A Complex Mode Evaluation Method for Finite Element Models of Structures with Damping

Abstract

The invention discloses a complex mode evaluation method of a finite element model with a damping structure. The method includes the steps: firstly, calculating a complex-frequency correlation coefficient according to relative errors of test complex frequencies and simulation complex frequencies, calculating a complex mode amplitude correlation coefficient of test and simulation by the aid of model assurance criterions, and calculating a complex mode phase position correlation coefficient by the aid of defined matrix norms; secondly, performing fuzzification on correlation coefficients of the complex frequencies, complex mode amplitudes and complex mode phase positions by the aid of a trapezoidal membership function to obtain fuzzy relation matrixes of three influencing factors, and performing mathematic operation on the fuzzy relation matrixes and all-order modal weight sets to obtain evaluation results of the influencing factors; finally, performing mathematic operation on the evaluation results and weight sets of the three influencing factors to obtain a comprehensive evaluation value. According to the method, influence of damping on structural response is considered, the method is applicable to correction of models with damping structures, error position identification and dynamic response accuracy of prediction models, calculation methods of the models are normative to implement, and implementation is facilitated by the aid of computer programming.

Description

technical field [0001] The invention belongs to the technical field of structural dynamics modeling, and relates to correction of a damping model, error position identification and model response estimation technology, in particular to a complex mode evaluation method of a damping structure finite element model. Background technique [0002] Model evaluation is a necessary means to measure the accuracy of finite element modeling, and an accurate finite element model can provide great convenience for the analysis of the dynamic characteristics of structures. At present, the commonly used evaluation method is to evaluate the finite element model from two aspects of real frequency and real vibration mode, but the evaluation results cannot be effectively used to estimate the calculation accuracy of the response of the damped structure model. The commonly used evaluation method of structural dynamics finite element model is to calculate the frequency relative error and modal conf...

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Problems solved by technology

The reason for the error is mainly in three aspects. First, there are too many evaluation results of the classical method, and it is difficult to grasp the model as a whole; second, the mode shape MAC evaluation cannot reflect the difference in the phase angle of each degree of freedom caused by damping; third, in the evaluation process It is necessary to realize the complex mode measured in the test, which will produce a secondary error

"Fuzzy evaluation of dynamic finite element model" (Zhang Anping, Wang Ke. Fuzzy evaluation of dynamic finite element model [J]. Journal of Nanjing University of Aeronautics and Astronautics, 2006, (03): 367-372.) proposed a The fuzzy evaluation method of the finite element model, which combines the evaluation results of frequency and mode shape by taking different weights, and uses one parameter to measure the finite element model, although this method avoids the disadvantages of multiple parameter evaluation, but due to the Evaluating the finite element model, ignoring the influence of damping, still cannot be effectively used to estimate the calculation accuracy of the model response

[0004] In short, the above prior art is only suitable for evaluating the modal accuracy of the finite element model because it does not consider the influence of damping factors, but cannot be effectively used to accurately predict the dynamic response of the finite element model

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