Dynamical Loads on the Bronze Age Crossbar Wheel of Mercurago

This paper follows a previous study on a Bronze age crossbar wheel found in Mercurago (Italy), likely used for lightweight war chariot. In that study, structural and technological issue related to the wheel where assessed; its performance was evaluated by considering dynamical loads, due to bumping and curving, hypothesized based on typical values occurring on modern vehicles. In the present paper, a deeper insight into the dynamics of the wheel is presented. The dynamical loads on the wheel where obtained by means of a finite element model of the whole chariot, whose possible assembly was reconstructed based on both the wheel geometry and the structure of a coeval chariot found in Armenia. The chariot framework was supposed to be made by wooden members connected by leather joints. The cockpit floor was supposed to be in interwoven leather stripes. Two people (the driver and the warrior) were transported by the chariot. Two dynamical loading conditions were considered: bumping with one wheel over an obstacle at 40 km/h and running a 5 m radius curve at 20km/h. The results in terms of dynamic loads on the wheel significantly differ from the hypotheses introduced in the previous study, but the conclusions drawn about the structural issues of the wheel were confirmed