The chassis or architecture on which a vehicle is based on is its very foundation, and this is a component that has see tremendous development and innovation over the decades
Any vehicle, be it two, three or four-wheelers, or for that matter even an off-highway vehicle or farm equipment all require certain basic components to function. The driveline is what makes a vehicle move and stop, the bodywork, exteriors, interiors, electronics and safety systems provide functionalities of their own. However, all these parts and components need to be placed on a frame or require to be held together strongly, for which the chassis is the base. There may be multiple types of chassis, such as ladder-on-frame, monocoque, space or hybrid, but they all perform the same role of providing the platform for all other components of a vehicle to be assembled on.
According to a report released by Inkwood Research, the automotive chassis systems market is expected to register CAGR of 4.60 % over the 2019-2027 period and is expected to reach a revenue of $ 114.575 bn by 2027. The research firm said the global automotive chassis systems market is driven by advancements in technology, growth in demand for low-emission automobiles, increasing demand for vehicles and financial flexibility for automobile purchase. The report also revealed that control arms are the majorly-used components of the automotive chassis system, with active kinematics control emerging as the fastest-growing chassis system.
The growth in demand for low-emission automobiles is considered the primary driver for the growth of the global automotive chassis systems market, since emissions and fuel consumption of a vehicle are directly proportional to the vehicle weight, noted Inkwood Research. The production of vehicles with lightweight chassis systems is expected to reduce vehicle weight, which has prompted various automotive design and engineering companies to line up plans to manufacture lighter and sturdy chassis. On the flip side, the market growth of this segment is restricted by the cost of these systems, with suppliers coming under high pressure to maintain costs, while maintaining the quality of these materials to meet stringent quality control, the report noted.
The chassis in its primitive form was a metal frame that consisted of cross bars that enabled the placement of the vehicle body along with other components such as the engine, transmission, axle, wheels and bumpers. However, the role of the chassis has transformed over time, especially with regards to safety systems and related electronics. From being an unconnected, separate component on a vehicle, the chassis now plays a significant role in enabling advanced driver assistance systems (ADAS) that eventually lead to autonomous driving vehicles. Adaptive chassis technologies are a major part of active safety systems in ensuring balance between safety and comfort, while operating a vehicle.
Modular systems that pack together multiple components into a package are a growing trend in the automotive industry. Such modules enable vehicles to become compact in terms of overall size, while also making them more efficient with regards to performance. This phenomenon has also been implemented around chassis systems, where complementing components of suspension, braking and drivetrain are clubbed into a single package to bring about expected benefits. Another form of modular chassis systems is where a single chassis can be modified to accommodate the development of different types of vehicle body styles in a few steps. A major advantage of such modular chassis designs is that they enable design alterations easily and reduce the time to market for new models.
A good example of advanced electronic systems-based chassis system is that of Integral Chassis Control (ICC) that has been developed by ZF. The ICC technology connects individual chassis systems to enable enhanced driving dynamics and achieves the goal of improving the driving experience to become more experiential, engaging and safe by connecting electronically-controlled components such as steering, suspension and braking systems.
Another technology worth mentioning is the Electromechanical Roll Control system, which uses a 48 V electric motor that is installed on the axle to offset vehicle roll motion in a short period of time. This system results in reduced body roll that can enhance cornering capabilities and improve ride quality on bad roads. Similarly, other electro-hydraulic levelling technologies use actuators to alter ride height, and make it easier for low-slung vehicles to overcome obstacles on the road.
MATERIALS OF CHOICE
Since the chassis is equated to the backbone of a human being, the importance of its strength and performance cannot be implied enough. This has always required the chassis to be one of the most robust components in any type of vehicle body. It should also be noted that the chassis is one of the most voluminous part of a vehicle, naturally meaning that it carries a lot of weight. There has been transition in the material used to make vehicle chassis over time, and this research continues to be carried out continuously.
In earlier times, the chassis of a vehicle was made of iron, due to the ideal characteristics of being strong and robust. However, the reaction of iron to collisions and impacts was not safe for vehicle occupants of four-wheelers, which then made the industry move towards high-strength steel for chassis manufacturing. This material offers improved crash worthiness, while increasing the level of safety of occupants. Even in two-wheelers, the use of steel in manufacturing chassis has been the norm as a result of the benefits offered by the metal in terms of strength, durability as well as cost.
Moving ahead, the material of choice for chassis and body structure construction on a wider scale has been aluminium. The use of aluminium results in decreasing the weight of the vehicle, and this feature combined with the metal’s high specific energy absorption and precise strength make it optimum for usage in various vehicle chassis systems. Another additional feature of aluminium is that it is corrosion-resistant, which also makes it a material of choice for the automotive industry. On the down side, the repair of aluminium is a tedious process, with certain repair processes not being able to be carried out at all. This is the limitation that aluminium has, but even then it is increasingly being adopted for construction of chassis and body structures, which can result in up to 20-30 % reduction in the total vehicle weight.
A material that has been in use for construction of various components to increase the strength exponentially, while reducing weight is carbon fibre. However, this material has been limited to sports vehicles, and has trickled into the top-most segment of luxury vehicles. The extremely high cost of carbon fibre manufacturing can be attributed as the reason for its limited usage as a material for constructing components such as chassis. However, it is also a material that manufacturers look to in case of extreme requirements.
INTO THE FUTURE
There is a growing demand for high performing chassis, wherein the mechanical features of the chassis are still intact, along with the addition of mechatronic systems. These electromechanical systems enable features like road stabilisation, braking and vehicle stability control. There is also a trend where the power source of these electromechanical systems on the chassis is provided by an electric motor, rather than the existing engine in the vehicle. This perspective is in line with making future chassis systems environmentally-friendly, while also making them connected and intelligent. These features also enable the chassis of the future to become easily adaptable with safety systems required for autonomous driving.
The increased level of electronics into chassis systems also enables them to offer customised functions that can be used to offer convenience for vehicle occupants. From lowering a bus to allow passengers to enter and exit, to increasing a car’s ground clearance to pass through a rough patch, and enhancing traction in a motorcycle, the mechatronic interventions in chassis systems play an important role in enabling a comfortable drive/ride combined with a high level of safety.
Therefore, the chassis is no longer an independent component of an automotive, rather a key part of the overall vehicle system that enhances multiple features. The areas that chassis systems cover include safety, convenience, driving dynamics and even cleaner mobility. Further, such trends of integrated systems in vehicles will be the direction of future mobility that will eventually look at being completely autonomous in nature.
(Inputs from Continental, Inkwood Research, ZF)
TEXT: Naveen Arul