Inverse Method to Determine Fatigue Properties of Materials by Combining Cyclic Indentation and Numerical Simulation

Abstract

The application of instrumented indentation to assess material properties like Young’s modulus and microhardness has become a standard method. In recent developments, indentation experiments and simulations have been combined to inverse methods, from which further material parameters such as yield strength, work hardening rate, and tensile strength can be determined. In this work, an inverse method is introduced by which material parameters for cyclic plasticity, i.e., kinematic hardening parameters, can be determined. To accomplish this, cyclic Vickers indentation experiments are combined with finite element simulations of the indentation with unknown material properties, which are then determined by inverse analysis. To validate the proposed method, these parameters are subsequently applied to predict the uniaxial stress–strain response of a material with success. The method has been validated successfully for a quenched and tempered martensitic steel and for technically pure copper, where an excellent agreement between measured and predicted cyclic stress–strain curves has been achieved. Hence, the proposed inverse method based on cyclic nanoindentation, as a quasi-nondestructive method, could complement or even substitute the resource-intensive conventional fatigue testing in the future for some applications.

Finite Element Modeling of Brittle and Ductile Modes in Cutting of 3C-SiC

“…To accomplish this, a genetic algorithm was used, in which the parameters of the DP model were updated at each subsequent iteration based on the fitness of the load-depth curve. The parameterization process was terminated once the NMSE is smaller than 3 × 10 −2 , following the criterion used by Sajjad et al [30]. It is noted here that only the load-displacement curve for an indentation depth of 105 nm was used for this inverse parameters identification; later we validated the optimized parameter set by conducting the nanoindentation for other applied maximum indentation depths.…”

Micromechanical Modeling of AlSi10Mg Processed by Laser-Based Additive Manufacturing: From as-Built to Heat-Treated Microstructures

“…The general feasibility of obtaining true material parameters from the inverse analysis of indentation results has been demonstrated by Schmaling and Hartmaier [60] for conventional hardness tests. In more recent work, the reliability of this inverse method has been shown for nanoindentation [61] and also for cyclic indentations [62]. Thus, nanoindentation tests were performed on the Al and Si-rich phases of the AB and HT states using a Berkovich indenter.…”

Cyclic Nanoindentation for Local High Cycle Fatigue Investigations: A Methodological Approach Accounting for Thermal Drift

“…Microindentation approaches have shown promising correlations with the macroscale fatigue behavior. [1][2][3][4][5][6][7][8][9][10][11][12][13] Large microindents make it difficult, however, to test very small structures. Further, the results average over the microstructure, thus concealing information on the influence of local microstructural variations and the interaction between single phases and fatigue mechanisms.…”