Flexbeam

A flexbeam having flapping portions and lead-lag and feathering portions, each lead-lag and feathering portion comprising:

• a first composite material extending in a beam length direction and having a plurality of fiber orientations;
• and second composite material extending in the beam length direction and having the fiber orientation in the same direction as the beam length direction, the first composite material and the second composite material being joined integrally,
• wherein the first composite material comprises:
• a center portion arranged at an approximate center in a beam thickness direction and extending in a beam width direction;
• first extending portions that extend in a beam front edge direction and a beam rear edge direction so as to branch from both ends of the center portion to beam upper and lower directions;
• and
• second extending portions that extend in the beam front edge direction and the beam rear edge direction so as to bend almost in parallel with the center portion at ends of the first extending portions, and
• the second composite material comprises:
• upper-and-lower portions arranged on upper and lower surfaces of the center portion, of the first extending portions and of the second extending portions, respectively;
• and
• front-and-rear edge portions arranged on beam front edge and rear edge side surfaces of the first extending portions and the second extending portions,
• wherein concaves are formed on at least one of branch portions formed by the center portion, the first extending portions, the upper-and-lower portions and the front-and rear edge portions, and bending portions formed by the first extending portions, the second extending portions, the upper-and-lower portions and the front-and-rear edge portions.