DESIGN VARIATIONS OF NONLINEAR ELASTIC STRUCTURES SUBJECTED TO FOLLOWER FORCES

The effect of incorporating the load-stiffness matrix due to follower forces on design variations of nonlinear elastic structures is studied for the first time in this paper. In general, presence of the followe r forces leads to unsymmetric equations for analysis and design variat ion calculations which are expensive to solve. However, the case of un iform pressure that remains normal to the deformed surface can be form ulated to give only symmetric contribution to the tangent stiffness ma trix. Analysis is focused on this case and an explicit expression for the load-stiffness matrix is derived. Numerical examples are used to c alculate design variations with and without the load-stiffness matrix included in calculations. It is shown that inclusion of the load-stiff ness matrix gives much more accurate design variations. Therefore, it is recommended to include it in the design optimization process for be tter numerical performance and optimum solutions.