Determination of the compliance of an instrumented indentation testing machine

Abstract A major factor in calibrating a depth-sensing indentation tester is to determine its load-frame compliance. In this work a simplified theoretical approach and a computerized iterative method were developed to calculate the load-frame compliance of our laboratory commercial instrumented indentation tester. In addition, this research discusses many of the problems associated with the calibration of this type of testing machine. Three materials were used for the load-unload tests: fused silica, 6066-O aluminum and electrolytic copper. A value of load-frame compliance of 0,23 nm/mN was obtained with fused silica. This value was considered acceptable because the calculated elastic modulus for fused silica was comparable to those found by other researchers using a similar strategy of unload curve analysis. This calculated load-frame compliance is in the range found in literature for other instrumented indentation testers. The load-frame compliance values obtained with the two metals were unacceptable because of errors probably associated with pile-up and strain hardening