Optimization Design of Vibration Characteristics of Ship Composite Brace with Rigid Vibration Isolation Mass

In considering the theory of structural dynamic optimization design, a design method of the structural style of ship composite brace with rigid vibration isolation mass was studied. Two kinds of structural dynamic optimization formulations minimizing the vibration acceleration of the non-pressure hull on the restraining condition of the gross weight of the ship cabin were established: 1) dynamic optimization of the sectional dimensions of the rigid vibration isolation mass in the composite brace; 2) dynamic optimization of the arranging position of the rigid vibration isolation mass. Through the optimization results, sectional dimensions and the arranging position of the rigid vibration isolation mass with better performance in reducing vibration were gained, and some reference was provided for practical engineering designs as well as enrichment of the design method of a novel ship vibration-isolation brace.

Optimizing Parameters of Rail-induced Vibration Isolation Trench Using Simplified FEM Approach

A simplified approach is proposed to reduce computational cost in conventional parametric optimization of open or in-filled trenches isolating rail-induced structural vibrations. In particular, it stands on an FEM-based hybrid optimization scheme consisting of multiple two-dimensional models and one global three-dimensional model. First, representative planar FE （finite element） models orthogonal to the rail-direction are identified. For each section, the sensitivity of the trench＇s design parameters, such as geometry and backfill materials, to its vibration screening effect is respectively evaluated. Second, a full trench along the rail-direction is determined according to the two-dimensional optimization result. The global performance of the optimal trench is simulated in the three-dimensional model and finally becomes a reference for practical design. By optimizing the design parameters of a case study project, the proposed approach has shown the capability of solving complex engineering problems at a minimum computational cost, therefore is applicable in determining design parameters of rail-induced vibration isolation trenches.

Application Research of Genetic Algorithm on the Whole-Spacecraft Vibration Isolation System

The objective of the whole-spacecraft vibration isolation (WSVI) system is to reduce the launch-induced dynamic loads and the quality control cost of the satellite and its components, and to increase the launch reliability by insertion of isolators between the satellite and the launch vehicle. A niche hybrid genetic algorithm (NHGA) is proposed to optimize stiffness and damping of the isolators. Through the comparison of the frequency response analysis results, it shows that the optimized WSVI system more effectively reduces spacecraft axial / lateral response due to the broadband structure-born launch environment. At the same time, the case of the whole-spacecraft vibration isolation optimization design demonstrates the efficiency and validity of the genetic algorithm.

Design optimization of a hexapod vibration isolation system for electro-optical payload

The electro-optical payloads on mobile platforms generally suffer undesirable vibrations generated by maneuvers and turbulence.These vibrations are in six degrees of freedom and cause line-of-sight jitters,resulting in image blurring and loss of tracking accuracy.In this paper,a Hexapod Vibration Isolation System(HVIS)is proposed and optimized to solve this problem.The optimization aims to centralize and minimize the natural frequencies of HVIS,for expanding the vibration isolation bandwidth and improving the vibration isolation in the higher frequency band.Considering that the design space for HVIS is limited and interfered with the frames of the mobile platform,a non-collision algorithm is proposed and applied in the optimization to obtain the feasible optimal design.The optimization result shows that the natural frequency bandwidth has been reduced by 42.9%,and the maximum natural frequency is reduced by 30.2%.The prototypes of initial and optimal designs are manufactured and tested.Both simulated and experimental results demonstrate the validity of the optimization,and the optimal design provides a maximum of 15 dB more isolation in rotation direction than the initial design.

Optimal design for rubber concrete layered periodic foundations based on the analytical approximations of band gaps and mapping relations

The seismic performance of rubber concrete-layered periodic foundations are significantly influenced by their design,in which the band gaps play a paramount role.Aiming at providing better designs for these foundations,this study first proposes and validates the analytical formulas to approximate the bounds of the first few band gaps.In addition,the mapping relations linking the frequencies of different band gaps are presented.Furthermore,an optimal design method for these foundations is developed,which is validated through an engineering example.It is demonstrated that ensuring the superstructure’s resonance zones are completely covered by the corresponding periodic foundation’s band gaps can achieve satisfactory vibration attenuation effects,which is a good strategy for the design of rubber concrete layered periodic foundations.

Optimal design of 6-DOF vibration isolation platform based on transfer matrix method for multibody systems

The structure parameters of 6-degree of freedom(DOF)vibration isolation platform have a significant effect on its performance.To make the designed vibration isolation platform perform well,non-dominanted sorting genetic algorithm version II(NSGA-II)was applied to optimize its structure based on the transfer matrix method for multibody systems.Firstly,the Jacobian matrix of 6-DOF vibration isolation platform was solved based on kinematics.Secondly,the transfer equation of 6-DOF vibration isolation system was established by the linear transfer matrix method for multibody systems.And the formula of its natural frequency was derived according to the boundary conditions of the system.Thirdly,the manipulability index was constructed based on a dimensionless Jacobian matrix.And a new performance index function was established considering the influence of dynamic isotropic and legs mass.Fourthly,genetic algorithm(GA)and NSGA-II were used to optimize the structure of the 6-DOF vibration isolation platform under the same conditions,respectively.It showed that NSGA-II had higher optimization efficiency,better calculation accuracy and shorter optimization time than that of GA.Finally,NSGA-II was adopted for multi-objective optimization design of 6-DOF vibration isolation platform based on the constraint conditions.Optimal Pareto solutions were obtained,which provides structural parameters for subsequent design work.Therefore,the proposed optimization method and the performance index in this paper provide a theoretical basis for the optimal design of relevant vibration isolation mechanism.

Optimal design and effectiveness evaluation for inerter-based devices on mitigating seismic responses of base isolated structures

The optimal design and effectiveness of three control systems,tuned viscous mass damper(TVMD),tuned inerter damper(TID)and tuned mass damper(TMD),on mitigating the seismic responses of base isolated structures,were systematically studied.First,the seismic responses of the base isolated structure with each control system under white noise excitation were obtained.Then,the structural parameter optimizations of the TVMD,TID and TMD were conducted by using three different objectives.The results show that the three control systems were all effective in minimizing the root mean square value of seismic responses,including the base shear of the BIS,the absolute acceleration of structural SDOF,and the relative displacement between the base isolation floor and the foundation.Finally,considering the superstructure as a structural MDOF,a series of time history analyses were performed to investigate the effectiveness and activation sensitivity of the three control systems under far field and near fault seismic excitations.The results show that the effectiveness of TID and TMD with optimized parameters on mitigating the seismic responses of base isolated structures increased as the mass ratio increases,and the effectiveness of TID was always better than TMD with the same mass ratio.The TVMD with a lower mass ratio was more efficient in reducing the seismic response than the TID and TMD.Furthermore,the TVMD,when compared with TMD and TID,had better activation sensitivity and a smaller stroke.

基于Adams/Insight的麦弗逊前悬架振动分析及优化设计

以某款紧凑型轿车的麦弗逊前悬架为研究对象,在Adams/Car模块中建立悬架系统动力学模型,进行仿真试验,并根据仿真结果分析车轮跳动时各项参数的变化规律。针对分析中存在的主销外倾角和主销内倾角变化范围较大的问题,使用Adams/Insight模块对该悬架的部分硬点位置进行优化设计。优化结果表明:调整下控制臂、转向横拉杆和滑柱的部分硬点坐标,可以减小各项参数在车轮跳动中振动幅度,改善车辆的行驶稳定性。

基于ADAMS的微车万向传动装置的振动优化

以多体动力学为基础,应用机械系统动力学仿真软件Adams建立某微车万向传动装置组成的仿真模型,通过调整传动轴轴管尺寸对万向传动装置的振动进行优化设计仿真,并用实车测试与仿真分析结果进行对比分析,实车测试结果验证了研究对微型车万向传动装置的振动所作的优化设计能有效的降低万向传动装置的振动与噪声,改善了整车的NVH特性,对传动系统的优化设计具有一定的指导作用.

基于Adams的汽车动力总成-整车系统隔振优化设计

应用已测得的动力总成各项参数,建立动力总成-整车动力学模型;运用能量解耦原理,考虑系统各阶振动固有频率的合理分配对优化过程加以约束;利用系统动力学仿真分析软件Adams对动力总成-整车动力学模型中的悬置系统进行优化设计。振动传递率和频域响应分析结果表明:该方法能有效地提高悬置系统的隔振性能。

基于ADAMS的某客车动力总成悬置系统分析及优化

汽车动力总成的振动是汽车整车振动噪音的主要来源,如何有效地隔离动力总成的振动向车架/车身的传递成为汽车设计的一个重要问题。以某客车为研究对象,应用ADAMS软件建立了动力总成悬置系统13自由度振动力学模型,通过仿真计算,得到了在不同工况下动力总成质心处的各种运动响应曲线和各个悬置点支承处的动反力曲线,并对悬置系统的固有特性和双向隔振性能进行分析,研究了其动力总成橡胶悬置系统的双向隔振性能。最后,对其进行优化设计,将优化前方案和提供的两种优化方案进行比较,优化后悬置系统的隔振性能有明显的改善。

基于ADAMS车用CD光驱的振动隔离研究

通过对某型号CD光驱的隔振系统作扫频实验,获得振动系统的阻尼比和竖直振型对应的固有频率。应用ADAMS软件建立CD光驱虚拟样机模型。用半正弦脉冲作为激振,优化隔振系统。实验表明,优化后隔振系统的振动特性大大改善,为设计新的CD光驱隔振系统提供了方法。

基于ADAMS的客车悬置系统隔振性能分析及优化设计

通过对某6 m中型前置客车发动机悬置系统采用ADAMS软件建立动力总成受力分析的简化模型,进行模拟优化计算;通过对比测试,验证该优化方案的效果。

基础隔震结构附加变化型调谐质量惯容阻尼器的优化设计研究

在强震作用下基础隔震结构的隔震层将发生非常大的水平变形。已有研究表明采用在基础隔震结构的隔震层附加变化型调谐质量阻尼器(VTMD)的混合控制策略能够有效降低隔震层的水平变形需求,然而该混合控制策略最大的缺陷在于需要很大的调谐质量。考虑到惯容装置具有明显的质量放大效应,本文提出将惯容装置(Inerter)与VTMD中的阻尼器并联,从而形成具有较小调谐质量的变化型调谐质量惯容阻尼器(VTMDI),并将其附加在基础隔震结构的隔震层,基于随机振动的分析框架开展了VTMDI参数的优化设计研究。研究表明直接将基础隔震结构的上部结构层间变形作为优化目标的传统优化策略并不经济有效。为此,本文提出了一种基于两步优化法的优化策略,该优化策略首先确保附加VTMDI的基础隔震结构相对于附加相同阻尼的基础隔震结构具有更优的控制效果;然后确保附加VTMDI的基础隔震结构的上部结构层间变形最小。通过动力时程分析结果表明:两种优化策略都能有效降低隔震层的水平变形和上部结构的层间变形,同时不会导致调谐质量出现过大的运动行程,基于两步优化法的优化策略更为经济有效。

预制式浮置板轨道隔振器/剪力铰设计参数优化研究

为减小列车通过板缝时车轨振动响应、提升预制式浮置板轨道减振性能,以某地铁预制式浮置板轨道为例,采用ABAQUS有限元软件建立列车-预制式浮置板轨道-隧道刚柔耦合动力学模型,计算预制式浮置板总支撑刚度恒定的条件下隔振器纵向间距2.4/1.8/1.2 m、横向间距1.84/1.64/1.44/1.24 m、剪力铰数量为3/4/5、布置形式为中置式/侧置式/上置式时车辆、浮置板轨道、隧道壁源强振动响应。通过对比分析各工况浮置板板端位移及隧道壁源强振动响应,提出了预制式浮置板隔振器布置、剪力铰布置的优化建议。研究结果表明:在预制式浮置板总支撑刚度恒定的情况下,适当增加隔振器的数量,可以降低浮置板板端位移,提高行车平稳性,同时不显著增加隧道壁源强振动。在1.24~1.84 m范围内,随着隔振器横向间距的增加,浮置板板端位移、隧道壁源强振动出现了先减少后增加的变化趋势,隔振器横向间距应存在一个最优值。随着预制式浮置板剪力铰数量的增加,浮置板板端位移和隧道壁源强振动均逐渐降低,但降低幅度亦有所下降,剪力铰对板端位移、源强振动的抑制作用应存在一个上限。在预制式浮置板轨道剪力铰数量不变的情况下,布置形式为上置式和侧置式时板端位移要小于中置式。研究成果为进一步优化预制式浮置板轨道的设计参数提供了参考依据。

航空弹性并车机匣模态分析与结构参数优化

针对某型航空并车机匣的模态共振问题,考虑航空机架弹性支承刚度,采用有限元法进行典型工况下约束模态分析,研究了并车薄壁机匣结构参数对约束模态固有频率的影响规律。结果表明优化支承位置是大幅度改变固有频率最有效的方式;当固有频率处在共振区间边缘时,可通过优化壁厚、筋板的方法小幅度调整。当2个支承位置位于机匣平面对称轴线时,固有频率最小且随支承距离减小而减小。随着薄壁厚度增大,1、3、5、6阶模态频率减小,2、4阶增大。1、3阶模态频率基本不受筋板参数的影响;2、4阶模态频率随筋板宽度、高度增大和宽高比减小而增大且4阶频率随筋板角度增大而增大;5、6阶模态频率随筋板角度增大、筋板宽度减小而增大。在此基础上,对弹性并车机匣的结构参数进行优化使固有频率避开共振区间,提高了机匣的抗振能力。

空调压缩机三点式橡胶隔振脚垫刚度优化与实验验证

针对某变频空调压缩机隔振系统性能不达标的问题进行优化设计,采用三点式隔振脚垫布置法搭建空调压缩机隔振系统模型,以橡胶隔振脚垫的刚度为关键优化参量,隔振系统固有频率及能量解耦率为优化目标,获取隔振脚垫刚度对隔振系统振动特性的影响规律及关键参量的最佳匹配方案,并通过隔振脚垫-压缩机系统振动特性测试验证方案的准确性。结果表明,优化后的压缩机橡胶隔振系统性能有较大提高,能够满足实际隔振需求。

地下动荷载作用下非饱和土地基中双层波阻板隔振性能研究

为了探究非饱和土地基中波阻板的隔振性能以及提升传统均质波阻板隔振的频宽。基于单相弹性介质理论和非饱和多孔介质理论,对地下动荷载作用下非饱和土地基中双层波阻板的隔振效果进行了研究。利用Fourier积分变换和Helmholtz矢量分解原理,建立了地下动荷载作用下非饱和土地基动力响应的计算列式。分析了双层波阻板各层弹性模量、密度、板厚、埋深、土体饱和度及荷载频率等物理力学参数对双层波阻板隔振性能的影响规律。研究结果表明:通过设计波阻板各层的弹性模量和密度可获得双层波阻板的最佳隔振效果,同等厚度下,双层波阻板的隔振效果要优于均质波阻板。双层波阻板提升了均质波阻板减振的频宽,其对低中高频振动(5 Hz≤f≤80 Hz)均有良好的隔振效果。双层波阻板的埋深越靠近振源处隔振效果越好,并且存在临界厚度,当波阻板厚度超过其临界厚度时,隔振效果随厚度的增大而减小。土体饱和度对双层波阻板隔振效果影响显著,在低饱和度时双层波阻板可以取得更好的隔振效果。

基于全寿命效费比的地铁上盖隔震(振)结构优化设计方法

隔震(振)技术是提升地铁上盖建筑抗震性能和舒适度的有效措施,优化此类结构设计方法具有现实意义和紧迫性。提出了适用于地铁上盖隔震(振)结构的全寿命效费比评估模型;采用基于结构响应的全寿命评估方法,研究了周期比、质量比、隔震层刚度及阻尼等关键结构参数对地铁上盖隔震(振)结构效益的影响;基于遗传算法提出了地铁上盖隔震(振)结构优化设计方法。研究结果表明:增加隔震层后结构地震损失主要集中于下部结构,上、下部结构质量比越大地震损失越小;上下部结构周期比越大,地震损失越小;隔振层刚度与隔振效益呈正相关;采用提出的优化算法对原型结构优化后,地震损失费用可减小30%,竖向振动加速度级可减小2 dB,验证了该方法的可行性。

汽车发动机悬置系统的隔振分析及优化设计

为提升汽车行驶过程中的舒适度,需保证汽车具有较好的隔振性能,因此,本文以汽车发动机悬置系统为例,研究汽车发动机悬置系统的隔振分析及优化设计。以该发动机悬置系统的实际参数为依据,进行汽车发动机悬置系统隔振性能解耦分析,并通过ADAMS软件,构建悬置系统仿真模型,获取悬置系统不同方向的解耦率结果,确定悬置系统隔振性能情况;并针对分析结果进行悬置系统设计优化。通过优化后的动刚度分析结果可知,优化设计后,发动机悬置系统的隔振性能满足标准需求。