疲劳寿命计算中钉孔填充作用系数的取值研究

使用液压伺服疲劳试验机,在程序块载荷谱作用下对铆接铝合金薄壁纯弯梁进行了疲劳寿命试验,并给出了疲劳寿命试验结果。采用应力严重系数法对该纯弯梁进行了疲劳寿命计算。通过对试验结果和计算结果的对比分析及研究,给出了采用应力严重系数法计算铆接薄壁结构疲劳寿命时的钉孔填充作用系数的合理选用值。     

双转子系统碰摩有限元接触分析模型及故障诊断

针对常用碰摩力模型的不足,应用AN SY S软件在求解转静子之间的碰摩力与法向相对位移之间的关系的基础上得到了碰摩力模型,并与整体传递系数法相结合建立转静件碰摩的动力学方程。采用整体传递系数法计算转子系统的动力特性,进而求解双转子系统的瞬态响应。利用时域波形、频谱分析和小波变换对响应进行了分析,得出并分析了相关的故障特征。      

TC9钛合金拉削加工性与表面完整性的试验研究

 本文介绍了用P18、M2Al、M42等三种高速钢拉刀低速拉削TC9钛合金时的刀具磨损、拉削表面完整性同拉削工艺条件的关系,同时也探讨了用H19硬质合金拉刀高速拉削TC9钛合金的可能性;并比较了两种拉削条件下的刀具磨损和表面完整性状况;分析了为提高钛合金拉削的表面完整性所应采取的措施。     

航空发动机转速数控系统的动态模拟研究

本文介绍航空发动机转速数控系统的动态实时模拟研究,包括微机内控制算法的设计,高频干扰信号对系统稳定工作的影响,超转和溢出故障的处理等内容。通过模拟试验,得出了一些有益的结论。      

管接头的热镦挤抽芯成型

过去金属材料管接头一般采用铸造、锻造和挤压工艺制造。本文介绍了一种新的工艺方法—热镦挤抽芯成型,并对其工艺和模具设计作了详细的论述。     

畸变对航空发动机稳定性的影响

简要地总结和对比了畸变对航空发动机稳定性影响的研究方法。以某型涡扇发动机稳定性数值计算为例,具体分析了进口动态压力畸变对发动机稳定性的影响,其计算结果与实际情况和理论分析基本一致。论证了数值计算作为一种指导和验证手段在工程应用中的重要作用。     

自组织神经网络航空发动机气路故障诊断

 为克服学习样本依赖于发动机精确模型的问题,提出了一种基于自组织神经网络的发动机智能故障诊断的方法,并运用故障特征提取的数据预处理方式,成功地对航空发动机气路部件的几种典型故障做出正确诊断。为验证网络的抗噪性能,引入了自联想神经网络。研究表明,自组织网络可以脱离发动机模型,并且对测量噪声有良好的鲁棒性,能基本满足航空发动机故障诊断的要求,具有较好的工程应用前景。     

Uncertainty analysis and design optimization of hybrid rocket motor powered vehicle for suborbital flight

In this paper, we propose an uncertainty analysis and design optimization method and its applications on a hybrid rocket motor(HRM) powered vehicle. The multidisciplinary design model of the rocket system is established and the design uncertainties are quantified. The sensitivity analysis of the uncertainties shows that the uncertainty generated from the error of fuel regression rate model has the most significant effect on the system performances. Then the differences between deterministic design optimization(DDO) and uncertainty-based design optimization(UDO) are discussed. Two newly formed uncertainty analysis methods, including the Kriging-based Monte Carlo simulation(KMCS) and Kriging-based Taylor series approximation(KTSA), are carried out using a global approximation Kriging modeling method. Based on the system design model and the results of design uncertainty analysis, the design optimization of an HRM powered vehicle for suborbital flight is implemented using three design optimization methods: DDO, KMCS and KTSA. The comparisons indicate that the two UDO methods can enhance the design reliability and robustness. The researches and methods proposed in this paper can provide a better way for the general design of HRM powered vehicles.In this paper,we propose an uncertainty analysis and design optimization method and its applications on a hybrid rocket motor(HRM)powered vehicle.The multidisciplinary design model of the rocket system is established and the design uncertainties are quantified.The sensitivity analysis of the uncertainties shows that the uncertainty generated from the error of fuel regression rate model has the most significant effect on the system performances.Then the differences between deterministic design optimization(DDO)and uncertainty-based design optimization(UDO)are discussed.Two newly formed uncertainty analysis methods,including the Kriging-based Monte Carlo simulation(KMCS)and Kriging-based Taylor series approximation(KTSA),are carried out using a global approximation Kriging modeling method.Based on the system design model and the results of design uncertainty analysis,the design optimization of an HRM powered vehicle for suborbital flight is implemented using three design optimization methods:DDO,KMCS and KTSA.The comparisons indicate that the two UDO methods can enhance the design reliability and robustness.The researches and methods proposed in this paper can provide a better way for the general design of HRM powered vehicles.     

基于误码率准则的窄带干扰抑制算法性能分析

采用有效的窄带干扰抑制技术,可极大地改善扩频通信系统的性能.首先详细介绍了频域干扰抑制算法的基本思想,给出了算法实现的模块框图;其次具体分析了算法实现的关键技术：重叠加窗,背景噪声估计,干扰门限确定及干扰消除策略;最后以误码率作为干扰消除算法性能的评判标准,仿真分析了频域窄带干扰抑制技术中干扰强度、干扰频带宽度、干扰频率位置、干扰消除门限、陷幅值、加窗重叠度等因素对系统误码率的影响,为在不同条件下算法最佳参数的选取提供了依据.仿真结果表明：当干扰消除门限值取4aF,陷幅值取2σF～6σF,加窗重叠度为50％时,该算法可获得最佳抗干扰性能.     

电脉冲除冰系统除冰激励的简化与影响因素

首先建立了电脉冲除冰系统的电路模型,求解了有无二极管条件下的理论脉冲电流曲线,通过分析计算电流与实验电流,提出了将正弦半波电流函数用于电磁场分析以简化研究除冰激励的观点,同时求解了不同电流方式下的电磁压力分布,再用结构动力学分析了不同压力载荷下实验铝板的响应位移。其次通过比较铝板中心位移实验值与动力学求解的响应位移值,其有效的吻合程度验证了用正弦半波函数电流简化电脉冲除冰激励分析的可行性。最后,在利用正弦半波电流函数简化分析脉冲激励的基础上,研究了电流大小、电频率、铝板厚度、铝板弹性模量、铝板密度以及铝板长宽比对最大响应位移的影响。研究结果表明,最大响应位移随电流增大而增大,随铝板厚度、弹性模量与密度的增大而减小,且随电频率的改变而改变,但几乎不受铝板长宽比的影响;在研究电频率时得出,可将电频率与系统结构固有频率以1:1的比例设计,此关系式是电脉冲除冰系统电路设计的基础。