13th International Conference on Fracture June 16–21, 2013, Beijing, China -4- residual strength of non-stiffened plate can be calculated, that is to say the curve of a c can be computed. However, it must be modified by Fedderson revision [9] when the crack length is quite small. When stiffened plate construction is subjected to load, partial load would transfer to stiffeners by way of rivet, which lower the stress intensity factor in the crack tip of stiffened plate. Simultaneously, the stress concentration occurs around the stiffeners. The decreasing coefficient of stress intensity factor of crack tip of stiffened plate C is calculated as [10,11] , d onstiffene C n stiffened K K／ （6） where, stiffened K is the stress intensity factor of stiffened plate construction with crack, ed nonstiffen K is the stress intensity factor of non-stiffened plate construction with crack. It can be seen from Equation (6) that the value of C is less than 1, i.e. C≤1. The coefficient of stress concentration L is written as, / L max (7) where, is nominal stress of stiffened plate construction, max is concentrated stress of stiffener, the parameters of C and L can be found in the stress intensity factor manual [8]. If the stiffened plate and non-stiffened plate construction with the same crack length fracture under the same stress intensity factor, the following Equation will be exist: C ned cnonstiffe cstiffened / (8) where， c tiffened s is fracture stress of stiffened plate construction, ned cnonstiffe is fracture stress of non-stiffened plate construction. It can be seen from Equation (8) that the fracture stress of stiffened plate increases by 1／C times. Using the Equation (8), the residual strength curve of stiffened plate construction can be calculated by that of non-stiffened plate construction. Under the non crack condition, when the stress of stiffeners reaches to tensile strength b , the stiffeners will fracture. Contrary, if the concentrated stress max reaches to tensile strength b , stiffeners would fracture. The following Equation can be derived from Equation (7): /L b (9) Where, σ is nominal stress of stiffeners. According to the Equation (9), failure curve of stiffeners can be attained. The residual strength curve of stiffened plate construction can be achieved by putting the residual strength curve of non-stiffened plate and stiffened plate construction and the failure curve of stiffener together into a common coordinate system，as shown in Figures 2 and 3. 4 Analysis of the crack arrest behavior of the stiffened plate construction The residual strength diagram of stiffened plate construction of the hull under the loading rates MPa m s/ ~105 and MPa m s/ ~106 at the temperature of 273K and 293K can be determined using
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