E-Mobility Engineering 016 l Aurora Powertrains eSled dossier l In Conversation: Thomas de Lange l Automated manufacturing focus l Torque sensing insight l Battery Show Europe 2022 report l Sodium batteries insight l User interfaces focus

The advantage of then making the spokes from metal (with forged aluminium and forged magnesium being the commercially available options at present) comes from the fact that carbon fibre works best structurally when under tension – indeed, the lay-up is designed so that the fibres are being ‘pulled’ as much as possible when the wheel is at rest. Whenever a wheel hits an uneven part of a road, the wheel is compressed, meaning carbon spokes would lose tension in many circumstances, making them unsuitable for use as such. “You could still use carbon if you made the spokes really thick, but sadly that’s really not what EV designers and customers want visually, even though many EVs hide their spokes with big, flat surfaces to enhance aerodynamics,” de Lange says. “Metallic spokes provide great support under compression, as we’ve proven through every automotive standard testing regimen, and they’re more than flexible enough to manufacture with the looks designers want.” Inside each carbon rim is a mounting flange (also carbon) for installing the spokes, which can be moved to accept different offsets, such as for wide-body vehicles or resto-modded Porsche 911s. In Dymag’s BX-F product for example, the flange is a separately installed part, while in the BX-E the flange is integral to the rim. Titanium or steel fasteners are used for securing the spokes to the flanges, with steel threaded inserts and washers to seal the bolts. This relates to the next key differentiator between Dymag’s wheels and conventional ones. The primary load path of Dymag’s rims goes under the bead seat, where the outer section of the tyre would sit, with foam filling the gap between the load path and bead seat. In 2016, the company’s researchers found that most of a tyre’s loading in road conditions will be transmitted laterally, into the outer wheel flange section of a conventional wheel, creating severe stress in the tyre well. “That is what typically causes a wheel to fail: you develop microcracks over time, and the failure mode is a slow puncture,” de Lange explains. “By transmitting the loads under the bead seat through our patented structure, we avoid concentrating stress in the tyre well, making our wheels not only more fatigue-resistant but also more impact-resistant and stiff. “We’ve run tests for hard radial impacts from potholes, kerb strikes and other shocks, and we’ve carbon fibre rim with a metallic centre, a combination that provides numerous advantages over the traditional typically 100%-cast aluminium wheel, the foremost of which is reducing the car’s unsprung mass. While lightweight materials are naturally applied with weight reduction as the primary goal, whether in motorsport or automotive applications, de Lange notes that what really counts when it comes to wheels is not weight but inertia. “Road vehicles run on these big, spinning cylinders, and their inertia is proportional to their radii, so any mass that’s further from the centre of the wheel will add more to its inertia,” he explains. “So by making the rim from carbon, you save mass on the part that has the biggest effect on inertia. “That’s what you’re trying to control with your suspension. It’s what affects the range of the vehicle, not to mention directionally similar effects on acceleration, feel, handling and other related qualities.” Thomas de Lange Thomas de Lange was born in 1977, in Rustington, West Sussex and attended the University of Southampton in 1995 while simultaneously interning with Penske Racing, achieving his MEng degree in Aerospace Engineering in 1999. That same year he joined Penske full-time as an aerodynamicist, becoming the US racing group’s lead aerodynamicist 3 years later. During his time in that position the team achieved 32 race wins, including four Indy 500 victories (2001 3 and 2006), after which he was a senior aerodynamicist at the Renault Formula One team for 2.5 years before rejoining Penske as head of aerodynamics at its NASCAR team for just over 4.5 years, culminating in Penske’s irst NASCAR championship victory in 2012. After that, following about 6 years at Dyson, he joined Dymag as its COO, becoming its managing director after 9 months and then CEO a year later, a position he has held for nearly 2 years. In addition to being made mostly from carbon, the wheels transmit shocks in a way that gives them greater longevity over conventional wheels Winter 2022 | E-Mobility Engineering 17 InConversation | Thomas de Lange