A six-axis mechanical tester for microspecimens

In order to determine the material properties on its micro scale, a new microspecimen tester is developed, which uses a linear servo motor in one axis of translations and five dc servo motors in other axes to build a six-axis stage and employs a six-degree load cell to sense the micro loading due to the deformation of the micro sample. The six-axis stage can achieve the resolution with 0.1 micron in translation and 0.001degrees in rotation, which is proved that there is no backlash, no hysteresis, higher machine stiffness and fatigue frequency of 11Hz in linear servo motor translation compared with dc-motor-screw-driven. The six-degree load cell with the fine resolution of 4mN is generally used to record the micro force, which is also to control the six-axis stage move to reduce the deformation as a feedback during the alignment of the fixed micro sample. A heating and cooling chamber is built up with the temperature from -40-250degreesC for the purpose of thermo-mechanical testing. The tensile testing experiments have been taken by the 6-axis tester and a mini single axis tester with the same samples, the error of which is kept within 2%-5%. Then lots of experiments with different thin films have been made under different conditions.