Static and modal analysis of sine-wave-shaped spar

Abstract

Sine-Wave-shaped Spar (SWS) is recently involved in wing design as one of the corrugated shaped spars that highly improve the torsion and buckling resistance. SWS is an I-beam made of sine wave shaped vertical web fixed to upper and lower flanges. The current research evaluates the behavior of SWS in comparison to the traditional straight-web spar in resisting two cases of loading; static bending loading and static torsion loading. For each case, deformation and stress are analyzed. Modal analysis is also performed for the two spar configurations. For this purpose, a finite element model is developed using Ansys Workbench software for the SWS and the straight web spar. To reach a fair comparison, similar weight is considered for the two spar structures. A parametric study is performed to investigate the effect of web thickness and flange thickness on the bending and torsion deformation and stresses. The effect of thickness variation on the natural frequencies and mode shapes is also considered. The current study can be considered a base to design wing spars that combine the merits of the two spar configurations.