Buckling & postbuckling of cocured composite stiffened panel under axial compression load- Computation & Testing

Masood, Nadeem and Viswamurthy , SR and Gaddikeri, KM and Arun, Kumar Singh (2014) Buckling & postbuckling of cocured composite stiffened panel under axial compression load- Computation & Testing. In: 18th NASAS (Eighteenth National Seminar on Aerospace Structures), 15-17 December 2014, VNIT Nagpur.

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      Abstract

      A cocured carbon fibre composite stiffened panel was designed to have an early onset of skin buckling and larger postbuckled strength. IMA/M21 prepreg was used for fabricating the panel using autoclave moulding process. Special end fixtures were developed using a metallic casing and the panel was encased in it using a mixture of epoxy resin and aluminium powder. The panel was tested under axial compression to its full load bearing capacity in a universal testing machine. Full field displacement measurement was carried out using advanced techniques like Digital Image Correlation (DIC) apart from acoustic emission technique and strain gauges for monitoring the structural response. After the test, the panel was subjected to ultrasonic scan to check for any delamination or disbonding that might have occurred due to post buckled response. Concurrently, a finite element model was developed to predict the buckling and postbuckling response of panel. DIC captured the onset of skin buckling and deformations/mode shapes in postbuckling regime. These experimental observations were correlated with numerical simulations. In the postbuckled regime, severe bending and twisting of skin and stringers was observed, resulting in complete loss of global axial stiffness of the panel. It is suspected that such a state of stress in the panel could lead to delamination, debonding or fiber failures. However, acoustic emission sensors bonded to the panel did not record any significant events during tests, even in the deep postbuckled regime. This was further corroborated through ultrasonic inspection conducted after unloading the panel.

      Item Type: Conference or Workshop Item (Paper)
      Subjects: CHEMISTRY AND MATERIALS > Composite Materials
      ENGINEERING > Structural Mechanics
      Division/Department: Advanced Composites Division, Advanced Composites Division, Advanced Composites Division, Advanced Composites Division
      Depositing User: Dr. Viswamurthy S R
      Date Deposited: 07 Jan 2015 15:33
      Last Modified: 07 Jan 2015 15:33
      URI: http://nal-ir.nal.res.in/id/eprint/12072

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