The comparison of one- and three-dimensional cure simulation of thick thermoset matrix laminates was conducted in this study. The applicable conditions of one-dimensional cure simulation were investigated. The transient heat conduction equation coupled to the cure kinetics was solved numerically using one- and three-dimensional finite element analysis. The evolution of temperature and degree of cure of the laminates during the curing process obtained by the simulation agreed well with the published experimental results. The results indicate that a wider one-dimensional analysis applicable region around the center point will be obtained in the laminate with a higher span-to-thickness ratio and in a less anisotropic material system. In the applicable region, the accuracy of the one-dimensional cure simulation can satisfy the engineering request and save the computational cost. While beyond the region, there is a steep increase in deviation of the one- and three-dimensional simulation results.
Stiffened composite structures are commonly composed of skins and stiffeners that are employed to transfer and carry load, respectively. An improved multiscale finite element method is presented for geometrically nonlinear bending analysis of composite grid stiffened laminates. In the developed method, two kinds of strategies for establishing stiffened multiscale models are presented, in which the stiffeners are modeled at different scale. By introducing a virtual degree of freedom and additional coupling terms, multiscale base functions are improved to consider the local effects of stiffeners and coupling effects of composites. To construct the multiscale base functions of stiffened multiscale models, an extended displacement boundary conditions are constructed, in which the displacements of stiffeners are imposed constraints based on the displacement continuous conditions between skin and stiffener. Incremental multiscale finite element formulations are derived based on Total-Lagrange description and von Karman's large deflection plate theory. The incremental displacement boundary conditions are constructed to consider the effect of microscopic unbalanced force on microscopic results. Numerical examples show high efficiency and applicability of the developed method for composite grid stiffened laminates. KEYWORDS displacement boundary conditions, geometrically nonlinear bending analysis, multiscale base functions, multiscale finite element method, stiffened composite structures, stiffened multiscale models Int J Numer Methods Eng. 2019;118:459-481.wileyonlinelibrary.com/journal/nme
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