DETECTION OF DAMAGE IN STIFFENERS OF AIRCRAFT WING STRUCTURE BASED ON INDUCED SKIN STRAINS AND LATERAL DEFLECTIONS

In this paper, the technique of structure health monitoring was applied to detect damage occurrence in the stiffeners of wing structure. A wing structure of airfoil shape according to digital NACA 0015 was considered for modelling the aerodynamic wing shape. Finite element models of the wing structure were created included undamaged and damage wing structures using high order eight nodes and six nodes shell elements. The damaged wing models included damaged at the main spar at 20%, 40%,60% and 80% the distance than the root chord. A mathematical model was developed using high order shell elements and programmed via MATLAB. The load cases were predicted experimentally using wind tunnel test on a wood airfoil prototype such that the pressure distributions through upper and lower wing skins measured at different attack angles. The static solutions were achieved for each finite element model under action of maximum pressure distribution at attack angle of 100 . Strains distributions and lateral deflections through lower skin were estimated. The results of strains through lower skin showed occurring of climax in strain values initiated in the distribution at the location of the damage for all the cases of damaged structures, which not appeared in the undamaged wing structure.