Thesis (M.S., Mechanical Engineering) -- University of Idaho, 2015 | In order to meet the demands of industries and academic research, a cost effective temperature control system was developed to provide accelerated heat up rates between 5-10°C/sec. This apparatus was used to perform tensile tests on a 70XX series aluminum alloy to determine mechanical properties at elevated temperatures.
The automated temperature control system is comprised of two propane torches which heat each end of a tensile specimen during elevated temperature testing. Specimen temperatures are controlled by a PID algorithm which regulates stepper motor position and thus propane torch flame intensity. User inputs to the system are provided via a graphical user interface, with overall system control provided by an Arduino microcontroller.
Successful testing of the 70XX series aluminum alloy occurred at temperatures of 25°C, 225°C, and 425°C and strain rates of 0.05/sec and 0.5/sec. The results clearly show a direct relationship between increased temperatures and material elongation. Yield and ultimate tensile strength, however, decreased in value as temperature increased. Strain rate had an opposite effect on material properties and elongations as elevated temperatures, causing yield strength and ultimate tensile strengths to increase and elongation to decrease.