I'm writing this to open a dialogue about Direct Digital Manufacturing with Carbon Fiber. As you know making anything out of carbon fiber is very expensive because it is extremely labor intensive. I believe developing a new system of automated design and manufacture is the key to unlocking the potential of carbon fiber.
I would like to propose that the time consuming hand layup process needs to be retired and in its place pressurize air bladers and free form jigs be utilized to give structural form to EV and EVTOL vehicle chases. A process where from a raw roll of carbon fiber woven fabric material can be cut to forms. These forms can be sown together inserting rigid foam material in some places or plastic bladers in others. During this process too low-E wiring harness and sensors can be inserted. When the final soft form is completed a plastic vacuum bag is placed around the whole of the form, the form is placed in a restraining gig and the internal bladders are inflated. Now resin can be pumped in between the exterior vacuum bag and the interior compressed air bladers. You can imagine a whole assembly line of these hanging from hooks on a ceiling mounted conveyor going through a curing oven.
The end product in the skeletal structure of your vehicle. Openings for doors and windows, etc... would be cut out. That material shredded and that carbon fiber chop recycled back into the manufacture process. Carbon chop infused thermal plastic would be better used for body panels.
This is what we need to work on to move American Industry forward. This process relies heavily on utilizing the advances in computer aided design and physics engines along with robotics. I imagine a symphony of sewing robots manipulating carbon fiber car bodies in the air in these automotive factories of the future instead of the ubiquitous welding robots of today.
David Elze 631-997-503 dvdelze@gmail.com
A revolution is taking place in the automotive manufacturing and design industry -
The Aptera Motors Paradigm car seeks to demonstrate two main ideas. The qualities of the in-hub motor system and its ability to allow for a complete rethinking of the basic architecture of the vehicle and the ability direct digital manufacturing, different types of 3D printing to create new more efficient, stronger structures and integrated systems. The dramatic architectural change in the Manta Ray design is the splitting of the front wheels and their inversion, facing the open side of the wheels inward taking advantage of the directed airflow to better cool both the drive motors and braking systems as well as the battery pack. This is only one possible configuration made possible by this innovative drive system.
In 2013, BMW Group launches production of the BMW i3, an electric-powered light motor vehicle. The car body referred to as the "life module" is entirely made of carbon fiber-reinforced synthetic material. This means less weight, a better cruising range, and greater safety. The joint venture SGL Automotive Carbon Fibers is developing and producing the preliminary products for the BMW i-series. It marks the first time in automotive history that carbon fiber-reinforced plastic will be used to such an extent in a production vehicle.
Two of the main challenges or problems to solve for in any in-hub motor system are unsprung mass and heat dissipation. In a traditional ICE ground vehicle the unsprung mass or unsprung weight consists of suspension, wheels, and other components directly connected to them, rather than supported by the suspension. Some of these components include the brakes, calipers, axles, wheel bearings, wheel hubs, tires, and a portion of the weight of the drive shafts, springs, shock absorbers and suspension links. The unsprung weight of a wheel controls a trade-off between a wheel's bump-following ability and it's vibration isolation. Bumps and surface imperfections in the road cause tire compression which induces a force on the unsprung weight. The unsprung weight then responds to this force with movement of its own. The amount of movement, for short bumps, is inversely proportional to the weight - a lighter wheel which readily moves in response to road bumps will have more grip and more constant grip when tracking over an imperfect road. For this reason, lighter wheels are sought after, especially for high-performance applications.
To solve for this first problem our in-hub motor system utilizes the superior performance qualities and form factor of a coreless permanent magnet axial flux electric motor and advancements in direct digital manufacturing. In recent years Axial Flux motors have been developed by companies such as YASA Motors of the UK. "YASA Motors proprietary axial flux motor is smaller and lighter than its competitors due to more efficient use of key materials (both magnetic and structural) and simple low cost manufacturing processes. This powerful combination enables the Company to produce motors with higher peak and continuous power and torque density at lower cost than its competitors." The high torque density of an axial flux motor at lower RPM means there is no need for gear reduction. The in-hub motor is integrated into the wheel and directly mounted to the vehicle. "The YASA motor offers class-leading power and torque density, saving both weight and vehicle space and enabling a simpler integration process. Critically, the YASA motor can deliver up to twice the continuous power and 50% greater continuous torque than equivalent peak power competitor motors, enabling superior performance in the most challenging of drive cycles or usage cases."
The current definition for 3D printing and current classification of printer types as per the 2014 CTC 3D printing show in Birmingham, UK
- 3D printing or additive manufacturing (AM) refers to any of the various processes for printing a three-dimensional object. Primarily additive processes are used, in which successive layers of material are laid down under computer control. These objects can be of almost any shape or geometry, and are produced from a 3D model or other electronic data source. A 3D printer is a type of industrial robot.
3D printers fall under 7 different categories. These are
Material extrusion
Vat photopolymerization
Material jetting
Binder jetting
Powder bed fusion
Sheet lamination
Directed energy deposition
A broader definition for 3D printing is Direct Digital Manufacturing. Direct Digital Manufacturing is any fabrication process by which a 3D model or digital file is inputted and where an automated assembly process can be fabricated in a multitude of variations with little to no retooling of the assembly process.
Currently, producing a new car from a new design represents a significant investment in tooling, and a large investment in time. This is the result of both the current standard in materials used, I. E. steel or aluminium and the manufacturing processes utilized to construct them. In addition the need for all that producing tooling is the result of just how many parts are required to produce a contemporary vehicle. Direct digital manufacturing promises the more rapid design iteration and production cycles with fewer parts counts using less material in stronger more efficient configurations. Multifunctional and integrated structures and systems will significantly reduce overall weight. "Many consider recent progress in 3D printing to be the start of the Third Industrial Revolution. 3D printing has the potential to move us away from the Henry Ford era mass production line, and will bring us to a new reality of customizable, one-off production. 3D printing is already being taken advantage of by major industries including aerospace, automotive, and defense. In fact, 3D printing, currently a few-billion dollar industry itself, is expected to be as significant to modern manufacturing as the advent of the assembly line - a process which greatly contributed to the Second Industrial Revolution. 3D printing is widely acknowledged for its disruptive potential." The Manta Ray utilizes direct digital manufacturing in many different ways such as the power reservoir, the batter. The heart of an electric car, the battery's performance determines how far the car can drive on one charge known as it's range. The battery is also a major factor in the overall cost of a vehicle. Using a breakthrough technology developed by Graphene 3D Lab.inc the batteries will be 3D printed.
Local Motors in partnership with Oak Ridge National Laboratories built the Strati, the world's first 3D printed car. This shows us the possibilities for 3D printing in the automotive industry. Many applications are opening up as researchers and developers explore 3D printing as a method for fabricating an ever expanding variety of complex systems. Engineers at Oak Ridge National Laboratories have also combined 3D printing and a wide-bandgap version of silicon carbide to produce a lightweight, compact 30-kW traction-drive inverter with 99% efficiency. Using 3D printing the engineers were able to quickly prototype and iterate on different configurations of heat sinks and components to optimize the inverter. The liquid-cooled inverter could lead to lighter, more powerful battery powered electric vehicles. The wide-bandgap silicon makes the inverter more efficient at a wider range of temperatures than conventional semiconductor materials. The material also lets the inverter be more reliable, lighter, more compact, and have a high power density. Another key to the project's success was using several relatively small, lower-cost capacitors hooked up in parallels to reduce heating compared to the conventional approach of using fewer, larger, and more expensive "brick-type" capacitors.
One of the problems with the slow incremental implementation of carbon fiber composite materials in the automotive industry threw replacing existing parts is that those parts were designed to be produced out of steel in a machine press, stamped from a sheet of material.
Row carbon fiber may come to the factory on a large roll like steel but that is where the similarities in the materials properties ends. Carbon fiber as a material has completely different characteristics and finding and harnessing its strengths requires some out of the box thinking. We can find structures in nature which much better take advantage of the qualities of composite materials in their construction and show use the way to do so with carbon fiber. The best example analogous to a vehicle in nature would be crustaceans. These marine creatures form their bodies with hard outer shells and a variety of latticework internal structures. We would be wise to learn and build upon millions of years of evolution in designing vehicles which we place the safety and security of our lives and the lives of our loved ones. Anyone who has ever eaten a lobster or crab still in the shell can appreciate the tough and elegant design of such a creature. So how can the raw material, roles of carbon fiber fabric be turned into finished products including complex automotive and aviation platforms. Traditional methods of carbon fiber layup manufacturing are labor intensive processes. Traditional processes using hard molds made from fiberglass or CNCed aluminum have the same manufacturing drawbacks as the steel or aluminum materials they are trying to replace. The problem with stamped metal manufacturing is that expensive molds have to be made for every part and charging those molds is extremely time consuming. Retooling of an entire assembly line can take weeks. Carbon fiber is a superior material not just because the end product is lighter and stronger but because the nature of a pliable fabric allows for different manufacturing techniques. Consider that fabric can be laser cut through an automated process reducing waste and there for cost and maximizing efficiency and use of material. The scraps can also be processed into chopped fiber and used in other carbon fiber manufacturing processes such as the manufacture of carbon ceramic disc brakes. The cut patter pieces can then be sewn together in an assembly which is analogous to the "soft shell" version of a crustaceans before hardening to become the final product. By laying up carbon fiber fabric in hard molds we are ignoring its basic characteristics and most versatile qualities. Only by embracing these qualities will we experience the full range of possibilities that designing with carbon fiber allows. Using the principle of biomimicry we can see how designing dynamic structures in carbon fiber are more like exoskeletal forms most notable crustaceans such as crabs or lobsters. This is where the "soft shell" analogy comes from. In nature when a crab molts, it's entire hard shell becomes soft. Similar to the crab, our soft shell can be the complete structural form of automobile or aircraft in addition to integrated systems such as wiring, sensors, and HVAC ducting. The vacuum infusion method is used to harden the structure but instead of hard molds a system of rigid foam and or honeycomb structures inserted and sewn into the soft shell form and that will be a permanent part of the vehicles final structure are used in conjunction with inflated air bladders to create the final desired shape. In order to implement this type of design a major effort and focus needs to be placed on 3D design software that can both calculate the necessary structural design specifications and translate them to the necessary machining, automated and robotic equipment that will manufacture those structures. Design software is a key lever to shift the industry toward carbon fiber intensive vehicles. Design software that takes advantage of carbon fibers' fluid ability to be formed will change the way designers in the automotive and aeronautical work. The assembly line in essence becomes a large building sized 3D printer and the variety of possible vehicle designs will explode in proliferation.
Thanks for your time. would love to know what you think about this concept.