综合离心环境试验技术研究进展

为了真实有效模拟航天飞行器的发射和再入环境,全面激发产品潜在的故障模式,需要发展综合离心环境试验技术。从环境耦合效应和试验技术研究两个方面,系统地总结了过载振动、过载温度、过载外压三种综合离心环境试验技术的研究进展,并对综合离心环境试验技术的工程应用和未来发展作了探讨与展望。     

仪器舱惯组支架角振动传递特性分析

大型的仪器舱角振动试验对试验能力提出了新要求,仿真计算十分必要。建立了仪器舱和惯组小系统的有限元模型,研究了惯组系统置于仪器舱支架上后角振动传递特性的变化规律,分析了线角交联响应特性。分析表明,放置于支架上的惯组角振动传递特性变得恶劣,而且线振动输入下交联响应较大。研究结论对于仪器舱角振动试验的实施具有很大价值。     

基于场路耦合方法的永磁同步电机温度场研究

针对永磁同步电机温度场精确求解问题,提出了一种场路耦合法来计算电机的温度场.以一台永磁同步电机为研究对象,利用MATLAB/Simulink搭建电机的控制策略,再通过有限元分析软件ANSYS Maxwell和ANSYS Simplorer搭建电机的二维电磁场模型和控制电路模型组成场路耦合模型.基于场路耦合模型计算电机的...     

涡轮冷却叶片参数化建模及多学科设计优化

建立了一个涉及结构、气动、传热、振动、强度和寿命等学科的涡轮冷却叶片多学科设计优化系统, 进行了单孔薄壁冷却叶片的多学科设计优化.提出了单孔薄壁冷却叶片的参数化造型方法, 叶片叶型采用5次多项式构造, 气动与传热为三维耦合分析;叶片体积平均温度与最高温度为优化目标, 强度、振动和寿命等学科相关参数为约束, 模拟退火与序列二次规划组合算法进行叶片参数空间寻优, 在保持冷却气体流量不变的条件下, 优化提高了冷却效果, 降低了叶片材料的性能要求.      

转子-滚动轴承-机匣耦合系统的不平衡-碰摩耦合故障非线性动力学响应分析

建立了含转子不平衡-碰摩耦合故障的转子-滚动轴承-机匣耦合动力学模型.在模型中,充分考虑了转子系统的不平衡和碰摩故障的耦合.对滚动轴承模型,充分考虑了轴承间隙、滚珠与滚道的非线性赫兹接触以及由滚动轴承支撑刚度变化而产生的VC(Varying compliance)振动.运用数值积分方法获取了系统响应,研究了系统的分叉与混沌运动,分析了旋转速度、碰摩刚度、转子偏心量,轴承座-机匣刚度以及机匣-基础刚度对系统响应的影响,得到了在转子不平衡和碰摩故障耦合下的转子-滚动轴承-机匣耦合系统动力响应规律.      

滚动轴承支承下的转子碰摩故障动力分析、特征提取与智能诊断

针对滚动轴承支承下的转子碰摩故障诊断问题,考虑滚动轴承非线性赫兹接触和轴承径向间隙,建立了含不平衡-碰摩耦合故障的转子-滚动轴承系统动力学模型.应用三维谱图分析碰摩诊断依据和确定频段特征,利用仿真数据获取结构最优的神经网络模型,并对试验碰摩故障数据进行诊断,识别率高达90%以上.计算结果充分表明了建立的动力学模型的有效性,同时,研究结果为有效结合故障机理分析与故障智能诊断提供了新的方法.      

Dynamic Response Analysis of Bird Strike on Aircraft Windshield Based on Damage-modified Nonlinear Viscoelastic Constitutive Relation

Damage-modified nonlinear viscoelastic constitutive equation and failure criterion are introduced and the three-dimensional incremental forms are deduced based on the updated Lagrangian approach. A simple tensile test model and a split Hopkinson pressure bar model are built to verify the accuracy of the subroutine implemented within the non-linear finite element program LS-DYNA. A numerical model of bird strike on windshield is established to study the responses of windshield under three different bird velocities at three sites. The bird is represented by a cylinder with a hemisphere at each end and the contact-impact coupling algorithm is used in this study. It is found that the implemented subroutine can properly describe the mechanical behavior of polymethyl methacrylate under low and high strain rates and large deformation, and can be used validly.     

Adaptive Control of Helicopter Ground Resonance with Magnetorheological Damper

The methodology for adaptive control of helicopter ground resonance with magnetorheological （MR） damper is presented. The adaptive inverse control method is used to control the output damping force of MR damper and the range of the damping force is given. Through the adaptive inverse control, the damping force of MR damper is fit to a desired damping force. With the background of applying MR damper to control of helicopter ground resonance, a model of loss force and an adaptive arithmetic for stabilization of the coupled rotor/fuselage system are presented. The simulation shows that the controller presented in this paper can stabilize the rotor/fuselage coupling system quickly and control the helicopter ground resonance effectively.     

A hazard analysis via an improved timed colored petri net with time–space coupling safety constraint

Petri nets are graphical and mathematical tools that are applicable to many systems for modeling, simulation, and analysis. With the emergence of the concept of partitioning in time and space domains proposed in avionics application standard software interface(ARINC 653), it has become difficult to analyze time–space coupling hazards resulting from resource partitioning using classical or advanced Petri nets. In this paper, we propose a time–space coupling safety constraint and an improved timed colored Petri net with imposed time–space coupling safety constraints(TCCP-NET) to fill this requirement gap. Time–space coupling hazard analysis is conducted in three steps: specification modeling, simulation execution, and results analysis. A TCCP-NET is employed to model and analyze integrated modular avionics(IMA), a real-time, safety-critical system. The analysis results are used to verify whether there exist time–space coupling hazards at runtime. The method we propose demonstrates superior modeling of safety-critical real-time systems as it can specify resource allocations in both time and space domains. TCCP-NETs can effectively detect underlying time–space coupling hazards.     

耦合的气动伺服弹性系统鲁棒稳定裕度估算

根据多输入－多输出控制系统理论，对飞行器耦合的气动伺服弹性系统进行了稳定裕度估算，耦合是在飞行器的横滚与偏航之间产生的，以闭环系统回差矩阵的奇异值理论作为估算方法的基础，应用鲁棒稳定性的充分条件，以某飞行器为例进行估算，得出飞行器在给定速度下保持稳定性的抵抗系统摄动的范围。