| 摘要 |
PURPOSE:To rapidly estimate a crack development speed with good accuracy under an optically and directly non-observable environmental condition such as the interior of an autoclave, by measuring load and a change curve with the elapse of time in the displacement of a loading point. CONSTITUTION:A crack speed is shown by a formula wherein (a) is a crack length, P is load, V is the displacement of a loading point, B is the thickness of a test piece, E is young modulas and K is coefficient of stress enlargement. Because K is an amount uniquely determined by (a), P, the crack speed can be analyzed theoretically. Load is applied to the breaking dynamics type test piece at a definite low tensile speed by a tensile testing machine and load P and the displacement V of the loading point are measured by a load meter and a displacement meter to be inputted to a computer while subjected to AD conversion while the time differentiation curves of the load P and the displacement V are fabricated. Succeedingly, a program for calculating coefficient K of stress enlargement is used to successively calculate a crack development speed, a crack development amount and the coefficient K of stress enlargement and the relation of the coefficient of stress enlargement and the crack development speed is calculated to be drawn by an XY-plotter. |
