According to my last post some weeks ago I now have translated the laboratory data from engineering strain to true strain with the following formula: epsilon(true)=ln(1+epsilon(engineering)). I compared then the the new values of the measurement data with the points on the graph of the ExCalibre output. And they a still different. For the Oedometer the measurement point (sigma 1/epsilon 1 true) is (1200/0,101) and on the graph of ExCalibre it is (1200/0,112). The same is for the triaxial tests. The maximum true strain epsilon 1 of the measurement is 0,197 and on the graph it goes until 0,244. Attached are the pictures of the ExCalibre output with the points and a picture of the excel table with the measurement values.
Is the transformation of strain different in ExCalibre or what can be the reason for that?