An innovative project that has potential for the automotive industry and emerging markets such as supercars and air taxis, adopts advanced and productive technologies, reconstructs car seats, and uses only the right materials in the right places based on demand, and Produce results quickly.
Through the use of simulation-driven design methods, agile project management methods, and close cooperation and system integration between participating companies, finally, a metal-composite ultra-light car seat prototype was developed. From design to manufacturing, only 7 Months.
Create a better seat
A number of German companies have cooperated to adopt a combined technology to carry out the feasibility study of Ultra leichtbausitz (abbreviated ULBS) ultra-light seats. The vision of the project is to create an ultra-light seat concept to lead the market in weight optimization.
As the sponsoring company, csi entwicklungstechnik GmbH (csi for short), Alba Tooling & Engineering (Alba for short) and Automotive Management Consulting (AMC for short) cooperated with Covestro, LBK Fertigung, Robert Hofmann and 3D Prototype seat concept.
The prototype of the seat developed by this cooperative project weighs slightly more than 10kg, including seat cushions, structural frames, functional inserts and seat controls, which makes it easy to install on the car. The seat is 20% lighter than similar lightweight seats on the market (many of which are rear market seats).
Stefan Herrmann, the person in charge of the ULBS project and the lightweight design of CSI, said that there are currently no competitive seats on the market that weigh less than 12kg.
"Direct comparisons are usually not one-to-one, because the definition of weight in the aftermarket seats usually does not include seat control." Herrmann said, "And, compared with the same weight seats, ULBS seats are more comfortable Much taller. Existing seats, usually bucket seats, are not very comfortable despite their low weight; or traditional super sports seats, they tend to be heavier.
The ULBS project uses several innovative technologies, of which the fiber roving skeleton structure based on xFK in 3D process technology plays the most important role.
The most fundamental advantages of this award-winning technology for continuous fiber roving deposition are:
Design freedom
Ability to accurately lay fibers along the load direction through simulation and material optimization
The fiber material can be applied simply, at low cost and without waste.
For the load transfer in the frame structure, 3D printed components are used: in the area with the highest load, such as the backrest device, the seat uses a high-strength, high-modulus stainless steel 3D printed structure; in the lower load area, the 3D printed parts made of aluminum.
The project is based on the idea initiated by AMC. The engineering company csi, which specializes in the production of automotive body-in-white structures and automotive interior and exterior trim, and is involved in carbon fiber reinforced polymer (CFRP) and additive manufacturing, is responsible for the supervision and coordination of the project.
csi is responsible for the work package in the field of digital processing chain, including the project's modeling, engineering design, surface design, CAE simulation, topology simulation, verification simulation and virtual confirmation.
The reason why the ULBS project stands out is not only the use of innovative materials and innovative production methods, but also the ability to develop complex designs with new components through close cooperation between partners in just 7 months component.
Winding skeleton
In the ULBS project, weight loss is mainly achieved by using AMC's xFK in 3D technology, which is a highly flexible, configurable, low-cost and sustainable fiber composite material technology suitable for winding components.
xFK in 3D has been used in a variety of products in many industries and markets. At the JEC World 2018 exhibition, SGL Group showed some auto parts and bicycle parts made with this technology. A carbon fiber bicycle link developed by AMC is 70% lighter than the corresponding aluminum products.
The xFK in 3D process uses continuous fibers impregnated with thermosetting resin to wrap the load-bearing structure in a waste-free manner. The fiber roving impregnated with epoxy resin is wound on a fixture or winding sleeve, so that the fibers are specially arranged to match the load and desired function of each component.
"An important advantage of xFK in 3D is that the weak points are eliminated when the load is transferred and loads are introduced into the structure." Herrmann explained that the weak points usually do not appear in the continuum of the structure, but in the structure to introduce the load Area, especially where adjacent components are connected to the structure. xFK in 3D technology supports load transfer across connections, allowing fibers to be arranged according to the required component functions and load conditions, and manufactured in three dimensions.
The fiber winding process also brings other benefits-it helps to minimize the waste of material, less than 1% of fiber roving is wasted.
After consulting with Dr. Clause Georg Bayreuther, the technical director of AMC, csi recognized the advantages of xFK in 3D technology and designed the ULBS seat frame to be manufactured.
Alba manufactures molds for the production of CFRP seat frames and provides engineering support. Although the seat frame is made of carbon fiber, natural fiber and basalt fiber are also good choices.
A mixed material structure
In addition to the skeleton, the ULBS seat prototype also includes some other new innovations. Alba provided the mold, also provided tooling, engineering and manufacturing support for the seat foam and implemented the seat assembly. A fiber velvet cushion covers the CFRP frame of the seat, and then covered with 3D printed PUR foam. The cushion is made of traditional foam material.
By applying 3D | CORE to the back shell structure of the seat back, the weight is further reduced.
3D | CORE is an in-layer reinforced core (IRC for short) material, that is, a foam core containing extruded polystyrene (XPS) and polyethylene terephthalate (PET) in the form of monolithic honeycomb Structure sandwich core. In the production process of composite parts, the honeycomb structure is filled with resin, which brings extremely high layer strength.
The 3D | Core is placed between two layers of glass fibers to create a preform, which is then infused with thermoplastic epoxy resin using a vacuum assisted resin transfer molding (VA-RTM) process.
Covestro provided its DisPErcoll adhesive for use as an adhesive for fiber velvet pads and 3D printed back pads. Herrmann said that the mechanical properties of Dispercoll adhesives ensure good wear resistance, which is very important, because the surface contact between the mat and the skeleton will cause the pad to wear.
"If you have a single fiber roving, when you put it in the fabric, it will cause a slight movement between the hard CFRP part and the velvet cushion, which will cause friction between the seat frame part and the fabric, and eventually destroy the fabric "" Herrmann explained.
Traditional seats usually have a large surface area to support the cushion, but the skeleton structure made by xFK in 3D technology has a small contact surface area.
"When the xFK in 3D structure pushes fleece fabrics, a special and durable adhesive must be used, and this is what the Dispercoll adhesive can provide," Herrmann added.
Covestro also provides what is said to be the world's first 3D printed cushion. Although the traditional seat back is usually made of foam molded by the mold, in terms of aesthetics, functional integration and comfort, the 3D printed seat back cushion made of TPU has further improved the ULBS seat Flexibility and adaptability.
Seat of the future
The ULBS project achieved several major goals. Although the concept generated by the project has not yet reached the market, it has the potential to serve many niche markets, such as super sports cars, air taxis, ultralight vehicles, miniature mobile vehicles, helicopters, multi-wing aircraft and aviation.
It is undeniable that although it is more expensive than mass-produced car seats, the ULBS project has verified several technologies to reduce waste and thereby reduce material costs. Compared to other carbon fiber technologies, xFK in 3D generates very little waste. In fact, the entire project aims to use the least resources and only the necessary materials. ULBS also offers the possibility of using renewable, sustainable resources, such as the use of natural fibers in skeleton structures, mats and fabrics.
More importantly, the project demonstrates how companies can shorten the time to market for new products through short and flexible collaboration. This is also a good example of using design thinking to successfully transform products from concept to hardware prototype by focusing on functional requirements and looking forward to future applications and sustainable development goals.