Experimental determination of torsional coefficients of torsion bars used in heavy commercial vehicle hydraulic steering

In this master's thesis, two different test setups with vertical configurations where torsion tests can be performed were created. In order to determine the working success of the mechanisms, 5 different geometric torsion shafts used in heavy commercial vehicle power steering gearboxes, providing the steering feel and recovery, were used as test samples. The theoretical torsion coefficients of torsion shafts with different geometric properties and neck torque values for 7° of torsion ,which is the maximum torsion angle, were calculated mathematically. The same calculations were made by performing Finite Element Analysis with ANSYS Structural and the highest difference \% 2.25 was seen between the theoretical and numerically calculated values. Torsion coefficients of the samples were measured with the torque-angle sensor in the first setup. The samples were subjected to +/- 7° torsion by using servomotor and torque sensor in the second test setup that was set up afterwards. The tests were performed in 5 replicates using 3 different samples from each sample. Torsion coefficients of the samples were calculated with the torque values recorded as a result of the tests. These values were compared with the values obtained in theoretical, finite element analysis and torque-angle sensor measurement. In the measurements made in test setup 2, there was a maximum difference of about \%3 compared to the theoretical and FEA results. Torque values and torsion coefficients were generally high in torque-angle sensor measurement. When the success of the two different setups created was evaluated, it was evaluated that the test setup number 2, which used servomotor and torque sensor, gave more successful results.