OBRABOTKAMETALLOV Vol. 23 No. 3 2021 MATERIAL SCIENCE EQUIPMENT. INSTRUMENTS 7 5 Fig. 7. Influence of grinding wheel hardness on the value of Poisson’s ratio and Young’s modulus – 25A F60 O has values ν = 0.227; E = 50.56 GPa; – 25A F60 R has values ν = 0.217; E = 60.713 GPa; – 25A F60 T has values ν = 0.175; E = 74.36 GPa. Values of Poisson’s ratio and Young’s modulus were also obtained for grinding wheels made of normal electrocorundum, white electrocorundum, chromotitanium electrocorundum, and green silicon carbide (see fig. 8). Since the abrasive material of the grinding wheel cannot be quantified, regression analysis and the development of empirical relationships are not applicable in this case, unlike in the study of the effect of grain size and hardness on the elastic parameters of the tool. The values of ν and E in fig. 8 do not permit further applications or insights beyond what is obtained directly. Fig. 8. Influence of abrasive material on the value Poisson’s ratio and Young’s modulus Conclusion 1. The order of appearance of the eigenmodes of grinding wheel vibrations remains unchanged over a wide range of ν and E values. The lowest eigenmodes used for acoustic monitoring of grinding wheels are a pair of bending modes f₁, f₂ (n = 2, s = 0) and the bending mode f₃ (n = 0, s = 1). 2. In the absence of boundary conditions, modes f₁ and f₂ (n = 2, s = 0) contribute most significantly to the dynamics of grinding wheel vibrations along the X and Y coordinate axes. In the Z direction, the largest contribution is made by eigenmode f₃ (n = 0, s = 1); however, this contribution is much smaller than that of f₁ and f₂. 3. The values of Poisson’s ratio and Young’s modulus for the studied grinding wheels were determined by correlating the experimental and calculated spectral compositions of the natural frequency distributions. The values vary within the following ranges: 0.16 < ν < 0.27 and 40 GPa < E < 67.5 GPa. Grinding wheels with significantly different characteristics (e.g., 25A F80 L and 25A F60 S) may have slightly different
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