Investigation on laser forming of stainless steel sheets under coupling mechanism. (August 2015)

• Record Type: Journal Article
• Authors: Chakraborty, Shitanshu S.; Maji, Kuntal; Racherla, Vikranth; Nath, Ashish K.
• Is Part Of: Optics & laser technology. Volume 71(2015)
• Page Start: 29
• Page End: 44
• Publication Date: 2015-08
• Subjects: Fourier number -- Finite element modelling -- 3D laser forming; Optics -- Periodicals; Lasers -- Periodicals; Electronic journals; 621.366
• DOI: 10.1016/j.optlastec.2015.02.013
• Languages: English
• ISSNs: 0030-3992

Abstract

Abstract: In laser forming of three dimensional surfaces simultaneous bending and thickening of the sheet being formed are often required. Laser forming by the coupling mechanism has the capability to generate both of them. However, literature is scarce on the study of laser forming under coupling mechanism. A part of this work investigates the effect of Fourier number and laser spot diameter on bending angle and thickness increment induced by laser scans promoting coupling mechanism. Peak surface temperature was maintained nearly constant. It was chosen so as to avoid surface melting and sensitization at the scan track on top surface. The required laser parameters were determined with the help of an analytical model for temperature estimation. The experimental results showed that while the bending angle reduced with the increase of Fourier number, the thickness increment increased. And, with the increase of laser spot diameter both bending angle and thickness increased. Finite element simulations were carried out using ABAQUS software on a three dimensional model for developing a better understanding of the deformation behaviour. Multimode intensity distribution of the laser beam and temperature dependant material properties were considered in the simulations. Finite element analysis and microstructure study showed that chances of sensitization are rare with the current laser parameter combinations. Based on temperature gradient and coupling mechanisms a different laser scanning strategy has been proposed for laser forming of deep pillow shaped surfaces retaining symmetry. Highlights: Laser forming under coupling mechanism studied at constant peak surface temperature. Analytical model for temperature in thin sheet developed for parameter selection. Bending reduces, thickness increases with Fourier no., both increase with beam diameter. 3D FE analysis done considering temperature dependant properties and multimode beam. A strategy for improving the pillow shaped surfaces by laser forming is proposed.