E-Mobility Engineering 019 | In conversation: Stephen Lambert l WAE EVR l Battery case materials focus l Quality control insight l Clipper Automotive Clipper Cab digest l Optimising battery chemistries insight l Powertrain testing focus

26 May/June 2023 | E-Mobility Engineering Metal components “The carbon tub is cut off at the belt line, just at the bottom of the A-pillars and B-pillars, and from there we’ve opted to go with a metallic upper structure,” McCaw says. “There’s a metallic roll cage, which allows us a certain flexibility regarding door closures, both for when customers want something conventional like a gull- wing design or something different, like a dihedral design,” he says. “The hinge location and where the door seal runs is of course fairly flexible since we haven’t tooled it into the fundamental carbon moulding of the structure.” The front and rear structures (forward and aft of the central composite tub) are also metallic, again to allow redesigns, ordering or cutting of new structural architectures – particularly for new wheelbase and track concepts – without needing to resort to the expense of newmoulds for the carbon. It also means that new side parts such as metal castings can be easily added. McCaw says, “It’s always interesting withmulti-material structures like this when you’re couplingmetals with composites and trying to get them to work. For instance, they typically have different rates of thermal expansion and contraction, and they can suffer galvanic corrosion as the carbon reacts electrolytically with certainmetals. Those kinds of problems need to be considered with every simulation, every iteration –we can’t just bolt ametal front end onto a carbon tub and hope for the best. “First, the tub needs metallic inserts that we bolt through to. Then, on top of that, those metal parts need to be either coated in glass before they’ve been bonded onto the carbon, or if they’re aluminium parts then we need to add an appropriate coating to change the electrical differential between the carbon and metallic parts.” Most of the metal parts are indeed aluminium for high strength-to-weight, although a significant proportion are also made from steels, particularly high-strength steels, as they can offer advantages such as better predictability and hence control of how structures will deform and collapse in response to impacts. The metallic crash tube structures extending from the front of the chassis are likely to be application-specific, and developed in the final stages of each EVR platform’s customisation, when the customer is expected to install their own bodywork. At that point, WAE will carry out detailed crash analyses through simulated and physical crash tests to see not just how the crash tubes crumple but also what contribution the body makes to the deformations. This can then inform steps for re- engineering, for example by identifying where strength and resilience might be removed from the crush structure or the underlying platform, in order to take out as much weight as possible while still maintaining levels of performance and safety for the customer. “And outside of the carbon and metal parts discussed so far, the chassis components themselves can be anything, from quite conventional coil-over dampers to an active air suspension,” McCaw says. “One thing we’ve tried to do at the rear, which is quite unique from a chassis suspension perspective, is to orient the dampers down the side of the vehicle rather than vertically or across the car, again just to give us that flexibility of extra powertrain or battery pack space at the rear. “Initially we thought we’d just put more packs in there, but we’ve since shown variations of the EVR where we’ve got our hydrogen range Dossier | WAE EVR Unlike most skateboards, the EVR’s battery pack is behind the seats, enabling a lower seating position more typical of high-performance sportscars