Displacement reconstruction method for lattice tower structure based on improved mode superposition

Patent metadata

Field	Value
Publication number	US-12044601-B2
Application number	US-202117628765-A
Country	US
Kind code	B2
Filing date	Jul 26, 2021
Priority date	Jul 26, 2021
Publication date	Jul 23, 2024
Grant date	Jul 23, 2024

Abstract

The present invention belong to the technical field of lattice tower structure monitoring, and discloses a displacement reconstruction method for a lattice tower structure based on improved mode superposition. The method comprises: uniformly arranging D strain sensors on main member of a lattice tower along the height, processing collected strain data {ε}D×1 using a stochastic subspace identification (SSI) method to obtain a matrix [Ψ]D×nT of first n-order strain modes; calculating a function relation y(x) between a distance from a measuring point to a neutral layer and a height according to a lattice tower design drawing; performing polynomial fitting on the first n-order strain modes with a height coordinate x of the lattice tower respectively to obtain a strain mode function Ψi(x), expanding a functionΨi(x)y⁡(x)according to a Taylor formula, performing double integration on the expansion result and substituting same into a boundary condition, to obtain a displacement mode function Φi(x); evaluating a modal coordinate {q}n×1 by means of the least square method, substituting the height coordinate x of a displacement object point to be reconstructed, and multiplying the displacement mode function value Φi(x) by the modal coordinate {q}n×1. The improved mode superposition method of the present invention has the advantages of a small number of sensors required, simple calculation process, accurate calculation result, and strong operability and practicality.

First claim

The invention claimed is:

1. A displacement reconstruction method for a lattice tower structure based on improved mode superposition, characterized in that a lattice tower is simplified into a thin-walled variable cross-section cantilever beam, a neutral layer is assumed to be located between two main members, a stochastic subspace identification method is introduced to identify strain modes, judge order of participating modes, and reduce the amount of calculation, and an existing mode superposition method is improved into a method suitable for variable cross-section structures, comprising the following steps:
(1) uniformly arranging D strain sensors on main member of a lattice tower along the height direction, the number of the strain sensors is at least four;
(2) processing strain data {ε} D×1 collected by the strain sensors using a stochastic subspace identification method, drawing a stabilization diagram according to the processing result, judging order n of modes participating in vibration according to the obtained stabilization diagram, where n is a natural number and does not exceed D, and extracting a matrix [Ψ] D×n T of first n-order strain modes;
(3) calculating a function relation y(x) between a horizontal distance y from any point of the main member to the neutral layer and a height x from the point to the ground according to a lattice tower design drawing;
(4) performing polynomial fitting on the first n-order strain modes with the height x from the strain sensor arrangement points to the ground respectively to obtain a strain mode function Ψ i (x), expanding a function

Ψ
i

(
x
)

y
⁡
(
x
)

according to a Taylor formula, performing double integration on the expansion result and substituting same into a boundary condition fixedly connected to the bottom of the lattice tower structure, to obtain a displacement mode function Φ i (x);
(5) in the case where the strain mode matrix [Ψ] D×n T and the strain data {ε} D×1 of the lattice tower are known, evaluating a modal coordinate {q} n×1 of the lattice tower in the vibration process by means of the least square method;
(6) substituting the height coordinate x of any point of the lattice tower into the displacement mode function Φ i (x), and multiplying the obtained displacement mode function value Φ i (x) by the modal coordinate {q} n×1 to obtain dynamic displacement of the point.

Assignees

• Univ Dalian Tech

Inventors

• Fu Xing
• Zhang Qing
• Ren Liang
• Li Hongnan

Classifications

• G01M5/0025 Primary

  of elongated objects, e.g. pipes, masts, towers or railways (G01M5/0058 takes precedence) · CPC title

• E04H12/10

  Truss-like structures · CPC title

• G01M5/0041 Primary

  by determining deflection or stress · CPC title

• G01M5/0066

  by exciting or detecting vibration or acceleration (vibration testing of structures G01M7/00) · CPC title

• G06F2119/20

  Design reuse, reusability analysis or reusability optimisation · CPC title