Exploring and exploiting complex nonlinear dynamical states in friction-excited mechanical systems

FIV代表了从汽车到航空航天工程的不同工业应用中的主要问题。尽管近年来投入了很大的努力，FIV仍然被定义为“随机”，“低重复性”，“反复无常”。FIV的数值和理论建模的最新进展表明，摩擦影响的动力学系统可能会经历多种动力学状态，特别是空间局部化的振动状态，粘滑/全滑传播的前沿和粘滑脉冲。在文献中，这些过渡状态在FIV的发展中发挥的作用往往被忽视，相反，主要集中在摩擦系统的静态，全局行为上。我们建议详细研究FIV的空间本地化现象及其在界面处的粘滑锋或脉冲的传播。实验观察到的“随机性”，事实上，可能是由于我们缺乏理解摩擦系统如何演变过程中的瞬态通过不同的过渡状态。我们将重点讨论摩擦激励的离散规则结构。前两个目标和工作包的目的是研究和表征的本地化和传播状态的存在，稳定性，传播速度，系统参数的敏感性和摩擦法。第三个目标和相应的工作包旨在利用所观察到的非线性状态。我们将集中在选择适当的动力学状态，以获得所需的摩擦系数和耗散行为的可能性。这个“第一次”的建议是申请人一个独特的机会，开始一个更独立的研究，并扩大他的知识在摩擦激励动力系统在动力学组在TUHH工作。他在接触力学和非线性动力学的背景将是至关重要的，面对这个具有挑战性的项目。

FIV represent a major problem in different industrial applications, from the automotive to the aerospace engineering. Despite the great effort that has been invested in the recent years FIV are still defined "random", "low repeatable", "capricious". The recent advances in numerical and theoretical modelling of FIV show that friction affected dynamical systems may experience a multitude of dynamical states, in particular spatially localized vibrating states, stick-slip/full-slip propagating fronts and stick-slip pulses. The role that those transitory states play in the development of FIV has been often neglected in the literature, which, instead, has focused mostly on the stationary, global behaviour of frictional systems. We propose to study in detail the phenomenon of spatial localization of FIV and their propagation at the interface as stick-slip fronts or pulses. The experimental observed “randomness”, in fact, may be caused by our lack of understanding of how frictional systems evolve during the transients through different transitory states. We will focus on friction-excited discrete regular structures. The first two objectives and workpackages aim at studying and characterizing the localized and the propagating states in terms of region of existence, stability, velocity of propagation, sensitivity to system parameters and to the friction law. The third objective and corresponding workpackage aim at exploiting the observed nonlinear states. We will focus on the possibility of selecting the proper dynamical state to obtain the desired friction coefficient and dissipative behaviour. This "first-time" proposal is for the applicant a unique opportunity to start a more independent research and broaden his knowledge in friction-excited dynamical systems working in the Dynamics Group at TUHH. His background in contact mechanics and non-linear dynamics will be of crucial importance to face this challenging project.