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This study focuses on investigating how grid-stiffened composite shells behave under external hydrostatic pressure. The critical buckling load is calculated using the first-order shear deformation theory (FSDT) and the Ritz method. Various factors, including shell thickness, angle of helical stiffeners, rib section area, and the number of stiffeners, are examined to understand their impact on the buckling load. To optimize the design, three multi-objective optimization algorithms are employed: Nondominated Sorting Genetic Algorithm II (NSGAII), Multiobjective Particle Swarm Optimization (MOPSO), and a hybrid method that combines NSGAII and MOPSO. The hybrid method intelligently divides the population into two groups and uses NSGAII and MOPSO to efficiently explore and exploit the solution space. The results yield a Pareto optimal front that showcases diverse solutions across different regions, providing decision-makers with the flexibility to select the solution that best fits their preferences. The solutions obtained through these algorithms are compared based on their diversity and distribution throughout the Pareto front. [ABSTRACT FROM AUTHOR]

Thin-walled composite beams of complex sectional contour are widely used along with the traditional elements of reinforced structures. Based on the generalized theory of elasticity of thin-walled beams, the mathematical model of flexural–torsional deformation of open-profile thin-walled composite beams of non-uniform cross section under thermo-mechanical loading has been developed. To confirm the reliability of developed approach to determination of the spatial displacements of thin-walled composite beams of non-uniform cross section, several experimental studies were conducted. Based on the analysis of the range of typical profiles, for the further analysis we selected several compound cross sections for which the analytical dependences were obtained regarding displacements of their characteristic points. Our studies can serve as a base for development of the practical recommendations for the optimal designing and manufacturing of thin-walled anisotropic profiles, as well as proposing the measures to reduce the value of deformations caused by the production process. [ABSTRACT FROM AUTHOR]

Tension–compression asymmetry, thermal-mechanical coupling, and finite deformation effects are common characters of many biological materials and engineering structures. By introducing different elastic constants under tension and compression, a thermo-mechanical bi-modulus constitutive model and a subsequent efficient computational analysis framework are proposed in the finite deformation regime. After we validate the convergence, accuracy, and robustness of the algorithm, we investigate the mechanical behavior of human brain tissue under varying intracranial pressure and temperature. Furthermore, with the use of the proposed bi-modulus thermoelasticity model, the classic tension-field theory is regularized, and wrinkling region and its evolution in membranes under thermomechanical loads can be effectively predicted, as an alternative to the computationally intensive post-buckling analyses. • A constitutive law accounting for TCA, thermal-mechanical coupling, and finite deformation effects is proposed. • An efficient iterative method for bi-modulus thermoelastic structures is developed. • Thermoelastic responses of human brain tissue is simulated. • Wrinkling regions of membranes in thermo-mechanical environment are efficiently predicted. [ABSTRACT FROM AUTHOR]