Tailoring Damping and Nonlinearities in Self-Excited Mechanical Systems

定制自激机械系统中的阻尼和非线性

基本信息

批准号：
264065013
负责人：
Professor Dr. Peter Hagedorn
金额：
--
依托单位：
Institut für Angewandte Dynamik
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2014
资助国家：
德国
起止时间：
2013-12-31 至 2019-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/264065013?language=en
关键词：
Tailoring Damping Nonlinearities Self Excited

项目摘要

In most mechanical engineering systems vibrations are unwanted. This is particularly true for self-excited vibrations, which manifest themselves as brake squeal in cars and trains, ground resonance in helicopters, galloping vibrations of overhead transmission lines, instabilities of high-speed rotors in oil-film bearings, among others. In some of these systems the consequences of the self-excited vibrations can be catastrophic. For none of the systems universally accepted solutions exist so far. All these vibration phenomena have in common that circulatory terms are present in their linearized equations of motion. They have different physical origins in each of the examples mentioned above. In the recent past, new results were obtained for optimizing the robustness of mechanical structures with respect to self-excited vibrations by avoiding symmetries in the spectrum. Even more recently, the interaction of circulatory terms and different forms of damping were studied systematically and some surprising new results were found. It was of course well known that damping may cause instability and self-excited vibrations in circulatory systems, but most of this knowledge was established for systems with a very small number of degrees of freedom only and not in a systematic way.In the equations of motion of engineering structures, the circulatory terms are difficult to alter, but damping usually can be modified, although in general the damping matrix can only be changed in certain ways. In the present project, the interaction of the different matrices characterizing a linear mechanical system (inertia, stiffness, gyroscopic, damping and circulatory) will be studied systematically, with view to designing structures with a greater robustness with regard to self-excited vibrations. The project will first be focused on autonomous linear systems and later also expanded to time-periodic and nonlinear systems. It is expected that this will lead to improved design methods for systems such as the ones mentioned above, with view to increasing the robustness against self-excited vibrations or at least to mitigate their consequences by reducing the limit cycles.

在大多数机械工程系统中，振动是不必要的。对于自激发的振动而言，尤其如此，这表现为在汽车和火车中尖叫，直升机中的地面共振，逐渐释放的架空传输线的振动，在石油膜轴承中高速转子的不稳定性等等。在其中一些系统中，自激发振动的后果可能是灾难性的。因为到目前为止，所有系统都没有普遍接受的解决方案。所有这些振动现象具有共同的循环术语，即在其线性运动方程中存在循环术语。它们在上面提到的每个示例中具有不同的物理起源。在最近的过去，获得了新的结果，以优化通过频谱中的对称性来优化自激发振动的机械结构的鲁棒性。甚至最近，系统地研究了循环术语和不同形式的阻尼的相互作用，并发现了一些令人惊讶的新结果。当然，众所周知，阻尼可能会在循环系统中引起不稳定和自振动的振动，但是大多数知识是针对仅有很少数量自由度的系统建立的，而不是以系统的方式建立的。工程结构的运动，循环术语很难改变，但是通常可以修改阻尼，尽管通常只能以某些方式更改阻尼矩阵。在本项目中，将系统地研究不同矩阵的相互作用（惯性，刚度，陀螺，陀螺，阻尼和循环）的相互作用，并将其视为设计具有更大鲁棒性的结构，以进行自我激发的振动。该项目将首先专注于自主线性系统，后来也扩展到时间周期和非线性系统。可以预期，这将导致上述系统的改进设计方法，以提高针对自我激发振动的鲁棒性，或者至少通过减少极限周期来减轻其后果。