Force Measurement Applied in Rod Ball End the Suspension of an Automotive Prototype

This study aims to determine the force acting on the rod ball end of an automotive suspension prototype from competition, participant in the Brazilian Tourism Championship 2016, used in training and to determine the fast lap time. The rod ball end is manufactured in SAE 4140 steel with heat treatment (body and ball) and the bush of polyacetal. To determine the force on the rod ball end the lower balance arm was converted into two load cells, through the setting of strain gage in each of the arms that compose it. It was recorded runway images with a camera in the cockpit and another camera placed inside the vehicle with the rear wheel housing, making possible to observe the suspension movement. When the prototype makes a chicane, the centripetal force is higher because the radius curve is small, when is accelerated it generates a force in line with the wheel, the front bar is compressed even more, and the rear is tensioned, that generates a load near to zero in this bar. The greatest force applied to the rod ball end was 9600 N. The largest loads in the rod ball end were generated during curves outputs, because in this condition the centripetal forces and the forces aligned with the wheels generated by the transmission system are high. In curve inputs the loads are relatively smaller, since the braking forces are smaller than the acceleration forces. In the straight line the resultant force is low due to high speed.