Plastic Anisotropy In Sheet Metal Forming

A general elasto plastic finite element formulation based on incremental deformation theory for planar anisotropy and its application to sheet metal forming int.

Plastic anisotropy in sheet metal forming.

Numerical analysis is carried out in order to investigate the influence of plastic anisotropy on sheet metal forming processes such as stretching and deep drawing. A profound survey is given of literature about yield criteria for anisotropic materials up to most recent developments and the calculation of forming limits of anisotropic sheet me tal. A general elasto plastic finite element formulation based on incremental deformation theory for planar anisotropy and its application to sheet metal forming int. From the results of the finite element analysis it is shown that puckering behavior of sheet metal is largely affected by plastic anisotropy.

Plasticity 15 1999 35 67. Planar anisotropy if by performing experiments on the sheet it is found that the measured r value is unchanged with orientation the sheet is said to have planar anisotropy. Finally the effect of plastic anisotropy on the puckering behavior in the spherical cup deep drawing process is investigated. The numerical results are compared to experiments.

A large chapter is devoted to formability testing both for bulk metal and sheet metal forming. A stress points forming contours of plastic work of aluminum alloy sheet 6016 o compared with the yield loci. The lankford coefficient also called lankford value r value or plastic strain ratio is a measure of the plastic anisotropy of a rolled sheet metal. Anisotropic one as accurately as possible 1 11.

This scalar quantity is used extensively as an indicator of the formability of recrystallized low carbon steel sheets. The type of plastic anisotropy usually desired in sheet metal forming is that the sheet is isotropic in the plane and has an increased strength in the thickness direction which is nor mally referred to as normal anisotropy. If r 1 then the sheet is of course isotropic 9 22 2015 39 40. Plast 15 1 1999 pp.

It is shown that the neglect of the anisotropy in the simulations leads to inaccurate results. The computer simulation of the sheet metal forming processes needs a quantitative description of the plastic anisotropy by the yield locus. More often however the type of plastic anisotropy is characterized by different strengths in different directions in the plane of the sheet as well which is called planar anisotropy. Advances in anisotropy of plastic behaviour and formability of sheet metals.