Friday, 23 April 2021
Researchers from the universities of Ghent and Oxford have discovered a new process for manufacturing shock absorbers that are not only more effective in their purpose but which have a longer effective lifetime.
The shock absorbers have two active ingredients, as it were: blocks made of material with tiny, water-resistant pores known as nanopores, and water. When a shock occurs, it forces the water into the pores, thereby absorbing the impact.
Afterwards, the blocks reject the water back into the surroundings, and the shock absorber goes back to normal, ready for a new shock.
In existing shock absorbers, once they have been subject to a shock once, they become deformed and less able to perform their function correctly. Manufacturers of cycle helmet, for example, advise renewing the helmet after a collision, as the original level of protection can no longer be guaranteed.
By contrast, the nanopore system not only performs well time after time, it even gets better, as the tiny pores expand with the shock and are able to absorb the water even better.
Researchers from Oxford discovered the nanoporous material known as ZIF-8 and wanted to find out why it was such an efficient shock absorber, so they turned to colleagues at the Centre for Molecular Modelling at Ghent University, who then carried out a variety of simulations based on quantum mechanics.
That led to the discovery that the water that surrounds the material is unable to get inside the pores in normal circumstances because they are too small, but that it can do so under certain levels of force.
The team was then able to draw up a set of rules on the ideal composition of the actual shock absorber: water-resistant pores to keep the surrounding water from entering spontaneously; pores in a network so that water may pass from one to the other; and pores large enough to receive enough water to be effective.
“Based on these design rules, we discovered about twenty materials that are currently not yet used as shock absorbers, but would actually be extremely suitable,” said researcher Aran Lamaire of Ghent University. “Some of those materials are now also being effectively tested experimentally, with very positive results.”
The Brussels Times