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In this paper, the experimental procedure and calculation model for the measurement of the indentation modulus by using the primary hardness standard machine at INRiM in the macro-scale range at room temperature is described. The indentation modulus is calculated based on the Doerner-Nix linear model and from accurate measurements of indentation lo...
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After conducting an experiment on steel and aluminum to failure, I treated the data of force and displacement to find the ultimate and yield stress of both materials. Moreover, we found both Rockwell and Brinell hardness of the materials.
Citations
... 2-6) [L. [25][26][27][28][29][30]. Therefore, the determined mechanical properties (H IT , E IT ) are the arithmetic mean of a series of 12 measurements for each of the assumed loads (F n ). ...
The mechanical properties, adhesion and roughness of polymer coatings depend on many factors, including the unevenness of the substrate surface. Nevertheless, the influence of the substrate surface roughness is related to the coating type and substrate material and the used deposition method. Therefore, the effect of the surface roughness of a structural steel substrate on the mechanical properties of a PEEK coating is ambiguous. The indentation tests conducted show that, at a specific load of the indenter, the roughness of the steel substrate surface does not significantly affect the Vicker’s hardness of the tested PEEK coatings. The average Vicker’s hardness and elastic modulus are approximately 300 MPa and 5.6 Gpa, respectively, at the lowest of the applied loads, regardless of the surface roughness level of the steel substrate. Nevertheless, the surface roughness of the steel substrate after fine grinding of Ra = 0.21 μm, compared to the polished one with Ra = 0.005 μm, meant that adhesion improved, and the scratch hardness increased by approximately 130 to 370 [MPa] of the PEEK coating.
... Materials investigated in this paper were copper alloy, aluminum alloy, stainless steel, and copper-chromium-zirconium alloy. Young's modulus Es and Poisson ratio νs of the tested materials were previously evaluated from accurate measurements of speeds of sound in solids and in tension at environmental temperature (~21 °C) [41][42][43][44]. Despite the known systematic difference between dynamic and static moduli, the reference data are accurate as the overall uncertainties are less than 1%. ...
... To estimate the actual frame compliance in this paper, according to ISO 14755-1 Annex C [21], a series of loading and unloading cycles, performed on a standardized stainless-steel reference block for hardness (ASAHI HV30) at a single indentation point, was applied. Actually, more procedures are available according to standards and recent literature [40,44], based on the actual indentation depth of Vickers indentation [49][50][51]. ...
... Contact stiffness S written as F/h was determined from the Doerner-Nix linear model, by taking into account a portion of 20% of the unloading curve data, as shown in the graph of Figure 2. The geometrical dimensions of Vickers indentations, such as length l of the indentation side, calculated from the two diagonals d were accurately measured by the optical microscopy imaging technique, as described in detail in [44]. ...
In this work, the experimental method and the calculation model for the determination of indentation moduli, indentation work, and indentation creep of metallic materials, by means of macroscale-level forces provided by a primary hardness standard machine at the National Institute of Metrological Research (INRIM) at the at room temperature were described. Indentation moduli were accurately determined from measurements of indentation load, displacement, contact stiffness and hardness indentation imaging and from the slope of the indentation unloading curve by applying the Doerner-Nix linear model; indentation work, representing the mechanical work spent during the force application of the indentation procedure, was determined by calculating the areas under the loading-unloading indentation curve, through fitting experimental data with a polynomial law. Measurements were performed with a pyramidal indenter (Vickers test). The applied force was provided by a deadweight machine, and the related displacement was measured by a laser inter-ferometric system. Applied forces and the occurring indentation depths were simultaneously measured: the resulting loading-unloading indentation curve was achieved. Illustrative tests were performed on metals and alloy samples. Discussion and comments on the suitability of the proposed method and analysis were reported.
