Abstract
The demand for premium motorcycles with engine capacity above 250 cc and top speeds above 120 km/h has increased in India. At such high speeds stability of a motorcycle is crucial for safety and aerodynamics plays a major role. The objective of this research is to study the influence of location of aerodynamic center of pressure (COP) and sensitivity of aerodynamic forces on stability and handling of a motorcycle. A comprehensive rigid body model of a motorcycle is built using a multi-body dynamics software (MBDS), VI Motorcycle. Simulations are performed using the verified multi-body dynamics (MBD) model simulated on a straight path at different speeds. Two methods of analysis are used to evaluate the effect of aerodynamic parameters on weave and wobble stability. In the first method, a linear Eigen value analysis is performed and real part of root locus is studied. In the second method, a non-linear analysis is performed by applying an impact about the steering pivot. Damping ratio corresponding to weave and wobble frequency from steer oscillation are studied. Further, front wheel reaction plots are compared to evaluate the handling behavior of the motorcycle. An optimal location for COP is identified for stability and handling performance, and also the sensitivity of aerodynamic forces is evaluated.