Comparison among nonlinear optimization methods for the static equilibriumanalysis of multibody systems with rigid and elastic elements

The present paper describes a set of procedures for the solution of the non linear static-equilibrium problem in complex multibody mechanical systems, including rigid and elastic elements. The error function is a simple one ba sed on the potential function, which includes rigid elements by means of no nlinear constraints. To this end Lagrange Multipliers, along with various v ersions of the Augmented Lagrange Multipliers (ALM) or Primal-Dual Method a re used, comparisons are made between them. A Newton-Raphson second-order m ethod is used in seeking function minima for equilibrium positions. This pr ocedure is also directly useful for other mechanism position problems, such as initial position, finite displacements, and deformed position, as well as direct and inverse problems. (C) 2000 Elsevier Science Ltd. All rights r eserved.