Experiment and Numerical Simulation for the Compressive Buckling Behavior of Double-Sided Laser-Welded Al-Li Alloy Aircraft Fuselage Panel.

Yunlong Zhang,Zhenkun Lei,Zhenglong Lei,Wang Tao,Yanbin Chen,Ruixiang Bai

doi:10.3390/ma13163599

Abstract

The aim of this work was to study the buckling behavior and failure mode of the double-sided laser-welded Al–Li alloy panel structure under the effect of axial compression via experimental and numerical simulation methods. In the test, multi-frequency fringe projection profilometry was used to monitor the out-of-plane displacement of the laser-welded panel structure during the axial compression load. In addition, the in-plane deformation was precisely monitored via strain gauge and strain rosette. The basic principles of fringe projection profilometry were introduced, and how to use fringe projection profilometry to obtain out-of-plane displacement was also presented. Numerical simulations were performed using the finite element method (FEM) to predict the failure load and buckling modes of the laser-welded panel structure under axial compression, and the obtained results were compared with those of the experiment. It was found that the fringe projection profilometry method for monitoring the buckling deformation of the laser-welded structure was verified to be effective in terms of a measurement accuracy of sub-millimeter level. The structural failure was caused by local buckling of the skin. The observed failure modes such as local buckling of the skin, bending deformation of the stringers, continuous fracture of several welds, and failure of local strength and stiffness were attributed to the deformed laser-welded panel structure under the axial compression. The predicted failure load in the numerical simulation was slightly smaller than that of the experimental test, and the error of the simulation result relative to the test result was −2.7%. The difference between them might be due to the fact that the boundary and loading conditions used in the FEM model could not be completely consistent with those used in the actual experiment.

Highlights

Laser beam welding (LBW) was proven to be an effective technique for manufacturing of the aircraft fuselage panels fabricated by heat-treatable aluminum alloys on account of its low distortion and excellent mechanical properties [1]
The full-field morphology measured by the fringe projection profilometry (FPP) technique can be used to distinguish the buckling convexes and concaves
When a small amount of compression load was applied to the panel structure, the strain of the corresponding positions on the front and back of the panel was basically the same upon adjusting the position of the panel and filling the gaskets

Summary

Introduction

Laser beam welding (LBW) was proven to be an effective technique for manufacturing of the aircraft fuselage panels fabricated by heat-treatable aluminum alloys on account of its low distortion and excellent mechanical properties [1]. As an alternative to the conventional aluminum alloy, the aluminum–lithium (Al–Li) alloy with low density, high elasticity modulus, high specific stiffness, and high specific strength can be used in welding as the panel materials for the aircraft fuselage [7,8]. The LBW technique is more suitable for optimizing the complex geometry of structures of the aircraft fuselage panel in terms of mechanical stiffness, strength, production speed, and visual quality [4].

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