Behavior of Aluminum at Elevated Strain Rates and Temperatures

Abstract

This thesis explores the thermomechanical behavior of aluminum. Experimental work has been conducted for a wide range of temperatures and strain rates for three AA6060 alloys in both quasi-static and split-Hopkinson tension bar test rigs. An induction heater system, pyrometer and high-speed camera was used to obtain elevated temperatures and information about the geometry in the necked section of the specimen. Some tests show slightly different material behavior between the alloys studied with respect to yield stress and strain hardening. However, no coherent difference can be established as the deviations are not seen from all tests, and are probably not significant. Three material models have been fitted with an available database containing material data for a similar alloy for a wide range of strain rates and temperatures. No adequate fit is obtained for the investigated models using the procedure described, but some significant differences between the models are seen. Numerical simulations of the split-Hopkinson tension bar experiments have been performed, but no good prediction for the material behavior until fracture was found. The reason for this is believed to be the material model parameters implemented. Numerical simulations with damage coupling have also been performed and show that fracture is predicted earlier.