Institute of Fundamental Technological Research

A general formulation of the problem of optimal design with geometric constraints is presented. Such constraints define an admissible region in which the variable portion of a structure should be placed. The optimal design of perfectly plastic disks of Tresca material is considered and two problems are discussed in detail: a disk simply supported at two points supports and a cantilever disk loaded by a concentrated force. The optimal design lies in the semi-plane below the line joining supports or within a strip of prescribed width.

The problem of optimal design of solid plates is concerned with the determination of a variable plate thickness that corresponds to minimum volume when the limit load is prescribed. In its solution, the condition of constancy of specific power of dissipation on the exterior plate surfaces is usually applied. This condition only assures a stationary value of the volume and may represent neither an absolute nor a local minimum. Examples of cantilever and circular plates are discussed, and alternative designs are presented which are of smaller volumes than the usual design. A modified formulation of the optimal design problem is discussed.