Application of Advanced Experimental Mechanics Techniques for Multiaxial Fatigue Testing of Titanium Alloys

This talk will present the recent application of advanced experimental mechanics techniques for biaxial fatigue testing with specific reference to the testing of titanium 6AL 4V specimens. Issues such as cruciform specimen... [ view full abstract ]

This talk will present the recent application of advanced experimental mechanics techniques for biaxial fatigue testing with specific reference to the testing of titanium 6AL 4V specimens. Issues such as cruciform specimen design, testing machine calibration, and fatigue crack nucleation and growth monitoring will be discussed. At first, a brief overview is given on the previous NRC biaxial testing for metallic and composite specimens, including the specimen development using photoelasticity. Since then NRC has acquired a suite of advanced experimental mechanics techniques including Digital Image Correlation (DIC), automated Photoelasticity, and Thermoelastic Stress Analysis (TSA). In a recent joint effort with IHI engineers, DIC techniques have been used for developing a cruciform specimen (smooth and notched), together with finite element modeling that is carried out by IHI. For the biaxial testing, the DIC results are used to examine the alignment of the test machine. During the testing, a combination of DIC and replica mold impression techniques are used to record, display and analyze results, aiming to detect and monitor crack nucleation and growth. In the end, this presentation will discuss the lessons learned during the cruciform specimen design, testing system calibration and measurements, as well as provide some initial results from the multiaxial fatigue testing of titanium specimens.