Wrinkling control in aluminum sheet hydroforming

Abstract In this paper, the wrinkling behavior of 6111-T4 aluminum alloys during sheet hydroforming process was numerically and experimentally investigated. In sheet hydroforming, one or both surfaces of the sheet metal are supported with a pressurized viscous fluid, while a punch forms the part. In sheet hydroforming the use of a matching female die is not needed. The use of the pressurized fluid delays the onset of material rupture (International Journal of Mechanical Science 2003;45:1815–48) and also acts as an active blank-holding force to control wrinkling in the flange area. To form a wrinkle-free deep-drawn hemispherical cup with sheet hydroforming, a theoretical analysis based on the work of Lo et al. (Journal of Materials Processing Technology 1993;37:225–39) was initially used to predict the optimum fluid pressure profile. Simplifying geometrical assumptions and Tresca material model used in the theoretical analysis provided a fluid pressure profile that resulted in premature rupture of the sheet metal. However, an optimum fluid pressure profile generated by the finite element method, using Barlat's anisotropic yield function (Journal of Mechanical Physics and Solids 1997;45(11/12):1727–63), was successfully applied in sheet hydroforming to make the deep-drawn hemispherical cup without tearing and with minimal wrinkling in the flange area. The finite element model was also capable of accurately predicting the location of the material rupture in pure stretch, and wrinkling characteristics of the aluminum alloy sheet in the draw-in process.

[1]  Johanne Denault,et al.  Thermoformed glass fiber reinforced polypropylene: Microstructure, mechanical properties and residual stresses , 1998 .

[2]  Thomas B. Stoughton,et al.  A general forming limit criterion for sheet metal forming , 2000 .

[3]  Thomas B. Stoughton,et al.  Stress-Based Forming Limits in Sheet-Metal Forming , 2001 .

[4]  Farhang Pourboghrat,et al.  Experimental and numerical study of stamp hydroforming of sheet metals , 2003 .

[5]  Peter Hartley,et al.  Numerical Modelling of Material Deformation Processes: Research, Development, and Applications , 1992 .

[6]  S. Clift,et al.  Fracture prediction in plastic deformation processes , 1990 .

[7]  S. Yossifon,et al.  On the Permissible Fluid-Pressure Path in Hydroforming Deep Drawing Processes—Analysis of Failures and Experiments , 1988 .

[8]  F. Barlat,et al.  A six-component yield function for anisotropic materials , 1991 .

[9]  S. Yossifon,et al.  Buckling prevention by lateral fluid pressure in deep-drawing , 1985 .

[10]  Tze-Chi Hsu,et al.  Theoretical and Experimental Analysis of Failure for the Hemisphere Punch Hydroforming Processes , 1996 .

[11]  A. A. Betser,et al.  Hydroforming Process for Uniform Wall Thickness Products , 1977 .

[12]  S. Yossifon,et al.  Rupture instability in hydroforming deep-drawing process☆ , 1985 .

[13]  F. A. McClintock,et al.  A Criterion for Ductile Fracture by the Growth of Holes , 1968 .

[14]  D. M. Tracey,et al.  On the ductile enlargement of voids in triaxial stress fields , 1969 .

[15]  S. Yossifon,et al.  On suppression of plastic buckling in hydroforming processes , 1984 .

[16]  F. Barlat,et al.  Yield function development for aluminum alloy sheets , 1997 .

[17]  Tze-Chi Hsu,et al.  An analysis of the hemispherical-punch hydroforming processes , 1993 .

[18]  Z. Marciniak,et al.  Limit strains in the processes of stretch-forming sheet metal , 1967 .