The longevity and robustness of automobiles and the long-term wellbeing of its occupants is dependent mainly on the chassis of a vehicle. In the last decade, on an average the time spent in commuting has gone up between 20 to 40 % on inner city roads and expressways. The traffic patterns, impatience of drivers, driving habits, and the quality of roads influences ride comfort and reliability of a vehicle.
The ‘g-levels’ of acceleration passed on to the driver and occupants at different driving speeds is dependent on the weight distribution of vehicle, steering, suspension, wheels, the body type and systems’ calibration of the vehicle. With an emphasis on low carbon footprint and better fuel efficiency, these sub-systems have evolved to become lighter, have better integrated controls with increased electronics and software that provides good flexibility and ride comfort.
Innovations in steering systems from the basic manual to electro-hydraulic to electric power assist have enhanced comfort through lower steering effort, resulting in reduced driver fatigue, improved driving confidence due to better steering response and better manoeuvrability of the vehicle that reduces turning radius. The lower energy consumption and better energy management of steering systems have contributed towards better fuel efficiency.
Suspension systems play a primary role as they are the conduit to transferring road disturbances and loads to the occupants in a vehicle. Over the years, advances in technology have changed suspension systems from the basic spring and damper systems to electronically controlled dampers, active sensing systems, changing of the fluids inside the dampers that are nano-particle impregnated and controlled magnetically or electronically for dynamic damping, and the capability to change the stiffness and ride-comfort real-time by the driver, when a vehicle is being driven on-road or off-road. This flexibility in the suspension, either an active, passive and semi-active, enhances the adaptability of the chassis with body in white options, which in turn affects styling options, types of powertrain, manufacturability costs and overall carbon footprint and fuel efficiency of the vehicle.
The chassis forms the foundation of a vehicle that holds it all together. This contributes between 21 and 33 % of the weight of a vehicle. From the simple tubular frames in the early automotive days, it changed to sub-frames and inverted I-beams to modular and concentric honey-comb structures using composites and advanced materials that are huge weight-savers. The joining techniques and virtual engineering tools and processes have opened avenues in lightweighting and opportunity for different vehicle architectures with a multitude of powertrain options. Other components, including the axles, brakes, wheels and tyres, employ a diversity of materials that also have well-established performance requirements and manufacturing infrastructure.
The gap to achieve better fuel efficiency and reducing weight is due to inadequate manufacturing capacity that can produce high-integrity components. Though advanced lightweight materials can result in 10 to 70 % weight reduction, the lack of robust joining processes, especially between different types of materials, are yet to be developed for mass manufacturing at an affordable cost.
Chassis and the related systems have developed significantly to provide enough flexibility in vehicle design, manufacturing and powertrains. With the ever increasing demand for lighter weight systems and with the growth in innovations in different materials of the chassis, low carbon footprint and better fuel efficiency are better achieved today. The measure of success of a vehicle is determined intrinsically by the driving and riding comfort and its safety. For successful global deployment of vehicles, it is becoming an imperative to have real-time adaptive chassis systems that have plug-in modules suited for target markets and terrains for a long-term sustainability.