Joint load measurement method based on strain identification multi-joint

Abstract

A joint load measurement method based on strain identification multi-joint comprises the following steps: firstly disassembling butted structural parts, then selecting one of the structural parts forcalibration, selecting a first joint A1 to be loaded step by step in an x direction for a total load of 8 levels, recording a load F1 and values of each of strain epsiloni1s, performing linear fittingto obtain a relationship line between the load F1 and each of the strain epsiloni1s to obtain 3m slope ki1s, calibrating each of the joints in any direction in the same way to form a transfer coefficient matrix between strain and load, performing linear superposition on the transfer coefficient matrix, identifying the load of a plurality of connecting hinge points among different structural members, especially the connecting load of aircraft wing joints, by measuring the strain, and inverting the joint load with an over-constrained system by measuring and calibrating the transfer relationshipbetween the strain and joint load, so as to achieve the measurement of the joint load inside the structure, thereby effectively overcoming the lack of load measured by the force sensor, and measuringthe joint load is of great significance for structural design optimization.

Description

technical field [0001] The invention relates to the technical field of joint load measurement, in particular to a joint load measurement method based on strain identification of multiple joints. Background technique [0002] The aircraft wing and the fuselage or other structural parts that need to be connected together through multiple joints are over-constrained due to the large number of joints, and the size of the joint load cannot be directly measured by force sensors, and it is difficult to measure according to the actual joint connection. Establishing an accurate finite element model, and how much load each joint transmits is of great significance to structural design and optimization. Scholars at home and abroad have published papers on the identification of boundary conditions, which is to divide the entire boundary Γ into unknown parts Γ 1 and the known part Γ 2 , using Γ through finite elements or boundary elements 2 The boundary conditions (forces and displacem...

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Problems solved by technology

Scholars at home and abroad have published papers on the identification of boundary conditions, which is to divide the entire boundary Γ into unknown parts Γ 1 and the known part Γ 2 , using Γ through finite elements or boundary elements 2 The boundary conditions (forces and displacements) of the inversion Γ 1 The boundary conditions (force and displacement) of Γ have made some theoretical progress, but there are still some shortcomings: first, Γ 2 There is often no way to obtain the boundary conditions under actual conditions; secondly, the load forms studied are often uniformly distributed loads, but the joint loads in actual situations are concentrated loads, and the loads of each joint are generally different

Chinese patent ZL201410154031.2 discloses a method of load measurement. The disadvantage of this method is that it is difficult to measure the load transfer to multiple joints; According to the stress characteristics of the structure, it is difficult to implement the arrangement of strain gauges once the structural connection form is too complicated; Singular value decomposition and structural load identification methods, both of which are load identification methods based on Tikhonov regularization method, essentially require the equation to satisfy the Picard condition

For load identification problems or general ill-conditioned problems, it may appear that the equation does not satisfy the Picard condition

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