DUAL FINITE-ELEMENT ANALYSIS FOR PLASTICITY-FRICTION TORSION OF COMPOSITE BAR

The quasi-static problem of torsion of an elastic-plastic, prismatic, composite bar is considered in the paper. The phenomenon of slip on th e interfaces between the components of the bar is taken into account. The elastic-plastic behaviour of the material is described by the Pran dtl-Reuss constitutive relation. The slip on the interface is governed by the Coulomb friction law-it is assumed that there is no cohesion b etween components of the bar. The stresses normal to the interfaces ar e considered to be caused by shrinkage of the matrix of the bar or by external forces acting perpendicularly to its longitudinal axis. The p roblem is set in the dual variational forms and solved with the help o f the finite element method. Two approximate kinematically and statica lly admissible solutions are obtained. The stress function is used for calculation of the second one. The iterative algorithms solving the p roblem and some numerical results are presented in the paper.