航空液压管路支架参数灵敏度分析及优化

为解决航空液压系统高速高压化发展带来的航空液压管路振动加剧问题,将液压管路与管路支架视为整体振动系统。基于灵敏度分析方法,采用ANSYS软件平台中的灵敏度分析工具,分析航空液压管路支架参数对振动响应的灵敏度;在灵敏度分析结果基础上,采用基于Pareto最优的多目标遗传算法对管路支架参数进行优化设计,得到振动控制效果更好的管路支架布局,形成一种有效的航空液压管路被动振动控制参数优化方法。为控制航空液压管路振动、推动国产大飞机发展提供理论和技术基础。     

火炮身管边界条件对其横向振动的影响

针对火炮身管振动对射击精度的影响问题,分析了射频对身管振动的激励作用,提出了通过改变身管边界约束条件进而改变身管振动特性的方法,建立了身管固有频率对支撑位置变化的1阶灵敏度模型。并以某小口径身管为研究对象,运用该模型对支撑位置进行优化搜索,最终从频率和振型两方面确定了炮口横向振动响应最小的最优支撑位置。试验结果表明该方法改善了身管的振动特性,提高了火炮连发射击的立靶密集度。     

航空发动机液压管路振动环境实验测试系统设计

为了深入研究航空发动机液压管路的振动情况,开发出模拟航空发动机液压管路振动环境的实验测试系统。该实验测试系统由液压动力单元、信号采集与控制单元、基础环境激振单元三部分组成。其中基础环境激振单元的引入,使之模拟了航空发动机液压管路安装机匣振动的情况,较好的复现航空发动机液压管路的实际振动环境。实验表明,该实验测试系统能够实现液压管路的振动特性检测,为深入研究航空发动机液压管路系统耦合振动提供实验基础。     

往复压缩机气流脉动及管道振动分析

为了提高大型往复压缩机管路系统运行的可靠性、安全性,基于转移矩阵的声学模拟分析方法,将机械领域的谐振问题转化为声学领域的问题,并借助CAESAR II分析软件建立工艺管道系统的数学模型,对复杂管系进行模拟分析,以获得整个工艺管系的振动特征和稳态动力响应特性。经过多年长期深入研究,探求出新的、更准确的压缩机组管道系统脉动及振动分析方法技术。该技术在解决很多实际压缩机工程振动问题时,获得良好的效果,同时也证明了这种方法技术对于解决复杂管系振动问题的有效性。     

基于多尺度模型的航空管接头密封状态影响分析

作为连接液压管路和密封管路内的高压流体的重要部件,航空管接头的可靠性和稳定性至关重要。为了更加准确地理解和分析材料参数对航空管接头密封状态的影响规律,基于管接头实际粗糙表面建立多尺度有限元接触模型,研究材料属性对管接头密封状态影响规律。结果表明：基于实际粗糙度的多尺度有限元模型可以更加准确反映出密封接触状态;当卡套材料屈服强度小于管路材料屈服强度时,管接头密封接触面积变化较小,管接头密封区域密封接触压力值随屈服强度增大而增大;当卡套材料屈服强度大于管路材料屈服强度时,管接头密封接触面积减小,对应管接头密封接触压力分布没有形成良好密封状态,即卡套材料屈服强度的选择应接近管路材料屈服强度,进而获得最佳的管接头密封状态。     

航空发动机管路调频方法研究

基于航空发动机的结构特点,运用有限元方法,通过计算机仿真,分析了复杂管路系统的结构振动,得到了管路的固有频率分布以及直观的振型特征.根据管路的结构特点,对管路进行了结构模式的分类.基于每种结构模式选取了影响管路动态特性的主要结构参数,并分析了其影响的规律.通过实际应用调频方法,验证了该方法的有效性.     

利用调谐质量阻尼器进行管路系统减振

对既成管系存在的振动进行了减振研究。考虑到既成管线增加额外支撑的困难,设计了可拆分的环形调谐质量阻尼器结构,建立管系实验装置并进行模拟计算。分析了在有、无调谐质量阻尼器时实验管系振动在时域和频域的情况,并进行了实验验证。结果表明,设计的调谐质量阻尼器可大幅减缓管系的稳态振动和快速衰减管系的瞬态振动,是一种有效、实用的管系减振手段。     

航空发动机液压弯管振动特性影响因素试验研究

针对航空发动机液压弯管振动情况的特殊性及其复杂的工作环境,利用试验测试及仿真的方法研究航空弯管结构参数对其流固耦合振动特性的影响。研究结果表明:对于不锈钢液压弯管随着内表面粗糙度降低,管路振动幅度和噪声明显降低,而铝合金弯管利用磁力研磨加工后其振幅和噪声变化不显著,同时验证了不锈钢硬质材料的航空液压弯管内表面在经磁力研磨加工前后其固有频率均高于铝合金弯管的固有频率,并且液压弯管的角度、长度等因素在软硬质材料中均对弯管振动特性产生明显的影响。     

液压管路系统可靠性设计与研究

目前国内外对液压管路系统冲击振动的可靠性设计研究尚处于初级阶段,液压元件及液压系统的可靠性定量研究尚不完善。该文基于液压管路随机参数数值特征,采用概率统计理论与随机扰动法对液压系统冲击振动进行可靠性设计。针对管路液压冲击瞬时脉冲压力,建立了可靠性分析模型,并提出了可靠性优化设计方法。该方法可准确反映液压管路系统的固有可靠性,解决液压系统实用性和有效性优化设计中的可靠性问题,加强了对液压系统可靠性的定量研究。     

船舶管系安装检验要点分析

船舶管系是船舶机体中的重要组成部分,也是正常运转的"血管",各种用途的管路,能够保证船舶机械设备正常工作,管系安装涉及管路较多,而且走向复杂,对管系安装检验工作显得尤为重要。为此,针对船舶管系安装检验要点进行了浅显探讨。     

随机振动载荷作用下航空液压管路疲劳寿命数值预估

液压管路作为飞机液压传动系统的重要组成部分,是飞机安全飞行的重要保障。由于飞机飞行环境的复杂性,随机振动载荷下的疲劳分析是飞机液压管路动力学设计的重要手段。选取大型客机C919左侧机翼的一段典型液压管路作为研究对象,应用ABAQUS有限元软件进行随机振动响应分析,获取随机振动载荷下的应力响应功率谱密度函数,对液压管路在随机振动载荷下的强度特性进行分析,结合S-N曲线对管路结构危险部位疲劳寿命进行预估,为航空液压管路的设计及优化提供了理论参考。     

液压/燃油管道系统的管径及其支撑的动力优化设计

建立了有、无弹性刚度支撑的液压/燃油管道系统,采用了动力优化的有限元分析方法,分析了在一个频率约束下以质量最轻为目标的管道系统,得出了管径、支撑刚度和固有频率的定量关系,提出了防止管道系统强迫共振的方法,最终为管道系统的安全性指导和设计提供了理论依据。     

Reliability Design for Impact Vibration of Hydraulic Pressure Pipeline Systems

The research of reliability design for impact vibration of hydraulic pressure pipeline systems is still in the primary stage,and the research of quantitative reliability of hydraulic components and system is still incomplete.On the condition of having obtained the numerical characteristics of basic random parameters,several techniques and methods including the probability statistical theory,hydraulic technique and stochastic perturbation method are employed to carry out the reliability design for impact vibration of the hydraulic pressure system.Considering the instantaneous pressure pulse of hydraulic impact in pipeline,the reliability analysis model of hydraulic pipeline system is established,and the reliability-based optimization design method is presented.The proposed method can reflect the inherent reliability of hydraulic pipe system exactly,and the desired result is obtained.The reliability design of hydraulic pipeline system is achieved by computer programs and the reliability design information of hydraulic pipeline system is obtained.This research proposes a reliability design method,which can solve the problem of the reliability-based optimization design for the hydraulic pressure system with impact vibration practically and effectively,and enhance the quantitative research on the reliability design of hydraulic pipeline system.The proposed method has generality for the reliability optimization design of hydraulic pipeline system.     

页岩气井下开采管路气固耦合振动特性分析

页岩气开采过程中,井下管路内气体与管路的耦合作用,会引起管路振动,这是此类管路振动失效的主要原因。管路振动响应特性与井下管路长度、气体流速及压力等参数有直接关系,因此,研究这些参数的影响对揭示页岩气管路振动规律,提高井下管路安全性及寿命有重要意义。针对页岩气井下管路,在ADINA软件平台中建立有限元分析模型,进行振动模态分析,研究管路长度、气体流速及压力对管路气固耦合振动特性的作用规律。研究结果为页岩气井下管路振动实验研究提供理论指导,同时为气固耦合振动特性研究奠定基础。     

多尺度能量熵与优化极限学习机的航空液压管路故障诊断方法

针对航空液压管路故障特征难以提取问题,考虑到航空液压系统中振动信号存在非平稳性以及非线性等特点,提出了一种基于局部均值分解(Local Mean Decomposition,LMD)的多尺度能量熵(Multi-scale Energy Entropy,MEE)和麻雀搜索算法(Sparrow Search Algorithm,SSA)优化极限学习机(Extreme Learning Machine,ELM)的航空液压管路故障诊断方法。首先,采用局域均值分解方法将采集的振动信号自适应分解;其次,综合考虑相关系数-能量比准则,选取最佳PF分量;最后,计算最佳分量的多尺度能量熵,选取合适的尺度因子并将其对应的能量熵值作为特征向量,输入到麻雀搜索算法优化的极限学习机网络模型进行学习训练,实现对航空液压管路的故障进行分类识别。结果表明:该方法能够有效地实现对航空液压管路故障类型的准确识别,为区分航空液压管路故障提供了一种可行的诊断思路。     

Experimental Investigation and Optimization Design of Multi-Support Pipeline System

The design of aircraft hydraulic pipeline system is limited by many factors,such as the integrity of aviation structure or narrow installation space,so the limited clamp support position should be considered.This paper studied the fre-quency adjustment and dynamic responses reduction of the multi-support pipeline system through experiment and numerical simulation.To avoid the resonance of pipeline system,we proposed two different optimization programs,one was to avoid aero-engine working range,and another was to avoid aircraft hydraulic pump pulsation range.An optimization method was introduced in this paper to obtain the optimal clamp position.The experiments were intro-duced to validate the optimization results,and the theoretical optimization results can agree well with the test.With regard to avoiding the aero-engine vibration frequency,the test results revealed that the first natural frequency was far from the aero-engine vibration frequency.And the dynamic frequency sweep results showed that no resonance occurred on the pipeline in the engine vibration frequency range after optimization.Additionally,with regard to avoiding the pump vibration frequency,the test results revealed that natural frequencies have been adjusted and far from the pump vibration frequency.And the dynamic frequency sweep results showed that pipeline under optimal clamp position cannot lead to resonance.The sensitivity analysis results revealed the changing relationships between different clamp position and natural frequency.This study can provide helpful guidance on the analysis and design of practical aircraft pipeline.     

气柱共振导致的核电站蒸汽管道振动分析与机理研究

针对某核电站机组4#汽动辅助给水泵蒸汽管道在大修后验收试验期间发生的振动超标问题,通过对蒸汽管道振动现象及测试数据分析,推测管道振动机理为主汽门活塞卡滞引发汽锤,汽锤激发管道气柱共振,并使得阀杆产生相应频率即69 Hz的振动.由于阀杆控制系统频响特性,69 Hz与阀杆控制系统耦合,导致管道振动烈度严重超标,达到76 m...     

Inverse identification of the mechanical parameters of a pipeline hoop and analysis of the effect of preload

To create a dynamic model of a pipeline system effectively and analyze its vibration characteristics, the mechanical characteristic parameters of the pipeline hoop, such as support stiffness and damping under dynamic load, must be obtained. In this study, an inverse method was developed by utilizing measured vibration data to identify the support stiffness and damping of a hoop. The procedure of identifying such parameters was described based on the measured natural frequencies and amplitudes of the frequency response functions (FRFs) of a pipeline system supported by two hoops. A dynamic model of the pipe-hoop system was built with the finite element method, and the formulas for solving the FRF of the pipeline system were provided. On the premise of selecting initial values reasonably, an inverse identification algorithm based on sensitivity analysis was proposed. A case study was performed, and the mechanical parameters of the hoop were identified using the proposed method. After introducing the identified values into the analysis model, the reliability of the identification results was validated by comparing the predicted and measured FRFs of the pipeline. Then, the developed method was used to identify the support stiffness and damping of the pipeline hoop under different preloads of the bolts. The influence of preload was also discussed. Results indicated that the support stiffness and damping of the hoop exhibited frequency-dependent characteristics. When the preloads of the bolts increased, the support stiffness increased, whereas the support damping decreased.