Nonlinear steady-state responses of weakly bonded composite shell structure under hygro-thermo-mechanical loading

Abstract

The nonlinear micromechanical finite element (FE) model is derived to compute the steady-state time-dependent deflections of the weakly connected layered composite panel. The distorted structural geometry is modelled mathematically via the nonlinear strain kinematics in the framework of two different displacement theories (constant and linear functions of the through-thickness stretching term). The thermo-elastic constitutive relation is invoked to count the modified composite properties due to the change in environment. Besides, a sub-laminate approach with end continuity conditions is adopted to model the loosely bonded layers. The equation of motion of shallow panel under the mechanical excitation and the environmental effect is expressed through Hamilton’s principle due to the environmental changes. The deflection parameters due to the steady-state loadings are predicted using the combinations of three different techniques, i.e., the FE, the direct iterative method and Newmark’s constant acceleration. The nonlinear model responses are compared with published data considering all of the strain terms to capture the actual structural distortion. The applicability of the micromechanical FE model is deliberated by taking the combined influences of geometry, property, end constraints and the debonding parameters (size, location and position). A few conclusions are dawn on the micromechanical model after the numerical experimentations.