An experimental device for depth-sensing indentation tests in millimeter-scale
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An experimental device for depth-sensing indentation tests in millimeter-scale N. Huber Universit¨at Karlsruhe (TH), Institute for Reliability and Failure Analysis, Kaiserstr. 12, Postfach 6980, D-76128 Karlsruhe, Germany
Ch. Tsakmakis Forschungszentrum Karlsruhe, Institute for Materials Research II (IMF II), Postfach 3640, D-76021 Karlsruhe, Germany, and Technische Hochschule Darmstadt, Institute of Mechanics 1, Hochschulstrasse 1, D-64289 Darmstadt, Germany (Received 18 June 1997; accepted 16 December 1997)
A device for spherical indentation using a tip radius of 2 mm and loads up to 10 kN is presented. This facility can be applied, for example, to verify methods for characterizing the behavior of materials exhibiting homogeneous and isotropic constitutive properties. The indentation device can be driven both load- and depth-controlled. The accuracy of measurements is about 1 N for load and 0.2 mm for depth at a total depth of 200 mm. Two materials, an austenitic steel and an aluminum alloy, have been tested and their Young’s moduli have been determined. For determining Young’s modulus from spherical indentation data, use is made of a so-called Lt method, which had been developed in Ref. 1. Results obtained in this way are compared with corresponding values measured by one-dimensional homogeneous tensile experiments.
I. INTRODUCTION
The investigation of constitutive properties using the indentation test has been continuously developed toward a decreasing scale down to several nanometers in depth. This development has been accompanied by various models, which have been proposed in order to interpret depth-sensing data.1–5 For example, various methods have been proposed for determining the value of Young’s modulus by using loading as well as unloading parts of depth-load trajectories (see, for example, Refs. 1 and 5). Evidently, in order to check the capabilities of these models, it is convenient to compare the results obtained by interpreting the indentation data with corresponding results obtained by evaluating the usual one-dimensional homogeneous tensile tests. Commonly, experimentally measured depth-load trajectories during indentation tests are referred to microscopic scales (see, for example, Refs. 3 and 4). However, to perform one-dimensional homogeneous tensile experiments on the microscale has up to this point been by no means an easy task. Even if such experiments are possible, they are very expensive and presume very complicated testing devices and measurement arrangements. On the other hand, to perform one-dimensional homogeneous tensile tests on the macroscale is today a standard technic. Therefore, it is useful to check the capabilities of the models rather on the macroscale by preparing specimens for tensile and indentation tests of the same material and then directly comparing results obtained by the two different experimental tests. 1650
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J. Mater. Res., Vol. 13, No. 6, Jun 1998
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