A Study on an Intelligent Optimum Material Design System for Utilization of the Anisotropy of Composite Materials

为了充分利用复合材料的各向异性，需要进行以下几方面的研究：1）结构力学中各向异性结构设计方法的构建；2）材料各向异性设计理论方法的发展；3）开发为结构设计者提供实际帮助的专家系统。从这些角度出发，进行了如下研究：(1)功能变形：构建了负泊松比材料和具有指定弯扭耦合变形的结构的设计方法。分析结果与实验结果之间具有良好的一致性。该方法的应用是悬臂管，在扭转载荷下在尖端处产生零扭转角。(2)基于应变能的优化材料设计：通过使板的应变能最小化来最大化板的弯曲刚度。使用该方法可以在任何载荷条件下获得板的最佳取向角。(3)基于可靠性的最佳材料设计：发现确定性载荷条件下的最佳纤维取向角与概率载荷条件下的最佳纤维取向角不同。对于概率载荷条件，使用AFOSM（先进的一阶二阶矩方法）获得了最佳方向。此外，还提出了一种基于可修复性确定最佳角度的分析方法。该方法对于评估可靠性的相对值非常有效。（4）人工智能材料设计系统：对最佳材料设计的知识进行了分析和分类，并构建了它们的层次结构。使用面向对象语言、Smalltalk和复合材料设计试验专家系统进行了知识的表示。已研制成功。

For the complete utilization of the anisotropy of composite materials, the following aspects are necessary to study: 1) the construction of the design method for structures with the anisotropy in structural mechanics, 2) the development of the theoretical method for designing anisotropy in the material, and 3) the development of an expert system which yields practical aid for structural designers. From these points of view, the research has been conducted as follows:(1) Functional Deformation : The methods for designing a material with negative Poisson's ratio and a structure which has a specified bending-torsion coupling deformation were constructed. Good agreement was found between the analytical and the experimental results. An application of the methods a cantilevered pipe which yields torsional angle of zero at the tip under torsional loading.(2) Optimum Material Design Based on Strain Energy : The bending stiffness of plates are maximized by making its strain energy minimum. Optimum orientation angle of a plate was obtained using this approach for any loading conditions.(3) Optimum Material Design Based on Reliability : It was found that optimum fiber orientation angles under deterministic loading conditions are different from those under probabilistic loading conditions. For probabilistic loading conditions, optimum orientations were obtained using the AFOSM ( advanced first-order second-moment method. Additionally an analytical method for determining optimum angles based on rehability has been proposed. The method is very effective in evaluating the relative value of the reliability.(4) Material Design System with Artificial Intelligence : The knowledges for optimum material design were analyzed and classified, and their hierarchical structures were constructed. The representation of the knowledge was performed by using object-oriented language, Smalltalk, and a trial expert system for composites design has been successfully developed.