Experimental and Numerical Analysis of Nonlinear Dynamic Behavior of Delaminated Composite Shell Panel under Hygro-thermo-mechanical Loading

Abstract

The nonlinear dynamic responses of the delaminated composite shell panel structure under the combined hygro-thermo-mechanical loading have been analyzed using a generic higher-order FE model in this dissertation. To compute the numerical responses (static, frequency and transient deflection), the nonlinear mathematical model has been developed with the help of two different higher-order polynomials (nine and ten degrees of freedom) and a sub-laminate approach for the inclusion of inter-layer separations. Further, to incorporate the realistic material behavior two different approaches are adopted, i.e., the macro and the micromechanical model including Green-Lagrange strain-displacement relations for excess geometrical distortion. Moreover, the current model is capable of solving for two kind of temperature loading (uniform and linear) and two transverse mechanical load (uniform and sinusoidal). The current macro/micromechanical FE model is capable of handling the variable type of structural problems, i.e., the variation in geometrical dimension, geometries (flat/curved) and elastic properties. The finite element solutions are obtained by resolving the structural governing equations (eigenvalue and equilibrium) with the help of the direct iterative method and Newmark’s integration technique. Further, the model accuracy has been established by comparing the current results with open source data evaluated via various techniques (numerical, exact and analytical). Additionally, to improve the confidence on the present numerical solutions, the results are compared with the own experimental data including the experimental elastic properties. Subsequently, the role of single/multiple debonding (size, location and position) and associated design input parameters on the linear and nonlinear structural responses are computed through a series of numerical examples. Finally, the influences of input parameters associated with material, the geometries including the geometrical configurations on the final responses (linear/nonlinear static, frequencies and transient deflections) are evaluated using the present higher-order nonlinear models and the corresponding inferences provided in details.