Wings Stress Analysis

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STRESS ANALYIS OF THE STIFFENED PANEL 3.1 Introduction: In the current project, a stiffened panel of the bottom skin of a transport aircraft wing is considered for analysis. The geometrical details of the panel are shown in drawing 1. The salient features of the stiffened panel are as follows • Large cutout • Integral stiffeners • Small holes around the cutout region The bottom skin is a machined component with integral stiffeners. These stiffeners run along the span-wise direction of the wing. The stiffeners are stopped at few locations where they are intersecting with the landing gear beam or the ribs in the chord-wise direction. There are several ribs oriented in the chord-wise direction of the wing. There are two landing gear beams in…show more content…
The magnitude of load as well as its distribution acting on different components of the airframe is needed for the stress analysis. During the flight starting from ground run to landing of the aircraft one can define several load cases. (With specific distribution and magnitude) The load considered in the present analysis is one of the critical load cases for the wing. During flight the wings will deflect in the upward direction. Due to this loading, bottom skin of the wing will experience tension and top skin will be under compression. The stiffened panel considered for the analysis is the bottom skin and has a big landing gear cutout. Essentially the bottom stiffened panel experiences tension-tension loading. The landing gear cutout is a zone of high stress concentration in the panel. The total load acting along the width of the cross section in the bottom skin is considered for the stress analysis. The root end of the stiffened panel is constrained with all degrees of freedom. At the other end a tensile load is applied. The magnitude of the tensile load is arrived as explained…show more content…
The all up weight (AUW) of the aircraft considered for the study is 6245 Kg. The fatigue load spectrum (section 5.3) considered has a peak load at ‘2g’ condition. Therefore the maximum load acting on the wing is equivalent to the load at ‘2g’ condition. Hence the total load acting on the wing at ‘2g’ condition is 12490Kg (6245 X 2). This resultant load is acting at a distance of 2900 mm from the root end of the wing (obtained from computational fluid dynamics CFD analysis). The moment created by this load at the sect A–A (The section A-A is the section at edge of the stiffened panel considered for the analysis). Moment at sect A–A = 12490 X 687 = 8580630 Kg – mm This applied moment is resisted by equal and opposite axial forces in top and bottom skin of the wing. Due to this moment, axial tensile load created at bottom skin of the wing which is given by Moment Axial Tensile load = ------------- Depth 8580630 = ------------- 500 Axial Tensile load = 17161.26 Kg Axial Tensile load ~17160

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