13th International Conference on Fracture June 16–21, 2013, Beijing, China -7- upon the loading rate and temperature, which is the same as the fracture toughness of steel. That is to say, at the same loading rate, the lower limiting value of residual strength under temperature 293K is higher than that under temperature 273K; on the other hand, at the same temperature, the lower limiting value of residual strength decreases drastically with increasing loading rate, especially under loading rate MPa m s / ~106 , the lower limiting value of residual strength reduces to the level of a quarter of σs. Suggesting the hull construction is no long suitable for use under impact condition with a loading rate MPa m s / ~106 . Thus, it is necessary to use stiffened plate construction according to the strength level. However, it is worth noting that the stiffened plate construction is the skin critical construction that has a limit crack arrest capacity. Therefore the stiffened plate construction is needed to modify to enhance the crack arrest performance of the construction. The data listed in Table 3 indicates that the crack length range of effective crack arrest in the skin critical construction is more than that in the stiffener critical construction. Under the loading rate MPa m s/ ~105 , the crack length range at temperature 273K is 0.225 m ~0.279 m, while at temperature 293K there is no crack arrest after the crack instable state. Under the loading rate MPa m s / ~106 , the crack length range of effective crack arrest is 0.130 m ~ 0.353 m whether temperature 273K or 293K because the stiffened plate construction belongs to the skin critical construction. 5 Conclusions Based on the linear-elastic fracture mechanic theory and the residual strength diagram of non-stiffened plate construction, the residual strength diagram of stiffened plate construction of the hull was proposed, and the crack arrest behavior, temperature and loading rate effects in the stiffened plate construction were discussed. The following conclusions can be drawn: (1) The lower limiting value of residual strength of stiffened plate construction is significantly influenced by temperature and loading rate. (2) The stiffened plate construction belongs to the stiffener critical construction at temperature 273K and 293K under loading rate MPa m s/ ~105 . While stiffened plate construction belongs to the skin critical construction because the fracture toughness of hull steel decreases sharply under loading rate MPa m s / ~106 . (3) The lower limiting value of residual strength of stiffened plate construction discussed in this paper and the crack length range of effective crack arrest are found to be 0.225 m ~ 0.279 m for the loading rate MPa m s/ ~105 and temperature 273K and 0.130 m ~ 0.353 m for the loading rate MPa m s / ~106 and temperature 273K or 293K. References [1] H. Vlieger. The residual strength characteristics of stiffened panels containing fatigue cracks. Eng. Frac. Mech.,5(1973) 447-477 [2] D. Brock. Engineering fracture mechanics foundation. K.Y. Wang (translator). Science press, Bingjing, 1981. [3] R.T. Liu, J.Wang. A discussion on the relationship between dynamic fracture toughness and impact toughness. Mater. Eng.. suppl (2003) 271-275.(In Chinese) [4] Fengchun Jiang and Kenneth S. Vecchio. Hopkinson bar experimental technique: a critical review on
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