Another sought-after material for the industry may also be utilized with this optimization workflow.
Recycled plastic isn’t a material often considered for use in the automotive industry—especially for any part that is expected to handle a load or dissipate an impact. Due to the wide array of plastics materials that enter a recycling facility, it’s hard to perfectly sort the used materials based on their makeup and mechanical properties. According to Kevin Lindsey, Director at Far-UK, a niche automotive part manufacturer, the result is “a residual mass of mixed plastics [that] is currently fit only for landfill.”
To change the narrative on recycled plastics, Far-UK teamed up with the testing and innovation center Impact Solutions, sustainability and plastics recycling organization Impact Recycling, and the prominent simulation company Ansys. The result was the Plastic Recycling in Stochastic Modeling (PRISM) Project which Lindsey says aims “to design with this mixed material.” Along the way, the team discovered that this technology could also open the door to another important material for the automotive sector.
Why It’s Rare to Use Recycled Plastics in Automotive Settings
Recycled plastic is very dependent on what went into the mix. As a result, there is no guarantee what the finished product would look like—let alone the mechanical properties it might have. This severely limits the applications of the material as it isn’t aesthetically pleasing enough to be used on the outside and it is hard to predict its performance in structural use cases.
“We always knew that it would be difficult to design with a material that has a varying set of mechanical properties from batch to batch,” says Lindsey. “Since the beginning of the industrial revolution, it has been the work of generations of engineers to try and make our materials more predictable within ever narrowing specifications. At the same time, other engineers have been toiling away to design better and better machines and those developments usually require input materials to be increasingly consistent.”
It’s common in the automotive industry to make parts lighter to increase mileage and reduce environmental impacts. But that’s hard to do with a variable material while still meeting appropriate safety factors. To hit that safety limit, and use the material, would require bigger, bulkier and overengineered designs.
How to Design Automotive Parts Out of Recycled Plastics
To combat the dilemma of designing automotive parts with variable, recycled materials, the PRISM Project utilized Ansys Granta MI, Ansys SpaceClaim, Ansys optiSLang and Ansys LS-DYNA. By combining these technologies together, the team produced a workflow that could design high-quality parts with variable stating materials.
Essentially, LS-DYNA was used to create the material card based on test data. That materials data was then stored in Granta MI. Far-UK validated and tested the materials data using test coupons and subcomponent geometries. Next, optiSLang was used to automate a workflow between SpaceClaim and LS-DYNA to simulate the performance based on various part geometries and materials properties until optimal parts were produced.
The workflow was tested to produce a honeycomb part that could live behind a car bumper to absorb and disperse the energy from a crash. The optimization cycle produced by PRISM reduced the mass of the part while minimizing displacement and maximizing the accumulated impact energy.
In essence, a lightweight optimal part was designed to meet the property and geometry tolerances of the OEM without virgin plastics. “We have now demonstrated that it is possible to reverse that [virgin plastics] thinking and to design with raw material variability in mind,” says Lindsey.
An Unexpected Benefit From PRISM: Using Natural Fibers in Composites
Though the added use of recycled materials in the automotive industry is a boon in itself, Lindsey suggests that this research might actually be a breakthrough for another important material for the industry: composites.
“For years the composites industry has struggled to adopt natural fibers and has followed the traditional approach of making the fibers more and more consistent by adding more and more expensive processing of the fibers once they have been harvested,” says Lindsey. “The result being that natural fibers struggle to get adopted because the weight benefits and cost penalties don’t add up.”
This is where the PRISM optimization process can come into play. It doesn’t have to be limited to just recycled plastics; any material with variable properties can utilize the workflow.
“What we have realized is that this is actually the same problem,” adds Lindsey. “From the viewpoint of PRISM, we have the tools and techniques to use natural fibers in their more natural form, that is to say with more variability and less processing. At Far-UK we feel this may be the biggest win from PRISM, which is now where our work is taking us.”
Are Recycled Parts the Future of the Automotive Industry?
Just because the PRISM process has come up with a good proof of concept, doesn’t mean that the automotive industry will utilize more recycled plastics or natural fibers in its product designs.
“There is still some work to be done to achieve higher levels of OEM adoption,” says Lindsey. “While it isn’t possible to ‘name names’ in an industry where secrecy over future designs is inevitably tight, it is possible to draw some broad pictures. The strongest progress to adoption of components designed using the techniques from PRISM has been in the niche vehicle and new entrant communities. Our customers in these segments tend to be early adopters of such new materials and approaches. Inevitably the larger OEMs tend to have a more elaborate R&D infrastructure which tends to deliver innovations with a more staged and internal approach.”
As more niche manufacturers utilize this technology, the more likely the big names in the automotive industry will catch up—by either adopting the workflow or creating their own. But there are ways to help speed up the process using similar incentives and regulations moving the automotive industry towards zero-emissions vehicles.
“The existence of landfill taxes is a good incentive,” suggests Lindsey. “It creates a financial incentive to find a use for these materials and with better design techniques this should create viable business models for the adoption of materials based on the PRISM project.”
