A Hybrid Approach To Determine Ductile Fracture Resistance

This article describes a hybrid approach to determine the ductile fracture resistance for laboratory specimens, combining both the numerically computed and experimentally measured load (P) versus load-line displacement (LLD) relationships for metallic fracture specimens. The hybrid approach employs the same principle as the conventional, multiple-specimen experimental method in determining the energy release rate. This method computes the P-LLD curves from multiple finite element (FE) models, each with a different crack depth. The experimental procedure measures the P-LLD curve from a standard fracture specimen with a growing crack. The intersections between the experimental P-LLD curve and the numerical P-LLD curves from multiple FE models dictate the LLD levels to compute the strain energy (U) using the area under the numerical P-LLD curves. This approach eliminates the requirement of using multiple fracture specimens and the requirement of measuring the compliance of the specimen via a multiple unloading procedure. In addition, this approach does not require the measurement of the crack-mouth opening displacement (CMOD). The validation procedure shows very accurate prediction of the J-Δa resistance curve for SE(B) specimens under mode I loading.