If you are coding your program, you must dervie the element stffness matrix induced by the initial stress sigma. The distributed moment produced by the initial stress sigma is sigma*w (w being the local deflection).

If you are using a commercial software package, you should search for the right keyword. Alternatively, you can input your derived element stiffness matrix into a commerical code. This requires a high level of programming skills and proficiency in the particular package.

Dear Aria Tsam,

Thanks very much for the link. I am following the reference but having problem to understand [G] matrix in eq. (11.22) and eq. (11.24). Can you help me in this context.

Dear Prof. Huajiang Ouyang,

Thank you for the help. Yes I am developing my own code in Matlab. I have calculated elemental stiffness matrix, calculated initial nodal displacement due to external load, followed by internal stresses at integration points. But I am able to understand how to calculate [K(sigma)] like we calculated elemental stiffness matrix [K]=integral([B][Q][B]dV). For [K(sigma)] what should be in place of [B] ? Can you please help..

Dear Anshul Sharma

I am study about nonlinear analysis of laminated plates and need to know about initial stress matrix. I tried to download Dear Aria Tsam reference but the link for the file was not valid.

I am so appreciated if you send me that file. (My Email: [email protected])

Sincerely yours