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Estimation of Interlaminar Stresses in Asymmetric Composite Sandwich Panels Under Impact Loading Using the Variational Asymptotic Method

Kandula, Rama and Prasad, PS and Harursampath, Dinesh Kumar (2016) Estimation of Interlaminar Stresses in Asymmetric Composite Sandwich Panels Under Impact Loading Using the Variational Asymptotic Method. In: International Workshop on Mechanical Behavior of Thick Composites, MAR 14-15, 2016, Montreal, CANADA, pp. 86-93.

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Abstract

Thick composite panels with sandwich construction are employed in a wide range of structural applications in the aerospace industry. For example, sections of honeycomb sandwich panels often exceed 50 mm in fan containment cases of commercial jet engines. Impact is the typical design load for the thick composites in this case. During the ballistic impact, energy transfer takes place from the projectile to the target, through a combination of deformation as well as damage initiation & progression. Delamination is one of the major damage & energy absorbing mechanisms. Finite element modeling using appropriate plate/shell elements can help in predicting the 2-D responses (displacement, strain, & stress fields) efficiently & accurately. However, the ability to precisely predict the thickness-wise distributions of transverse shear & normal stresses as well as 3-D displacements had long remained an elusive feature. An accurate & thorough stress analysis of a composite sandwich structure can be carried out using 3-D finite elements for each layer. However this method has serious limitation due to the large number of thin plies for the thick shells, the large number of degrees of freedom to account for, compounded by the requirement to retain element quality & reasonable time step size. In the current work, the Variational Asymptotic Method (VAM) is used semi-analytically to predict the response of an asymmetric composite laminated sandwich plate under the influence of an impact load. VAM reduces the dimensionality of the 3-D problem systematically into a closed-form 1-D through-the-thickness analysis & a numerical 2-D plate/shell analysis. The variational form retains all the important parameters required for accuracy. The asymptotic expansion at every stage includes minimal additional terms that are required to enhance accuracy to enable refined engineering judgment of the design capability with short turnaround time. The 3-D fields recovered in a much more computationally efficient manner using VAM are validated using commercial 3-D finite element models.

Item Type: Conference Proceedings
Additional Information: Copy right for this article belongs to the DESTECH PUBLICATIONS, INC, 439 DUKE STREET, LANCASTER, PA 17602-4967 USA
Department/Centre: Division of Mechanical Sciences > Aerospace Engineering (Formerly, Aeronautical Engineering)
Date Deposited: 30 Dec 2016 06:17
Last Modified: 30 Dec 2016 06:17
URI: http://eprints.iisc.ernet.in/id/eprint/55625

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