Toshihisa Ohtsuka

Microscopic Stress Analysis by 3-D FEM of Twill Woven Fabric Composites

The woven fabric composites are used in many fields: The reinforcing composite of fabrics are classfied into plain, twill and satin woven fabrics. In spite of the various applications, the traditional microscopic stress analyses of woven fabric composites limits itself to the analysis of Plain Woven Fabric Composite (TWFC) [1], [3], [4], [5]. Also, the authors analysed the microscopic stress state of the PWFC by a new method [7]. However, it was found that there were few research works on the microscopic analysis of Twill and Satin Woven Fabric Composites (TWFC and SWFC) [2],[6], Haga researched the failure of the woven fabric composites [2]. Ishikawa studied Young’s modulus for the fabric composites without TWFC by applying his new analytical method, because his method was not applicable with TWFC [6]. Our analytical method for the analysis of PWFC was applied to examine the property of TWFC.

Study on Torsion Property of FW-RP Cylinder with a Side Circular Hole

It is necessary to get a fundamental data of FW-RP cylinder setting up a side circular hole for a design of mechanical structures transmitting torsion load. In this study, the torsion rigidities near the side hole were measured by static torsion tests. Moreover, the properties of FW-RP cylinder with a side circular hole were calculated by an original FEM program that is able to simulate FW-RP cylinder. As a result, the following conclusions were obtained. (1) The partial torsion rigidity of FW-RP cylinder with a side circular hole is remarkably dropped down near the side hole. Especially, the reduction of the partial torsion rigidity is very large in thick FW-RP cylinder. (2) When the diameter of a side circular hole is large, the distribution of the stress around the hole is much influenced by the fiber orientation angle θ. (3) The maximum value of normalized stress around the side circular hole occurred at inside of the FW-RP cylinder in a thin cylinder (t=1mm). The reason of the movement of the maximum normalized stress is based on the difference of the rotation displacement about z-axis along thickness.