发动机ECU支架振动疲劳分析及其优化设计

为了解决某发动机ECU支架开裂失效问题,首先采集ECU与车架端的实车加速度,并且将其时域信号转换为频域信号。然后基于有限元方法建立ECU支架分析模型,对其进行频率响应分析,分析结果表明其最大应力值超过其材料屈服强度。再基于Miner线性累积损伤理论和功率谱密度函数对其进行振动疲劳分析,分析结果表明其最小寿命为低于设计要求值,与实际失效位置相吻合。最后基于Isight集成优化平台并且采用多岛遗传算法对ECU支架进行优化设计,得到了其最佳的设计参数,优化之后其最大应力值和疲劳寿命均能够满足设计要求,并且其优化方案通过了路试验证,成功解决了该故障问题。     

汽车安全气囊ECU共振分析

安全气囊ECU的主要功能是用于检测碰撞加速度信号,控制安全气囊的起爆时间。为保证ECU安装位置的共振性能,防止由于共振而产生误起爆,在整车开发过程中要求安全气囊ECU安装支架必须满足一定的动刚度设计要求。文中利用Altair/HyperMesh软件进行有限元建模,通过RADIOSS求解器对某车型ECU安装支架进行动刚度分析计算,并结合试验结果进行验证使其达到设计要求。     

某柴油机发电机支架有限元分析及优化

本文是基于有限元分析方法对某柴油发动机的发电机支架进行仿真分析,从模态、静强度和疲劳安全系数三个方面进行校核。计算结果表明,发电机支架的可靠性满足设计要求且拥有较大的安全裕度。因此,结合计算结果对支架进行轻量化设计,由原先的8.1kg减至4.9kg,优化后的发电机支架满足设计要求。     

特种车辆发动机支架模态分析

利用有限元理论以及大型通用有限元分析软件MSC.Nastran(前、后置处理软件采用MSC.Patran)对发动机支架进行了自由模态的有限元分析,得出该发动机支架的前十阶模态参数(固有频率和模态振型),计算结果对特种车辆采取减振降噪措施具有一定的参考价值。     

商用车油箱支架的有限元分析及优化

应用HyperWorks软件,在四种工况下通过RADIOSS求解器对油箱支架进行静强度计算分析,得出其应力和变形结果。根据分析结果,以减小危险位置最大应力、增强结构稳定性为目的,对油箱支架进行了优化设计,将设计结果与原模型的强度、位移进行对比分析,采用最佳优化方案。     

基于虚拟仪器的频响分析系统

频响分析作为一种系统分析方法有着广泛的用途.介绍了一种基于虚拟仪器的频响分析系统.相对于传统的频响分析仪,它具有性能价格比高、功能覆盖面广、系统可升级性好等优点.     

盘式制动器支架疲劳分析及优化

取盘式制动器摩擦块的标准试样进行压缩试验,建立制动盘-摩擦块制动过程的数值模型,根据计算结果分析支架受力分配,并利用疲劳台架试验对数值模型进行验证;基于支架应力测试试验,建立支架有限元分析数值模型,研究盘式制动器支架的应力应变分布规律,结果表明:支架应力最大值出现在较细拱桥一侧,大于屈服强度,数值解与试验值吻合程度较好,说明模型可靠;基于20万次疲劳台架试验,建立盘式制动器的疲劳分析模型,研究盘式制动器支架疲劳寿命的影响因素;结合有限元分析和疲劳分析的结果,对盘式制动器支架进行形状优化,优化后支架应力得到明显改善,解决了目前盘式制动器支架易出现疲劳破坏的关键性问题。     

螺栓连接方式对齿轮箱柔性支架频响特性影响分析

针对不同连接方式对齿轮箱柔性支架频响特性影响机制不明的问题,本文提出了建立普通螺栓、铰制孔螺栓以及蛛网固联三种连接方式下的齿轮箱柔性支架的三维有限元模型,采用ANSYS Workbench有限元软件对建立的模型进行模态和谐响应分析,探明了不同连接方式对齿轮箱柔性支架频响特性的影响。该研究可为类似结构柔性支架连接方式选择提供理论基础依据。     

频响分析下的特种车辆结构优化设计研究

当前,特种车辆的应用领域逐渐拓宽,其生产规模不断扩大,生产数量日益增多。特种车辆具有轻便灵活的特点,且稳定性较强。为保障特种车辆在实际应用中充分发挥其效能作用,有必要对特种车辆结构进行优化设计。本文简述了特种车辆的概念,探究了频响分析下的特种车辆结构优化设计,以期为特种车辆设计研究提供借鉴。     

车削加工中工件的模态分析

车削加工中工件的振动会严重影响零件的尺寸精度及表面粗糙度。为分析工件系统的动特性,分别用有限元法和试验法（频响函数法）对系统进行模态分析。结果表明两种结果之差低于10％,因此有限元求解比较精确。     

Topology optimization of compressor bracket

Topology optimization is very useful engineering technique especially at the concept design stage. It is common habit to design depending on the designer’s experience at the early stage of product development. Structural analysis methodology of compressor bracket was verified on the static and dynamic loading condition with 2 bracket samples for the topology optimization base model. Topology optimization is able to produce reliable and satisfactory results with the verified structural model. Base bracket model for the topology optimization was modeled considering the interference with the adjacent vehicle parts. Objective function was to minimize combined compliance and the constraint was the first natural frequency over 250 Hz. Multiple load cases such as normal mode calculation and gravity load conditions with 3-axis direction were also applied for the optimization, expecting an even stress distribution and vibration durability performance. Commercial structural optimization code such as optistruct of Altair Engineering was used for the structural topology optimization. Optimization was converged after 14 iterations with the satisfaction of natural frequency constraint. New bracket shape was produced with the CATIA based on the topology optimization result. The new bracket from topology optimization result was compared with the traditional concept model and topology optimization base model under 4 load cases. 14 % 1’st natural frequency of new bracket with only 4 % mass increment increased compared to the concept model. 31 % mass decreased compared to the base model without the increment of stress under gravity load cases. It was analyzed thata new bracket would not fail during a vibration durability test, and these results were verified with a fabricated real sample under the durability condition.     

基于UG的发动机支架强度分析

随着计算机软硬件的发展,有限元分析技术得到了广泛应用.将有限元应用于发动机支架分析,介绍了仿真分析的理论基础及有限元模型建立的一般过程,并运用UG软件对发动机支架进行强度分析.结果表明:发动机支架能够满足强度要求,为工程设计提供依据.     

陀螺仪安装支架的动态特性分析与优化

陀螺仪是惯性导航系统的关键部件,其安装支架的动态特性直接影响陀螺仪的测量精度.文中利用ANSYS软件建立了陀螺仪安装支架的三维实体模型及有限元模型,分析了陀螺仪安装支架自由状态下的模态.结合模态分析结果,讨论了陀螺仪抖动的激励和发动机激励对陀螺仪安装支架动态特性的影响,发现了安装支架结构设计的不足,并提出改进方案.理论模态和实验模态分析表明,改进后的陀螺仪安装支架的结构动态特性明显改善.经试验测试,激光陀螺仪输出精度符合惯性导航系统的要求.     

水轮发电机转子支架静态强度及动态特征研究

对某水电站水轮发电机转子支架进行有限元分析,通过分析发现转子支架原设计不足;转子支架改进型比较合理,腹板应力大大下降。     

基于Ansys Workbench的矿井架空乘人装置驱动轮支架的有限元分析

应用参数化设计软件Pro/E对架空乘人装置的驱动轮支架进行三维建模,将建好的模型导入AnsysWorkbench软件进行有限元分析,并以此为依据对驱动轮支架进行改进设计,再对改进后的支架进行有限元分析。改进前后的有限元分析结果对比显示,改进后的零件机械性能得到提高,为提高矿井架空乘人装置的可靠性提供了参考。     

微小卫星星敏感器支架的优化设计与试验

针对卫星结构中星敏感器支架在随机激励下加速度响应均方根(RMS)值过大的问题,提出了星敏感器支架优化设计方法。简述了星敏感器安装点随机响应的基本理论,对卫星结构进行了模态和加速度响应灵敏度分析。以星敏感器安装点RMS值最小为目标,以基频和体积分数为约束,建立了星敏感器支架随机响应优化模型,并对支架进行了拓扑优化设计。最后,利用MSC.PATRANNASTRAN对优化处理后的支架模型进行了工程分析。结果显示:星敏感器安装点随机响应RMS值降低了20%以上,支架结构轻量化率达到了50%。另外,利用振动试验台对支架进行了振动试验。实验显示:有限元分析结果与试验数据相对误差低于15%,表明设计的支架的性能参数满足设计指标,验证了所采用优化方法的可行性。     

Frequency response characteristics of gas sensors

This paper presents the novel experimental observations and analysis of the frequency response of a sensed gas surface. The main objectives of this study were: (i) to characterise the gas sensors with additional A.C. parameters apart from reported D.C. conductance response, and (ii) to understand the A.C. conduction mechanism. The outcome of this study was that the gas sensors from Motorola, Capteur and Figaro behaved similarly with an A.C. frequency sweep. Essentially their behaviour can be characterised into three distinct frequency bands. For the Motorola micro gas sensor, the flat response from 10 Hz to around 100 kHz range was like a simple R_PC_P (a zero in admittance function) parallel circuit. From 100 kHz to around 1 MHz, the real part of admittance decreases indicating the presence of an inductive pole in admittance function. Beyond 1 MHz and up to 13 MHz, both real and imaginary parts of admittance increase significantly revealing the presence of higher order zeros. The frequency band differs for Figaro and Capteur sensors. The lumped circuit representation may be a form of representing the distributed reacting layers on the surface. Best fitting of the entire frequency range response using MATLAB indicated the presence of two poles and two zeroes or more. Cleaning by finite triangular or pulse waves restored the surface for sensing. R_P, C_P, f_C, the frequency at which reactive impedance was maximum, the measured negative peak of reactive impedance (Z_i), the slope of estimated capacitance with frequency (C_P/f) and pole/zero locations can be used as additional parameters to improve the sensitivity and selectivity of gas and other contaminating environments. The A.C. conduction mechanism indicates that the ohmic conduction (1/R_P) in the intergranular region follows the barrier theory. The majority charge carriers in the semiconductor increases with sensing temperature (T). The barrier potential decreases at high absolute humidity and longer cyclic heating duration (PW). The capacitance (C_P) may be due to the geometry of the semiconducting intergranular separation between grains. It increases with T due to the closeness at high T. The variation of C_P with f may be due to the polarisation contribution of adsorbed gas molecules.     

半挂汽车车架有限元模态分析及优化设计

车架是半挂汽车结构件中结构和载荷都很复杂的关键部件,为提高车架整体性能,对某型半挂汽车车架进行了有限元模态分析和基于频率、刚度和强度约束的优化设计,降低了车架结构自重,提高了车架的低阶频率,改善了动态性能,为车架的设计和改造提供了理论依据。     

Output-only modal analysis of wind turbine tower based on vibration response under emergency stop

The identification technique of output-only modal parameters is proposed for the large wind turbine tower under emergency stop. Compared with the response of regular operating conditions, the immediate tower structural response under emergency stop much more resembles a state of free vibration, which is more appropriate for the modal identification of the wind turbine tower. The vibration response is measured in the nacelle, which is easy to perform in the field modal test. The variational mode decomposition (VMD) is applied to decompose the vibration response into several band-limited intrinsic mode functions. The free responses of decomposed functions are extracted by applying the random decrement technique (RDT). Finally, the modal damping ratio and natural frequency are identified from each free modal response by using the Hilbert transform method. Simulations and a 1.5 MW wind turbine field modal test results verify the effectiveness of the proposed identification method. The main modal parameters of wind turbine, including weak modes, are effectively extracted by using output-only vibration responses under emergency stop. The modal parameter identification method is provided for the large wind turbine structure under the engineering condition.