Application of Micromechanical Models to the Analysis of Ductile Fracture under Dynamic Loading

Dynamic tensile tests and instrumented impact tests with Charpy-V-notch specimens and precracked Charpy specimens (SENB) are performed and simulated. Two strain-rate dependent micromechanical models based on the modified Gurson flow function are compared by simulating different dynamically loaded specimens. one purpose of the study is to investigate the influence of strain rate on the parameters of the micromechanical models and thus to check the applicability of these models for dynamic loading. Another purpose is to find out the relation between the micromechanical approach and conventional fracture mechanics. The results indicate that the critical void volume fraction fc and the characteristic length lc, are practically independent of strain rate and specimen geometry. The deformation and fracture behavior of the Charpy-V and SENB specimens can be well calculated with the parameters determined from a dynamic tensile test and a static fracture mechanics test. The tunneling of the cra ck in the interior of the Charpy specimen is predicted in a satisfactory way by a three-dimensional analysis with the strain-rate dependent Gurson model.