DESIGN AND GROWTH RULES FOR BIOLOGICAL STRUCTURES AND THEIR APPLICATION TO ENGINEERING

Starting from the well-accepted but not proved hypothesis that biological load carrying structures are highly optimized by growth, some examples are given and their degrees of optimization are demonstrated. Especially branch joints, deer antlers, branch holes in trees and modelling growth of trees loaded by contact stresses are discussed. On the basis of the knowledge that biological structures always try to avoid localized stress peaks (notch stresses), and that they try to grow into a locally homogeneous surface stress state, a new method of CAO (computer aided shape-optimization) is proposed which relies on biological growth. Its efficiency and success are demonstrated for two- and three-dimensional structures with very homogenous stress states after optimization.