Estimating Constraint Parameter in 3D Models of Specimens Based on Curve Shape Similarity

To analyze fracture characteristics more accurately, two parameter approaches (e.g.,
$J$
-
$A (\boldsymbol{A}_{2}), \boldsymbol{J}-\boldsymbol{Q}$
, etc.) of elastic plastic fracture mechanics are introduced, especially for low crack constraint condition which commonly observed in practical engineering structures. However, theoretical solutions of the constraint parameters (e.g.,
$\boldsymbol{A}(\boldsymbol{A}_{2}), \boldsymbol{Q}$
, etc.) in the two parameter approaches are not available currently. Meanwhile, with substantial consumption of resources and time, numerical determination of constraint parameters is quite inappropriate to engineering application (3D solid models). In this work, based on the curve shape similarity, estimation theory and formulae for the constraint parameter
$A$
in 3D solid models are developed through theoretical and numerical analyses. Using them, solutions of parameter
$A$
can be predicted quickly and efficiently, so as to enable the two parameter approaches to be applied in practical engineering structures.