PROGRESS IN DYNAMIC MECHANICAL PROPERTIES TESTING TECHNOLOGY OF MICRO-ZONES MATERIALS—FROM INDENTATION HARDNESS MEASUREMENT TO INSTRUMENTED INDENTATION TESTING

For the dynamic mechanical properties testing technology of material micro-zones, the principles and mechanisms of indentation hardness measurement and instrumented indentation test are explained. The potential issues of dynamic indentation testing are analyzed. The measurement principles of static and dynamic indentation loads, the meaning of indentation strain rate, the dynamic characteristics of impact indentation, and the influence of deposition heat are introduced. Two development paths of dynamic indentation technology are reviewed: based on traditional dynamic loading techniques such as low-speed impact with a striking rod, falling/swinging hammer, and split Hopkinson pressure bar impact, as well as high-speed impact with particles, the development of macroscopic indentation hardness measurement technology is based on these techniques; based on dynamic calibration, direct load measurement, and indirect load measurement using nanoindentation instruments, the development of dynamic nanoindentation testing technology is based on these techniques. The analysis method of instrumented indentation test requires high signal-to-noise ratio for indentation load-depth measurement, and traditional dynamic loading measurement techniques cannot meet the requirements. Currently, it is necessary to improve the dynamic characteristics and measurement signal-to-noise ratio of nanoindentation technology based on the dynamic model of the measurement system. The future development of dynamic instrumented indentation testing technology focuses the design theory of instrument dynamics, the principles of dynamic micro-force and displacement measurement technology, and calibration and verification methods for measurement influencing factors. The emphasis should be on improving the dynamic measurement signal-to-noise ratio of indentation instruments, developing robust parameter identification analysis methods, and strengthening research on fundamental issues of dynamic instrument indentation.