Moving-load Distributions in Structural Dynamics

这个项目解决了一类对许多设计应用很重要的移动载荷问题，这是过去的研究人员没有考虑到的。轨道、桥梁、地面在行驶车辆的激励下产生的振动、计算机硬盘旋转产生的噪声和振动以及制造加工过程中产生的振动是典型的动载问题。在这个项目中，用有限元模型表示的运动部件可能具有复杂的几何形状和在感兴趣的范围内的许多固有频率。另一方面，平稳分量将由解析微分方程模型和连续体的模态展开序列来表示。静止和运动部件之间的运动接触区域是未知的，并且由于部件的灵活性和两个部件的可能分离而在空间和时间上变化，必须与整个系统的动态行为一起确定。这通常会导致一组复杂的积分-微分方程。提出了一种基于准静态滑动接触分析中接触面积先验估计的摄动法或谐波平衡法来处理变接触面积。它涉及到接触面积“小”变化和无影响的假设。这一发展将允许数学表示许多困难的工程问题，具有先验未知的接触区域和负载分布的动态移动载荷。该项目涉及移动载荷问题的基本问题，并将为加工操作，车辆-支撑交互，车辆制动等应用提供更准确的解决方案。当成功完成后，工程师将对实际的移动荷载问题有更好的理解和更有效的分析方法。这将使他们能够扩大其设计系统的操作范围（例如，通过提高计算机磁盘的数据存储和数据检索速度），避免过度设计和减少材料浪费。

This project addresses a category of moving-load problems, important to many design applications, that has not been considered by past researchers. Vibration of track or bridge or ground excited by travelling vehicles, noise and vibration from spinning computer hard discs and during machining processes in manufacturing are some typical moving-load problems.In this project, the moving component, to be represented by a finite element model, may have a complicated geometric shape and many natural frequencies within the range of interest. The stationary component, on the other hand, will be represented by an analytical differential-equation model and subsequently a modal expansion series for a continuum. The moving area of contact between the stationary and moving components is unknown and varies spatially and temporally because of the flexibility of the components and possible separation of the two components and must be determined together with the dynamic behaviour of the complete system. This is expected to result in a set of complicated integro-differential equations in general.A perturbation method or a harmonic balance method based on a prior estimate of the contact area from a quasi-static sliding contact analysis is proposed to deal with the variable area of contact. It involves the assumption of 'small' change in the contact area and no impact. This development will allow the mathematical representation of many difficult engineering problems having dynamic moving loads with a priori unknown contact areas and load distributions.This project deals with fundamental issues of moving-load problems and will provide more accurate solutions to applications such as machining operating, vehicle-support interaction, vehicle brakes and so on. When successfully completed, engineers will have an enhanced understanding of and a more efficient analysis method for practical moving-load problems. This will allow them to widen the operation envelope of their designed system (by increasing the speed of data storage to and data retrieval from computer discs, for example), avoid over-design and reduce material waste.