Abstract
The fracture toughness must be evaluated under the dynamic loading condition, when the materials are used for structures which are desired to a higher safety and must be taken into account of the effect of dynamic loading. Moreover, in order to obtain the valid JIC value, a criterion about both specimen thickness B and ligament width b0 must be satisfied, which is called as “valid condition” and is described in the following equation.
B, b0≥α(Jin/σfs), (α=25)
However, this equation is presented in the case of static loading and there is no assurance to be able to apply in the case of dynamic loading. Therefore, under static and dynamic loading conditions, the effects of both B and b0 on Jin value and the flow stress σfs are investigated and the valid conditions are discussed. The results are presented that the factor α of the above equation is reduced as α = 20 about b0 and is increased as α=28 about B under dynamic loading condition.
