Three dimensional analysis of thermal shock effect on inner semi-elliptical surface cracks in a cylindrical pressure vessel

摘要

Transient mode I stress intensity factors (K{sub}(IT)) distributions along semi-elliptical cracks fronts resulting from a thermal shock is investigated. K{sub}(IT) distributions for various crack arrays of n=2÷48 cracks bearing cracks of relative depth of a/W=0. 1÷0.4 and with ellipticities of a/c=0.5, 1.0 and 1.5 are evaluated for a cylindrical pressure vessel of radii ratio of R{sub}0/R{sub}1=2. Temperature distributions through the vessel's wall are evaluated for various time steps in theinterval 2÷10 msec. Both the thermal and the elastic analyses are performed via the finite element (FE) method using the standard ANSYS 5.1 code. The temperature fields evaluated in the first step serve as input to the second step, the elastic analysis,in which the K{sub}(IT) is evaluated.