August 12, 2004
Plastic car panels on the horizon
Ordinary plastics, reinforced with knitted fibres like carbon and glass, could be used to make aircraft parts and car
body panels, according to a University of Auckland PhD student.
The study by Faculty of Engineering student and part-time lecturer, Miro Duhovic, shows that when stiff and strong
fibres are knitted into fabric and combined with plastic, the result is a material, which can produce complicated parts
with high stiffness and strength.
Entitled, "Knitted Composite Forming", the idea behind the study was to better understand the behaviour of materials
like plastic, when reinforced with knitted fibres.
Composites are a combination of two or more dissimilar materials whose combined properties are better than the sum of
the two.
Engineers found long ago that reinforcing plastic with fibres produces a material that is stronger than either the fibre
or the plastic alone.
"Even in ancient times, straw was used to reinforce clay to make bricks. Today the types of reinforcement are becoming
quite complicated," says the Onehunga resident.
Based within the University's Centre for Advanced Composite Materials, Miro's research has found that by knitting the
fibres of materials such as carbon and glass the composite material produced is of much better quality. In fact the
quality is so good that Miro says it can easily be used for aircraft parts, which require strong but light materials.
"Knitted fabric composites are produced using an economically viable industrial process of knitting. Knitting machinery
has evolved to the point where entire garments or parts can be produced seamlessly," says Miro.
This means that any three-dimensional shape can be produced straight off the knitting machine.
"Basically I take a sheet of plastic and combine this with 'knitted' glass or carbon fibres. The sheet can then be taken
and moulded into any shape or form."
Miro says he aims to understand enough about the materials to predict their forming behaviour and avoid the costly trial
and error process during manufacturing.
While the techniques Miro has employed in his study are not new, his research is unique in that it looks at a particular
type of plastic, fibre, and knitted structure - there are many combinations of fibres which can be used but all yield
different results.
Knitted fabric composites offer many advantages in a diverse range of applications from lighter and more impact
resistant aircraft and car components such as dashboards, bumpers and body panels, to high performance sporting goods
such as snowboards and protective armour.
Miro, who is studying on a Faculty of Engineering Doctoral Scholarship, says he enjoys engineering because it spans
everything from designing to actually making parts.
"I like engineering because it is challenging. You can practically design anything you like from a car to a bridge and
more, there are no limitations. But you need to ensure that what you design can actually work," says Miro.
A former student of St Peters College in Epsom, who enjoyed design at school, Miro says he has thoroughly enjoyed
mechanical engineering.
In the final year of his Bachelor of Engineering degree, Miro worked on a project which involved the design and
manufacture of a composite wheelchair.
"I really enjoyed that process and decided to explore more in the area of composite materials. It is an interesting
process, as you try and compromise between the complexity of the new material and its strength."
ENDS