“This is typical of a new generation of legislation that seeks to be more pertinent to how the vehicle is used by mandating standards for the vehicle’s usage pattern rather than for a standard drivecycle,” explains Bryan. “Vibration dose is particularly important for the military because drivers can potentially spend long periods behind the wheel of vehicles that may have relatively poor Noise, Vibration and Harshness (NVH) characteristics.”

There is however a question over how the vehicle’s typical usage is defined. “What is a typical working day and what quality of surfaces will it pass over,” says Millbrook’s vibration project manager Jim Clarke. “If it is working in a desert, for example, what proportion will be over smooth loose surfaces such as sand and how much will be over rough rock surfaces? Will the engine be running at speed when the vehicle is stationary, for example to operate a power take-off?” It’s not just through compassion that the MoD is interested in these questions. A healthy soldier with low physical stress is also a more effective soldier.

To measure the vibration dose created by these conditions, Millbrook has invested in a new generation of highly integrated test and analysis equipment. The data recorder can accommodate triaxial accelerometers on the seat backrest, at the seat base (embedded in a seat pad)

and at the foot position for many seats simultaneously. It is also small and light so that it can be easily mounted in the vehicle without affecting the results of these or any parallel tests. Fitted with this system, vehicles are driven along a carefully controlled route through Millbrook’s outstanding track and off-road facilities, which simulate virtually any usage pattern worldwide. The drive cycle simulates real usage, in the field, so that the test engineers can be confident they are measuring the vibration (and optionally, noise) that soldiers will experience in their daily activities. Using these techniques, Millbrook has already assessed forty five different military vehicles and vehicle / trailer combinations, taking around half the time typically required for the test procedure.

“We would like military vehicle engineers to bring us their problems and challenge us to solve them,” concludes Bryan. “Tell us what your objectives are – to increase capability, to improve cab refinement or to validate a new drivetrain, for example – and we will use our 30 plus years of vehicle engineering experience to propose a fast, cost-effective solution.”