And particularly the enclosing boxes approach, filters needs to be applied on
And particularly the enclosing boxes system, filters needs to be applied around the principal surface. This implies that the surface needs to be ready for evaluation, so the microroughness s should be removed as well as the kind or slope c, employing levelling operations. Soon after levelling, the angle no longer has any impact on the fractal dimension parameter. This paper is depending on the promising benefits based on fractal dimension analysis, partially presented previously by the author [36,37]. The study compares fractal dimension with the surface areal parameters, regardless of various recommendations, and devoid of the usage of surface major filters. The analysed surfaces are fatigue fractures right after bending, torsion and also a mixture of these loadings. This evaluation would assistance to interpret the connections between fracture surface topography and trying to figure out the models in between fractal dimension and fatigue loading circumstances. 2. Materials and Techniques 2.1. Fatigue Test Materials and Campaign 10HNAP and S355J2 steels and 2017-T4 IQP-0528 Purity aluminium alloy have been investigated, and also described earlier within this set by Macek et al. [37,38]. A nominal composition and mechanical options, like Young modulus E–215, 210, 72 GPa and Yield stress y –418, 358, 382 MPa, for 10HNAP and S355J2 steels and 2017-T4 aluminium alloy, respectively, are shown in these performs. Fatigue experiments had been carried out around the specimens shown in Figure 1. Two V-notched configurations and a single (S355J2) smooth profile have been utilised. The tests had been run for 3 categories of loading: (1) pure bending, (2) combined torsion with bending, and (3) pure torsion. Proportional and non-proportional, but additionally constant-amplitude and random loading applications, have been applied. The 10HNAP steel specimens had been tested with stationary and ergodic random loadings and had a normal probability distribution and wide-band frequency spectra from 0 to 60 Hz. Fatigue tests of S355J2 steel specimens integrated non-proportional bending-torsion histories. In the case of your 2017A-T4 aluminium alloy specimens, tests had been performed under diverse pressure ratios R. To examine the various situations, the loading strain ratio, r, was determined by Equation (1). r= max , max + max (1)exactly where r = 1 is related to pure torsion, r = 0 to pure bending and 0 r 1 to bending and torsion mixture. The values from the loading tension ratio r and pressure ratios R studied within the fatigue tests are shown in Table 1 [37].Table 1. Fatigue tests parameters. Material 10HNAP S355J2 2017-Tr= maxmaxmax + min R= maxReference [14] [39] [40]0; 0.five; 1 0; 0.16.6; 1 0; 0.18.44;-1 -1 -1; -0.five;Metals 2021, 11, 1790 Metals 2021, 11,3 of 21 three ofFigure 1. Specimen geometries utilised in fatigue campaign: (a) 10HNAP steel, (b) S355J2 steel, and Figure 1. Specimen geometries utilised in fatigue campaign: (a) 10HNAP steel, (b) S355J2 steel, and (c) 2017-T4 aluminium alloy (dimensions in millimetres). Adapted from [37]. (c) 2017-T4 aluminium alloy (dimensions in millimetres). Adapted from [37].two.two. Fracture Surface Topography Measurement Table 1. Fatigue tests parameters. Surface topographies were investigated by means of the Infinite Focus G4 optical measuring = = Reference technique Material Imaging GmbH, Graz, (Alicona Austria), utilizing focus variation technology [38,41]. + The evaluation of 3D scans, for0; 0.5; 1 whole fracture regions, was carried out with MAC-VC-PABC-ST7612AA1 Purity & Documentation magnification of 10HNAP -1 [14] 10 79.3 nm vertical resolution, and 3.91 lateral resolution. Settings have been applied to S355J2 0.