As a follow up to my first blog , I would like to know if the experimental data of applied loads and crack sizes or lengths, are sufficient to model the R-curve behaviour via the Fracture Mechanics approach.

In this approach i need to determine the traction stress field and the deflection of ligaments in the bridging zone. Tests were perfomed in 4-Pt-Bending. What are the differences, if any, between the load/load point separation relation/curve of the system on the one hand, and the Traction stress/deflection relation/curve in the bridging zone. Is there any useful theoretical link between them?

I need help to determine or contruct the crack reistance (R-curve) of a material that show crack bridging. I have the experimental data of applied load and crack lengths due to these applied loads. the SENB specimen was used and loading was 4-pt-bending. The plot of Kapp versus crack size did not give the usual rising curve which plateaus, but rather increases exponentially. How do I get the Kb (i,e K due to bridging) or the normal R-curve. I am not a mechanical engineer but into applied mechanics.