STOCHASTIC BUCKLING ANALYSES OF LAMINATED COMPOSITE PLATES UNDER HYGROTHERMAL, GEOMETRIC AND MATERIAL UNCERTAINTIES MODELED AS NON-GAUSSIAN RANDOM FIELDS

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© 2024, International Council of the Aeronautical Sciences. All rights reserved.The combined effects of hygrothermal conditions and material characteristics on the buckling response of laminated composite plates are numerically studied in this paper. As the physical mechanisms determining the environmental and operational conditions are very complex, the temperature and moisture variations throughout a structure can hardly be controlled in many cases of industrial interest. Also, inherent material variability are present in the structure domain due to manufacturing processes, specially involving composite materials. As a consequence, the characterization of the environmental and material influences as random quantities is more appropriate. Motivated by situations found in aerospace structural engineering, this paper aims to investigate the influence of space-dependent random hygrothermal conditions, geometry and material properties on the critical buckling loads of composite laminate plates. The main contributions lie in the consideration of simultaneous random quantities affecting the structural stability and combined influences of the environmental effects both on the degradation of material properties and the occurrence of stresses induced by hygrothermal changes. Under the hypotheses of the Classical Lamination Theory, a finite element model is employed to perform buckling analysis considering hygrothermal and mechanical loadings, where the degradation of material properties is predicted using a micromechanical approach. The space-dependent fluctuations of temperature, fiber-direction angle, ply thickness, and fiber volume fraction are discretized as stationary two-dimensional random fields by the Karhunen-Loève expansion (KLE), considering non-Gaussian marginal distribution functions, where the simulation are conducted using a methodology based on the Iterative Translation Approximation Method (ITAM). Monte Carlo Simulation, combined with the Latin Hypercube Sampling, is used to generate sampling-based statistics for the critical buckling load considering different values of standard deviations and correlation lengths associated to the random fields. From the simulation scenarios analyzed, the necessity of accounting for random environmental and material uncertainties in the analysis and design of reliable and robust composite structures is highlighted.

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