Abstract
Using V-notched specimens of 0.36% carbon annealed steel, the effects of one impulsive load on the crack propagation and the final fracture are examined and the following results are obtained. (1) Only one impulsive load also affects the subsequent crack propagation and the final fracture and the fatigue lives are shortened. This phenomenon is more remarkable when the impulsive load is imposed during the crack propagation process and in one case fatigue life decreases to 20% of the original fatigue life. (2) There is a critical crack depth above which the effects of the impulsive load are more severe. This depth seems to correspond to the non-propagating crack depth. (3) The parallel law of crack propagation is applicable to the present results and even in the worst case results are situated in the safety range of the expected values.
