Designing a Production-Ready Ultra-Lightweight Carbon Fiber Reinforced Thermoplastic Composites Door

Vehicle lightweighting has been a constant theme of research at numerous Original Equipment Manufacturers (OEM’s) as it provides one of the best opportunities for improving fuel efficiency. In this regard, the Department of Energy (DOE) Vehicle Technology Office set a challenge to lightweight a fully assembled driver’s side front door by at least 42.5% with the cost constraint of a maximum $5 increase for every pound saved. A baseline door of an OEM’s 2014 mid-size SUV was selected, and an integrated design, analysis, and optimization approach was implemented to meet this goal. The ultra-lightweight door design had to meet or exceed the fit & function and mechanical performance (static and dynamic) of the baseline door while being suitable for mass production. The design strategy involved parts consolidation, and multi-material distribution to enable mass reduction without compromising the fit and functional requirements. The primary structural component of this ultra-lightweight door design is a composite inner-frame made of a woven carbon/Nylon-6 composite material. While a finite element composite optimization technique was implemented to design the ultra-lightweight door that met the static and dynamic performance targets, it lacked manufacturing inputs. This study focuses on the feasibility of large-scale manufacturing of the composite inner-frame using thermoforming processes. One benefit of employing these processes is that the existing OEM stamping lines can be utilized with minor modifications with no additional capital cost for equipment. The scope of this paper is to identify the challenges in thermoforming of the thermoplastic door - including shear angle, tearing, and wrinkle formation - using draping simulation and share the solution in the form of countermeasures in the part design and tool concept to make the manufacturing of the final part feasible.