Makoto Imura

Mechanical Behaviours for Textile Composites by FEM Based on Damage Mechanics

To make an expansion of composite consumption ever widening with use at demanding and safety critical applications, it is important to establish the evaluation technique of the strength, the safety, etc. To reach the goal with a useful reliable technique, we have developed a numerical simulation program on damage development of composites based on damage mechanics. The following points are the keys to simulate the mechanical behavior; (1) The generation technique of FE model with yarns and matrix, (2) The classification of anisotropic damage mode based on damage mechanics, (3) Multi-scale modeling by Mesh superposition method. In this paper, the numerical technique and the results of multi-scale analysis of woven composites are described.

Identification of the Replication Region of a 111-kb Circular Plasmid from Rhodococcus opacus B-4 by λ Red Recombination-Based Deletion Analysis

The replication region of the 111-kb circular plasmid pKNR from Rhodococcus opacus B-4 was identified. A PCR-based deletion analysis using the λ Red recombination technique followed by restriction digestion and PCR-amplification analyses revealed that a 2.5-kb fragment covering one putative open reading frame (ORF) was involved in the replication of pKNR. The product of this ORF showed significant similarity to a functionally unknown protein encoded in the replication region of the 70-kb circular plasmid of Clavibacter michiganensis and to ones in other bacterial large circular plasmids. These observations suggest that the product of the identified ORF and its orthologs can serve as novel replication proteins for large circular bacterial plasmids.

A Multi-Scale Analysis for an Evaluation of the Mechanical Properties of Composite Materials

Fiber reinforced composite materials have been applied widely to many structures, because they have some advantages like easy handling, high specific strength, etc. The numerical method like finite element method has been applied to design and to evaluate the material properties and behavior as the development of Computer Aided Engineering. It is very difficult to calculate with accuracy not only in structural scale but also in detail material scale (for example, the order of fiber diameter) by the traditional FEM, becausecompositematerials like woven fabric composites have the geometrical complexityand the large difference between above mentioned scales. The development of multi-scale analysis method is one of the major topics in computational mechanics. Mesh superpositionis one of multi-scale analysis methods and is an effective method to solve the problems which have the large difference between the structure scale and the reinforcement scale. We have expanded the finite element mesh superposition method with 3 scales and have defined as M3 (Macro-Meso-Micro) method. In this paper, we have proposed a new approach method combined with M3 method and homogenized method to obtain the mechanical properties and to simulate the behavior of woven fabric composites. In addition, the elastic-plastic mechanics and the damage mechanics have been introduced into M3 method to investigate the effects of matrix-crack on the structural and material properties. From the numerical results, it is revealed that it is very useful for the evaluation of mechanical properties of composite materials.