Non-intrusive reduced-order modeling for nonlinear structural systems via radial basis function-based stiffness evaluation procedure

This paper presents a new radial basis function-based stiffness evaluation procedure developed in the framework of nonlinear, and non-intrusive reduced-order modeling. For structural nonlinear systems, a stiffness evaluation procedure (STEP) and its variants use a cubic polynomial for evaluating nonlinear stiffness coefficients and have been developed as non-intrusive reduced-order models (ROM) using data obtained from numerical simulation model. In this paper, we propose using a radial-basis function (RBF) instead of the cubic polynomials on evaluating nonlinear stiffnesses. As the RBF shows a good performance for approximating nonlinearities, the efficiency and robustness of the ROM are substantially enhanced in a non-intrusive manner. In particular, the proposed R-STEP ROM can be constructed for elastoplastic analysis without any additional treatments. Various numerical examples verify the performance of the proposed R-STEP ROM comparing with the STEP methods and commercial finite element software, ABAQUS.