Fatigue predictions for flexible marine propellers using FSI analysis considering Euler force in the rotating frame

Analysis of flexible marine propellers in terms of their structural response and stress is the key to accurate fatigue prediction. At present, finite element method (FEM) analyses of flexible propellers have been performed as a part of the fluid–structure interaction (FSI) analysis using a numerical method for the flexible structures, which is identical to that used for their rigid counterparts. In this study, the Euler force in a rotating frame is employed as an additional external force on the blades of the marine propeller during the FSI analysis. The Euler force is an inertial force component in the rotating frame due to angular acceleration. Acceleration of the rotating frame arises from large deformations of the propeller due to its flexible characteristics. The angular acceleration of the propeller is obtained for each time step, and the resulting Euler force is accounted for as a body force. The FSI analysis results are compared to experimental results in terms of the structural response, stress, and fatigue. It is clear that the Euler force has a major effect on the fatigue characteristics of the propeller because it amplifies the main response components. In conclusion, incorporating the Euler force in FSI analyses of flexible marine propellers is necessary for adequate prediction of the propeller fatigue.     

白车身总拼系统“6+2”柔性扩展研究

文章基于车身总拼系统"5+1"车型方案,评估地坪承载,优化现有钢结构,打通第二、三排X向存储库,预留未来6+2扩展性,在不增加场地面积情况下,实现更多的车型柔性切换,节省了工艺面积,满足八车型同时Launch制造生产要求。通过新概念、新结构、新工艺的高效总拼柔性切换系统,可以解决焊装车间八车型同时在线生产的切换效率低、总拼工位空间布置等问题。为高节拍、高精度、高效率运行的汽车焊装主线总拼系统的可靠制造带来了显著效益,为汽车行业智能制造做出了应有的贡献。     

“柔性管理”在高职学生工作中的应用

＂柔性管理＂是相对＂刚性管理＂提出来的,以人为本,注重情感依托,追求思想和行动的统一。本文针对高职生的群体个性和共性,提出＂柔性管理＂的使用原则及应用方法。     

浅谈柔性石笼在公路工程中的应用与研究

根据不同的公路工程条件,使用不同的柔性石笼结构或组合,并在公路的水毁恢复、防护、公路改造等工程实践中进行了大量的应用,通过几种应用案例,对柔性石笼在公路工程中的使用效果和工程意义进行探讨。     

钢悬链线的涡激振动分析

文章介绍了立管在不同流剖面下的涡激振动实验,然后给出了简支钢悬链线的静态方程和基于能量平衡原理的涡激振动频域预报理论.之后提出把钢悬链的参数转化为顶部张紧钻井隔水管的参数的思想.通过预报顶部张紧钻井隔水管的涡激振动响应,得到钢悬链线的涡激振动响应.文中还研究了不同的顶部预张力和不同流剖面对钢悬链线的涡激振动响应影响.结果表明立管的固有频率和模态数的关系足线性的,并且立管的均方根位移和激励的模态数不仅与流速的大小和变化范围有关,还与顶部预张力有关.     

Comfort enhancement by an active vibration reduction system for a flexible railway car body

In order to improve the ride comfort of lightweight railway vehicles, an active vibration reduction system using piezo-stack actuators is proposed and studied in simulations. The system consists of actuators and sensors mounted on the vehicle car body. Via a feedback control loop, the output signals of the sensors which are measuring the flexible deformation of the car body generate a bending moment, which is directly applied to the car body by the actuators. This bending moment reduces the structural vibration of the vehicle car body. Simulations have shown that a significant reduction in the vibration level is achieved.     

土工织物加筋柔性桥台合理间距的模型试验对比研究

由于台背路堤和桥台两者形成差异沉降,桥头跳车成为普遍且复杂的问题,对这一特殊路堤病害的成功处治尚不多见。近年来,加筋土结构的柔性桥台开始应用于工程实践,这种结构有可能在根本上防止桥头跳车的产生,但其加筋间距的确定具有较大的盲目性。本文对土工织物加筋柔性桥台进行了4组室内大模型试验,对不同加筋间距下柔性桥台的工程特性进行了详尽的对比分析。试验结果表明,土工织物加筋柔性桥台的合理间距为30～50cm。     

Comfort enhancement by an active vibration reduction system for a flexible railway car body

In order to improve the ride comfort of lightweight railway vehicles, an active vibration reduction system using piezo-stack actuators is proposed and studied in simulations. The system consists of actuators and sensors mounted on the vehicle car body. Via a feedback control loop, the output signals of the sensors which are measuring the flexible deformation of the car body generate a bending moment, which is directly applied to the car body by the actuators. This bending moment reduces the structural vibration of the vehicle car body. Simulations have shown that a significant reduction in the vibration level is achieved.     

新型沥青路面结构在我国的应用研究

中国的高速公路沥青路面绝大多数采用半刚性基层沥青路面,为发展高速公路建设起到了重要作用。但采用一种沥青路面结构存在许多不足,不少高速公路沥青路面产生了耐久性差、使用寿命短的现象。文章分析了国际上多种路面结构在高速公路上的使用现状,介绍了我国开展的包括柔性基层、组合式基层在内的不同结构的沥青路面在高速公路上的应用情况。最后建议对沥青路面的设计进行完善,明确其适用范围,应推广采用组合式基层、柔性基层等其它路面结构。     

软轴式变速控制系统在汽车工程中的应用

软轴式变速控制系统具有换挡阻力及噪声小、质量轻、布置灵活、更换容易等优点。近年来随着我国客车向准低地板、超低地板发展，软操纵已逐渐呈现出流行趋势。在简述了软轴式变速控制系统构成框架的基础上，以客车为例，主要从操纵器的选型、变速杆的设计、软轴的设计选用、固索架和转换器安装方案的设计等方面介绍了软操纵设计选用的方法。