Shimming design and optimal selection for non-uniform gaps in wing assembly

Abstract

Purpose This paper aims to provide a shimming method based on scanned data and finite element analysis (FEA) for a wing box assembly involving non-uniform gaps. The effort of the present work is to deal with gap compensation problem using hybrid shims composed of solid and liquid forms. Design/methodology/approach First, the assembly gaps of the mating components are calculated based on the scanned surfaces. The local gap region is extracted by the seed point and region growth algorithm from the scattered point cloud. Second, with the constraints of hole margin, gap space and shim specification, the optional shimming schemes are designed by the exhaustive searching method. Finally, the three-dimensional model of the real component is reconstructed based on the reverse engineering techniques, such as section lines and sweeping. Using FEA software ABAQUS, the stress distribution and damage status of the joints under tensile load are obtained for optimal scheme selection. Findings With the scanned mating surfaces, the non-uniform gaps are digitally evaluated with accurate measurement and good visualization. By filling the hybrid shims in the assembly gaps, the joint structures possess similar load capacity but stronger initial stiffness compared to the custom-shimmed structures. Practical implications This method has been tested with the interface data of a wing tip, and the results have shown good efficiency and automation of the shimming process. Originality/value The proposed method can decrease the manufacturing cost of shims, shorten the shimming process cycle and improve the assembly efficiency.

Effect of Gap and Shims on the Strain and Stress State of the Composite-Aluminum Hybrid Bolted Structure

“…Bakker et al [9] developed a new general method to predict the assembly gap between components and estimates the number of shims required. Wang et al [10] proposed a gap filling method based on scan data and finite element analysis for the uneven gaps appearing during the assembly of aircraft wing box. Liu et al [11] developed a numerical method for predicting gaps.…”

Einsatz vom duroplastischen Spaltausgleichsmaterial DIAMANT MM1018 in vorgespannten geschraubten Verbindungen

“…B. in der Flugzeugindustrie weitverbreitet. Um das Tragverhalten solcher Verbindungen zu erfassen, werden laufend Untersuchungen durchgeführt [2–12]. Im Bereich des Stahlbaus ist jedoch der Einsatz derartiger Materialien, v. a. in Kombination mit geschraubten Verbindungen, noch nicht üblich.…”

A Review on Variation Modeling of Aircraft Assembly

“…For controlling the gap between the composite panel and metal frames, Wang [115,116] first optimize the gap distribution between skeleton frame and panel skin by tansforming the pose of the composite panel, and then a reasonable shim scheme could be designed based on the residual gap values. Moreover, Cheng, on the other hand, conducted an experimental and simulation study on the mechanical properties of the overall structure after shimming compensation for the wing panels.…”