Fiber structure and fiber reinforced composite material

Abstract

A fiber structure includes a first corner section, which is a boundary section between a first structural portion and a second structural portion, a second corner section, which is a boundary section between the first structural portion and a third structural portion, and a third corner section, which is a boundary section between the second structural portion and the third structural portion. A first yarn that extends continuously in the first structural portion and the second structural portion is bent at the first corner section. A second yarn that extends continuously in the first structural portion and the third structural portion is bent at the second corner section. At least one of the first yarn and the second yarn, which extend continuously in the second structural portion and third structural portion, is bent at the third corner section.

1 . A fiber structure comprising:
 a first forming portion that forms a first structural portion;   a plurality of second forming portions that are stacked together and form a second structural portion that crosses the first structural portion;   a plurality of third forming portions that are stacked together and form a third structural portion that crosses the first structural portion and the second structural portion;   a first corner section that is a boundary section between the first structural portion and the second structural portion;   a second corner section that is a boundary section between the first structural portion and the third structural portion; and   a third corner section that is a boundary section between the second structural portion and the third structural portion, wherein   the first forming portion, the second forming portions, and the third forming portions are each constituted by a multilayer woven fabric having a plurality of fiber layers that are stacked together and a binding yarn that binds the fiber layers together in a stacking direction,   the fiber layers includes a fiber layer formed by a plurality of first yarns that are parallel to one another and a fiber layer formed by a plurality of second yarns that are parallel to one another,   those of the first yarns that extend continuously in the first structural portion and the second structural portion are bent at the first corner section,   those of the second yarns that extend continuously in the first structural portion and the third structural portion are bent at the second corner section, and   at least either those of the first yarns that extend continuously in the second structural portion and the third structural portion or those of the second yarns that extend continuously in the second structural portion and the third structural portion are bent along the third corner section.   
     
     
         2 . The fiber structure according to  claim 1 , wherein
 the second forming portions include a primary second forming portion that is connected to the first forming portion and a secondary second forming portion that is stacked with the primary second forming portion,   the third forming portions include a primary third forming portion that is connected to the first forming portion and a secondary third forming portion that is stacked with the primary third forming portion,   the first forming portion and the primary second forming portion are connected to each other at the first corner section by the first yarns,   the primary second forming portion and the secondary third forming portion are connected to each other at the third corner section by the second yarns,   the first forming portion and the primary third forming portion are connected to each other at the second corner section by the second yarns, and   the primary third forming portion and the secondary second forming portion are connected to each other at the third corner section by the first yarns.   
     
     
         3 . The fiber structure according to  claim 2 , wherein the primary second forming portion and the primary third forming portion each have the same number of fiber layers as the first forming portion. 
     
     
         4 . The fiber structure according to  claim 2 , wherein
 a number of the fiber layers that the primary second forming portion has is smaller than a number of the fiber layers that the first forming portion has,   a number of the fiber layers that the secondary third forming portion has is smaller than a number of the fiber layers that the first forming portion has,   a number of the fiber layers that the primary third forming portion has is smaller than a number of the fiber layers that the first forming portion has,   a number of the fiber layers that the secondary second forming portion has is smaller than a number of the fiber layers that the first forming portion has, and   a number of the fiber layers that each of the second structural portion and the third structural portion has is equal to a number of the fiber layers that the first structural portion has.   
     
     
         5 . A fiber reinforced composite material comprising:
 the fiber structure according to  claim 1 ; and   a matrix resin with which the fiber structure is impregnated.