Optical fiber tomography method for load distribution monitoring of flexible thin plate structures

Abstract

The invention relates to introduction of a distributed optical fiber sensor and a tomographic imaging technology into monitoring of load distribution of a flexible thin plate structure and belongs tothe field of structural health monitoring. The introduction comprises the following steps: firstly, describing a bending mechanical model of the flexible thin plate structure by adopting a field theory method; secondly, constructing a mechanical model matched with a tomographic imaging method taking Radon conversion as a mathematical foundation; thirdly, adopting a sensor composed of two fiber bragg gratings which are mutually orthogonal in 0 degree / 90 degrees; and according to strain measured by the sensor, calculating spatial second derivative of location deflection where the sensor is located, wherein a difference value of any two spatial second derivatives is namely the Radon conversion of a shear force field; fourthly, according to a principle that a monitored area is covered most widely while the most scanning lines are generated, constructing a sensor observation matrix; fifthly, according to the Radon conversion of the shear force field obtained in the step three, reconstructing the shear force field by adopting Radon inversion; and sixthly, solving divergence of the shear force field, wherein the divergence of the shear force field is namely the load distribution of the flexible thin plate structure.

Description

technical field [0001] The invention belongs to the field of structural health monitoring, and specifically proposes an optical fiber tomographic imaging method for monitoring the load distribution of flexible thin plate structures. Background technique [0002] Load distribution measurement is an important experiment in the research of aircraft aerodynamics. Its purpose is to measure the distribution and change trend of surface loads on various parts of the aircraft, such as wings, empennages, and external stores. It also provides data for the structural strength calculation of the aircraft and its components, as well as aerodynamic load distribution data. [0003] Wings are one of the main components that determine the overall performance of an aircraft. The measurement methods of wing load distribution are: direct measurement method and indirect measurement method. The direct method refers to the pressure measurement method, which is a method of obtaining the aerodynami...

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Problems solved by technology

However, this method requires a large number of optical fiber integrating optical fiber sensors arranged in a criss-cross pattern on the thin plate, and the number of channels of the Mach-Zehnder optical fiber interferometer is limited, which is difficult to implement in engineering

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