Test method using a test piece and it is used under biaxial tensile stress

摘要

PROBLEM TO BE SOLVED: To enable a biaxial tensile stress test with high accuracy by a simple apparatus by gradually increasing the wall thickness of a protruding curved surface closing a cylindrical part on the single end side thereof as separating from a center axis part to smoothly continue the same to the wall thickness of the cylindrical part. ;SOLUTION: A cylindrical test piece 1 is formed so as to be closed by a protruding curved surface consisting of a connection part 4 smoothly continued from the single end surface 2 of a cylindrical part 5 and a test part 3. The wall thickness of the protruding curved surface gradually increases as being separated from a center axis part to smoothly continue to the wall thickness of the cylindrical part 5. Herein, the test part 3 and the connection part 4 have an almost spherical shell shape and, especially, the test part 3 protrudes as a part of a thin-walled spherical shell uniform in thickness and having the same center as the cylindrical part 5 at the cylindrical center axis part of the protruding curved surface. Since the outer peripheral surface of the test part 3 is spherical and thin, when the test part 3 receives internal pressure, the stress in the thick wall direction thereof is zero and the test part 3 receives axial tensile stress equal in two directions right-angled to the wall thickness direction, that is, equal biaxial tensile stress. Therefore, an equal biaxial tensile stress test can be performed by a simple apparatus.;COPYRIGHT: (C)1997,JPO