A study to determine an adequate constitutive equation for the behaviour of beech wood

Living organisms are optimized by nature due to minimize the consumption of material and energy for building and maintaining themselves. Therefore all load bearing structures are weight minimized for resisting a particular lo ad. Technical materials are still far away from load/weight relations adchi eved by nature [4]. It is worth while to examine these "natural experiments " to use the results for building more efficient structure with regard to m aterials. As an objekt of investigation wood stems were chosen because the load cases are quite simple (bending by wind forces and compression by the crown and stem's own weight) and the internal structure of the composite ma terial shows only transversal isotropy.