Construction of Stable and Lightweight Technical Structures Inspired by Ossification of Bones Using Osteogenetic P Systems

摘要

Vertebrates come with a skeleton of bones whose inner structure combines two contradicting properties in a fascinating way: On the one hand, bones are stable and robust against mechanical stress, and on the other hand they are lightweight to minimise the energy necessary for motion of the organism. By means of a biological process called ossification, the inner structure of bones becomes permanently optimised during organism's lifetime which implies a high adaptability to varying environmental and behavioural needs. An appropriate computational model of ossification provides a promising bionics tool with widespread applicability for instance in architecture for construction of technical structures. To this end, we introduce the framework of osteogenetic P systems able to generate and to manage the spatial inner structure of bones in a dynamical manner during ossification. Starting from an initial porous network of interwoven filaments surrounded by vesicles, a variety of osteoblasts and osteoclasts is placed alongside the filaments throughout the whole network. External forces, freely configurable in their intensity and effective direction, affect the outer nodes of the network inducing a spatial distribution of mechanical stress in its inner filamentary structure. Now, the osteoblasts move towards heavily loaded positions and strengthen the corresponding filaments while osteoclasts eliminate filamentary material wherever dispensible. Over time, the inner network structure adapts to its demands by strong filaments along the main force lines. Complementing our framework of osteogenetic P systems, we demonstrate its practicability using two case studies: The first one describes generation of a dice-shaped cage resistant against weights on top. The second study addresses construction of an arched bridge with two opposite bearings.