Stress-strain state simulation and calculation of a microprofile under orthogonal impact depending on loading conditions

The present study aims to establish the effect of loading conditions on the shaping mechanics and stress-strain state of a surface microprofile for machine parts under the initial roughness impact. The used calculation model of microroughness includes physical and mechanical characteristics of a soft copper-simulating material. A numerical model of microsettlements on the surfaces of machine parts is developed for various loading conditions. The transition from free to restrained loading of the microroughness model increases the angle at the base of the deformed microprofile from 35 to 58°, relative length of the smoothed section from 0.46 to 0.8, and vertical rise of the microprofile depression point from 0.012 to 0.21. For one unfastened pair of side microprofile surfaces, orthogonal pair is deformed to a greater extent relative to the corresponding freely fastened surface. The maximum elongation of the sample in the direction of oX and oZ axes is 7 and 13%, respectively. Depending on loading conditions and location of microprotrusions, the full-settlement stress under the microroughness peaks ranges from 1050 to 1370 MPa exceeding the ultimate strength of the samples by 5–7 times. The stress of depressions on rigidly fastened samples reaches a maximum value of 1190 MPa, which exceeds the values for other fastening options and ultimate strength of the samples by 4–12 and 0.5–6 times, respectively. The lowest stress homogeneity across the microprofile cross-section has been found in freely fastened samples; rigidly fastened samples have the highest stress homogeneity. The optimal microprofile smoothing is typical for rigid fastening loading with a more uniform stress across the microprofile cross-section. The studies are relevant for assigning the conditions of workpiece processing using local deformation methods under the varying degree of restrained loading within the boundaries of the processed surfaces.