Metallics and composites bond to form hybrid anti-roll bar

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A collaboration has led to the development of a high-performance anti-roll bar for trucks and trains that is 30 per cent lighter than those currently on the market. 

anti-roll bar
The University of Sheffield AMRC worked with Tinsley Bridge and Performance Engineered Solutions to create a lighter alternative to the tubular steel bar currently used for suspension units (Image: AMRC)

The AMRC Composite Centre worked with Sheffield-based Tinsley Bridge and Performance Engineered Solutions, in Rotherham, on the Lightweight Metal Composite Hybrid (LiMeCH) project which, with £400,000 in funding from Innovate UK, created a lighter alternative to the tubular steel bar currently used for suspension units.

“Lightweighting is top of the agenda for our customers,” said Russell Crow, director of engineering at Tinsley Bridge. “That is even more so when they are looking at alternative propulsion systems, such as electric drive trains and alternative fuels, because every gram they can save offsets the additional mass they have to carry for the batteries or hydrogen fuel tank.”

In the two-year LiMeCH project, the consortium aimed to create a suitable joint between a composite tube and a metallic end fitting that together form an anti-roll bar (ARB).

Crow said as a minimum the joint needed to be capable of transmitting the same loads as the equivalent part manufactured from steel spring.

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“The key was finding a modular system,” he said in a statement. “This project was not about making a very expensive composite part, but about how we could bond together metallics and composites to create high configurability from a low number of stock parts.”

Tinsley Bridge had previously worked with the AMRC to develop a metallic and carbon fibre reinforced plastic (CFRP) hybrid composite roll bar, joined with an adhesive, on the Lightweight Composite Suspension Components (LiCoSuCo) project.

Craig Atkins, research engineer at the AMRC Composite Centre, said while that project made advances in the areas of volume composite manufacture, metallic arm production and bonding, it created other issues that required solutions.

He said “We took outcomes from LiCoSuCo that didn’t succeed, in particular with the integrity of the bonded joint between the metallic and carbon fibre. The continued LiMeCH project builds upon the results of the previous project and continues the collaboration and research.”

Performance Engineered Solutions (PES) designed the ARBs, employing Finite Element Analysis (FEA) to simulate the process prior to manufacture to determine whether the proposed designs could resist the loads an ARB is subjected to.

Stefan Dalberg, senior design engineer at Performance Engineered Solutions, said: “We needed to consider the ease of manufacture as well as the material selection, adhesive selection and how it would perform during non-destructive testing (NDT).”

The AMRC’s Composite Centre produced four anti-roll bar prototypes using its MF Tech filament winding system. PES penetratively inspected the inside of the bar with a CT scanner, then used an in-house light scanning system to visually inspect the parts.

Crow said the prototypes were then subjected to rigorous testing.

“Inspection of the composite system was key because these parts have different failure modes to the traditional steel that everyone in the industry knows, understands and is very comfortable with,” he said. “We researched and developed a whole range of non-destructive testing techniques, both in situ and on a test track, to understand if the part had been damaged, to what extent it had been compromised and whether it was suitable for continual use or not.”

Dalberg said that non-destructive testing means the consortium can now assert that they can bond metallics to composites in a manner that passes the industrial fatigue requirements.