Because C*-integral calculation is based on creep materials, a nonlinear static analysis is performed. For a C*-integral calculation, it is necessary to perform both of the following tasks at each crack tip:
A nonlinear static analysis is performed. The load is applied instantaneously and then held constant until steady-state creep conditions are reached. Typically, a response of 500~2000 hours is sufficient to reach a steady-state condition.
Example 44.2: Applying a Load in 1E-7 Hours for Elastic Response
NSUB,2,5,2,OFF TIME,1.E-007 RATE,OFF NLGEOM, ON SOLVE !ENABLE CREEP RELAXATION AND WAIT FOR STEADY-STATE *SET,HOUR,2000 AUTOTS,ON NSUB,50,100,10 TIME,HOUR OUTRES,ERASE OUTRES,ALL,ALL RATE,ON NLGEOM, ON SOLVE
44.6.2. C*-integral Calculation (CINT)
To obtain the C*-integral value, a crack tip and its parameters must be defined.
Example 44.3: Defining Parameters for C*-integral Calculation
! INITIATE A NEW CONTOUR INTEGRAL, AND DEFINE TYPE AS CSTAR CINT,NEW,4 CINT,TYPE,CSTAR ! ! DEFINE CRACK TIP NODAL COMPONENT CINT,CTNC,cmCrackTipNodes,,1 ! ! DEFINE SYMMETRY DETAILS AND NUMBER OF CONTOURS TO BE CALCULATED CINT,NCON,4 CINT,SYMM,ON