Determination of micro-scale plastic strain caused by orthogonal cutting

Abstract

Abstract:An Electron Beam Lithography technique has been used to produce microgrids in order to measure local plastic strains, induced during an orthogonal cutting process, at the microscopic scale in the shear zone and under the machined surface. Microgrids with a 10 µm pitch and a line width less than 1µm have been printed on the polished surface of an aluminium alloy AA5182 to test the applicability of the technique in metal cutting operations. Orthogonal cutting tests were carried out at 40 mm/sec. Results show that the distortion of the grids could successfully be used to compute plastic strains due to orthogonal cutting with higher accuracy compared to other techniques reported in the literature. Strain maps of the machined specimens have been produced and show high strain gradients very close to the machined surface with local values reaching 2.2. High resolution strain measurements carried out in the primary deformation zone also provide new insight into the material deformation during the chip formation process.

Quantitative Strain Analysis of the Large Deformation at the Scale of Microstructure: Comparison between Digital Image Correlation and Microgrid Techniques

“…7-a, was used to quantify E G as the maximum error value generated when clicking on grid intersections following the procedure described in [6]. The resulting strain map is shown in Fig.…”

“…The micrograph of the etched specimen shows the optimal conditions found in terms of contrast generated at the grain boundaries in order to process the SEM images using DIC. After etching, Electron Beam Lithography technique [6,9] has been used to lay square microgrids of gold with a pitch of 5 microns on the surface of the specimen. The distortion of the grids during the test is used to determine the in-plane components of the local deformation gradient tensor under the framework of large strain deformation.…”

“…The distortion of the grids during the test is used to determine the in-plane components of the local deformation gradient tensor under the framework of large strain deformation. The local true plastic strain maps are then calculated according to the procedure given in [6].…”

“…The micro-scale deformation of materials has been mostly studied through the observation of microstructural evolution using different techniques including in-situ mechanical testing combined with strain measurements at a microscopic scale [2][3][4][5] with the aim to relate local strain distributions within microstructural constituents to identified deformation mechanisms [6][7][8]. Allais et al [9] developed a technique to measure strain distributions from the distortion of microgrids laid onto the surface of dualphase materials , i.e.…”

Development of a precision machine to perform and study orthogonal micro-cutting

“…However, the cutting speeds were low (around 1-3 m/min for brass), limiting the range which can be experimentally studied. Ghadbeigi et al [11] developed an orthogonal cutting device in order to analyze the material plastic deformation during orthogonal cutting, the cutting speed used was 2.4 m/min. In this study, the cutting forces were not measured.…”