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Nonlinear Modal Testing and Analysis of Multiple Degree of Freedom Engineering Structures using a Frequency Domain method

使用频域方法进行多自由度工程结构的非线性模态测试和分析

基本信息

批准号：
EP/I030387/1
负责人：
David Wagg
金额：
$ 12.46万
依托单位：
University of Bristol
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2011
资助国家：
英国
起止时间：
2011 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FI030387%2F1
关键词：
Nonlinear Modal Testing Analysis Multiple

项目摘要

Despite the combined improvements in computing power and modelling capabilities one major hindrance to optimal design is the present incapability to capture experimentally (identify) nonlinear dynamic behaviour which characterise many engineering structures. It can be argued that a step-change in the accuracy of structural dynamics prediction capability (i.e. the accuracy of the models used for simulations) can only occur if the nonlinear characteristics are opportunely captured and modelled. Currently, it is standard engineering practice to apply techniques that can provide an answer to whether or not the system being tested is nonlinear but do not help to identify the type and magnitude of nonlinearity. There is thus scope for implementing, within a standard dynamic experiment, a method for 'detection and quantification' of the nonlinear behaviour. Experimental Modal Analysis, or Modal Testing, is practiced on a daily basis in dynamics labs of universities and industries alike. The final goal is to transform a set of measured data into a set of modal parameters which eventually will allow the (re)construction (or validation) of a spatial model (most notably a Finite Element model). However, the theory developed to perform modal analysis so far ceases to be valid if the vibrating structure exhibits nonlinear behaviour. The work proposed in this project intends to initiate a more structured effort for the continuation and the expansion of theory and practice of modal analysis in nonlinear structural dynamics. This proposal responds to the need of introducing a novel modal analysis technique for nonlinear structures which aims, at least to a first degree of approximation, to extract type and magnitude of structural nonlinearity from measured frequency response functions. This is necessary in order to progress beyond the current boundaries of the well established linear techniques set decades ago and which no longer suffice to respond the expanding capabilities of simulation methods such as the finite elements.

尽管计算能力和建模能力得到了综合改进，但优化设计的一个主要障碍是目前无法通过实验捕捉（识别）许多工程结构的非线性动态行为。可以认为，结构动力学预测能力的精度（即用于模拟的模型的精度）的阶跃变化只有在非线性特征被适当地捕获和建模的情况下才能发生。目前，标准的工程实践是，应用技术可以提供被测试系统是否非线性的答案，但不能帮助识别非线性的类型和大小。因此，在一个标准的动态实验中，有可能实现一种“检测和量化”非线性行为的方法。实验模态分析，或模态测试，每天都在大学和工业的动力学实验室中进行。最终目标是将一组测量数据转换为一组模态参数，最终将允许（重新）构建（或验证）空间模型（最明显的是有限元模型）。然而，如果振动结构表现出非线性行为，迄今为止用于进行模态分析的理论就不再有效。本项目提出的工作旨在为非线性结构动力学中模态分析的理论和实践的延续和扩展发起更有组织的努力。这一建议回应了引入一种新的非线性结构模态分析技术的需要，该技术的目的是，至少在一级近似上，从测量的频率响应函数中提取结构非线性的类型和大小。这是必要的，以便超越几十年前建立的完善的线性技术的当前边界，这些技术不再足以响应诸如有限元等模拟方法的不断扩展的能力。