Session: 18-01-05: Conventional Manufacturing

Paper Number: 150101

150101 - Rebar for Plastics – Unlocking Design Through Advanced Manufacturing 

WEAV3D has developed a novel hybrid-material approach, Rebar for Plastics®, combining existing thermoforming, compression molding or injection overmolding processes with woven composite lattices formed from unidirectional thermoplastic tapes to produce high-rate, cost-effective structural composites. The resulting structural panel exhibits high stiffness, strength, and ductility, equivalent or better than sheet metal, while offering weight savings of up to 65% compared to steel. WEAV3D’s patented continuous composite forming process enables topology optimization within 2D composite structures, as tape spacing and reinforcement types can be varied on-the-fly during production to create components with heterogenous lattice reinforcements that enable different mechanical properties at different locations within the part. While this unlocks significant design freedom in tuning the cost and performance of the end component, design engineers need to rethink how they approach part design and the tools they use to realize the full benefit.

Thermoset composite approaches are generally incompatible with high-rate, thermoplastic molding processes used in automotive production. Thermoplastic composites have seen limited automotive adoption via automated tape laying or organosheet compression molding processes; however, these technologies are still cost and/or rate prohibitive in many applications as they are fundamentally laminate approaches that utilize expensive materials to build up ply stacks that provide both material properties and cross section properties of the component. Recent efforts have attempted to leverage back injection of laminate sheets to enhance bending stiffness, but this approach still relies on the laminate to provide the majority of the part volume, which keeps part costs elevated.

Our Rebar for Plastics® design solution takes the inverse approach – utilizing inexpensive molded materials for the majority of the part volume, with highly optimized, woven lattices produced from unidirectional tapes providing structural enhancement in critical regions of the part. Rather than using material properties as a fixed input in part design, stiffness, strength, and toughness can be tuned independently and in parallel with part geometry, based on overall performance targets for the component and the relative ratios of unidirectional tapes and molded plastic in the part.

Within an automotive door structure case study, unidirectional tapes were concentrated in high stress areas of the part, with sparser patterns comprising less expensive tapes applied to lower stress regions or areas that will be trimmed out in the finished part. This lattice reinforced design achieved 50% cost savings, 23% weight savings, and 62% scrap reduction vs. the baseline component made using carbon fiber PA6 organosheet. Furthermore, the lattice reinforced component was cost neutral to and ~60% lighter than the prior generation steel door component.

This presentation will provide a summary of the WEAV3D advanced manufacturing technology, its applications, and recent NSF SBIR funded efforts to improve throughput and reduce embodied energy. Additionally, it will include a case study highlighting the benefits of applying WEAV3D’s lattice materials to automotive structures and a discussion of relevant design principals and techniques.

Presenting Author: Christopher Oberste WEAV3D Inc.

Presenting Author Biography: Christopher Oberste is the President and Chief Engineer of WEAV3D Inc. He holds a Ph.D. in Materials Science and Engineering from Georgia Tech and a Bachelor of Polymer and Fiber Engineering from Auburn University. Christopher focused his Ph.D. thesis on developing novel, low-cost composite manufacturing processes, including the WEAV3D composite forming technology, and founded WEAV3D as a spin out from Georgia Tech in 2017. He is named as the lead inventor on eight issued patents and three patent applications related to the WEAV3D technology and is the Principal Investigator on WEAV3D's NSF SBIR Phase II award.

Authors:

Christopher Oberste WEAV3D Inc.