE) analysis is performed to check the structural strength with the stress distribution in the gear teeth. Second, by means of the dynamic contact FE method, the internal dynamic excitations of teeth mesh are obtained, including mesh stiffness excitation, transmission error excitation and mesh impact excitation. According to the established model for dynamic FE modal analysis, the natural frequencies and mode shapes of the planetary gear apparatus (PGA) are calculated, and its structural dynamic response and acceleration noise are researched with the comprehensive consideration of internal and external excitations. Finally, the noise and vibration testing on the PGA is carried out by utilizing the vibration test equipment. The results confirm that the predicted values are consistent with the experimental results.     

基于矩阵逼近的模型修正方法的研究

提出一种新的以试验振动和参数辨识的数据为参数,进行有限元分析模型修正的方法。该方法基于矩阵最佳逼近理论,运用Ｂａｙｅｓ估计原理来处理试验结果误差带来的试验模态可信度问题,求取分析模对试验获得的不完备模态的谱点的最佳逼近结果,最后获得质量阵的最小修正模型。     

A study on finite element of pre damaged stress concentration factor for a composite laminate member with central circular

The study investigates the pre damaged stress concentration factor (SCF) for a composite laminate member (CLM) with central circular hole subjected to tensile loading. The presence of holes yields high stress concentrations in the structural members termed as stress raiser and often regarded as an important design deriver. The pre damaged SCF refers to the stress concentrations within elastic (undamaged) range of the CLM prior to the failure initiation. The traditional experimental and analytical methods for the estimation of SCF offer macro level behaviour which is not considered appropriate for CLM where lamina by lamina behaviour is more significant. A meso level finite element (FE) model is presented to capture the lamina by lamina influence on the overall SCF for a CLM using commercial software Abaqus. The paper deals with the fundamental influencing factors such as laminae orientation effect, stress distribution effect around periphery of the hole, decaying effect and ligament effect on SCF for CLM. Analytical models have been formulated to validate the FE models. The results of FE models have been found in close agreement with the analytical results.     

Failure analysis of support during profile cutting process using horizontal milling machine

In this study, the effects of cutting forces on the support of horizontal woodworking milling machine are examined during profile cutting process using both experimental and analytical approaches. The support modeled in 3D using SolidWorks software is a crucial component of the horizontal milling machine used to locate and fix the wood workpiece during the cutting process on the workbench. The effects of cutting forces on the support specimens are measured experimentally considering vibration and failure analyses. Analytical stresses and modal analyses of the support were also calculated using finite element-based analysis approach. Chatter vibration forces of the cutting tool which resulted from cutting forces in x-, y-, and z-directions were calculated analytically during the profile cutting process. The results showed that both cutting and chatter forces are highly effective on the support component failure of the woodworking milling machines.     

Evaluation of Disc Brake Materials for Squeal Reduction

A nontraditional evaluation tool is introduced to examine the effects of different materials, in practical applications, that are used in fabricating disc brake components for commonly used or special requirements such as heavy-duty performance and racing cars. As an extension to earlier finite element (FE) disc brake models, a detailed FE model of the whole disc brake corner that incorporates the wheel hub and steering knuckle is developed and validated using experimental modal analysis. Stability analysis of the disc brake corner using the finite element software ABAQUS is carried out to predict squeal occurrence also taking into account the negative and positive damping effects and friction material real surface to increase the accuracy of prediction. A Taguchi method–based design of experiment is used to better assess the contributions of different materials and its interaction effects for effective reduction of brake squeal. The results showed that the pad friction material contributes 56% to the total system instability (squeal generation). The rotor material contributes 22% of the system instability. Caliper and bracket materials participate 11 and 11%, respectively.     

Vibro-acoustic characteristics of an annular disk with narrow radial slots

Analytical solutions for vibro-acoustic characteristics of a thin annular disk containing narrow radial slots have been proposed with numerical and limited experimental verifications. Structural characteristics of split and repeated modes of the disk are expressed in terms of eigensolutions for the corresponding uniform disk that has same geometric configuration. Sound radiations due to the modal vibrations are calculated using pre-developed analytical solution based on the structural data obtained above. Structural and acoustic responses of the disk for a stationary concentrated harmonic force have been studied using the modal expansion technique. Based on these results, the effects of relative location of the excitation to the slots on the vibro-acoustic responses as well as interactions between sound radiations for two split modes are investigated. The results demonstrate that the introduced procedure has reasonable accuracy obtaining vibro-acoustic characteristics of a thin annular disk containing narrow radial slots.     

基于结合面参数的整机动态特性分析与试验研究

机床结合面特性对其整体性能具有很大影响,利用ANSYS软件分别对立式数控铣床AVCP1200H结合面刚性联接、柔性联接的有限元模型进行模态分析,然后通过整机模态试验验证两种有限元模型的分析吻合,并对试验误差产生的原因进行分析,提出了优化模型的建议,为该型机床动力学研究及数字化设计制造提供了参考。试验结果表明:结合面柔性联接的模态分析与锤击试验结果较为吻合,3阶以上的误差均在20%以内,证明结合面处的动态特性参数对机床性能有很大影响。     

大型铣钻专用机床的动力学分析

采用CAD/CAE/MSS技术对铣钻专用机床进行动力学分析。首先,在Pro/E中建立机床三维实体模型;然后在ADAMS/View形成虚拟样机模型,对机床进行运动学和动力学分析,得出机床导轨的接触力曲线;最后以接触力作为边界条件,用ANSYS对导轨进行应力应变分析,得出机床的静态特性和动态特性。从而提高了专用机床设计成功率、减少了设计周期。     

Numerical analysis and experimental investigation of modal properties for the gearbox in wind turbine

Wind turbine gearbox (WTG), which functions as an accelerator, ensures the performance and service life of wind turbine systems. This paper examines the distinctive modal properties of WTGs through finite element (FE) and experimental modal analyses. The study is performed in two parts. First, a whole system model is developed to investigate the first 10 modal frequencies and mode shapes of WTG using flexible multi-body modeling techniques. Given the complex structure and operating conditions of WTG, this study applies spring elements to the model and quantifies how the bearings and gear pair interactions affect the dynamic characteristics of WTGs. Second, the FE modal results are validated through experimental modal analyses of a 1.5 WM WTG using the frequency response function method of single point excitation and multi-point response. The natural frequencies from the FE and experimental modal analyses show favorable agreement and reveal that the characteristic frequency of the studied gearbox avoids its eigen-frequency very well.