I am using ABAQUS to model the response of a finite-sized, repeating 2D truss structure under compressive loading. The trusses are very slender. I have conducted tests on metallic specimens and I'm having trouble correlating the experimental data to the ABAQUS predictions, specifically the stiffness (N/m). Although the peak load values correlate well (within 3%), ABAQUS is predicting approximately 1.8 times the experimental stiffness of my 304 Stainless structure, and 1.4 times the stiffness of my Titanium structure. Elastic-plastic material properties were taken from ASTM E8 tension tests done in-house.
I'm using B21 elements, enough of them that the stress-strain behavior has converged nicely.
One of my colleagues suggested the element itself may be too stiff? Any ideas would be great.