接口前处理在光机系统动力学分析和面形优化中的应用

为了解决光机系统动力学分析与面形优化过程中由于光机接口程序后处理方式所引起的计算数据量大或接口处理失效的问题,提出将光机接口处理过程移到有限元前处理中,并进行了光机系统的集成分析与优化。首先,为了解决标准Zernike多项式在环形离散点域内的非正交性,引入了节点面积加权因子和环域Zernike多项式。提出了通过对镜面施加均匀压强求节点支反力的方式求取节点面积加权因子的计算方法。然后采用最小二乘法推导出镜面刚体位移和拟合镜面变形的Zernike多项式系数与镜面各节点变形量之间的线性关系式。最后,编写接口程序将这些线性表达式以多点约束(MPC)的方式导入到有限元模型中,在前处理过程中完成系统的光机接口处理过程。通过对非稳态风载引起的某1.2m地基望远镜视轴抖动和液压whiffletree支撑下的主镜镜面高阶变形量进行结构动力学随机响应分析,验证了光机前处理方法对解决光机系统动力学问题的有效性。此外,还以镜面面形为优化目标对1.2m轻量化主镜的镜体结构和尺寸进行敏感度分析,证明了光机前处理方法可以有效地简化镜面面形的优化分析过程。

面向系统性能最大化的装备经费结构SD优化

为通过在装备的各组成单元之间,对装备的研制经费实施最优分配,继而获得最大化的装备整体作战使用能力的现实需求,选择由锅炉、主汽轮机、主冷凝器、汽轮给水泵等4个基本单元组成的船舶蒸汽动力系统为对象,运用系统动力学(system dynamics,SD)方法,建立各项费用与动力系统总体性能之间的关系模型,并转化为SD仿真平台上的动力系统各设备经费结构优化模型。经过系统分析和对照仿真结果,找出费用在动力系统中各个设备之间分配的特殊规律,在功率既定情况下,确定动力系统费用的最小值以及在各个设备之间的最优分配结构,形成基于SD理论、面向系统性能最大化,在装备组成单元层面开展经费结构优化的方法。

我国体育产业结构优化多驱动路径的仿真研究

运用系统动力学研究方法,建立了体育产业结构优化动力系统模型,对不同优化路径进行仿真,对比不同的优化路径与我国体育产业支柱型产业目标、体育产业就业人数增长的目标契合程度,旨在探索当前我国体育产业结构优化较为科学的路径模式。研究表明,在产业部门发展导向层面,体育产业结构的优化过度追求某一产业部门“比重”,会造成产业发展空间与资源被挤压、体育资源的不合理流动,弱化结构效益的转换。各产业均衡协调发展是最佳路径选择,可以实现体育产业结构优化的目的,而且有利于完成“体育产业成为国民支柱产业”指标任务和达到稳定就业的目标。从产业要素驱动的层面,体育资源配置型优化路径更值得关注,既保证了产业结构效益产出的效率,又充分满足社会效益要求。

某型汽车麦弗逊悬架的ADMAS/Car优化设计

汽车的悬架系统是多个刚体与柔性体相结合的多部件体系统,各部件之间的运动关系复杂。在动力学仿真软件ADMAS/Car模块中建立该车型的麦弗逊悬架系统模型,对悬架的各参数进行优化仿真计算,并根据仿真数据提出相应的优化方案,为实车试验提供一定的理论基础。

Novel sensitivity analysis method and dynamics optimization for multiple launch rocket systems

This study establishes the launch dynamics method,sensitivity analysis method,and multiobjective dynamic optimization method for the dynamic simulation analysis of the multiple launch rocket system(MLRS)based on the Riccati transfer matrix method for multibody systems(RMSTMM),direct differentiation method(DDM),and genetic algorithm(GA),respectively.Results show that simulation results of the dynamic response agree well with test results.The sensitivity analysis method is highly programming,the matrix order is low,and the calculation time is much shorter than that of the Lagrange method.With the increase of system complexity,the advantage of a high computing speed becomes more evident.Structural parameters that have the greatest influence on the dynamic response include the connection stiffness between the pitching body and the rotating body,the connection stiffness between the rotating body and the vehicle body,and the connection stiffnesses among 14^(#),16^(#),and 17^(#)wheels and the ground,which are the optimization design variables.After optimization,angular velocity variances of the pitching body in the revolving and pitching directions are reduced by 97.84%and 95.22%,respectively.

Prediction and optimization of aerodynamic noise in an automotive air conditioning centrifugal fan

The high aerodynamic noise induced by automotive air conditioning systems has important effects on the ride comfort, and the centrifugal fan is the largest noise source in these systems. It is very important to reduce the aerodynamic noise generated by the centrifugal fan. The flow field and the sound field on the whole centrifugal fan configuration have been carried out using the computational fluid dynamics. Simulation results show that the sound pressure level near the outlet of the centrifugal fan is too high. Based on the relationship between flow characteristics and the aerodynamic noise, four parameters of the centrifugal fan, i.e., impeller blade＇s outlet angle 0, volute tongue＇s gap t, collector inclination angle fl, and rotating speed n, were selected as design variables and optimized using response surface methodology. While keeping the function of flow rate unchanged, the peak noise level is reduced by 8 dB or 10.8%. The noise level is satisfactorily reduced.

Structural Dynamic Optimization for Flexible Beam of Helicopter Rotor Based on GA

As one of the most important steps in the design of bearing-less rotor systems,the design of flexible beam has received much research attention.Because of the very complex working environment of helicopter,the flexible beam should satisfy both the strength and dynamic requirements.However,traditional optimization research focused only on either the strength or dynamical characteristics.To sufficiently improve the performance of the flexible beam,both aspects must be considered.This paper proposes a two-stage optimization method based on the Hamilton variational principle:Variational asymptotic beam section analysis(VABS)program and genetic algorithm(GA).Consequently,a two-part analysis model based on the Hamilton variational principle and VABS is established to calculate section characteristics and structural dynamics characteristics,respectively.Subsequently,the two parts are combined to establish a two-stage optimization process and search with GA to obtain the best dynamic characteristics combinations.Based on the primary optimization results,the section characteristics of the flexible beam are further optimized using GA.The optimization results show that the torsional stiffness decreases by 36.1%compared with the full 0°laying scheme without optimization and the dynamic requirements are achieved.The natural frequencies of flapping and torsion meet the requirements(0.5 away from the passing frequencies of the blade,0.25 away from the excitation force frequency,and the flapping and torsion frequencies keep a corresponding distance).The results indicate that the optimization method can significantly improve the performance of the flexible beam.