Next seminar: 20 February 2025 at 14:00 (Moscow time = UTC+3:00) prof A.V. Lopatin, A.E. Burov + E.A. Lopatin Federal Research Center for Information and Computational Technologies, Novosibirsk + Steklov Mathematical Institute of the Russian Academy of Sciences,

Title:  Model and bending analysis of sandwich beam with composite facings and compressible orthotropic core using Abramov’s sweep method

       Annotation

Modern sandwich structures are employed in a broad range of aerospace, marine and civil structural applications. They are efficient and lightweight constructions with high bending stiffness, high strength, and high buckling resistance. Such modern sandwich structures are combination of composite facings with a lightweight core layer. The facings carry the tensile and compressive loads, while the core transmits shear loads and serves to hold the facings in positions, which maximize the flexural stiffness of the structure. Therefore, the general structural response of a sandwich structure is an action, consisting of couple, compression or tension stress resultants in the facings and shear stresses along with vertical normal stresses within the core. Note that, in such structures, the facings may undergo different displacements due to the compressible core that may change its height. Proper reflection of this effect in the strain-stress analysis would require the application of the advanced modeling and computational techniques and approaches.

In this study the new computational model of sandwich beam is developed. The beam one-dimensional model by virtue of its relative simplicity is useful for preliminary analyses of the more complicated two-dimensional sandwich structures. The model for the facings was built based on the traditional hypotheses that allow a transverse shear deformation to be taken into account. The deformation model created for the elastic orthotropic core is original. This model considers a non-linear character of variation of the transverse and axial displacements over the thickness of core. Governing system of differential equations, describing join deformation of facings and core, was derived using static and kinematic contact conditions between these parts of the structure. System of governing differential equations has 14th order. Numerical analysis of the stress-strain state of the sandwich beam for various loading cases and boundary conditions has been performed. System of differential equations, together with the corresponding boundary conditions, represented the boundary value problem that was solved using Abramov’s sweep method. Finite element modeling of the sandwich beam was executed using the FEM software package MSC Nastran® and the results were compared with the developed theory. The computational model of deformation of the sandwich beam and method of its analysis developed in this study provide an opportunity to investigate a strong oscillating behavior of the components of stress-strain state of the structure under consideration. This allows the results of analyses performed to be used for the verification of solutions for similar problems found using numerical techniques, including the finite element method.