In this paper. within the range of the so-called deformation theory of
plasticity, the determination of unknown coefficients in a nonlinear
system of equilibrium equations from overspecified data measured at th
e boundary is considered. This inverse problem is reformulated as a mi
nimization problem for a certain functional. It is shown that this fun
ctional has at least one solution (quasisolution) in an admissible cla
ss of coefficients. Then the existence of an exact solution of inverse
problem is proved, A numerical algorithm and examples related to dire
ct and inverse problems are presented.