DAMAGE TOLERANCE EVALUATION OF WING IN PRESENCE OF LARGE LANDING GEAR CUTOUT THROUGH STRESS ANALYSIS USING FEM

Madhura B M, N.G.S.Udupa, Rajanna S

Abstract: Aircraft is symbol of a high performance mechanical structure, which has the ability to fly with a very high structural safety record. Aircraft experiences variable loading in service. Rarely an aircraft will fail due to a static overload during its service life. For the continued airworthiness of an aircraft during its entire economic service life, fatigue and damage tolerance design, analysis, testing and service experience correlation play a pivotal role. The present study includes the stress analysis and damage tolerance evaluation of the wing through a stiffened panel of the bottom skin with a landing gear cutout. Wing bottom skin experiences tensile stress field during flight. Cutouts required for fuel access and landing gear opening and retraction in the bottom skin will introduce stress concentration. Fatigue cracks will initiate from high tensile stress locations. An integral stiffened panel consisting a landing gear cutout is considered for the analysis. Stress analysis will identify the maximum tensile stress location in the panel. In a metallic structure fatigue manifests itself in the form of a crack which propagates. If the crack in a critical location goes unnoticed it could lead to a catastrophic failure of the airframe. A critical condition will occur when the stress intensity factor (SIF) at the crack tip becomes equal to fracture toughness of the material. SIF calculations will be carried out for a crack with incremental crack lengths using MVCCI method. Analytical evaluation of the crack arrest capability of the stiffening members ahead of the crack tip will be carried out.

Keywords: Key Aircraft, Design, wing, landing gear cutout, stress analysis, FEM, damage tolerance, integral stiffened panel.

DOI: https://doi.org/10.15623/ijret.2014.0301002