IRONING OUT THE BUMPS
BVT Surface Fleet
Ships are put together by welding and have been for many years now. However, there’s a drawback to this technique — welding requires heat, and when heating a sheet of metal, it tends to buckle. This can be tackled after it happens, but reworking buckled metal is a timeconsuming and costly process. Looking for a way to avoid this problem, BVT Surface Fleet teamed up with researchers from the universities of Strathclyde, Newcastle and Malta to find a way to keep heat down.
The collaboration examined the effects of heat on steel plate, with Strathclyde using a thermomechanical finite element model, while Newcastle used an artificial neural network approach; neural networks have never been applied to a distortion problem before, said BVT. The FEM team examined the effects of the thermal and mechanical aspects of the distortion separately — also a novel approach.
The goal of these studies was to minimise or eliminate design issues that introduced unnecessary heat into the structures to be welded. Using its new techniques to reduce heating to build a destroyer for the Royal Navy, BVT used 15,000 man hours to rework distorted steel sheets, whereas previous techniques would have taken 59,000 man hours. This was a reduction in the rework rate from 25 man hours per tonne of steel to five man hours per tonne.
A TWO-STROKE/FOUR-STROKE SWITCHING ENGINE
Ricardo, Denso, Jaguar Land Rover and University of Brighton
An engine capable of switching between two-stroke and fourstroke cycles is the result of a
collaboration between some of the biggest names in the UK automotive sector — Ricardo, Denso and Jaguar Land Rover — and the Centre for Automotive Engineering at the University of Brighton. The engine could improve fuel economy by up to 25 per cent and will be used in a Jaguar demonstration vehicle next year.
The project, aimed at engines for passenger cars, was one of the Technology Strategy Board’s 12 key strategies for low-carbon transportation and brings technology from motorsport into the production car sector. For the past century, two-stroke and four-stroke engines have been separate entities with different applications: four-stroke engines, after decades of refinement, are now fuel-efficient and produce emissions close to their theoretical limit, but they have a lower power-to-weight ratio than two-stroke engines. However, these have a reputation for being noisy and smoky.
The new engine can switch between modes to give it the advantage of both types of engine. Individually controlled poppet valves regulate the flo of petrol, air and water through the engine, allowing the two- and four-stroke engines to operate with their very different demands for fuel injection, air motion and mixing. The power boost obtained from the dual-mode operation enables the engine to be downsized, thus reducing the fuel needed to generate the car’s performance. According to the researchers, the engine is ‘on a par’ with a hybrid power plant in terms of fuel economy and emissions.
500NM MODULAR YASA MOTOR
Delta Motorsport & University of Oxford
Electric cars are developing fast, and the motors that drive them are becoming more specialised and refined. It is becoming apparent that the most important parameters for an automotive electric motor are low weight and high torque. Professor Malcom McCulloch of Oxford University has been in the
vanguard of electric automotive development, working on projects such as Morgan’s LIFEcar concept. Delta Motorsport called on his expertise to design a motor for a new lightweight four-seater passenger car.
McCulloch’s team came up with a new design for the motor’s electromagnets, using sintered metal powders to build up a novel topology, known as a YASA (yokeless and segmented armature) motor. This can be broken down into simple subassemblies that can be assembled on a production line, and has a direct liquid-cooled stator, allowing it to be run close to its peak torque capacity for long periods.
Delta, meanwhile, contributed mechanical design know-how, such as a bearing arrangement that allowed several motors to be ‘stacked’ together to increase torque output.
A 25kg motor generates 500Nm of torque, enough to drive the car directly, without a step-down gearbox. But stacking could provide enough power even for a high-performance vehicle, with 1000 or 1500Nm torque per wheel. Delta’s bearing design has also cut the number of components in the engine, as well as the size, weight and engineering tolerances of those components, reducing weight and cost.