Biomechanics Investigation of Skillful Technician in Hand Lay Up Fabrication Method

Abstract

Hand lay-up is one of methods for FRP molding and it is the most traditional and common molding method that can deal with various shapes according to workmen skill. However, the quality of the composites depends on the techniques of workmen and the judgment with hand lay-up technique is too difficult, because it has not clarified that the difference of that techniques has how influence with manufactured products. In this study, motion analysis was used to compare the difference between hand lay-up techniques by expert and non-expert. Expert’s carrier of hand lay-up was 25 years and non-expert’s carrier was a year. Motion analysis, which is applied to various fields like sports or traditional crafts and so on, can visualize human motion. The Mac 3D System was used as equipment, since it is the most powerful tool for the motion capture and analysis particularly. The sampling rate was 60 Hz. The object of this study was to contribute that technique back to fabrication fields by analyzing and considering what was important factor. Furthermore, this trial is thought that leads to the development of new technology. As the result, the motion of expert’s lower half of body indicated different motion compared with non-expert one. Expert’s centroid moved smoothly and his motion showed constant tendency. On the other hand, non-expert’s motion was awkward in several points and his motion didn’t show the tendency like expert. Furthermore their total processes were almost same; however, non-expert spent more time on finishing touches than expert. Expert spent a third of his total time on finishing touches but non-expert one was a half of his total process. In addition, the quality of manufactured products that they made was different. Hand lay-up technique is discussed based on the motion analysis method, and moreover, it is possible to evolve hand lay-up technique further (We are calling “advanced-Hand lay-up”).