Random Vibrations with Impacts

本研究项目涉及预测碰撞振动系统对随机激励的响应的方法和程序的发展。典型的应用领域包括工程（系泊体对海浪的响应）和动力工程，特别是核（通道管内燃料束的流致振动;以及热交换器管撞击支撑板的流致振动）。其他潜在的应用包括铁路机械（具有冲击型车轮/轨道相互作用的车辆动力学）和旋转机械（具有反向运动的齿轮箱）。一个quasconservative随机平均方法一起使用的傅立叶级数展开在一个“快速”的时间，在一个响应周期内。此外，一个新的近似程序的开发和评估，这是基于轻阻尼系统的响应加速度的整体谱密度的影响的主导贡献。随机相位调制的周期性激励的模型被用来预测系泊海洋平台对海浪的次谐波响应，并预测热交换器中的管的平面和旋转流致振动之间的转换。非线性振动和控制的基础理论将受益于新的分析方法和程序，在本研究过程中，获得一些新的具体解决方案（强非线性）系统。此外，这项研究将有助于响应预测和控制，以及预测和/或测试可靠性和开发海上和电力工程系统的设计指南。

This research project deals with the development of methods and procedures for predicting response of vibroimpact systems to random excitation. Typical fields of applications include Engineering (response of moored bodies to ocean waves) and Power Engineering, particularly Nuclear (flow- induced vibrations of fuel bundles within channelling tubes; and of heat exchanger tubes impacting against support plates). Other potential applications include Railway Machinery (vehicle dynamics with impact-type wheel/rail interactions) and Rotating Machinery (gearboxes with reversals of motion). A quasiconservative stochastic averaging method is used together with a Fourier series expansion in a `rapid` time, within a response cycle. In addition, a new approximation procedure is developed and evaluated which is based on the dominating contribution of the impacts into overall spectral density of response acceleration for lightly damped systems. The model of a periodic excitation with random phase modulation is used to predict subharmonic response of moored offshore platforms to ocean waves, and to predict transitions between planar and whirling flow-induced vibrations of tubes in heat exchangers. Fundamental theory of nonlinear vibration and control would benefit through new analytical methods and procedures developed during the course of this research and some new specific solutions obtained for (strongly nonlinear) systems. Also, this research will assist in response prediction and control, as well as predicting and/or testing reliability and developing design guidelines for systems in offshore and power engineering.