Article Mathematical Simulation of Nonlinear Problem of Three-point ...

Have you considered the orthotropic material properties for composite material? Did you checked with capping the stress results for its yield or ultimate strength depending upon whether the composite material is ductile or brittle?

Thank you the reply @Arun. Yeah absolutely i have consider all the Points you have reffer to. As you see from the comparison graph the numerical model is behave well in the elasticity region but the problem is the lack of plastic domaine.

I assume that the red continuous curve on the figure is the experimental force-deflection curve, and the black dots are the simulation result?

Remember that Hashin was a brittle failure criteria, not a plasticity model. So if you haven't defined a damage model to manage what happens after an element reaches (one of the several) Hashin failure criteria, most FE codes will simply delete the failed element.

From the curvature of your experimental force displacement curve: it looks like there is some indentation / taking up clearance at the start of loading, and the departure from linearity as load increases is very gradual. That suggests either a very ductile tensile response for an FRP, or that some kind of failure is initiating on the compression side (micro-buckling of fibres / plastic compression of matrix). So your simulation would need to incorporate either of these phenomena.