Portale di Ateneo - En.Unibs.it

VEHICLE MECHANICS

Aim of the course. The course is an introduction to modelling and design of the chassis of a road vehicle, where “chassis” means the assembly of driveline, braking system, suspension as well as the tyres. In detail both the phases of vehicle behaviour analysis (in terms of active safety, driveability, and comfort) and design are undertaken.
The course is composed of lectures as well as workshops with the help of self-developed and commercial software packages. The final part of the course is mostly focused on racing cars as a reference case study.

The vehicle system
The vehicle-user interface. Driving systems: driveline, steering, brakes, suspension, tyres. User appreciation: active safety, driveability, comfort. Reference systems.

Aerodynamics
Aerodynamic forces on the vehicle. Aerodynamic resistance and lift. Internal aerodynamics.

Ride
Road profile characterization. Vehicle modelling: quarter car model. The targets: comfort, tyre vertical force, working space. Dampers. Half car model.

The tyre
Introduction to the structure of the pneumatic tyre. Longitudinal slip. Slip angle. Self-aligning moment. Linear and non-linear models. Pacejka’s Magic Formulae. Test systems.

Performance
Performance evaluation and user appreciation. Top speed and acceleration. Gear ratios. Fuel consumption: driving cycles. Braking.

Handling
Understeer and oversteer. Steering pad and understeer characteristics. Bike model. Load transfer. The transient behaviour: step steer. Frequency response.

Suspension and steering systems
Suspension layouts. Typical parameters and their effects. The roll centre. Anti-dive systems. Elastic mountings. Multi-link systems. Steering geometry.

Driveline systems
Typical layout. Front and rear wheel drive. All wheel drive. The gearbox: synchromesh. Self-locking differentials and their effects.