A104 構造物を自律的に形成するセル・オートマトン(形態形成関連)

概要

論文の詳細を見る
Living systems have significant features to flexibly adapt to circumstances. Remodeling process is one of the important adaptive functions in living systems. The remodeling process is a kind of local feedback mechanism. The adaptive formation process of remodeling can be explained by an autonomous decentralized model. It consists of identical autonomous elements which sense mechanical states and change the material properties themselves. This is a sort of a cellular automaton which consists of autonomous cells. Cellular automata are generally known as pattern generators. The proposed model has a new feature to generate mechanical structures as each cell includes mechanical properties. This study deals with self-organization of a mechanical structure based on remodeling of living tissues. In our previous reports, we showed the performance of the cellular automaton and discussed topological structures inhered in the decentralized mechanical system. The adaptive formation process is simulated by the following iterative procedures. Step 1. Give an acting space of cells. Step 2. Set loads and boundary conditions on cells. Step 3. Calculate stresses produced in the cells with the finite element method. Step 4. Change Young's modulus of the cells. Step 5. Apply "death" and "birth" rules to the cells. Step 6. Return to Step 2. In the step 1, the acting space of cells is a design area of mechanical structure. In the step 2 and 3, a stress analysis for each iteration is performed by the finite element method to obtain stresses produced in the cells. And in the step 4, Young's modulus E of each cell is independently changed. The degree of change is proportional to difference between equivalent stress and target stress in each cell. In the step 5, after changing Young's moduli of cells, "death" and "birth" rules are applied to the cells. The proposed cellular automaton showed the following performances. 1. Iterative calculations lead the converged state that is nearly equal to target stress value for almost cells. The formation is uniquely determined once the mechanical conditions are given. 2. The relationship between the target stress and Young's modulus of the cell gives effect on the formation of the structure. The proposed non-linear relationship generated clear mechanical structure as the Young's moduli of cells were converged to almost equal values. 3. The initial distribution of Young's modulus greatly affects the topological formation. The model has an ability to generate various biomimetic topological structures which are almost satisfied with fully stress design. It is difficult to predict the final topological structure although the initial mechanical conditions shall be determinately given. 4. We introduced a method that threshold level to apply "death" and "birth" rules gradually increased for each iteration step. The method showed effective structural formation avoiding structural collapse caused by rapid vanish of cells. 5. A new simulation method with multiple mechanical conditions was proposed. The method will be useful to discuss shape of bones from biomechancal view points.
一般社団法人日本機械学会の論文
2001-11-14

A104 構造物を自律的に形成するセル・オートマトン(形態形成関連)

スポンサーリンク

概要

著者

関連論文

スポンサーリンク