Flow reconstructions and aerodynamic shape optimization of turbomachinery blades by POD-based hybrid models

This study presented a hybrid model method based on proper orthogonal decomposition(POD) for flow field reconstructions and aerodynamic design optimization. The POD basis modes have better description performance in a system space compared to the widely used semi-empirical basis functions because they are obtained through singular value decomposition of the system.Instead of the widely used linear regression, nonlinear regression methods are used in the function response of the coefficients of POD basis modes. Moreover, an adaptive Latin hypercube design method with improved space filling and correlation based on a multi-objective optimization approach was employed to supply the necessary samples. Prior to design optimization, the response performance of POD-based hybrid models was first investigated and validated through flow reconstructions of both single-and multiple blade rows. Then, an inverse design was performed to approach a given spanwise flow turning distribution at the outlet of a turbine blade by changing the spanwise stagger angle, based on the hybrid model method. Finally, the span wise blade sweep of a transonic compressor rotor and the spanwise stagger angle of the stator blade of a single low-speed compressor stage were modified to reduce the flow losses with the constraints of mass flow rate, total pressure ratio, and outlet flow turning.The results are presented in detail, demonstrating the good response performance of POD-based hybrid models on missing data reconstructions and the effectiveness of POD-based hybrid model method in aerodynamic design optimization.

Combustion simulation and key parameter optimization for opposite axial piston engine in small-scale

As potential alternative power sources used in portable electric generators, opposite axial piston engines in small-scale were investigated to show their advantages in power density. A novel cylinder charge system was introduced, based on which a quasi-dimension model and a CFD(computational fluid dynamics) model were established. Comparison of those two models was carried out to validate the quasi-dimension model. Furthermore, optimal diameter of charge cylinder and speed were determined after evaluating the quasi-dimension model based on different parameters. High agreement between the quasi-dimension model and the CFD model validates the quasi-dimension model. Further studies show that the power of engine increases with the diameter of charge cylinder. However, a too big charge cylinder lowers the fuel efficiency instead. Taking economic influence into consideration the charge cylinder should be 1.4 times power cylinder, which could ensure the power density, volumetric efficiency and fuel economic at the same time. Axial piston engine running at 1.0×104 r/min could achieve a better overall performance. The maximal power of engine with optimal parameters is 0.82 k W, which fits the power need of the portable electric generators completely.

Fuzzy optimization of pneumatic half-floating slide ways

Dynamic modeling was carried on by combining the dynamic of machinery with composite triology, and the critical condition in which the ways would not produce composite-friction self-excited vibration was obtained. The movement regularity and characteristic of the airflow in exhaust gas slit were analyzed, and the relationship between pressure lost and geometry parameters of exhaust gas slit was obtained. A dynamic model and a mathematical model were established for pneumatic half-floating slide ways by combining the dynamics of machinery with hydrokinetics. The objective function for the optimization of slide ways was established based on the fuzzy optimization theory. The membership function of fuzzy constraint was deduced, the fuzzy constraint limit was established by amplification coefficient method, and the optimal value was resolved by the multilevel fuzzy comprehensive evaluation method. By combining the internal penalty function method with the variable metric method, the fuzzy optimization design program of ways was designed based on the Matlab platform. The validation was carried on by an example, and ideal results of fuzzy optimization design of slide ways were obtained.

MODELING, VALIDATION AND OPTIMAL DESIGN OF THE CLAMPING FORCE CONTROL VALVE USED IN CONTINUOUSLY VARIABLE TRANSMISSION

Associated dynamic performance of the clamping force control valve used in continuously variable transmission （CVT） is optimized. Firstly, the structure and working principle of the valve are analyzed, and then a dynamic model is set up by means of mechanism analysis. For the purpose of checking the validity of the modeling method, a prototype workpiece of the valve is manufactured for comparison test, and its simulation result follows the experimental result quite well. An associated performance index is founded considering the response time, overshoot and saving energy, and five structural parameters are selected to adjust for deriving the optimal associated performance index. The optimization problem is solved by the genetic algorithm （GA） with necessary constraints. Finally, the properties of the optimized valve are compared with those of the prototype workpiece, and the results prove that the dynamic performance indexes of the optimized valve are much better than those of the prototype workpiece.

Optimal Design and Dynamic Simulation of Mountain Bike with Rear Suspension

This paper investigates the dynamic design methodology of mountain bikes with rear suspension. Firstly, a multi-rigid body dynamic model of rider and mountain bike coupled system is constructed. The rider model includes 19 skeletons, 18 joints and 118 main muscles. Secondly, to validate the feasibility of the model, an experiment test is designed to reflect the real cycling status. Finally, aiming at enhancing the performance of the rider vibration comfort, the scale parameters of rear suspension are optimized with computer simulation and uniform design. The mathematical model in the vibration performance and the design variables is constructed with regression analysis. The result shows that when the length of side link is 90 mm, the length of connected rod is 336.115 1 mm and the included angle between absorber and side link is 60°, the mountain bike has better vibration comfort. This study and relevant conclusions are of practical importance to the design of the mountain bike＇s rear suspension system.

Research on the Infuence of Multiple Parameters on the Responses of a B-type Subway Train

To obtain improved comprehensive crashworthiness criteria for a B-type subway train,the infuence laws of the vehicle design collision weight M and empty stroke D on the train’s collision responses were investigated,and multiobjective optimization and decision-making were performed to minimize TS(total compression displacement along the moving train)and TAMA(the overall mean acceleration along the moving train).Firstly,a one-dimensional train collision dynamics model was established and verifed by comparing with the results of the fnite element model.Secondly,based on the dynamics model,the infuence laws of M and D on the collision responses,such as the energy-absorbing devices’displacements and absorbed energy,vehicles’velocity and acceleration,TS,TAMA and the coupling correlation efect were investigated.Then,surrogate models for TS and TAMA were developed using the optimal Latin hypercube method(OLHD)and response surface method(RSM),and multi-objective optimization was conducted using the particle swarm optimization algorithm method(MPOSO).Finally,the entropy method was used to obtain the weight coefcients for TS and TAMA,and multi-objective decision-making was performed.The results indicate that D and M signifcantly afect the compression displacements and energy absorption of the frst three collision interfaces,but have limited impact on the last three collision interfaces.The velocity versus time curves of vehicle M1 and M2 are shifted and parallel with diferent D.However,the velocity versus time curves of all the vehicles are shifted but gradually divergent with diferent M.The maximum collision instantaneous accelerations of the vehicles are directly determined by M,but are only slightly afected by D.Under the coupling efect,all concerned collision responses are strongly correlated with M;however,the responses are weakly correlated with D except for the compression displacement at the M2-M3 collision interface and the maximum collision instantaneous acceleration of vehicle M2.The comprehensive crashworthiness criteria of the B-type subway train were signifcantly improved after multi-objective optimization and decision-making.The research provides more theoretical and engineering application references for the subway train crashworthiness design.

印刷装备齿轮系统优化设计及动态特性研究综述

目的齿轮系统作为印刷装备核心子系统之一,其优化设计直接影响着印刷装备的动态特性,进而对印品质量产生重要影响,因此亟须对其研究进展进行综述。方法通过文献综述法,梳理总结印刷装备齿轮系统动力学建模方法、优化设计及动态特性,以及与印品质量之间的关系等方面的研究成果,归纳概括各研究方法及其适应性,并展望未来的研究方向。结果目前,针对印刷装备复杂齿轮系统精细化动力学建模方法及运行稳定性分析的研究相对匮乏,针对印刷装备齿轮传动系统、执行系统、结构系统动力学建模与优化设计中的耦合作用的研究相对较少,针对印刷装备复杂齿轮系统的动态特性与印品质量指标之间的关系规律的研究相对缺乏,这些将成为未来的研究重点。结论采用高精度多物理场仿真技术有望进一步对印刷装备齿轮系统进行精细化、复杂性建模,采用拓扑优化算法可以满足印刷装备齿轮系统高稳定性、高耦合性优化设计的需求,采用深度学习方法能够挖掘动态特性与印品质量评价指标的关联规律,可为高端印刷装备关键自主可控技术的研发攻关提供支撑。

缓冲行走一体式月面探测器性能分析与优化

针对缓冲行走一体式月面探测器将着陆缓冲与月面行走功能融为一体,导致设计优化困难的问题,提出一种综合考虑缓冲特性和行走特性的性能分析与优化方法。根据月面探测器着陆腿的功能需求,设计了构型为RUP-2RUPS的冗余自由度并联机构,并建立其参数化模型,该构型可通过运动副生效或失效实现缓冲和行走2种功能的构型切换。结合全因子实验方法分析月面探测器的两功能运动学特性与动力学特性,依据月面复杂着陆和行走工况,给出综合优化的目标函数和约束条件。在敏感度分析的基础上,利用随优化过程更新的全工况响应面模型与非劣排序遗传算法,完成月面探测器着陆腿构型参数的优化。所提方法在提高运算效率的同时,保证了每轮优化均能筛选出当前构型的最恶劣着陆工况,并计算其极限值。优化后,最大有效工作空间增加了8.7%,抗翻倒性能最小值提高了4.0%,抗底面触月性能最小值提高了0.2%,整体性能更优。

人机协同设计中的AI伦理决策模型:基于可解释性、公平性、责任感的均衡优化

人工智能在设计领域的应用引发了一系列伦理决策困境,如机器行为不可解释、算法偏见导致决策不公平、人机责任边界模糊等,为应对挑战,亟需构建兼顾可解释性、公平性与责任感的AI伦理决策模型。可解释性提升人机协同设计中的信任,公平性确保设计决策的正义,责任感促进人机共担,三者相互交织,形成AI伦理决策的“三位一体”。基于动态均衡理念,通过价值嵌入、多目标优化与人机交互,可构建面向人机协同设计的AI伦理决策模型,该模型立足三要素的动态权衡,针对不同情境进行差异化决策,体现从静态到动态、从单一到多元、从外在到内在的理论创新,它将在智能设计助手、自主化设计系统等场景中重塑设计价值取向,开拓设计伦理新维度,完善治理体系,提升伦理合规性,优化流程,创新范式,最终实现人机共生的设计伦理愿景。

小型船主机齿轮箱轴匹配设计优化方法探究

通过建立小型船主机齿轮箱轴系统的动力学模型,分析齿轮箱轴匹配设计的关键参数对系统动力学性能的影响规律。在此基础上,提出一种基于多目标优化算法的小型船主机齿轮箱轴匹配设计优化方法,并通过实例验证该方法的有效性和可行性。研究结果表明,所提出的优化方法可以有效提高小型船主机齿轮箱轴系统的动力学性能,为小型船主机齿轮箱轴匹配设计提供了一种新的思路。

Dynamic Analysis and Dimensional Synthesis of Easy-to-Protect Large-Load Robot for Extracting Fermented Grains

To improve the operation situation of difficulty and low efficiency in the extraction of fermented grains(FG),a high-load and large-workspace reclaiming robot for ceramic cylinder fermentation is designed,and a reclaiming effector is designed according to the operating characteristics.Firstly,the kinematics and singularity of the mechanism are analyzed.A multi-domain polar coordinate search method is proposed to obtain the workspace and the volume of the mechanism.Secondly,the dynamic modeling is completed and the example simulation is carried out.Thirdly,the motion-force transmission index of the mechanism is established.And based on the global transmissibility and the good-transmission workspace,the dimensional synthesis of the driving mechanism is completed by using the performance atlas-based method.Finally,aiming at the regular workspace size,stiffness and loading capacity,the Pareto optimal solution set of the executive mechanism dimension is obtained by using the multi-objective particle swarm optimization(MOPSO)algorithm.This paper can provide a theoretical basis for the optimal design and control of FG reclaiming robot.

动态水力旋流器结构参数的优选设计

简要描述了动态水力旋流器的结构组成及工作原理。在深入开展动态水力旋流器的分离机理和性能试验研究的基础上 ,进一步证实了只要合理地优化选取其结构参数 ,即可获得良好的分离效果。重点介绍了动态水力旋流器主要结构参数的优选设计过程 ,通过对油水分离用动、静态水力旋流器进行对比分析 ,进一步证实了动态水力旋流器在油水分离方面存在的优势。其成功研制为今后深入进行分离机理、流场测试及分离性能的研究奠定了基础 。

风力机行星齿轮传动系统动力学研究综述

风力机行星齿轮动力学研究对降低其振动和噪声、延长风力机使用寿命和提高运行可靠性具有重要意义。行星齿轮传动自由度多、结构复杂、非线性因素和内部激励丰富,而且风力机外部激励复杂,国内外学者已对其进行较为广泛、深入的研究。从系统建模、动力学方程求解、动力学特性分析、动力学优化设计等方面系统评述国内外学者对行星齿轮系统动力学的研究现状,从固有特性、参数稳定性、非线性动态响应等方面详细介绍动力学特性的研究进展,其中齿侧间隙、轴承间隙和齿面摩擦等是现有研究关注较多的非线性因素。根据风力机行星齿轮系统的工作环境和行星齿轮动力学研究的发展趋势,给出了风力机行星齿轮系统需要深入研究的方向。

一种应变式六维力传感器的动态设计

以欧拉—伯努利梁的动力学为基础,建立十字梁六维力传感器的动力学模型,以该动力学模型为基础分析传感器各个方向的固有频率,探讨传感器的动态设计问题,并探讨了传感器维间耦合的本质关系。用有限元分析方法证实了建立的解析模型的有效性,传感器的解析模型可以作为传感器主动设计和优化设计的依据。

大功率风电增速器的多目标优化设计

针对风电增速器的动态性能优化问题,以某型号大功率风电增速器齿轮传动系统为研究对象,采用双参数威布尔分布函数作为随机风速来模拟随机风速下的外部激励,依据集中质量法及牛顿第二定律建立了两级行星一级平行轴的大功率风电增速器动力学模型,研究其传动系统的动力学特性。在此基础上,以传动系统体积最小和构件扭转振动加速度振动幅值最小为优化目标,以可靠性和强度等为约束条件进行多目标动态优化设计,优化结果表明:优化后的风电增速器齿轮传动系统不仅实现了轻量化,而且在保证系统可靠度的前提下动态性能也得到了有效改善,达到了减振降噪的目的。

炼钢组炉问题优化模型及其动态规划算法

针对炼钢组炉计划编制中的集约优化问题,建立了各优化目标下的数学模型,并利用动态规划法,对该优化问题进行了求解.经算法时间复杂性分析和实际生产数据仿真演算,结果表明在一定的生产条件下,该算法能在合理的时间范围内给出一批合同最优的组炉方案,使得生产余材最小,可显著降低组炉计划余材量,经济效益非常显著.

基于Kriging模型的汽轮机基础动力优化设计

随着汽轮机容量的增加和核电站的迅速发展,汽轮机基础动力优化设计已经成为世界前沿的研究课题。本文提出一种基于Kriging模型的有效优化方法,用以求解上述动力优化设计问题。该问题的优化模型是在汽轮机基础框架重量约束条件下,优化汽轮机基础中柱的位置和梁、柱的截面面积,使基础振动的最大幅值最小化。Kriging模型用于建立基础振动的最大动位移幅值与设计变量间的近似函数关系,从而避免了优化迭代中灵敏度分析。开发了动力分析程序,作为黑箱用于动力响应分析。算例结果表明,本文方法在效率和稳定性上优于序列线性规划方法。

超声切割刀动力学分析和结构优化设计

为定性地分析一种超声切割刀的结构因素对其纵振模态的影响规律,并优化其结构设计,首先建立了超声切割刀的动力学模型,由其得到结构的一阶纵振模态解析解,据解析解计算的振动频率结果(52.5kHz)与ANSYS计算结果(52.3kHz)以及实验结果(53.5kHz)相吻合;然后建立了该超声切割刀结构优化设计的数学模型;最后根据该模型,设计了一套结构优化程序,并借助MATLAB的GUIDE工具完成了人机交互优化界面的开发。优化后的切割刀节面位置与夹持件中心位置偏差约为1μm,切割刀刀头处的振幅提高约27%。

基于灵敏度分析与优化设计原理的大跨桥梁动力模型修正

建立一个满足工程精度要求、反映桥梁力学特性的有限元模型是进行结构健康监测研究的第一步。根据大跨桥梁现场实测的模态数据,采用基于特征灵敏度的优化设计方法对润扬长江大桥斜拉桥进行了模型修正,分析结果为大跨桥梁的结构损伤识别和安全监测工作提供了一定的依据。

主轴单元参数化建模、分析与优化设计

为实现主轴单元静动态特性的快捷分析,本文提出了主轴单元有限元建模基本参数的概念,建立了主轴单元通用有限元简化模型。以某厂新型五面体加工中心主轴单元为研究对象,利用简化模型得到了主轴单元的静刚度和前十阶模态。与简化前的分析结果比较,证明了简化模型的正确性。分析了不同轴承预紧工况下前两阶固有频率的变化,通过对主轴单元进行动态优化设计,使一阶固有频率提高了32.2%,主轴重量减少了42.9%。