Material modeling and high-speed machining process

Orthogonal machining experiments have been conducted at moderate speeds with 6061-T6 aluminum and Ti-6Al-4V titanium alloys to measure strain distributions in the deformed chip, using a grid technique. While the aluminum alloy displayed large uniform strain within continuous chips, the titanium alloy exhibited highly nonuniform strain distributions within segmented chips, a feature known to occur under high-speed machining. Concurrently, a set of simple constitutive equations are formulated in order to describe the plastic flow behavior of materials over wide ranges of strain, strain rate and temperature. Based on experimental data, the proposed form of constitutive equation is capable of simulating stress-strain-strain rate relationships of 6061-T6 aluminum and Ti-6Al-4V over the range of strain rates applicable to the high-speed machining process. Given the constitutive relations, analytical problems that will be encountered in modeling the localized shear process are outlined based on the experimental observations of chip formation. As a step toward modeling the high-speed machining process, a partially successful finite element analysis of a simplified, continuous chip orthogonal machining process was made using the ADINA code. Some of the relevant analytical and experimental results that have been obtained for the aluminum and titanium alloys are examined. 47 references, 14 figures.