Method and system for testing high-order modal frequency and high-order modal damping of thin wall member

Abstract

The invention provides a method and a system for testing high-order modal frequency and high-order modal damping of a thin wall member. The method comprises steps that theoretical modal frequency and modal shape calculation for the thin wall member is carried out, and the high-order modal frequency quantity and corresponding nodes, corresponding to nodel lines, the corresponding to pitch circle position and distribution of the modal shape can be acquired; the constraint boundary condition for testing the high-order modal frequency and the high-order modal damping of the thin wall member are determined; the high-order modal frequency of the thin wall member is tested; the high-order modal damping of the thin wall member is tested. According to the method, a piezoelectric ceramic vibration exciter is employed to realize high frequency excitation for the thin wall member, and a problem that traditional excitation equipment can not effectively excite the high-order modal of the thin wall member is solved. The frequency domain bandwidth method can be utilized to effectively acquire high-order modal damping of same-type structures, and problems of a traditional frequency domain damping test method existing in thin wall structure application can be solved. The method and the system are advantaged in that the test system is easy to establish, the test method is concise, simple and clear, and good repeatability and relatively high test precision are realized.

Description

technical field [0001] The invention belongs to the technical field of vibration testing, in particular to a method and system for testing high-order modal frequencies and damping of thin-walled components. Background technique [0002] Modal frequency and damping are important dynamic parameters of thin-walled components, and it is of great engineering and academic significance to accurately obtain its modal frequency and identify its damping. Thin-walled components represented by blades, disks, bushings, thin-walled drums, etc. usually work in the environment of multi-field coupling excitation, and are often excited to high-order modal frequencies (above 6kHz), and the corresponding high-order modes are simultaneously It also has the characteristics of dense frequency distribution, small vibration, rich local vibration, and complex stress distribution, which are usually difficult to obtain through traditional excitation equipment testing. For the damping test of thin-wall...

AI Technical Summary

Problems solved by technology

The principle of the time-domain free vibration attenuation method is simple, but its original data is the time history of the structural vibration response, which inevitably includes the influence of background noise, and the accuracy of the damping test will be difficult to guarantee

The frequency-domain half-power bandwidth method is only applicable to the situation where the modal distribution is scattered and the formant waveform in the frequency spectrum is ideal. When the distance between two formant peaks of adjacent orders is relatively close, the frequency value near the half-power point may be very large Difficult to find, which affects the test accuracy of damping

In addition, in the practical research of vibration testing of thin-walled components, it is also found that there are often nonlinear characteristics of stiffness in complex boundary or coating damping applications, which will also increase the difficulty of damping identification and limit the traditional half-power bandwidth in the frequency domain application of law

In view of these characteristics of thin-walled components, the traditional modal frequency and damping test methods have been unable to accurately obtain the high-order modal frequencies and damping of thin-walled components.

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