Abstract
The mechanical properties of a component are significantly influenced by the prevailing residual stress state. A deliberate induction of compressive residual stresses or a reduction of tensile residual stresses can improve the component properties, such as fatigue strength. Single point incremental forming is a flexible manufacturing process to produce complex shaped parts by the computerized numerically controlled movement of a hemispherical forming tool. Because the process parameters can be locally adjusted it is possible to influence the residual stress state of the component. The influence of the forming mechanisms bending, shearing and membrane stretching, as well as the role of the hydrostatic compression on the residual stress state is widely unknown. This work aims to fill this gap. Therefore, linear grooves are formed into AA5083 sheets in a single-stage incremental forming process. The residual stress state of the unclamped sheet is measured on both sides of the groove center by means of X-ray diffraction. The relative intensity of the dominant forming mechanism is adjusted by adapting the relevant process parameters step-down increment Δz and tool radius RTool. The forming mechanisms are analyzed numerically by splitting the total plastic energy into the three forming mechanisms bending, shearing and membrane stretching. The numerical results for bending and membrane stretching could be validated by crystallographic analysis. A shift in the energy ratio of the forming mechanism from bending to shearing with increasing relative step-down increment Δz/RTool could be observed numerically. The maximum residual stress amplitudes are found for Δz/RTool < 1. The results indicate that a deliberate residual stress state can be induced by adjusting the dominant forming mechanism of the process.
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Martins PAF, Bay N, Skjoedt M, Silva MB (2008) Theory of single point incremental forming. CIRP Ann Manuf Technol 57:247–252
Kim TJ, Yang DY (2000) Improvement of formability for the incremental sheet metal forming process. Int J Mech Sci 42:1271–1286
Bambach M, Hirt G, Junk S (2003) Modelling and experimental evaluation of the incremental CNC sheet metal forming process. In: Proceedings of the VII international conference on computational plasticity. International center for numerical methods in engineering, pp 1–17
Allwood JM, Shoulder DR, Tekkaya AE (2007) The increased forming limits of incremental sheet forming processes. Key Eng Mater 344:621–628
Emmens WC, van den Boogaard AH (2007) Strain in shear and material behaviour in incremental forming. Key Eng Mater 344:519–526
Eyckens P, Duflou JR, van Bael A, van Houtte P (2010) The significance of friction in the single point incremental forming process. Int J Mater Form 3:947–950
Jackson K, Allwood J (2009) The mechanics of incremental sheet forming. J Mater Process Technol 209:1158–1174
Emmens WC, van den Boogaard AH (2009) Incremental sheet forming analysed by tensile tests. Key Eng Mater 410:347–354
Sebastiani G (2016) Erweiterung der Prozessgrenzen inkrementeller Blechumformverfahren mittels flexibler Werkzeuge. Dissertation, TU Dortmund University
Sawada T, Matsubara S, Sakamoto M, Fukuhara G (1999) Deformation analysis for stretch forming of sheet metal with CNC machine tools. In: Proceedings of the 6th international conference on technology of plasticity. Springer Berlin, Heidelberg, New York, (1999), pp 1501–1504
Benedyk J, Parik N, Stawarz D (1971) A method for increasing elongation values for ferrous, nonferrous sheet metals. J Mater 6:16–29
Emmens WC, van den Boogaard AH (2008) Tensile tests with bending: a mechanism for incremental forming. Int J Mater Form 1:1155–1158
Bridgman PW (1952) Studies in large plastic flow and fracture: with special emphasis on the effects of hydrostatic pressure. McGraw-Hill, New York, pp 351–355
Maqbool F, Bambach M (2018) Dominant deformation mechanisms in single point incremental forming (SPIF) and their effect on geometrical accuracy. Int J Mech Sci 136:279–292
Tanaka S, Nakamura T, Hayakawa K, Nakamura H, Motomura K (2007) Residual Stress in sheet metal parts made by incremental forming process. In: Proceedings of numiform conference, pp 775–780
Radu C, Herghelegiu E, Tampu C, Cristea I (2013) The residual stress state generated by single point incremental forming of aluminum metal sheets. Appl Mech Mater 371:148–152
Maaß F, Gies S, Dobecki M, Brömmelhoff K, Reimers W, Tekkaya AE (2018) Analysis of residual stress state in sheet metal parts processed by single point incremental forming. In: AIP conference proceedings 1960. https://doi.org/10.1063/1.5035043
Macherauch E, Müller P (1961) Das sin2-Ψ Verfahren von röntgenographische Eigenspannungen. Zeitschrift für angewandte Physik 13:305–312
Dölle H, Hauk V (1976) Röntgenographische Spannungsermittlung für Eigenspannungssysteme allgemeiner Orientierung. Härterei-Tech Mitt 31:165–168
Lutterotti L, Vasin R, Wenk HR (2014) Rietveld texture analysis from synchrotron diffraction images. I. Calibration and basic analysis. Powder Diffr 29:76–84
Hammersley AP (1998) Fit2D: V99.129 reference manual version 3.1. Intern Rep ESRF 98:HA01
Rietveld HM (1969) A profile refinement method for nuclear and magnetic structures. J Appl Crystallogr 2:65–71
Grzancic G (2018) Verfahrensentwicklung und Grundlagenuntersuchungen zum Inkrementellen Profilumformen. Dissertation, TU Dortmund University
Boas W, Schmid E (1931) Zur Deutung der Deformationstexturen von Metallen. Zeitschrift für technische Physik 2:71–75
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Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)—TE 508/67-1; RE 688/76-1.
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Maaß, F., Hahn, M., Tekkaya, A.E. et al. Forming mechanisms-related residual stress development in single point incremental forming. Prod. Eng. Res. Devel. 13, 149–156 (2019). https://doi.org/10.1007/s11740-018-0867-3
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DOI: https://doi.org/10.1007/s11740-018-0867-3