Dear Abbas,

the process is such, it is described with a differential equation of second order. The determination of the coefficients is done by identification. To fit the chosen function to the data it must be used specialized software. For this purpose I use KORELIA.

Once you have the equation that presents data, the different graphs can be compared to a number of parameters.

I would recommend you the following articles, which deal with problems about identification and evaluation of non-linear processes:

Tolekova A., K. Yankov, Model of a plasma renin activity after nicardipine treatment. Journal of Information, Control and Management

Systems, Vol. 4(2), 2006, Slovakia, pp.203-212. ISSN 1336-1716

https://www.researchgate.net/publication/234101009_Model_of_a_plasma_renin_activity_after_nicardipine_treatment

Tolekova A., K. Yankov, Mathematical Model оf Plasma Renin Activity After Nifedipine Treatment. Bulgarian Journal of Veterinary

Medicine (2008), 11, No 1, 21-29.

https://www.researchgate.net/publication/234014919_mathematical_model_of_plasma_renin_activity_after_nifedipine_treatment

Yankov, K., Evaluation of Characteristic Parameters of Dynamic Models. Proc. of the Int. Conference on Information Technologies

(InfoTech-2011). St. Constantine and Elena resort, Bulgaria,sept.15-17, 2011, pp.225-234. ISSN 1314-1023.

https://www.researchgate.net/publication/235425892_Evaluation_of_Characteristic_Parameters_of_Dynamic_Models

Yankov, K., Assessment of Characteristic Parameters of Oscillating Models. Proc. of the Int. Conference on Information Technologies

(InfoTech-2012). St.Constantine and Elena resort, Bulgaria, sept.20-21, 2012, pp.114-123. ISSN 1314-1023.

https://www.researchgate.net/publication/235429284_Assessment_of_Characteristic_Parameters_of_Oscillating_Models

Dear Abbas,

If you have consolidated drained triaxial test results with respect to varying confining pressure..it is better to draw a Mohr's circles for varying confining pressure and connecting all peak points in Moh'r's cicles by drawing tangent line. This tangent line is called strength envelop this line intercept with y-axis called as cohesion and slope for this line is called angle of internal friction. In Moh'r Coulomb model cohesion, angle of internal friction and Young's modulus are material properties that need to assign in numerical analysis. The Young's modulus of soil can be obtained from stress - strain curves as attached in your question..these details you could get from any standard soil mechanics book..ok all the best..