nThe suggestion to try 500 mm was to put in a number so large that it would surely become nonlinear. It looks like it starts being nonlinear after just 0.125 x 500 = 62.5 mm and the force reaches a peak at about 0.375 x 500 = 188 mm and after that the force is reducing. A reducing force is what you have in your experimental data.nWhat was the loading point for that first model?nWhen you have two loading points, you just apply the displacement to two places on the beam.n