Institute of Fundamental Technological Research

Disks and plates subjected to stretching and flexure are stiffened by curvilinear ribstiffeners whose shape and cross-sectional area are subject to optimization. Sensitivity analysis is first discussed for an arbitrary integral functional of generalized stress, strain and displacement and boundary domains. The optimality conditions are next derived. The general theory is illustrated by three examples of optimal design of ring-stiffeners in circular disks and plates and of rib-stiffeners in a rectangular plate.

The optimal design problem concerns vibrating beams having unspecified thicknesses and lengths as well as supports whose positions and stiffnesses are to be determined. The character of optimal solutions is discussed, and it is shown that the optimal support position may correspond to unimodal or multimodal vibrating states.

An iterative design procedure is discussed and applied to generate optimal designs in simple cases. Optimal design for more complex cases can be achieved by proper scaling and connecting basic solutions.

Formulation of the problem of optimal design for beams with unspecified support position and stiffness is presented. It is assumed that the beam is composed of segments of unspecified cross-sections and lengths which are to be determined together with support positions and cross-sections. Design for specified mean compliance, first frequency of free vibrations or buckling force is considered and proper optimality criteria are derived. Illustrative examples are presented and the iterative algorithm of numerical solution is discussed in detail.