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- ISO 14577 (2) (entfernen)
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Nowadays the Instrumented Indentation Testing (IIT), in the nano range often named as nano indention, is one of the most commonly used methods to determine the mechanical properties of materials in the micro and nano range. This method is already extensive standardized in DIN EN ISO 14577 part 1-4. In the past, the application of this standard in testing praxis shows that the established values have an excellent precision. On the other side, the trueness as comparability of obtained results with reference values is not so good. To improve accuracy of IIT the use of a variable ε and the consideration of the lateral displacement during indentation became normative requirements during the last revision of ISO 14577.
Starting with the beginning of instrumented indentation testing in 1898 the historical background and the main assumption of the Oliver and Pharr method will be explained and critical discussed. It will be shown how to apply the use of a variable ε and the consideration of the lateral displacement during indentation in the daily testing work to improve accuracy of IIT.
Finally, ongoing standardization projects in the field of IIT will be briefly presented.
The draft of part 5 of ISO 14577 specifies verification and calibration of testing machines for carrying out the measurement of the dynamic material response when an oscillatory force or displacement, with amplitudes small in comparison to the prescribed target values, is imparted to the indenter while the indenter is continuously loaded to a prescribed target load or target depth or while the load or displacement is held constant at a prescribed target value. In case of a material showing plastic-elastic behavior, the measured dynamic response is used for continuous evaluation of the dynamic stiffness of the contact as a function of depth and frequency. Using the dynamic stiffness of the contact a reduced dynamic modulus will be calculated. In case of a material showing visco-elastic behavior from the measured dynamic response also the dynamic contact damping coefficient as function of depth and frequency is evaluated continuously. Using dynamic contact stiffness and dynamic contact damping coefficient reduced lost and storage modulus for visco-elastic materials will be calculated. The main normative requirements of the draft are discussed and their applications are illustrated by examples from daily experimental praxis.