涡轮泵长程寿命的模糊可靠性设计和评估

根据涡轮泵的主要失效模式,建立了涡轮泵模糊可靠性设计方法。即对各部件进行模糊可靠性分配,再对涡轮叶片静强度、转子工作转速、转子轴疲劳强度、端面密封及轴承进行模糊可靠性设计,从而获得涡轮泵整机的可靠度。此处基于涡轮泵寿命服从威布尔分布,用模糊可靠性理论推导出涡轮泵长程寿命的可靠性评估公式。实例验算表明,评估值与预估值一致,设计与评估方法可行。     

涡轮泵转子次同步进动的机理

阐明次同步进动的发生机理和特征,讨论内阻尼（材料内阻尼、结构阻尼）、干摩擦、气弹效应、动压密封等诱发次同步进动的因素和消除次同步进动的措施。     

压电类智能梁元的优化布局

分别对具有无限小长度驱动器的悬臂和简支智能梁的一阶模态和二阶模态进行了具体的分析和计算,确定了驱动器在梁元中的最优布局,总结了有关驱动器在梁元中布局的一些基本性质,并从解析的角度对驱动器的最优布局点给予解释.由于以上有关驱动器最优布局的分析是在忽略驱动器的长度的假设基础上进行的,所以又对有限长度的驱动器的布局问题进行了初步的探讨.     

交流光伏水泵系统控制策略

光伏水泵系统具有无污染、全自动等优点,且应用的场合较多,为此设计了一种以TMS320F28335为主控制器的光伏水泵控制系统。控制系统中的三相异步电机调速部分采用基于空间矢量脉宽调制(SVPWM)方式的变压变频(VVVF)控制,最大功率点跟踪部分采用恒定电压法(CVT)和扰动观察法结合最大功率点跟踪(MPPT)技术。试验结果表明系统实现最大功率点跟踪并稳定运行。     

双泵电静液作动器控制研究

功率电传技术是未来全电飞机发展须攻克的难点,其中具有集成化优势的小型高效电静液作动器是功率电传技术领域的一项重要内容。智能材料驱动的电静液作动器由于具备集成度高、能量密度大、响应快、精度高等优势,已逐步成为电静液作动器的主流发展方向之一。本文针对一种双压电泵驱动、电机配流的封闭式电液作动器,从驱动幅值、频率、相位3个控制维度出发,提出幅相控制、频相控制与纯相控制3种控制方法。试验证明,幅相控制与纯相控制误差低于频相控制,当该作动器在跟踪 0.5 Hz 频率、7.5 mm 峰峰值的正弦目标位移时,幅相控制和纯相控制的均方根误差分别为0,09 mm 与1.101 mm,相对低于频相控制时的0.169 mm。文中所提出的3种控制方法均可实现双泵电静液作动器的伺服控制,但幅相控制和纯相控制方法的控制精度优于频相控制。     

基于Virtual.Lab的燃油泵调节器结构的模态分析

在燃油泵调节器模态分析过程中,高集成装配体的模型简化和以螺钉连接为主的多种连接方式的有限元建模对分析结果的影响是一个难点.本文从实际工程应用角度出发,提出了关键子结构验证结合整体有限元建模的模态分析方法.首先,根据燃油泵调节器的结构特点对模型进行简化和网格处理;然后,开展了关键子结构壳体模态的仿真分析和实验测试,并在V...     

Analysis of the cylinder block tilting inertia moment and its effect on the performance of high-speed electro-hydrostatic actuator pumps of aircraft

Electro-hydrostatic actuator (EHA) pumps are usually characterized as high speed and small displacement. The tilting inertia moment on the cylinder block produced by the inertia forces of piston/slipper assemblies cannot be ignored when analyzing the cylinder block balance. A large tilting inertia moment will make the cylinder block tilt away from the valve plate, resulting in severe wear and significantly increased leakage. This paper presents an analytical expression for the tilting inertia moment on the cylinder block by means of vector analysis. In addition, a high-speed test rig was built up, and experiments on an EHA pump prototype were carried out at high speeds of up to 10,000 r/min. The predicted nature of the cylinder block tilt at high speeds corresponds closely to the witness marks on the dismantled EHA pump prototype. It is suggested that more attention should be given to the tilting inertia moment acting on the cylinder block of an EHA pump since both wear and leakage flow between the cylinder block and the valve plate are very much dependent on this tilting moment.     

Effects of splined shaft bending rigidity on cylinder tilt behaviour for high-speed electro-hydrostatic actuator pumps

High-speed axial piston pumps are hydraulic power supplies for electro-hydrostatic actuators(EHAs). The efficiency of a pump directly affects the operating performance of an EHA, and an understanding of the physical phenomena occurring in the cylinder/valve plate interface is essential to investigate energy dissipation. The effects of the splined shaft bending rigidity on the cylinder tilt behaviour in an EHA pump need to be considered, because the deflection and radial expansion of a steel shaft rotating at a high speed cannot be ignored. This paper proposes a new mathematical model to predict the cylinder tilt behaviour by establishing a quantitative relationship between the splined shaft deflection, the cylinder tilt angle, and the tilt azimuth angle. The moments exerted by the splined shaft are included in the equilibrium equation of the cylinder. The effects of solid and hollow splined shafts equipped in an EHA pump prototype are compared at variable speeds of 5000–10,000 r/min. With a weight saving of 29.7%, the hollow shaft is experimentally found to have almost no influence on the volumetric efficiency, but to reduce the mechanical efficiency by 0.6–2.4%. The results agree with the trivial differences of the simulated central gap heights of the interface between the two shafts and the enlargement of the simulated tilt angles by the hollow shaft. The findings could guide designs of the cylinder/valve plate interface and the splined shaft to improve both the efficiency and power density of an EHA pump.     

柔性自适应桁架及其振动最优控制实验

基于dSPACE系统和所研制的锆钛酸铅(PZT)压电作动器,建立了第一阶频率低达5Hz的三棱柱自适应桁架实验平台,通过有限元建模和实验参数修正,利用异位加速度反馈信号进行了线性二次型Gauss(LQG)最优反馈控制实验和仿真.结果表明:对比无控状态,采用最优控制只需很小控制电压,可使桁架在低阶典型频率激励下的振幅降低90%以上;而当桁架受扰动后,振动衰减时间减少超过80%;验证了实验平台配置的合理性和所研制的PZT压电作动器、控制模型的有效性;控制数值仿真与实验在加控前后振幅抑制程度相同,控制仿真与实验中振幅衰减过程的差别通过激振过程仿真与实验的对比得到了阐明.     

Structural Design and Control Strategy Analysis of Micro/Nano Transmission Platform

A fully flexure micro/nano transmission platform(MNTP)which has five degrees of freedom is designed on the basis of bridge type amplification mechanism.According to the kinematic theory and the elastic beam theory,the theoretical output displacement equation of the platform is derived,and then piezoelectric actuator(PZT)is calibrated.Meanwhile,a full closed-loop control strategy of the platform is established using the feedforward proportional-integral-derivative(PID)compound control algorithm based on the Preisach model.Moreover,the total transfer function of the micro positioning system is derived,and the calculation method of output signal is acquired.Finally,the theoretical output displacement is verified by finite element analysis(FEA)and positioning experiments.