2018 年 67 巻 2 号 p. 284-290
In the automobile industry, CFRTP (Carbon Fiber Reinforced Thermoplastics) are expected to be used because of their superior properties such as high toughness, high productivity and high recycling efficiency. Although the composite materials allow the integral molding of complicated structure, a large number of joints such as bolts and rivets still exist for assembly of the vehicle. These fastening implements cause an increase of the weight and the stress concentration at the holes. In the current aerospace industry, the welding technique for fiber-reinforced thermoplastics by direct resistance heating to metal mesh has been developed and applied. In this process, weight increase due to the use of metal mesh and bonding strength between metal mesh and matrix are issues to be overcome. We have been developing a resistance welding technique in which carbon fiber itself was used for the heating elements. To reduce the bonding area, further improvement of bonding strength is needed. In this study, waterjet surface treatment was applied to CFRTP to improve bonding strength. The influence of scanning direction of waterjet treatment (vertical or parallel to the fiber direction of CFRTP) on the ablation of the CFRTP was analyzed by means of the microscope. Bonding strength evaluated by tensile shear tests was improved under the condition of the waterjet treatment in parallel to the fiber direction.