FRP tubular body and method for manufacturing FRP tubular body

A method for manufacturing a FRP tubular body, wherein

• the FRP tubular body includes a fiber structure having a tubular wound member and a reinforced fiber sheet that covers an outer side of the wound member, the reinforced fiber sheet being made of fabric,
• the fiber structure includes first reinforced fiber bundles and second reinforced fiber bundles, the first reinforced fiber bundles being bundles of reinforced fibers arranged on the wound member such that a yarn main axis direction of the first reinforced fiber bundles extends in a circumferential direction of the wound member, the second reinforced fiber bundles being bundles of reinforced fibers and forming the fabric together with the first reinforced fiber bundles,
• the method comprising:
• stretching the first reinforced fiber bundles in a state of being arranged in an axial direction of the wound member;
• inserting the second reinforced fiber bundles in the axial direction of the wound member into sheds created between adjacent ones of the first reinforced fiber bundles in the axial direction of the wound member;
• pushing the second reinforced fiber bundles toward the wound member through a beat-up motion to weave the fabric of the first reinforced fiber bundles and the second reinforced fiber bundles;
• and
• rotating the wound member about a central axis of the wound member to wind the woven fabric onto the wound member,
• wherein the reinforced fiber sheet includes a starting end where winding onto the wound member is started in the circumferential direction of the wound member, the starting end extending in the axial direction of the wound member, a finishing end where winding onto the wound member is finished in the circumferential direction of the wound member, the finishing end extending in the axial direction of the wound member, and a general portion located between the starting end and the finishing end and connected to the starting end and the finishing end by the reinforced fibers,
• the method further comprising:
• weaving the general portion using, as warp yarns, the first reinforced fiber bundles arranged on the wound member such that the yarn main axis direction of the first reinforced fiber bundles extends in the circumferential direction of the wound member and using, as weft yarns, the second reinforced fiber bundles arranged on the wound member such that a yarn main axis direction of the second reinforced fiber bundles extends in the axial direction of the wound member;
• and
• weaving at least one of the starting end or the finishing end as a decreased portion that is smaller than the general portion in an amount of the reinforced fibers per unit length in the circumferential direction of the wound member.

A method for manufacturing a FRP tubular body, wherein

• the FRP tubular body includes a fiber structure having a tubular wound member and a reinforced fiber sheet that covers an outer side of the wound member, the reinforced fiber sheet being made of fabric,
• the fiber structure includes first reinforced fiber bundles and second reinforced fiber bundles, the first reinforced fiber bundles being bundles of reinforced fibers arranged on the wound member such that a yarn main axis direction of the first reinforced fiber bundles extends in a circumferential direction of the wound member, the second reinforced fiber bundles being bundles of reinforced fibers and forming the fabric together with the first reinforced fiber bundles, and
• the reinforced fiber sheet made of the woven fabric includes a starting end where winding onto the wound member is started in the circumferential direction of the wound member, the starting end extending in the axial direction of the wound member, a finishing end where winding onto the wound member is finished in the circumferential direction of the wound member, the finishing end extending in the axial direction of the wound member, and a general portion located between the starting end and the finishing end and connected to the starting end and the finishing end by the reinforced fibers,
• the method comprising:
• using blended yarns of reinforced fibers and thermoplastic fibers for at least one of the first reinforced fiber bundles or the second reinforced fiber bundles;
• heating at least one of the starting end or the finishing end to melt the thermoplastic fibers so that the at least one of the starting end or the finishing end becomes a decreased portion that is smaller than the general portion in an amount of the reinforced fibers per unit length in the circumferential direction of the fiber structure;
• and
• pressurizing the at least one of the starting end or the finishing end to become smaller in thickness than the general portion.