The dynamic fracture toughness of Magnesium alloy is the basic data for the design of the anti-impact magnesium alloy component and safety assessment of magnesium alloy structure under dynamic load.The combining method of experimental and numerical was improved to obtain the dynamic fracture toughness of magnesium alloy AZ91.The dynamic load for the three point bending specimen was supplied by the Hopkinson pressure bar,and the dispersion and inertia effect were considered and corrected by numerical method, simultaneously,based on the FFT and the VC++ object-oriented programming method.Then the response of dynamic stress intensity factor vs. time was calculated with visual crack close technique method based FEM.Finally,the crack initiation time was computed from the strain gauge message,and the corresponding value on the response of dynamic stress intensity factor vs. time was obtained as the dynamic fracture toughness.Considering that,the actual three-point bending condition,which is guaranteed by the monitoring message during the process,was acquired through the adjusting of specimen span.The results showed that the dynamic fracture toughness of magnesium alloy AZ91 is (6.7±1.8) MPa·m1/2.In addition,the method mentioned extends the application of Hopkinson pressure bar for measurement of dynamic fracture toughness.
