優良解探索遺伝的アルゴリズム系解法による自由曲面グリッドシェルの構造形態創生: 構造形態と曲面を記述するNURBSの階数の関係

摘要

In this paper, the genetic algorithm with immune system (ISGA) to obtain the decent solutions is applied to the structural morphogenesis for a free-form grid shell.the decent silutions have comparatively high evaluations.These solutions contain a global optimal solution and local optimal solutions,and maintain the diversity of the design variable space.The use of the decent solutions satisfies a structural rationlity,and enriches the designer's ideas about structural froms and systems. In general, when the structural morphogenesis concrning a curved surface stucture is treated,to represent a smooth curved surface and to decrease the unknown the parametric surface is adopted. However, the parameinc surfece has the possibility to give influencing for the form of the obtained solutions. Here, NURBS that the degrees-of-freedom of the shape representation is high is adopted as the parametric surface, and the relation between a decent solution form and the order of NURBS is examined When the structural morphogenesis for a free-form grid shell is treated, the knowledge on the numerical analysis using NBRBS is indicated from the numerical results.%経済性や環境意識の向上に伴い、軽量·高剛性の特性を持つダリッドシェルが再評価され空間構造に多く採用されている。ダリッドシエルに代表される離散系空間構造が普及し始めた19世紀後半、その多くは単純な幾何形状であり、自由曲面形態は部材·接合の問題により実現が困難であった。しかし、20世紀後半からの計算技術の進歩やCAD-CAMによる生産技術の発展により、自由曲面のグリッドシエル空間構造が構築可能となっている。