【作者】 许峰；

【导师】 鲍明；

【作者基本信息】 南京航空航天大学 ， 机械设计与理论， 2002， 博士

【摘要】 由于工程中结构的复杂性及激励形式的千差万别，工作状态下激励载荷常常难以测量，甚至因载荷作用点的不可达等原因而使实际载荷不可测量。为此，人们发展了种种载荷识别(或称载荷重构)理论与方法。本文就动态载荷的非平稳特性对有关前沿理论作了系统研究，着眼于结构响应输出与频率响应函数间的关系，建立了一类单独利用响应数据进行动载荷及其位置识别的新颖理论体系与方法。 本文首先对动载荷识别的模态模型法及其精度作了详细分析，提出了基于广义域模态模型的动载荷识别方法。以系统中的其他点作激励位置以代替常常为结构上不可达的实际载荷作用点，通过系统辨识得到系统的模态参数并在模态和物理两种坐标下对动态载荷作出估算，从而避免了通常需作的对系统结构的修改或改变边界条件而导致的识别误差。指出了重构冲击型载荷的技术关键和应该避免的问题。 在动载荷识别的模态模型法理论基础上，通过引入控制领域业已应用的空间滤波概念，提出利用离散模态滤波器的正交特性以分离出各阶模态对系统响应的独立贡献，构造的动载荷识别模型减少了算法实现的计算量。通过对离散模态滤波器的改进，避免了载荷重构阶段模态向量误差引起的载荷识别误差积累，从而实现了对经典载荷识别模态模型的校正。 鉴于时间一频率分析在信号处理多种场合下的种种成功应用，本文讨论了应用小波变换构造动载荷识别模型的可行性。利用小波变换作时域内的解卷积计算，分析了结构在冲击载荷作用下的弹性波的散射特性，结合非线性优化方法实现了载荷冲击位置的识别。本文还通过构造基于p-范数的模糊推理神经网络对高速铁路轮轨耦合系统作了辨识。 利用上述动载荷识别模型，本文分别对超音速歼击机模型和高速铁路轮轨耦合系统作了动载荷识别实验验证。结果表明，本文提出的方法能有效地进行未知激励下的动态载荷识别及作用位置识别，从而验证了本文理论的有效性。 本文研究工作获国家航空“九五”预研基金资助。更多还原

【Abstract】 It is generally very difficult to measure excitation in operating environment in the case of the complexity of the structure or the variant forms of the excitations, sometimes it is even immeasurable for the impact location is usually inaccessible. Nevertheless, certain theories and techniques were developed for force identification or so-called force reconstruction. Aiming at the nonstationary characteristic of the dynamic loads and the relation between the responses and the frequency response functions, by use of the responses only, some novel theories are conducted to develop force identification and impact location approaches in this dissertation.The modal-model-based method for force identification and the error propagation of the method are analyzed, and an approach is presented based on the modal model within a general domain. By exciting at the other sites of the structure rather than the actual input points which are usually inaccessible, the modal parameters of the system and the dynamic loads are estimated through computations under both modal and physical coordinates. The errors of identification caused by the usual modification of the structure or boundary conditions are consequently evitable. The kernel for the development of impact identification techniques and the means for error elimination are proposed.On the basis of the modal model theory and the conception of spatial filtering which is derived from the field of control, a more precise force identification model is developed based on the discrete modal filter. The error accumulation caused by the errors of modal vectors is banished and an emendation to the classical modal model is conducted, due to the extraction of the independent contribution of each mode by means of the orthogonality of the modal filter. The computation size is reduced with the technique as well.In the light of the applications of time-frequency analysis hi many cases of the signal processing, the possibility of constructing a force identification model by wavelet transfer is discussed. By means of the wavelet transformation the deconvolution is done in the time domain. The dispersive properties of the elastic wave within the impacts acted are analyzed, and with the nonlinear optimization method concerned the impact location is identified. On the other hand, by the p-norm based fuzzy inference neural network as proposed in this dissertation, a wheel-rail coupled nonlinear system identification is addressed.Utilizing the force identification approaches above mentioned, experiments on the model of a supersonic fighter and on a wheel-rail coupled system are performed respectively, in order to verify the validity of the proposed theories in this dissertation. The results show that unknown inputs as well as their locations can be identified feasibly by these developed methods.This project is sponsored by the Aeronautics Prospective Research Fund of the National "Ninth Five-year Plan" of China.更多还原