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Linear time-varying structure modal shape identification method

A technology of structural mode and identification method, which is applied in special data processing applications, instruments, electrical digital data processing, etc., and can solve the problem of weak identification ability of low-order mode shapes, inability to specify bandwidth, and inability to carry out multiple experimental average values and other problems, to achieve the effect of solving practical engineering technical problems, wide application prospects and benefits

Inactive Publication Date: 2018-08-17
BEIJING INSTITUTE OF TECHNOLOGYGY
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Problems solved by technology

Although some modal shape identification methods for time-varying structures have been proposed in the above literature, these methods identify the modal shapes at a series of discrete moments, and are not strictly time-varying modal shape identification methods
For example, the time-domain identification method based on the FS-VTARMA model has incomplete mode shapes on the time axis in the actual solution, cannot specify the bandwidth, cannot perform multiple experiments and take the average value, and the identification of low-order mode shapes Weak ability and other shortcomings

Method used

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  • Linear time-varying structure modal shape identification method
  • Linear time-varying structure modal shape identification method
  • Linear time-varying structure modal shape identification method

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Embodiment 1

[0146] The finite element simply supported beam model of the uniform distribution of 18 units in this embodiment, such as figure 2 shown. The length of the beam is l=1m, the cross section is a circle with a diameter of d=0.0065m, and the density of the beam is d=0.0065kg / m 3 , the modulus of elasticity is E=2.1×10 11 . The beam is evenly divided into 18 elements. The elastic modulus of the 9th and 17th units varies with time t as E(t)=E·X(t), and X(t) is shown in formula (36). Assume that the excitation F is Gaussian white noise with a magnitude of 100dBw, and acts on the 9th degree of freedom of the beam.

[0147] X(t)=-0.9sin(πt / (2t end ))+1 (38)

[0148] The theoretical mode shape of the simulated simply supported beam can be obtained by calculating the structural dynamic equation, and the obtained theoretical mode shape is normalized by the maximum value. The response is calculated by the Newmark-β algorithm, the sampling time is 4s, and the sampling frequency is d...

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Abstract

The invention discloses a linear time-varying structure modal shape identification method, and belongs to the technical field of structural dynamics. On the condition that the linear time-varying structure model frequency and model damping are known, a parameterized model describing a time correlation time division form of a linear time-varying structure is built; a time orthogonal polynomial basefunction is introduced, the parameterized model is unfolded on the basis of the base function, and a time correlation power spectrum defined in the description is decomposed in a time-invariant system in the traditional frequency domain; the linear time-varying structure-based time correlation power spectrum is unfolded, and a parameter estimation method is adopted for solving the linear time-varying structure modal shape. The technical purpose of providing the method for integrally estimating the linear time-varying structure modal shape in the whole time within the time-frequency domain isachieved; in addition, the integrity of the model shape on a time shaft is improved, the identification effect is improved by assigning a bandwidth mode, multiple experiments can be conducted, a random error is reduced by taking the average value, and the identification capacity of the low-order model shape is improved.

Description

technical field [0001] The invention relates to a method for identifying the mode shape of a linear time-varying structure, in particular to a method for identifying the mode shape of a linear time-varying structure based on a time-frequency domain, and belongs to the technical field of structural dynamics. Background technique [0002] Time-varying structures are generally defined as structures with time-varying properties, where structural parameters such as stiffness, damping ratio, and mass vary with time. [0003] Existing modal parameter identification methods for time-varying structures, including the identification of modal frequencies and modal damping ratios, have been extensively studied. For example, Roshan-Ghias et al. proposed a method for identifying modal parameters using time-frequency distributions. Spiridonakos et al. identified the modal parameters by measuring the vector vibration response. Zhou et al. proposed a time-varying structure two-step least s...

Claims

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Application Information

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IPC IPC(8): G06F17/50
CPCG06F30/23
Inventor 刘莉袁赫周思达康杰马源辰
Owner BEIJING INSTITUTE OF TECHNOLOGYGY
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