en Optimal design Optimal design پژوهشي Research <p>The paper is concerned with a methodology of optimal design of shells of minimum weight with strength, stability and strain constraints. Stress and strain state of the shell is determined by Galerkin method in the mixed finite element formulation within the geometrically nonlinear theory. The analysis of the effectiveness of different optimization algorithms to solve the set problem is given. The results of solving test problems are presented.</p> optimization, variable thickness, ribbed shells, nonlinearity, Galerkin method, mixed finite element. 231 240 http://ijoce.iust.ac.ir/browse.php?a_code=A-10-66-137&slc_lang=en&sid=1 L. Stupishin 180031947532846001100 180031947532846001100 Yes K. Nikitin 180031947532846001101 180031947532846001101 No A. Kolesnikov 180031947532846001102 180031947532846001102 No F. Altuhov 180031947532846001103 180031947532846001103 No