An Improved Experimental Technique to Characterize Micro-Diameter Copper Wires in Torsion

The experimental technique was improved with direct measurement of small torque and rotation angle to characterize micro-diameter copper wires in torsion. This method allows precise measurement of torque applied to micro-diameter wires as low as 10(-8) N center dot m with reasonably high resolution. The rotation angle is also able to be directly measured such that the shear strain rate on the wire surface can be easily controlled. This experimental design removes the misalignment issue that has affected previous efforts in micro-diameter wire torsion testing. Using this technique, the copper wires with four different diameters (12, 16, 20, and 30 mu m) were characterized in torsion. The normalized torque-rotation results showed insignificant size effects for the copper wires investigated in this study.