[Geoqus] On Mises stress and Yield strain

[bsaad at po-box.mcgill.ca]

It is considered in the example

http://www.abaqus.com/solutions/tb_pdf/TB-06-SLOPE-1.pdfI

that the ratio of the Mises stress at a point to the maximum Mises 
stress that can be generated at the existing pressure  (called DP= 
Yield Factor) will reach 1 when the material point undergoes yielding 
(plastic behavior);i.e. equivalent plastic strain (PEEQ) > 0 . I do not 
think this is a right failure measure for strain hardening materials in 
which plastic strain will appear when DP < 1 (no failure yet). Do you 
agree with me.?