A method to include the distribution of strains in the identification of the planar anisotropy of sheet metals is proposed.
Anisotropy in sheet metal.
In cold rolled sheets elastic deformation is much smaller compared with the plastic deformation so only the anisotropic plasticity is nor mally considered.
A general elasto plastic finite element formulation based on incremental deformation theory for planar anisotropy and its application to sheet metal forming int.
B forming limit diagrams fld for various sheet metals.
R is the normal anisotropy of the sheet as described in section 4.
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 this scalar quantity is used extensively as an indicator of the formability of recrystallized low carbon steel sheets.
In other words the material will react differently to stress applied in one direction than it would to the same stress applied in a different direction.
The type of plastic anisotropy usually desired in sheet metal forming is that the sheet is isotropic in the plane and.
Aime 236 pp489 495 1966.
In all other cases anisotropy to some degree is to be expected.
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.
Although the major strain is always positive stretching the minor strain may be either positive or negative.
Anisotropy is an important factor in sheet metal forming.
Metal matrix composites with aligned fibres may have highly directional stiffness and strength properties 1 but their utilisation at present is rather little and they will not be considered further here.
If r 1 then the sheet is of course isotropic 9 22 2015 39 40.
It is also worth mentioning here that the efforts currently under.
A theory of plastic anisotropy based on a yield function of fourth order int.
Figure 15 the deformation of the grid pattern and the tearing of sheet metal during forming.
Sheet metal manufacturers do not routinely use online inspection techniques to monitor the texture of the metal as it is produced and most tend to perform x ray pole figure 1 2 spot checks on the final product.
Anisotropy includes elastic and plastic anisotropy.
Plasticity 15 1999 35 67.
Hu in mechanics of sheet metal forming second edition 2002 1 2 2 anisotropy if the magnitude of the planar anisotropy parameter δ r is large either positive or negative the orientation of the sheet with respect to the die or the part to be formed will be important.
The method includes the optical measurement of strains on a flat specimen with a varying cross section and an inverse parameter identification scheme which minimizes the differences between the numerical simulation results and the experimental measurements by using.
19 1977 505.
