Fluid bumpers cut injuries

Bumpers that use shock-absorbing liquid technology to lessen injuries suffered by pedestrians hit by cars is under development.

Researchers at Manchester University believe the impact-dispersal characteristics of Shock-Absorbing Liquid (Sali) could produce bumpers that give if they hit people, yet remain rigid when they strike another vehicle.

Sali will be tested as an alternative to conventional materials such as plastic and rubber in a three-year project backed by the Department of Transport and Dow Automotive, a subsidiary of Dow Chemical.

Sali is made by combining small elastomeric capsules such as polystyrene beads with a matrix composed of liquid or grease.

Manchester University research fellow Bill Courtney said the mixture acquires unique impact-dispersal characteristics when it is enclosed within a tight-fitting package made from a suitably robust material.

Courtney – who first developed Sali in 1997 – claimed the technology could offer a solution to a major dilemma facing vehicle manufacturers.

From 2005 new EU regulations on pedestrian protection will require vehicles to meet strict impact protection criteria at speeds of 40km/h.

These include reducing the potential damage caused by collision with a car’s bumper, bonnet edge and wing.

Courtney said the problem for manufacturers is that simply replacing existing bumpers with those made from softer foam materials is impractical.

‘That would be fine for protecting the legs of pedestrians, but no good for cushioning the vehicle itself during the type of low-speed bumper-to-bumper accidents that regularly happen at traffic lights,’ said Courtney. ‘You would end up with lots of damaged cars, and insurance costs would go through the roof.’

According to Courtney, Sali could solve the problem because of the unusual way it deals with impacts. This would allow the material inside a Sali bumper to move to each side when it comes into contact with an object such as a pedestrian’s leg. When hit by a similarly shaped bumper, however, the material would not disperse but remain stiff, giving the vehicle sufficient protection in a collision.

‘You could describe it as a smart material because it reacts differently to different types of impact,’ said Courtney. ‘It solves the conflict of stiffness problem that you get with other materials.’

The team at Manchester University’s school of engineering is developing Sali formulations that are suitable to be used in vehicle-impact protection.These will then be handed to Dow Automotive which will create prototypes for full-scale testing.

Courtney said Sali-based bumpers would need to operate effectively in the wide range of temperatures encountered by European motorists, and remain stable enough for long-term use.

He claimed Sali could offer significant environmental benefits because it is easily recyclable.

Vehicle protection is one of a range of applications for which Courtney believes Sali could be suitable. He said early research suggested it was highly effective at dispersing the force of an explosion, raising the prospect of new types of blast shields.

Courtney’s company, Altrincham-based Cheshire Innovation, also hopes to develop crash helmets and protective clothing based on the technology.

Sidebar: Improve pedestrian safety, car manufacturers told

Car makers are likely to face renewed pressure to improve their record on pedestrian safety after crash tests on a range of leading models produced damning results.

Automotive research body Euro NCAP said its latest assessment showed virtually no progress in making cars less dangerous for pedestrians or cyclists.

State-of-the-art vehicles such as the new Mini and Jaguar X-Type scored well on a series of tests for occupant safety.

But when it came to measures for pedestrian protection the Mini was described as ‘poor’ while the X-Type was condemned outright by Euro NCAP for its ‘dire performance’.’The Ford subsidiary was told it needs to raise its game ‘in this vital area’.

Only Honda, which has invested heavily in pedestrian safety features since the 1990s, scored reasonably well. The Honda CRV achieved a three-star rating, the highest in the group, with a range of features for pedestrian safety designed into its front end.

Euro NCAP said it wanted to see more manufacturers follow Honda’s lead by considering the well-being of other road users in the original engineering design of new models.