Large liquid binding rocket complex modal identification method

Abstract

The invention discloses a large liquid binding rocket complex modal identification method. Existing carrying rocket modal identification is carried out mainly through an engineering method, and a certain error is probably produced by directly applying the engineering method to a large liquid binding rocket with the complex modal crosslinking character. A relational expression between modal quality and node displacement is established based on the elastic vibration theory, and a carrying rocket complex modal distinguishing basis is put forward. Compared with the distinguishing basis of an existing engineering application, the large liquid binding rocket complex modal identification method has the advantages that the theoretical basis is more reliable, and the distinguishing precision is higher; the difference is larger between the localized modal quality and the whole modal quality which are obtained through the method in number value, the precision of localized modal is distinguished according to the relative size of the modal quality is improved to some degree, and the theoretical basis is provided for large liquid binding rocket complex modal identification.

Description

technical field [0001] The invention relates to a complex mode recognition method, in particular to a complex mode recognition method for a large-scale liquid-bound rocket, which belongs to the general field of launch vehicles. Background technique [0002] Compared with the launch vehicles currently in service and under research, the size and weight of large-scale liquid-bound rockets are increased, and the liquid boosters are bundled. The low-frequency modes of the rocket are dense, and the phenomenon of vertical and horizontal torsional coupling is serious. The modal test and model correction technology put forward higher requirements, and the characteristics of modal cross-linking also bring difficulties to modal identification and modal mass calculation. [0003] Existing rocket modal identification is mainly carried out by engineering methods: for a certain order mode, the modal category is determined by the one with the largest absolute value among the 6 directional d...

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Problems solved by technology

[0005] For the identification of local modes, the literature "Effects of local vibrations on the dynamics of space truss structures" uses the ratio of the maximum overall amplitude to the amplitude of a single component in the same mode to identify the local mode of a large truss structure, which is better than using the modal quality The accuracy of the method for identifying local modes is poor; the literature "Using Modal Mass Distribution to Identify Local Modes" uses the method of modal mass spatial distribution to identify the local modes of large truss structures. This method needs to calculate the distribution of modal mass in space , for a complex system, the calculation process of its modal mass distribution in three-dimensional space will be very cumbersome, and the calculation result display is inconvenient, which will increase the difficulty of modal identification

The methods introduced in the literature "Effects of local vibrations on the dynamics of space truss structures" and the literature "Using Modal Mass Distribution to Identify Local Modes" can identify local modes, but it is difficult to distinguish which direction the mode belongs to.

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