Elasto-Plastic Stress Analysis of a High Stress Region Of Saras Aircraft Wing

Murthy, Sridhara S (2007) Elasto-Plastic Stress Analysis of a High Stress Region Of Saras Aircraft Wing. In: Symposium on Aircraft Design, 14th June 2007, Bangalore, India.

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    Abstract

    This paper addresses the problem of high local stress observed during the SARAS structural wing test under Design Limit Load (DLL) at a stress concentration point in the Main Landing Gear (MLG) cutout of SARAS transport aircraft wing. The description of the problem is followed by the stress analysis results from a local two-dimensional finite element stress analysis. The two-dimensional model deployed was a fused model, where the parts of the wing which are riveted together are modelled through a single finite element by specifying their combined thickness. The latter analysis predicts a maximum von Mises stress and strain of 31 kg/mm2 and 3062 ms respectively (Material: 2024-T351 alloy; Yield strain: 450013; ms). During the structural test, however, a strain gauge near the same location recorded a recoverable elastic strain of 8753 ms under loading, unloading and re-loading up to DLL. This was much higher than the material yield strain and thus points to the local plastic yielding. The problem was addressed by taking recourse to a local13; three-dimensional elasto-plastic stress analysis by deploying HEXA8 solid elements of MSC/NASTRAN. The bi-linear material model, von Mises yield criterion and isotropic hardening were deployed in the EP simulation. The analysis results are presented as load vs. strain13; and load vs. stress and growth of plastic zones near high stress point up to DUL (1.5 times DLL) with unloading and reloading at DLL. These results show that the local von Mises strain at DLL is 14060 ms, with 9818 ms as the plastic component. The recoverable elastic strain upon unloading at DLL is 8243 ms which is close to the test13; value of 8753 ms.

    Item Type: Conference or Workshop Item (Lecture)
    Uncontrolled Keywords: Elasto Plastic Stress Analysis;High Stress Region;Saras Aircraft Wing
    Subjects: ENGINEERING > Structural Mechanics
    Division/Department: Structures Division
    Depositing User: Ms Indrani V
    Date Deposited: 09 Jan 2009
    Last Modified: 07 Jun 2010 15:01
    URI: http://nal-ir.nal.res.in/id/eprint/4209

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