The considerable developments happening in the area of chassis will be largely driven by overwhelming focus on driving improved fuel economy, emission reduction, safety and comfort
The longevity and robustness of a vehicle as well as the safety of its occupants is hugely dependant on the vehicle chassis. The growing demand for vehicles to offer a near-perfect blend of power and comfort has prompted OEMs to develop customised chassis systems that can be leveraged across a range of vehicles. This explains why vehicle platforms have evolved over the years with a strong leaning towards modularity.
Essentially, the modular platform is an outcome of three developments happening across the industry – commonising across body styles, sharing among brands and adapting to new manufacturing as well as energy/ propulsion systems, say experts. The larger an OEM is in terms of brands, partners and body styles, the bigger is the challenge to design and develop the right number of modular platforms, like in the case of General Motors, Toyota and Volkswagen.
VEHICLE PLATFORM TRENDS
Going forward, electric platforms will be a big focus area. Many auto majors have either announced or introduced their electric platforms, while some have joined hands to develop them, like Volkswagen’s MEB platform that will be used by Ford. Experts say platforms will have to be designed to accommodate greater space and scope for non-constant items, even as innovations will continue to happen in common architecture, common operating parts, common software and common safety standards.
A well-designed platform can offer a range of options, right from a hatchback to a sedan, MPV and SUV. The key leverage of a platform is to share the development costs over multiple top hats (body styles) that enables quicker ROI and cash needed to develop newer platforms within shorter timespans. Customers will relate to the body style and won’t be concerned about what lies beneath the skin, as long as the body style is distinct and stays true to the personality of the brand, observed Avik Chattopadhyay, Co-Founder & Partner, Expereal.
Arun Malhotra, industry veteran and former Managing Director, Nissan India believes that no OEM can afford to have more than two or three platforms. “Vehicle manufacturers would be better served if they focus on three or four products on each platform. Of course, there can be nothing better than offering the best products of different vehicle segments under one platform, but such an exercise has its challenges, in terms of chassis design and weight,” he pointed out.
Platform flexibility holds the key, insists Malhotra. There shouldn’t be any design limitations for vehicle chassis. A lesser number of platforms will stand OEMs in good stead but these platforms must offer more flexibility and should be able to take more capacity, he said.
The chassis development over the next five years will be driven by various technologies such as connectivity, autonomous or semi-autonomous driving. Stringent mandates on safety, emissions and fuel consumption will ensure the focus of chassis development is on lightweight construction and reducing friction that involves use of newer materials and existing materials with enhanced characteristics in terms of rigidity, strength, and ensuring safety.
Vinay Piparsania, Director – Automotive, Counterpoint Research said the vehicle chassis design is witnessing fast-paced innovations largely dictated by the industry’s focus on fuel economy and safety, among other attributes. “Chassis design-related innovations are aimed at providing improved fuel economy, emission reduction, increased safety, and a better ride handling experience that is prompting companies to adopt new materials and production methodologies to improve strength, durability and NVH. The focus is on adding more electronically-controlled systems, while continuing to innovate for new ways to reduce weight,” he explained.
TYPES OF CHASSIS
The automotive space is largely dominated by the use of monocoque and ladder chassis. Monocoque chassis has been traditionally designed for sedans, hatchbacks and compact SUVs to some extent, while the full-fledged SUV space has been leveraging the ladder chassis for a long period of time – Ford Endeavour and Toyota Fortuner are ladder chassis SUVs that readily come to mind.
However, the SUV space in India is witnessing a steady shift from ladder chassis to monocoque chassis – Tata Harrier and MG Hector are prime examples. The growing trend of SUVs adopting monocoque chassis is nothing but a logical progression. “Most SUVs are purchased for the style quotient and not much for off-roading capabilities, and this is why a monocoque chassis is considered an ideal fit for SUVs. The ladder chassis architecture despite its robust characteristics, have limitations in terms of safety, gross vehicle weight and emissions. The materials used in monocoque platforms ensure equal structural rigidity and enables lower development costs for a SUV model,” elucidated Chattopadhyay.
Does that mean ladder chassis will be a thing of the past? Some carmakers still opt for the traditional ladder frame chassis for some of their models. It is difficult to say if the ladder-frame chassis will ever become obsolete, viewed Piparsania. Vehicle manufacturers will have to strike a balance between weight, cost, and intended function when deciding which type of chassis to incorporate in a vehicle. Each chassis option will have its own advantages and disadvantages, which in turn, will determine the vehicle’s behaviour and character, he said.
VEHICLE COMFORT & RELIABILITY
The ride comfort and reliability of a vehicle is influenced by traffic patterns, driver impatience, driving habits and road quality. The acceleration of a vehicle (driving at different speeds) is dependent on the weight distribution of a vehicle, steering, suspension, wheels, the body type, and systems’ calibration of the vehicle. Given the industry’s focus on carbon footprint and fuel efficiency, these sub-systems have evolved to be lighter, with better-integrated controls and augmented with electronics and software that provide improved flexibility and ride comfort.
In the area of steering systems, the shift from basic manual to electro-hydraulic to electric power assisted has enhanced comfort through lower steering effort, paving the way for reduced driver fatigue, improved driving confidence with better steering response and improved overall manoeuvrability of the vehicle with lower turning radius. Further benefits include improved fuel efficiency through lower energy consumption and enhanced energy management by such advanced steering systems.
There have been considerable advancements in the area of suspension systems as well. Setting-up a suspension traditionally meant mechanically lowering or stiffening the suspension springs and making pre-set adjustments to the suspension struts. But as the industry evolved these settings are moving towards being electronically controlled. Such a control of suspension systems created a scenario, wherein the chassis set-up of vehicles can also be controlled and altered according to driving conditions, making them active chassis systems. Such systems are generally looped in vehicles along with driving modes that control throttle output, transmission control and brake delivery.
It is observed that traditional suspension components like coil springs, struts and suspension arms are being replaced with a number of substitutes, some even with electronically-controllable modules. Further, suspension springs are replaced with airbags, while struts are replaced with electronically-controlled damping systems. The active chassis system features all or a combination of various adjustable suspension systems depending on the vehicle body style, level of luxury and comfort as well as degree of sportiness and control to be offered.
Active chassis system also drives value in offering rear-wheel steering (RWS) feature that provides higher vehicle agility, when it works along with the forward steering and is handy in congested city environment, especially during parking. This RWS, when combined with automated parking systems, also enables vehicles to be parked in tight spots, which is otherwise not possible. On the safety front, the RWS is also programmed to work along with advanced driving assistance systems (ADAS). When a vehicle’s ADAS senses an upcoming obstacle or situation, it can actuate the RWS to help the vehicle overcome that situation without any issue.
There is also focus on use of new-age materials to reduce vehicle weight besides the obvious objective to improve fuel economy. These new-age materials offer several advantages – they can be manufactured adopting sustainable methods and environmentally-friendly processes with a lower carbon footprint.
A vehicle’s success is determined by its driving and riding comfort as well as safety. Going forward, the automotive industry will witness considerable developments in the areas of chassis all focussed towards improved fuel economy, emission reduction, enhanced vehicle safety, comfort among others.
TEXT: Suhrid Barua