AFRL Researchers Perform Functionally Graded Material Bending Tests Published June 4, 2007 By Air Vehicles Directorate AFRL/VA WRIGHT-PATTERSON AIR FORCE BASE, Ohio -- AFRL researchers completed quasi-static bending tests of functionally graded titanium/titanium boride test specimens. The twofold purpose of this test effort was to gain a better understanding of the material-structure interactions and to evaluate laboratory testing tools and techniques. Functionally graded materials (FGM) such as the titanium/titanium boride composite have the potential to reduce or eliminate the need for parasitic thermal protection systems in hypersonic and other extreme environment aerospace vehicles. These FGMs are another tool designers can use to help maximize structural response and minimize weight in high-temperature aeronautical applications. The testing involved 6" x 1" x 1" specimens--some of the thickest titanium/titanium boride bend specimens ever produced. During the testing, the research team loaded each specimen in a four-point bending fixture in order to determine the specimen's stress, strain, and displacement fields. To measure these quantities, the researchers employed experimental techniques such as differential thermography, digital image correlation, fiber-optic strain gauging, and conventional-resistance strain gauging. The testing validated the theory that FGMs can be tailored to improve the structural bending response. Furthermore, it gave AFRL researchers the opportunity to assess some of their more unique experimental tools as applied to work involving complex material-structural geometries.