Modal damping ratio rapid calculation method based on pulse excitation response spectrum

Abstract

The invention discloses a modal damping ratio rapid calculation method based on a pulse excitation response spectrum. The method comprises the following steps: firstly, determining excitation and vibration pick-up positions of a structure, wherein the excitation and vibration pick-up positions are on a node and a nodal line adjacent to a modal shape, and have remarkable responses under various test modal shapes; recording a vibration pick-up point response signal by a signal acquisition device, and performing discrete Fourier transform to obtain a response spectrum; extracting corresponding responses under a resonance (or peak) frequency an adjacent frequency thereof on the basis to obtain a stable response amplitude; and lastly, calculating relevant parameters such as a frequency ratio and a response ratio in order to realize identification of a modal damping ratio of the structure. Through adoption of the method, the technical problems that semi-power points are difficult to find accurately in a conventional semi-power method, a frequency response function needed for calculating the modal damping ratio cannot be acquired sometimes in a frequency domain method since certain excitation time domain signals are difficult to measure directly, and transient components are attenuated incompletely, operations are complicated and the like in response under contact type excitation in the prior art can be solved.

Description

technical field

[0001] The invention belongs to the field of structural modal parameter identification, and relates to a method for testing the modal damping ratio of structural vibration, in particular to the inversion of the modal damping ratio of each order by using the impulse response spectrum of the structure in each order resonance region Implementation. Background technique

[0002] As an important dynamic performance index, the damping parameter has a significant impact on the response of the structure in the resonance region. The damping components of actual engineering structures are complex, and are generally determined by the combination of internal damping (material), structural damping, and fluid damping. It is difficult to directly apply the material damping measurement of the specimen to the response prediction. A linear vibration system obeys the principle of modal superposition, and its dynamic response calculation must depend on the modal damping ratio ...

Images