Core and method of forming structural body

A core that is to be inserted into a space between a skin and a stringer in a step of integrally molding the skin and the stringer, the skin including fiber-reinforced resin, the stringer having a hat-shaped section that is open toward the skin,

• the core comprising:
• a first die that extends along a longitudinal direction of the stringer and contacts the skin;
• a second die that extends along the longitudinal direction of the stringer, is adjacent to the first die, and contacts the skin;
• a third die that extends along the longitudinal direction of the stringer, is located at an opposite side of the skin across the first die and the second die, and contacts both the first die and the second die;
• and
• a fourth die that extends along the longitudinal direction of the stringer and is located at an opposite side of the first die and the second die across the third die, the fourth die including sides that extend towards at least one of the first die and the second die, and at least partially surround the third die.

A core that is to be inserted into a space between a skin and a stringer in a step of integrally molding the skin and the stringer, the skin including fiber-reinforced resin, the stringer having a hat-shaped section that is open toward the skin,

• the core comprising:
• a first die that extends along a longitudinal direction of the stringer and contacts the skin;
• a second die that extends along the longitudinal direction of the stringer, is adjacent to the first die, and contacts the skin;
• a third die that extends along the longitudinal direction of the stringer, is located at an opposite side of the skin across the first die and the second die, and contacts both the first die and the second die,
• wherein:
• a side of the first die which is opposite to and parallel to a side of the first die which contacts the skin includes a portion that does not contact the third die and another portion that contacts the third die, such that the portion of the first die that that does not contact the third die is perpendicular to and forms a right angle with an edge of a side of the third die that contacts the first die and is perpendicular to the skin,
• a side of the second die which is opposite to and parallel to a side of the second die which contacts the skin includes a portion that does not contact the third die and another portion that contacts the third die, such that the portion of the second die that that does not contact the third die is perpendicular to and forms a right angle with an edge of a side of the third die that contacts the second die and is perpendicular to the skin,
• the first die includes two surfaces that are parallel to the skin which is adjacent to the first die and are different distances from the skin, and
• the two surfaces of the first die contact different surfaces of the third die.