Inelastic strain estimation based on line search and direct secant methods.

摘要

Several traditional secant techniques were developed to update the secant stiffness directly in FEA based on nonlinear schemes. The present study explores simple and systematic methods for determining inelastic effects based on line search and direct secant modulus. The main concept of these methods is the minimization of the total residual energy after first linear FEA. A line search with the displacements due to the unbalanced forces spreads the yield zone considerably closer to the actual state.; The present study summarizes important categories of available techniques based on the Newton-Raphson and secant schemes (traditional as well as robust). Seven different possible alternatives for robust estimation of inelastic strain based on line search are examined. Two schemes based on Neuber's rule are examined. These are compared with full nonlinear analysis and EGLOSS, etc. The schemes are applied to study the problems of simply supported beam, propped cantilever, fixed beam (all with UDL), bending of rectangular plate with irregular boundary, simple truss, stretching of a plate with a hole, thick cylinder with internal pressure, thick cylinder with a circumferential notch, and torisherical shell. (Abstract shortened by UMI.)