A new test method for high-temperature fracture of alloys and some corresponding results

A moiré interferometry-based experimental method is first introduced for high-temperature, mixed-mode fracture testing. The method allows real-time observation of surface deformation of cracked specimens and crack-tip plastic zone at elevated temperatures. Based on the moiré fringe patterns captured real time through image acquisition system, important fracture parameters, such as the crack open displacement, the crack initiation load, the ultimate load, etc., can be determined. With these data, the stress intensity factor, load bearing capacity, fracture ductility, strain, and stress fields near the crack-tip can be obtained. The method has been successfully applied to investigate pure mode I, I-II mixed-mode fracture performance of high temperature alloys. Furthermore, some significant thickness effects achieved by the group of researchers on the mixed-mode fracture performance of TC11 titanium alloy at high temperatures are cited and briefly introduced. Finally, three dimensional finite element simulations are performed for the tensile-shearing specimens at an elevated temperature. Simulation results are in agreement with measurements.