Modification Method of Dense Mode Containing Damped Structural Model

Abstract

The invention discloses a method for correcting a closely spaced mode model with a damping structure. The method is mainly characterized in that it is assumed that errors of matrixes of a finite element are formed by accumulating errors of corresponding sub-matrixes of each unit, and the sub-matrixes of each initial unit and an accurate matrix only differ by a correction factor; the method includes the steps that a kinetic equation is converted into a state equation in a correction algorithm, and a characteristic solution is solved; pre-multiplying and testing are carried out on initial state equations of different orders and hypothetical accurate characteristics equations of the state equations to obtain complex modes of different orders, and then subtracting and sorting are carried out to obtain a linear equation set about the correcting factor; the correcting factor is calculated through a least square method, and accordingly a corrected finite element matrix is obtained. The method is implemented in a standard mode, facilitates computer programming, and is suitable for correcting of the closely spaced mode model with the damping structure due to the fact that one-to-one correspondence situations of tests and calculation modals are not required to be known. The corrected model can be used for modal calculation and can also be used for kinetics response calculation analysis.

Description

technical field [0001] The invention relates to a model correction method of dense mode containing damping structure, which is especially suitable for model correction of damping structure with dense mode characteristics such as airplanes and automobiles. Background technique [0002] In practical engineering, many mechanical structures are damped structures with dense modes, and using test results to correct the initially established finite element model is the only way to accurately model the dynamics of such structures. But up to now, the model correction is to use the normal modal test results to correct the undamped model; and generally require the modal separation to be clear, that is, no dense modal phenomenon occurs, so as to ensure the order correspondence between the test mode and the finite element calculation mode clear. In 2007, Sau-Lon JamesHu proposed the CMCM method based on the classic undamped system, which avoided the mode pairing problem in model correct...

AI Technical Summary

Problems solved by technology

In 2007, Sau-Lon JamesHu proposed the CMCM method based on the classic undamped system, which avoided the mode pairing problem in model correction for the first time, but it is not suitable for the most widely existing damped system in engineering, and its basic equation assumption also determines that it cannot Consider the effect of damping

Although this method improves the correction accuracy, it cannot handle neither the model correction problem of structures with damping nor the model correction problem of structures with dense modes

In addition to the problem of accuracy, the model corrected by the above method does not involve the correction of the damping matrix, so it can only be used for structural modal calculations, but cannot be effectively used for dynamic response calculation and analysis

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