Author(s)

C. Mattheck & I. Tesari

Abstract

Due to the permanent competition in nature and the survival of the fittest, trees are highly optimised structures. The expenditure of energy and material for failsafe constructions would be uneconomically high for a species and a natural failure rate has to be accepted, but the optimisation prevents early failure. Five theorems are exemplified in the paper which describe the mechanical selfoptimisation mechanisms of trees. - Minimisation of lever arms. Trees minimise stresses by reducing the length of the loaded lever arm. Length reduction can be achieved by active self-bending of stiff parts by forming reaction wood or through passive yielding of flexible parts of trees. - Axiom of uniform stress. Adaptive growth reduces stress-concentrations on the surface. Unavoidable stresses are distributed evenly on the surface of a tree. - Minimisatio

Keywords