These equations are a little confusing. Equations (1), (2) and (4) all define and are set equal to 0. Need more info before I can say how (8) is arrived at. What is actually?
Thank u about your respone.
But we can ignore equations (1),(2) and just use of another equations. Please just use of equations (3),(4),(5),(6),(7) and (8). and sigma is a constant. and f is a yield function in plasticity. In fact, f represents a surface in the space of (sigma1,sigma2). I have uploaded piece of this paper for u, maybe that help.
Link of paper: [COLOR="rgb(0, 0, 0)"]Document1.pdf - 4shared.com - document sharing - download[/COLOR]
Thank u again