The deformation mechanics of cloth are complex owing to its mesoscopic structure, and its destruction is one of the most intricate processes. In this study, the destruction of a low-density porous material is examined to gain understanding regarding its destruction, because this material has a simpler structure than cloth. In addition, it is useful to observe the fundamental destruction of a porous material similar to cloth. In this study, ball indentation is adopted because it can evaluate the mechanics without considering the directionality and fixing by pinching. In the ball indentation test of the low-density porous material examined herein, a plateau region is observed, in which the reaction force is nearly constant, and this force is larger than the value considered only for uniaxial compression. Numerical analysis is performed considering the shear fracture, and it validates the result of the plateau force obtained from the experiments. Furthermore, it is shown that the plateau force varies with the shear strain of the fracture.

On the tubular knitted fabric produced by the circular knitting machine, the following defects in fabric sometimes appear such as vertical lines, horizontal lines, contamination, and holes, which are caused by malfunctions of the knitting machine or the poor quality of yarn used. The proposed detecting systems for these defects by other researchers have not been implemented in the industry because they appear to need excessive operating time. Therefore, development of a defect detection system using simple analysis is required. Therefore, the aim of this study is to find a simple analyzing system for vertical line defects because they often cause massive wastes of fabric. Vertical line defects could be recognized easily by analyzing brightness distribution obtained from the captured fabric image. The irregular brightness distribution obtained from our proposed method agreed with the vertical line defects; therefore, it was possible to identify the vertical line defects easily. As mentioned above, our proposed method is useful as a simple defect detection system.

The purpose of this study is to develop adhesive materials for joining different kinds of materials such as FRP and metals, and to decompose the bonding structures conveniently. As the first step, we proposed the adhesive with epoxy and ceramics particles (SiC) for a GFRP joint, and tried to decompose it by microwave irradiation. A tensile shear test of GFRP joints with the proposed adhesive was carried out with/without microwave irradiation, and effects of the volume fraction of SiC particles on the adhesive strength were investigated. As the results, it was obvious that the optimum amount of volume fraction of SiC existed to satisfy the high strength before irradiation and low strength after irradiation. Furthermore, the strength could be decreased by one irradiation and the repeat of irradiation was not necessary, and the fracture surfaces were different caused by the volume fraction of SiC particles and the effect of microwave irradiation.