Necked areas in the pure shear tests. Real strain-stress???.
Dear Dr. Bergstrom and other experts,
I’m really new in the field of rubber and in the field of FEA too so, I’ m sorry if my questions are too simple. I’m carrying out my Master Thesis (Diplomarbeit) and one area consists of validating the test data of a rubber obtained with pure shear tests (conventional device: load cell) using FEA and then using an optical device. The main problem of the test data obtained with the load cell is how to convert the engineering stress-strain to the real stress-strain, because of the appearance of a neck to low strains.
Although there is a necked area and a heterogeneous distribution of the strain along the gage length, can I use the conventional equations s=s(e+1); e=ln(A0 / A) to obtain real stress-strain data?. Is there a mathematical model to obtain a corrected real strain-stress curve for necking, like Bridgman, Aronofsky, Tegart, … analysis in metals?. Any mathematical model to describe the stress state in the necked area and the influence of it in the test data results, for rubbers?. Bibliography?.
Another question: how does Abaqus interpret these necked areas in the job results (strains, stresses,…)?.
Thank very much for everything and for your great help.
See my comments here.