Aero-engine pipeline systems are critical auxiliary structures that can affect engine service performance and reliability. Due to complex spatial configurations and multi-component coupling， excessive vibration and fatigue failure are easily induced under multi-source excitations and multi-physical-field interactions. Therefore， accurate and efficient dynamic models are required. Optimization design and vibration suppression should also be considered to improve the service performance of pipeline systems. In this study， the mechanical modeling methods of support components are first reviewed. Then， the principles， characteristics， applicability， and theoretical differences of semi-analytical methods， transfer matrix methods， finite element methods， spectral element methods， absolute nodal coordinate formulations， and hybrid modeling methods are summarized. The research progress in dynamic optimization design is discussed from two aspects： clamp layout optimization and pipeline routing optimization. Vibration suppression methods are further reviewed from three technical routes： support-structure-based vibration isolation， additional damping and energy dissipation， and source-side fluid pulsation attenuation. Finally， key scientific issues and future technical directions are discussed. This review is expected to provide theoretical guidance and technical support for dynamic modeling and low-vibration design of aero-engine pipeline systems.
Quasi-zero stiffness(QZS)vibration isolation,by introducing stiffness nonlinearity,effectively ad-dresses the inherent contradiction between load-bearing capacity and isolation bandwidth in conventional linear isolators.As a result,it exhibits superior low-frequency isolation performance.The core challenge in realizing QZS isolation lies in designing mechanical structures whose force-displacement curves simultaneously demon-strate high static stiffness and low dynamic stiffness.Focusing on QZS isolation design methodologies,this pa-per first outlines the fundamental principles of QZS isolation and categorizes the traditional approaches according to the means of stiffness nonlinearization into four groups:geometric motion nonlinearity,geometric deforma-tion nonlinearity,magnetic nonlinearity,and stress-strain nonlinearity.Subsequently,it introduces emerging de-sign strategies based on nonlinear positive-stiffness structures,including hardening and softening types,and compares them with conventional approaches,with particular attention to their differences in static and dynamic behavior.Finally,the paper summarizes and discusses future directions from the perspectives of negative-stiffness structure design,QZS characteristic tuning,and potential applications,aiming to provide a comprehen-sive overview of the latest research progress and to offer insights into future development trends of QZS isolation systems.
Oil pipeline leakage will not only cause economic losses, but also pollute the environment, so the leakage detection of pipelines is very important. The acoustic wave method is widely used in pipeline leak detection, and the leak acoustic signal collected by the acoustic wave sensor often contains a lot of noise, which makes it impossible to accurately determine the inflection point of the signal curve and reduces the accuracy of pipeline leak detection. This paper proposes a denoising algorithm based on mutual information optimization complete ensemble empirical mode decomposition with adaptive noise combined with cross-spectral analysis. Compared with other methods, this method can accurately select the effective intrinsic modal function for signal reconstruction, the denoising effect is more obvious, and the original information is preserved to a greater extent. Acoustic waves are attenuated during the propagation process, and will be affected by factors such as pipe connection ports and elbows, making it impossible to accurately determine the amplitude of acoustic waves around the pipeline. According to the propagation characteristics of acoustic waves and various factors that affect the propagation of acoustic waves, this paper establishes a model for calculating the amplitude of acoustic waves, which can accurately determine the amplitude of acoustic waves everywhere in the pipeline. Finally, according to the model, the relationship between pipeline characteristics and detectable leakage rate is analysed. Field experiments show that the proposed model is accurate and the denoising algorithm is efficient. The minimum detectable leakage rate of the oil pipeline can reach 0.43% when the acoustic wave method is used for leak detection.
为了提高平面运输设备的传送效率与定位精度,针对x-y轴平面滚珠丝杠副的多机械装配界面,应用吉村允效法确定螺栓联接界面的法向压缩刚度和切向运动刚度,采用赫兹接触理论确定丝杠螺母、轴承和导轨内接触界面的径向或法向压缩刚度.基于ABAQUS软件建立x-y直线进给系统的动力学模型,通过锤击法模态试验和文献对比研究,证明了所提理论模型以及结合面刚度计算的正确性.数值仿真了工作台质量、滑块间距及导轨间距对于系统动态行为的影响,并给出设计建议值.通过医疗剪刀毛坯平面进给机床设计试验,验证了所获得动态系统设计规律的有效性.
基于复合材料的航空航天器结构在服役过程中受到外界物体冲击易造成损伤,常规光纤Bragg光栅冲击监测模式需要借助大量试验建立冲击响应样本库,不仅工作量大,还会影响被测结构力学性能,甚至造成预先损伤.为此,提出了一种基于应变幅值非线性加权原理的复合材料层板结构分布式光纤冲击位置辨识方法,通过提取结构应变响应幅值作为特征量,结合无需先验样本的非线性加权原理实现冲击载荷位置辨识.借助有限元数值仿真,模拟得到冲击载荷作用下复合材料层板结构应变响应与分布特征,并根据仿真结果对该辨识方法加以验证.构建了基于高空间分辨率分布式光纤传感器的冲击监测系统,平均定位误差约为8.44 mm.研究表明,所提方法具有便于集成、通用性强以及无需构建样本库等特点,能够为航空航天器结构健康监测、寿命评估和快速维护提供技术支撑.
