Test piece for tensile testing and tensile testing method

A test piece for tensile testing comprising:

• a tensile testing part having a three-dimensional shape that has n-fold symmetry (where “n” is an even number equal to or greater than four) around a central axis that extends in a pulling direction and;
• “n” number of load applying pieces that are integrally formed with the tensile testing part, and are radially connected to the tensile testing part around the central axis in a direction orthogonal to the pulling direction, wherein
• the tensile testing part includes a first end portion arranged on one side in the pulling direction and a second end portion arranged on the opposite side of the first end portion in the pulling direction, and
• the “n” number of load applying pieces are constituted by a first load applying piece and a second load applying piece, wherein
• the first load applying piece is connected to a part between the first end portion of the tensile testing part and a probable rupture location of the tensile testing part,
• the second load applying piece is connected to a part between the second end portion of the tensile testing part and the probable rupture location,
• the first load applying piece includes
• an application surface that receives a load transmitted from the second end portion side toward the first end portion side;
• and
• a groove formed with a depth corresponding to the probable rupture location at a part that connects the tensile testing part and the first load applying piece, and that partitions the first load applying piece and the second end portion of the tensile testing part, and
• the second load applying piece includes
• an application surface that receives a load transmitted from the first end portion side toward the second end portion side;
• and
• a groove formed with a depth corresponding to the probable rupture location at a part that connects the tensile testing part and the second load applying piece, and that partitions the second load applying piece and the first end portion of the tensile testing part.