Constraint method for laminated composite flat stiffened panel analysis using variational asymptotic method (VAM)

Abstract

Abstract In this work, a new methodology is developed for constructing the stiffened panel structure. Here we introduce the constraint method to integrate the stiffener and plate. The geometric nonlinear analysis is performed to analyze the stiffened panel behavior in terms of load-deformation response curve. Variational Asymptotic Method (VAM) is applied to analyze composite flat stiffened panels. The VAM development begins with the 3-D nonlinear strain energy functional which splits into a 1-D through-the-thickness analysis and a 2-D plate analysis. The 2-D constitutive law that is an output of 1-D analysis is used as an input to perform the 2-D nonlinear plate analysis. The integration of skin and the stiffener technique is implemented by introducing a constraint matrix. At the skin and stiffener interface, the developed constraint matrix is used in realization of 3-D displacements of stiffener and skin are same. The proposed approach is simple and reliable to address the complexity in analyzing stiffened structures. This methodology is developed using a computational symbolic tool Mathematica and the implemented computer program named as NASSVAM (Nonlinear Analysis of Stiffened Structures using Variational Asymptotic Method). The obtained results from NASSVAM are compared and showed good agreement with the 3-D FEA results.