Comparative Study of a Flexible and Rigid Two Degree of Freedom Half Car Model

Ride quality is concerned with the feel of the passenger in the environment of a moving vehicle. It is one of the key indices in determining comfort levels of a vehicle. Although, “ride comfort” evaluation is subjective in nature, researchers have developed mathematical models to study and evaluate vehicle ride performance. Some popular models for vehicle ride analysis are – quarter car model, two dof (degree of freedom) and four dof half car model. These models model the chassis as a rigid body. This work removes this assumption and models the chassis of the vehicle as a flexible beam on a spring damper system at the front and rear using Euler beam theory. This elastic model has two dof – vehicle bounce and pitch, and has been compared with the rigid two dof model. Euler beam theory and Lagrangian mechanics are used to derive the equations of motion. Finite element method is used to validate this model. Experimental validation of the natural frequencies of this flexible beam is presented.