1. 1. FURI Mid-Semester Summary Mentor Signature: ______________________________________________ Date: __________ Name: Brian Chang ID: 1206011829 Semester: Spring 2015 I approve the FURI office publishing excerpts from my summary to promote my research experience on the FURI web site: Yes or No My project this semester is investigating the role of stress triaxiality in the high strain rate behavior of AZ31 magnesium alloys. From the initial tests conducted during winter break, we compiled a true-stress- true-strain curve for the different notch samples. From those curves, we observed that there was some twinning below the proportional limit for the small notches along the A and B directions, as well as the medium notch in the B direction. The letters represent either the rolling or transverse direction of the rolled AZ31 magnesium alloy. Microstructural characterization is still underway to determine which direction is rolling and which is transverse. For this, we will use scanning electron microscopy (SEM). The first round of high strain rate testing was performed with complicated grips which have generated improper results due to bending of specimens. We solved this problem by redesigning the samples to allow the samples to be threaded directly into the bars. To increase the number of tests, I designed and implemented a new I-beam structure, once it arrived we were able to set it up and have since begun high rate testing to complete the first phase. We have currently completed 25% of the second phase and we expect to continue running high rate tensile testing followed by quasi-static tensile testing. From the tensile tests, we see the B direction has the highest ultimate tensile strength. We currently use SEM to observe the fracture surfaces of the tested samples in order to understand the fracture modes of the material. We have observed directionality of pores which we believe to be due to the twinning observed under high rate deformation but further analysis is required to be certain. The final results will be analyzed and compiled in the final report and presented at the symposium.