Ride Comfort Evaluation of an Motorbike with Random Excitation by a Multi Body Dynamic Model

Abstract An motorbike is designed with full technical specifications regarding size and weight distributed on the front and rear axles of the vehicle. The wheel is connected to the vehicle body frame through a suspension system including linkage, spring, and shock absorber elements. The designed suspension system specifications play a very important role in ensuring the vehicle’s ride comfort, safety and road holding ability. To ensure technical requirements, the suspension system is designed with the spring and damper parameters selected as reality. The ride comfort greatly affects the quality of the vehicle’s design and the health safety of people using the vehicle. This paper focuses on the ride comfort of an electric motorbike. The assessment of ride comfort is analyzed by a Multi-Body Dynamic (MBD) model with 4 degrees of freedom (4DOF) subjected under the random excitation, according to ISO 8608 standard. The simulation is performed with three random types of road profile, class A, class B, class C. The velocity is in the range of from 10 ÷ 80 (km/h), at each value of velocity the Root Mean Square (RMS) index of the acceleration in the time domain is determined. The acceleration index includes to frequency weighting according to ISO 2631:1-1997 standard is used to evaluate the ride comfort. The MBD model in 3-dimensional (3D), including wheels in contact with the road surface, linkage bars and suspension systems linked to the vehicle frame through linkage joints, is employed. The obtained results show that, with the same v value, when the vehicle moves on road surface A class, the ride comfort is always smaller than road surface B class and C class. Considering the same type of road surface, as v increases, the ride comfort index increases, leading to a decrease in comfort and an increase in suspension working space requirement.