№74-10

Numerical investigation of convergence of Fourier series, poly-nomials, and method of finite elements

V. Andriievskyi¹, I. Martyniuk¹, O. Maksymiuk¹

¹Kyiv National University of Construction and Architecture, Kyiv, Ukraine

Coll.res.pap.nat.min.univ. 2023, 74:124-132

https://doi.org/10.33271/crpnmu/74.124

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ABSTRACT

Purpose. To compare the efficiency of using finite elements with variable and averaged mechanical and geometric parameters and to investigate the convergence of results obtained by the semi-analytical finite element method (SAFEM) using Fourier series and polynomials with the results obtained by the finite element method (FEM).

The methods. The construction and development of an algorithm for studying the stress-strain state of spatial bodies with variable and averaged mechanical and geometric parameters were carried out based on SAFEM.

Findings. Solvability indicators of SAFEM were obtained for calculating nodal reactions and stiffness matrix coefficients of finite elements with variable and averaged mechanical and geometric parameters. Numerical convergence studies of results obtained using SAFEM with Fourier series, polynomials, and the finite element method were conducted for a benchmark example, which was the Boussinesq problem for a half-space subjected to a concentrated force. The results indicate that the convergence of the investigated coordinate functions in the considered problem is of the first order.

The originality. The obtained solvability indicators of SAFEM for calculating nodal reactions and stiffness matrix coefficients of finite elements with variable and averaged mechanical and geometric parameters allow for the study of various classes of problems. Numerical convergence studies using Fourier series, polynomials, and the finite element method were conducted for the benchmark example.

Practical implementation. The practical significance lies in the development of a methodology for determining the stress-strain state of relevant spatial elements of structures with variable and averaged mechanical and geometric parameters subjected to arbitrarily distributed spatial loads.

Keywords: finite element, finite element method, semi-analytical finite element method, stress-strain state, nodal reactions, stiffness matrix, Fourier series, polynomials, numerical investigations.

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