TY - JOUR A1 - Kalinka, Gerhard A1 - ElAbshihy, K. T1 - Circumventing boundary effects while characterizing epoxy/copper interphases using nanoindentation JF - Composite Interfaces N2 - Characterization of the size and mechanical properties of interphases is essential when designing multicomponent materials. When nanoindentation is used to investigate the size and mechanical properties of an interphase, a common challenge is that the indenter or the stress zone formed around it are often restricted by the reinforcement, making it difficult to distinguish the mechanical property variations caused by the interphase itself from those caused by the boundary effect. In this work, a testing system was developed that allows determining the indent affected zone and accounting for it in the interphase measurements of an epoxy/Cu system. Using finite element analysis, we confirmed the validity of the proposed system. Nanoindentation was used to investigate the Interphase between copper and two different epoxy systems; amine-cured and anhydride-cured. Nanoindentation results showed that a copper layer that is only 10 nm thick still exhibits a constriction effect on the indentations in its vicinity. The amine-cured epoxy did not show any sign of interphase existence using the introduced method. However, a soft interphase with a thickness of ~1.7 μm was measured on theanhydride-cured epoxy. Furthermore, we show that the proposed system can be used to determine the interphase thickness as well as its relative mechanical properties regardless of the indentation depth. This system can be further used for investigating other polymer/metal interphases to better understand the factors influencing them, thus helping engineer the interphase size and properties to enhance composite performance. KW - Interphase KW - Polymer-metal KW - Epoxy KW - Copper KW - Composites KW - Nanoindentation PY - 2017 DO - https://doi.org/10.1080/09276440.2017.1286878 SN - 0927-6440 SN - 1568-5543 VL - 24 IS - 9 SP - 833 EP - 848 PB - Taylor & Francis CY - UK AN - OPUS4-39128 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Griepentrog, Michael T1 - Instrumented Indentation Testing (IIT) - A critical journey from the very first steps to the modern state of the art N2 - 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. T2 - Advanced nano-mechanical techniques for academic and industrial research. MML Conference and Workshop CY - Warwick, UK DA - 13.12.2017 KW - ISO 14577 KW - Instrumented Indentation Testing KW - Nanoindentation KW - IIT KW - Mechanical properties KW - Variable epsilon KW - Lateral displacement PY - 2017 AN - OPUS4-43466 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Griepentrog, Michael T1 - Dynamic instrumented indentation test application and standardisation N2 - 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. T2 - 13th Conference on Local Mechanical Properties CY - Košice, Slovak Republic DA - 06.11.2017 KW - ISO 14577 KW - Instrumented indentation testing KW - Nanoindentation KW - IIT KW - Mechanical properties KW - Dynamic testing KW - Visco-elastic KW - Loss modul KW - Storage modul PY - 2017 AN - OPUS4-43468 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -