| 摘要 |
PURPOSE:To exactly grasp a fracture toughness value of a material by a small amount of test pieces, by deriving by an experiment one of a compressive yield stress and a modulus of longitudinal elasticity which can obtain a data from a minute test piece and the breakdown energy amount. CONSTITUTION:A test piece 4 is placed between a pedestal 5 and the upper cover 6, and fixed firmly with a set-screw 2. Subsequently, it is placed on a steel ball 3 and set through a hole 6a of the center of the upper cover 6. A punching test is executed by fixing the test piece 4 to a jig, and thereafter, applying a compressive force until the test piece 4 is broken down by the pedestal 5 and a push rod 1 by a tension tester in a state that the whole jig is in an extremely low temperature. A relation of a load and a displacement in this case is recorded. In this case, there is a strong correlation between impact absorbing energies of 100 deg.C and 200 deg.C of a breakdown energy of a punching test at -196 deg.C, and a fracture toughness value of 100 deg.C and 200 deg.C can be calculated by using each different experiential expression with regard to the upper shelf area and the transition temperature area.
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