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

A technology of modal damping ratio and response spectrum, applied in calculation, design optimization/simulation, special data processing applications, etc., can solve the problem that the frequency response function cannot be obtained by the frequency domain method, it is difficult to accurately find the half power point, and the excitation time domain signal Difficult to measure and other problems, to achieve the effect of fast speed, low interference and high test

Inactive Publication Date: 2017-07-18
NAVAL UNIV OF ENG PLA
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Problems solved by technology

[0006] The purpose of the present invention is to provide a fast calculation method for the modal damping ratio based on the impulse excitation response spectrum, which can solve the following technical problems in the prior art: it is generally difficult to accurately find the half-power when calculating the damping ratio by the traditional half-power meth

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

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Embodiment 1

[0121] Embodiment 1: simulation numerical test

[0122] In Embodiment 1, the specific operation description and verification are carried out for the extraction of the steady-state response amplitude and the inversion calculation of the damping ratio from the impulse response spectrum. Taking the total vibration parameters of the hull girder model analysis in the field of ship engineering as an example, the parameters of a ship are identified according to the inversion calculation method of the damping ratio. The model scale parameters are shown in Table 1.

[0123] Table 1 Scale parameters of a ship owner

[0124]

[0125] The whole hull girder model of the ship is established, which is an equivalent beam of the main hull structure with variable cross-section. At the same time, the total weight of the whole ship and the mass of the attached water are considered, and the elements of each section are calculated. MSC.Nastran is used to analyze the response of the finite eleme...

Embodiment 2

[0139] Embodiment 2: Plate unit model test

[0140] In order to verify the effectiveness of the method described in the present invention, the modal test of the composite material plate element model of the local structure of the hull has been implemented, and its structure is schematically shown as Image 6 . Among them, structure 2 is the unit structure of the tested glass steel plate, Figure 7 It is a three-dimensional solid test model. The material of the tooling structure is Q235 steel, the modulus of elasticity is 210Gpa, Poisson's ratio is 0.3, and the material density is 7800kg / m 3 , according to the numerical calculation in advance to ensure that the resonant frequency of each order of the design tooling and the test plate unit model has a sufficient stagger rate. The material of the composite plate used is hand lay-up glass steel plate, which is currently mainly used for the preparation of structural parts of the hull fairing. Its main design parameters are show...

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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 ...

Claims

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Application Information

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IPC IPC(8): G06F17/50
CPCG06F30/20
Inventor 唐宇航陈志坚梅志远
Owner NAVAL UNIV OF ENG PLA
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