某SUV轿车副车架模态分析的实例研究

根据某SUV轿车副车架的实际结构,运用ANSYS Workbench 分析软件对其建立有限元模型。通过对有限元模型的模态模拟分析得到副车架的固有频率和相应振型,然后对副车架进行模态试验,通过比较实验结果与计算结果,验证有限元模型的正确性。最后通过改变U型横梁壁厚验证其对副车架整体模态特性的影响,为后续的结构优化提供参考。     

基于CAE/CAT/CAO的齿轮箱轴承结合部等效刚度识别方法

基于CAE/CAT/CAO技术,提出一种有限元模态分析、试验模态分析与Isight集成优化方法相结合的精确识别轴承结合部等效刚度的方法:1采用Abaqus有限元分析软件建立齿轮箱有限元分析模型,通过spring单元模拟轴承三个方向的等效刚度,并将其作为设计变量;2基于LMS模态测试分析系统对齿轮箱进行试验模态分析,得到包含轴承结合部信息的各阶固有频率和振型,并以试验模态分析得到的固有频率值作为优化目标值;3通过Isight软件集成Abaqus对轴承刚度进行寻优,使有限元模态分析的结果与试验模态分析的结果相一致。分析结果表明,该方法综合考虑了齿轮轴、箱体的柔性,具有较高的精度,优化后的齿轮箱有限元模型与试验模型动态性能一致性好。     

预紧力对螺栓联接机匣模态频率的影响研究

为研究预紧力对螺栓联接机匣模态频率的影响,首先,从理论上建立预紧力作用下螺栓联接结构模态方程;其次,以螺栓联接板试件为例,基于有限元分析和试验相结合的方法,验证螺栓联接接触面处理方法的准确性;然后,建立较为精细的机匣有限元模型,进行不同预紧力作用下的机匣模态分析;最后,分析刚性机匣和预紧力作用条件下的实体机匣各阶固有频率相对差异,重点研究预紧力变化对各阶模态频率影响程度。研究表明,随着预紧力增大,机匣各阶固有频率总体上有所增大,并且预紧力对各阶固有频率的影响程度各不相同,结合振型图发现,对于连接面处相对变形较大的振型,其模态频率受预紧力影响较大;而对于连接面处相对变形较小的振型,其模态频率受预紧力影响较小。     

机械式停车设备框架结构模态分析与试验研究

针对机械式停车设备故障频发问题,以市场占有率较高的两层升降横移类机械式停车设备为研究对象,采用CAD/CAE技术开展框架结构模态分析与试验研究。首先利用SolidWorks和ANSYS软件建立框架结构三维及有限元模型,开展理论模态分析;然后利用AVANT MI-7008一体式数据采集与分析仪开展模态试验测试,并通过Modal Genius软件处理试验数据,分析得到停车设备各阶固有频率及振型。最后将试验结果与理论分析进行比对研究,分析结果表明停车设备的有限元模型是正确的,理论模态分析方法是可行的,该方法为停车设备的设计与优化提供有效参考和理论基础。     

结构动态测试传感器优化配置的预试验技术

传感器配置是结构动态测试的一项重要的技术措施,其效果决定了结构的各阶主要测试模态的有效程度。由此,首先对结构仿真模型进行预先的主元素分析,优化传感器的布置。在结构有限元模型(FEM)中,对模型固有特性进行分析,确认重要的结构模态和结构动态测试目标。利用Guyan缩减方法对模型的自由度进行主从划分;选取感兴趣的结构振型的主自由度,对应从有限元模型中提取缩减的"试验模型"。针对提取的缩减模型重新开展模态分析,采用模态置信度(MAC)指标评估各阶振型之间的相关性,进而量化并直观显示传感器的配置效果。对某型号无人直升机机身结构进行地面振动试验。通过从仿真模型中选取合适的振型主元,改进传感器的配置,能保证试验中获得期望的结构测试模态,验证了利用结构仿真模型在动态测试之前预先进行传感器优化配置的效果。     

考虑弯曲效应的弯管高精确度模态分析

基于塑性理论和有限元软件ANSYS,考虑弯曲效应对各种不同材料参数、不同直径、不同弯曲半径和弯曲角度的弯管固有频率和振型的影响,建立了高精度弯管有限元模型进行模态分析,并利用实验结果进行验证.研究表明,考虑弯曲效应后的有限元模型计算结果更接近实验结果,特别是第一阶固有频率和振型的精度得到了提高,说明应用该模型可以得到高精度的弯管模态.     

工程车辆车架动态特性分析及结构改进

车架的动态特性直接影响着整车的性能,因此车架结构动态特性分析在工程车辆设计工作中占有重要地位。以某工程车辆车架为研究对象,采用有限元分析方法与模态试验技术获取其固有频率与振型,结合发动机及路面的激励频率对其低频动态特性进行分析,并给出改进方案。结果表明,改型后车架的固有频率避开发动机怠速频率及路面激励频率,避免该工程车辆在怠速及路面行驶中可能产生的共振问题。     

轿车白车身模态分析

运用HyperMesh建立了某轿车白车身的有限元模型。分别通过Optistruct软件和试验对白车身进行了仿真模态分析和试验模态分析,得到仿真和试验条件下白车身的固有频率及对应的各阶振型。将仿真模态与试验模态进行对比,结果吻合度高,验证了白车身有限元模型的准确性。仿真与试验结果均表明,该车身整体一阶扭转频率较低,车身容易发生共振现象,需要改进设计。     

基于模态分析理论的结合部动刚度辨识EI北大核心CSCD

结合部动力学特性对机械系统动力学性能具有显著影响,结合部动力学信息的准确辨识是组合结构动力学建模的重要前提。基于模态分析理论对结合部动刚度辨识方法进行了深入研究:首先,建立了包含结合部动力学信息的广义动力学模型,从模态分析理论出发,讨论了结合部动力学特性对组合结构固有频率的影响,建立了两者的映射关系;进而,采用质量单元与弹簧阻尼单元建立了理想的动力学有限元模型,通过模态分析所得的固有频率对结合部刚度进行辨识,辨识值与理论值之间最大误差为1.92%;最后,对螺栓连接组合结构进行了模态试验,以所测得的法向及切向典型振型对应固有频率为指标,通过搭建的MATLAB-ANSYS集成平台对螺栓结合部刚度进行辨识,并将所辨识的结合部刚度录入有限元模型,栓接结构固有频率的有限元预测值与实测值之间最大误差率为3.01%;数值模拟试验与现场模态试验的辨识效果均较为理想,验证了方法的可行性。同时,以栓接结构典型振型对应固有频率为指标辨识的结合部动力学刚度信息很好预测其他各阶固有频率的分布,表征和印证了栓接结构在较大预紧力作用下,螺栓结合部非线性动力学特性得到了抑制,满足线性条件假设。     

小型客车车轮模态分析

汽车行驶过程中,受到不同幅值和频率的激励,通过车轮传递到车内,进而影响车辆的舒适性。通过Pro/E软件建立车轮的三维模型,使用有限元分析软件Hyperworks建立车轮的有限元模型;采用Optistruct模块进行计算,得到车轮在自由状态下的固有频率和模态振型。通过对车轮进行自由模态实验分析,得出车轮的固有频率和模态振型。将模态实验结果与有限元分析结果进行对比分析,得出低阶模态振型主要集中在轮辋边缘部位,而高阶模态振型主要集中在轮辋中间部位;同时实验结果也验证了车轮有限元模型的正确性。     

变形反射镜薄膜应力与元件变形有限元研究

残余应力是变形反射镜面临的一个重要问题。考虑薄膜中残余应力的起源,利用有限元软件建立了变形反射镜有限元模型。基于所建立的有限元模型,计算变形镜各部分受薄膜残余应力作用后的变形与应力分布。与试验测量结果进行对比,计算结果表明,建立的模型是合理的,薄膜产生的残余应力为张应力,氟化物薄膜产生的张应力大于ZnS薄膜产生的压应力,残余应力主要集中在变形反射镜镜面上,基本呈放射状分布,外圈驱动器受到应力较大。     

Analysis of the bullet nose of an aero-engine for bird impact through virtual and rapid prototyping

Flying was inspired by birds. But ironically bird strikes are a menace. Therefore, aero-engines have to be designed to survive these strikes. The design of the bullet nose of an aero-engine during a bird strike is presented in this paper. A Finite Element Analysis (FEA) model was developed for this purpose. It was then fine-tuned through experiments on bullet noses built using Laser-Engineered Net-Shaping (LENS). Through this approach, several design alternatives could be evaluated virtually and only a few physical experiments were required for validation. The outcome is not only a rapid and safe bullet nose design but also a realistic FEA model.     

一种水下被动目标运动分析与仿真

文章讨论了一种水下运动的目标和观测平台在不同平面的三维情形下,被动目标运动分析与仿真问题,文中从声呐测量的方位角、爷角和频率的数据入手,采用伪线性估计、最大似然估计两种不同的方法,对水下被动TMA问题进行了研究,并分析了两种不同方法的状态参数估计的误差特性。仿真结果表明：由于增加了观测的信息量,上述方法均能得到较好的参数估计结果,且伪线性估计方差向CRLB界接近。上述方法可推广到目标和观测平台处于同一平面的二维情形。     

Numerical Simulation and Characterization of Slurry Erosion of Laser Cladded Surfaces by Using Failure Analysis Approach

A material failure model (MFM) of progressive damage initiation and propagation for the impingement of solid and liquid particles on the solid surfaces was used to numerically simulate the slurry erosion process. The commercially available 3D Finite Element Analysis (FEA) package ABAQUS/Explicit was used to evaluate this problem. The damage caused on the solid surfaces by the impingement of solid and liquid particles is called the slurry erosion. The proposed model uses the FEA concepts of adaptive meshing, strain-dependent damage initiation criteria, a general contact algorithm, damage propagation, enhanced hourglass section control, and multiple particle impingements to study the slurry erosion process. For the purpose of experimental validation and due to the availability of material properties, surface coatings of an alloy of steel are deposited by the Laser-Based Direct Metal Deposition (LBDMD) process. The slurry erosion tests are performed on these depositions using the ceramic proppant at different impingement angles. The tests are made in a centrifugal force driven erosion testing machine. From these tests, the material removal rate (MRR) values and depth of penetration including the profiles of the craters are computed as a function of the slurry jet impingement angles. The numerically computed results are compared with the experimental results and are shown to be in good agreement.     

大行程变形镜有限元分析

针对自适应光学系统对变形镜行程的更高要求,本文对提高变形镜行程技术进行了分析,提出了一种解决变形镜大行程的方法:匹配、优化变形镜的结构参数;利用有限元软件分析了该结构的各参数对变形镜主要性能指标:最大变形量、交连值及最大应力等的影响.根据分析结果,利用有限元分析方法对一自适应光学望远镜所用变形镜的镜面、驱动器结构参数进...     

What makes an accurate and reliable subject-specific finite element model? A case study of an elephant femur

Finite element modelling is well entrenched in comparative vertebrate biomechanics as a tool to assess the mechanical design of skeletal structures and to better comprehend the complex interaction of their form–function relationships. But what makes a reliable subject-specific finite element model? To approach this question, we here present a set of convergence and sensitivity analyses and a validation study as an example, for finite element analysis (FEA) in general, of ways to ensure a reliable model. We detail how choices of element size, type and material properties in FEA influence the results of simulations. We also present an empirical model for estimating heterogeneous material properties throughout an elephant femur (but of broad applicability to FEA). We then use an ex vivo experimental validation test of a cadaveric femur to check our FEA results and find that the heterogeneous model matches the experimental results extremely well, and far better than the homogeneous model. We emphasize how considering heterogeneous material properties in FEA may be critical, so this should become standard practice in comparative FEA studies along with convergence analyses, consideration of element size, type and experimental validation. These steps may be required to obtain accurate models and derive reliable conclusions from them.     

A novel model for determining tensile properties and hardness of steels by spherical indentations

An energy-based spherical indentation (ESI) model according to equivalent energy principle is developed to determine the stress–strain relation, tensile strength and hardness of steels. Several parameters in the model are determined with finite element analysis (FEA). For a wide range of homogeneous and isotropic materials in power stress–strain law, a large number of FEA calculations are carried out to verify the ESI model. Results show that both the forward-predicted load-depth relations and the reverse-predicted stress–strain relations from the model agree well with the results from FEA. For 12 steels, the tensile properties, Rockwell and Brinell hardness predicted by the ESI model are close to the standard testing results.     

风力发电机组复合材料机舱罩的有限元分析

基于有限元分析理论,利用MSC.Patran/Nastran对某MW级风力发电机组复合材料机舱罩的结构强度进行分析。通过比较多种壳单元特点确定以shell单元为机舱罩的建模单元。对特殊结构板的铺层方法进行了研究,有孔板采取先补单元再铺层的方法,多曲率板采取更改铺层起始点或划分区域铺层的方法。对机舱罩有限元模型的边界约束和施加的载荷进行了研究,并进行了静强度和模态分析。计算结果表明机舱罩不会发生分层破坏,固有频率远离激振频率,不会发生共振破坏。     

钢铝结构连接耦合损耗因子计算方法研究

统计能量法已广泛用于解决高频振动与噪声问题,耦合损耗因子是其关键参数之一。研究基于统计能量法、有限元法和功率输入法,提出一种钢铝连接耦合损耗因子数值计算方法,并运用MATLAB编写了计算软件。通过对含过渡接头的T型连接结构进行数值和实验研究,验证了该法的可靠性。这对提高钢铝混合结构的噪声预报精度及指导其结构声学设计具有重要意义。     

Examples of adaptive FEA in plasticity

Adaptivity and error estimation in finite element analysis (FEA) has received considerable interest, but most of the work has been in the linear range. Its use in materially non-linear processes has been investigated by the authors in a recent paper [J.S. Sandhu et al., Adaptive Finite Element Analysis in Plasticity, COMPLAS III (April 1992)]. In this paper we present some examples which further illustrate the use of adaptive FEA in materially non-linear analyses. At present, this area has received little attention mainly due to there being no reliable and simple error estimators. We have used linear and non-linear error indicators in an attempt to develop a simple and efficient materially non-linear FEA adaptive program. The non-linear plasticity model is based on an incremental theory using the Von Mises yield criterion.