Researchers at the University of Delaware’s  Centre for Composite Materials (CCM) have created the world’s strongest short fibre composite material that can be stamped into complex shapes, just like sheet metal can be stamped, in less than one minute. The new high-performance material, known as TuFF (Tailored Universal Feedstock for Forming), can stretch up to 50 per cent, achieve properties equivalent to the best continuous fibre composites used in aerospace applications and reduce part manufacturing costs. TuFF can also be produced inexpensively and sustainably from recycled composite parts or scrap carbon fibre manufacturers typically throw away and be reused to make high performance, high-value materials and parts. (In the world of advanced manufacturing, “feedstock,” refers to organic materials developed and adapted in ways that serve a manufacturing process.)

TuFF was patented in June 2020 with 32 claims. According to the U.S. Patent Office, the claim(s) within a patent application clearly define the invention, its scope and what aspects are legally enforceable.

TuFF represents a paradigm shift in composites design and opens the door for composites to replace metals in a variety of applications in the automotive, aerospace, infrastructure, electronics industries and more. Many common products, from kitchen appliances to smartphones and more, are now made with stamped sheet metal, and manufacturers might someday use TuFF instead.

While transforming existing industries, TuFF could enable the development of new products, such as flying cars, said John Tierney, senior scientist at CCM. “For urban air mobility, you need aerospace performance at automotive rates, which is exactly what TuFF provides,” he said.

Researchers at CCM started working on TuFF in 2016 when they received a $14.9 million, three-year cooperative agreement from the Defense Advanced Research Projects Agency (DARPA) for the Tailorable Feedstock and Forming (TuFF) Program. The objective of the TuFF program was to develop new composite materials with properties equivalent to previously used materials and develop a single-step manufacturing process that enables the use of the advanced materials for small parts weighing less than 20 pounds at costs competitive with aluminium. The project also included CCM faculty alumni collaborators at Clemson, Drexel and Virginia Tech universities.

About four decades ago, scientists theorised that if they could align these short carbon fibres precisely, they could make composites with desirable properties, but no one achieved this feat in practice until now. It took a few years, but after trying several different alignment mechanisms, the team at CCM figured out how to bring everything in line. The process can now use any type of fibre (or combinations) with nearly all polymers (thermoplastics and thermosets).

The Composites Centre has established a semi-automated pilot plant incorporating new control systems and inline sensors for quality control. TuFF product forms range from 20-inch wide rolls, tailored blanks for forming parts and narrow and steerable tapes for additive manufacturing processes. The team has demonstrated the feasibility and scalability of novel technologies developed through this program and are looking to supply TuFF material to designated industry partners for evaluation, prototype development and scale-up.

Researchers are now conducting additional experiments, including modelling and simulation, to further understand the behaviour of TuFF so that they can tailor it for more applications.

TuFF was patented in June 2020 with 32 claims. According to the U.S. Patent Office, the claim(s) within a patent application clearly define the invention, its scope and what aspects are legally enforceable.

TuFF represents a paradigm shift in composites design and opens the door for composites to replace metals in a variety of applications in the automotive, aerospace, infrastructure, electronics industries and more. Many common products, from kitchen appliances to smartphones and more, are now made with stamped sheet metal, and manufacturers might someday use TuFF instead.

The U.S. Navy is moving towards higher utilization of composites to reduce weight and improve structural properties, while meeting other requirements including cost, maintenance and signature control. Structures fabricated from unidirectional prepreg laminae processed using autoclave exhibit the highest mechanical performance due to the superior quality of the laminate in terms of fiber volume fraction and void content, and show the best fatigue resistance due to the complete straightness of the fiber layup. Nevertheless, this process and material forms are often too expensive for most naval applications. Alternatively, low-cost and scalable processing approaches such as Vacuum Assisted Resin Transfer Molding (VARTM) meet cost and most structural targets but typically exhibit reduced fatigue performance due to fiber undulation even when using non-crimp (NCF) fabric.

A multi-scale/multi-physics software will be developed to predict manufacturing-induced defects due to materials, parts, tools and processes. Potential defects include voids, ply waviness, delaminations, fiber wrinkling, resin starvation/rich areas, and distortion/warpage caused from tool-part interaction. .Analytical tools will be integrated into a commercial available finite element design and analysis suite to allow the evaluation of effect of these defects on the performance of complex geometries in real processing environments. This STTR will demonstrate the approach on autoclave processing and high-performance composites materials for aerospace structures but the methodology can be implemented for a variety of materials and processes.