Estimation of Wheel Loads using a Mathematical Model and Correlation with Vehicle Measurements on Motorcycles

This paper aims at the estimation of dynamic wheel loads of a two-wheeler through mathematical modeling that will aid during the initial stages of product development. A half car model that represents a two-wheeler was used for this purpose. Road displacements were given as input to the model and the wheel loads estimated. Actual road data obtained from two-poster rig was used as input to the model thereby making it possible to calculate the wheel loads for different customer usage conditions on different roads. In this paper, a severe rough road was chosen for verification of the model with that of the rig as the rider dynamics on such roads are the most difficult to simulate even on the rigs. The estimated values from model were verified with those measured using a two-poster rig for the same road displacement. Attempt has been further made to establish a correlation between the ride comfort predictions from the model and the two-poster rig. The acceleration levels on the frame were considered for assessment and comparison of comfort. The fact that both the estimation of wheel loads and ride comfort optimization can be accomplished much before building complex multibody models for simulation makes the approach very cost effective and faster. Also, the advantage of predicting the fatigue life of various components that go into a vehicle based on dynamic wheel loads even before the part is made makes this a very useful exercise.