Lightweighting The C8

[John]

Will GM’s “Lightweighting” program apply to the C8? We all sure hope so!

We all wish that GM’s extreme success in reducing weight from their vehicles as they change from one generation for that vehicle to the next one, specifically reducing over 5,000 pounds from fourteen (14) of them (an average of over 350 pounds per vehicle), transfers into the C8’s base weight being less than the C7’s.

We have bits and pieces of GM’s lightweighting program in several different threads, but due to the importance of it, this thread will become our stickied thread on this subject.

Here is the critical GM video (2:14) showing how GM in conjunction with AutoDesk, has such a successful program now on-going.

Below is GM’s official press release, but first a couple of pictures from within it.

Advanced Software Design Technology Leads GM into Next Generation of Vehicle Lightweighting

https://media.gm.com/media/us/en/gm/...weighting.html

Alliance with Autodesk includes advanced AI-based generative design technology and 3D printing advancements to help lighten and transform future vehicles

2018-05-03

General Motors is using new, advanced software design technology to introduce the next generation of vehicle lightweighting. The technology is key to developing efficient and lighter alternative propulsion and zero emission vehicles.

GM is the first automaker in North America to use new generative design software technology from Bay Area-based software company Autodesk. It uses cloud computing and AI-based algorithms to rapidly explore multiple permutations of a part design, generating hundreds of high-performance, often organic-looking geometric design options based on goals and parameters set by the user, such as weight, strength, material choice, fabrication method, and more. The user then determines the best part design option.

“This disruptive technology provides tremendous advancements in how we can design and develop components for our future vehicles to make them lighter and more efficient, said GM Vice President Ken Kelzer, Global Vehicle Components and Subsystems. “When we pair the design technology with manufacturing advancements such as 3D printing, our approach to vehicle development is completely transformed and is fundamentally different to co-create with the computer in ways we simply couldn’t have imagined before.”

GM is leading the industry into the next phase of vehicle lightweighting. The new design technology provides significantly more vehicle mass reduction and parts consolidation opportunities that cannot be achieved through traditional design optimization methods.

GM is utilizing the innovative technology on future product designs. GM and Autodesk engineers have applied this new technology to produce a proof-of-concept part – a seat bracket – that is 40 percent lighter and 20 percent stronger than the original part. It also consolidates eight different components into one 3D-printed part.

As part of a multi-year alliance focused on innovation, GM and Autodesk will collaborate on projects involving generative design, additive manufacturing, and materials science. Executives and engineers from the two companies will participate in a series of onsite engagements to exchange ideas, learnings, and expertise. GM also has on-demand access to Autodesk’s full portfolio of software and technical specialists.

“Generative design is the future of manufacturing, and GM is a pioneer in using it to lightweight their future vehicles,” said Scott Reese, Autodesk Senior Vice President for Manufacturing and Construction Products. “Generative technologies fundamentally change how engineering work is done because the manufacturing process is built into design options from the start. GM engineers will be able to explore hundreds of ready-to-be-manufactured, high-performance design options faster than they were able to validate a single design the old way.”

GM has been a leading end-user and innovator in additive manufacturing. For more than three decades, GM has used 3D printing to create three-dimensional parts directly from digital data through successive addition of layers of material. GM possessed the first and has some of the auto industry’s most comprehensive 3D printing capabilities in the world with more than 50 rapid prototype machines that have produced more than 250,000 prototype parts over the last decade.

Since 2016, GM has launched 14 new vehicle models with a total mass reduction of more than 5,000 lbs., or more than 350 pounds per vehicle. Most of the weight reduction are a result of material and technology advancements. Of those models, more than half of the vehicles shed 300-pounds or more including the all-new 2019 Chevrolet Silverado, which reduced mass by up to 450-pounds.

Eliminating mass in parts where material is not required for performance combined with parts consolidation yields benefits for vehicle owners including the potential for more interior space and vehicle content, increased range, and enhanced vehicle performance. It also paves the way for new features for customers and provides vehicle designers a canvas on which to explore designs and shapes not seen today.

General Motors Co. (NYSE: GM, TSX: GMM), its subsidiaries and joint venture entities produce and sell vehicles under the Chevrolet, Cadillac, Baojun, Buick, GMC, Holden, Jiefang and Wuling brands. GM has leadership positions in several of the world's most significant automotive markets and is committed to lead the future of personal mobility. More information on the company and its subsidiaries, including OnStar, a global leader in vehicle safety, security and information services, can be found at http://www.gm.com.

Autodesk (NASDAQ: ADSK) makes software for people who make things. If you've ever driven a high-performance car, admired a towering skyscraper, used a smartphone, or watched a great film, chances are you've experienced what millions of Autodesk customers are doing with our software. Autodesk gives you the power to make anything. For more information visit autodesk.com or follow @autodesk.

[SheepDog]

The plant was recently recreated at Bolingreen. That provided opportunities that were presumably taken. The C8 is a new design with new challenges and new opportunities. This thing is a lab experiment. What's coming out of the well guarded test tube and when is it coming?







MARCH 1, 2018 | AEROSPACE | AUTOMOTIVE | ENERGY | MATERIALS | TRANSPORTATION

Pros & Cons of Advanced Lightweighting Materials


Although cars have been around for more than a century, the material they are made of (steel) has mostly stayed the same. It has only been in the past few decades that advanced materials ranging from aluminum and magnesium alloys, to carbon fiber composites, have made their way into mass-produced passenger cars. The Audi R8 Spyder includes carbon-fiber-reinforced polymer (CFRP) in the rear section, including the convertible-top compartment lid. (©Audi AG)
Advanced materials are essential for boosting the fuel economy of modern automobiles while maintaining safety and performance. Because it takes less energy to accelerate a lighter object than a heavier one, lightweight materials offer great potential for increasing vehicle efficiency. A 10% reduction in vehicle weight can result in a 6 to 8 percent fuel economy improvement. Replacing traditional steel components with lightweight materials such as high-strength steel, magnesium (Mg) alloys, aluminum (Al) alloys, carbon fiber, and polymer composites can directly reduce the weight of a vehicle’s body and chassis by up to 50 percent, and therefore reduce a vehicle’s fuel consumption. Using lightweight components and high-efficiency engines enabled by advanced materials in one-quarter of the U.S. fleet could save more than 5 billion gallons of fuel annually by 2030.

By using lightweight structural materials, cars can carry additional advanced emission control systems, safety devices, and integrated electronic systems without increasing the overall weight of the vehicle. While any vehicle can use lightweight materials, they are especially important for hybrid electric, plug-in hybrid electric, and electric vehicles. Using lightweight materials in these vehicles can offset the weight of power systems such as batteries and electric motors, improving the efficiency and increasing their all-electric range. Alternatively, the use of lightweight materials could result in needing a smaller and lower-cost battery while keeping the all-electric range of plug-in vehicles constant.

Scientists already understand the properties of these materials and the associated manufacturing processes. Researchers are working to lower their cost and improve the processes for joining, modeling, and recycling these materials.

The U.S. Department of Energy’s Vehicle Technologies Office (VTO) develops advanced materials that help boost the fuel economy of modern vehicles, while maintaining safety and performance. Further developing advanced materials requires increasing understanding of their composition and morphology. Computational materials science should bring advanced materials into the market much faster than in the past. Researchers can also use computational approaches to create vehicle designs that maximize the potential of these materials. To improve these tools, VTO works with the Lightweight Materials National Laboratory Consortium (LightMAT), a network of 10 national laboratories with technical capabilities highly relevant to lightweight materials development and utilization.

Research and development into lightweight materials is essential for lowering their cost, increasing their ability to be recycled, enabling their integration into vehicles, and maximizing their fuel economy benefits. Although many materials show promise in reducing vehicle weight, there are pros and cons to each, ranging from production costs to property deficiencies. ADVANCED HIGH-STRENGTH STEEL


Stronger and more ductile than typical steel, advanced high-strength steel could reduce component weight by up to 25 percent, particularly in strength-limited designs such as pillars and door rings. It is generally compatible with existing manufacturing and materials currently used in vehicles.

Pros: High strength, stiffness, formability, and corrosion performance, as well as low cost.

Cons: High cost, and wears out stamping molds faster than for lesser grades. Ductility decreases as strength increases, adding issues in forming and joining. Challenges also include design, component processing, and behavior in harsh environments. The Audi A8 L features a Multimaterial Space Frame that relies on a mix of steels, aluminum, polymers, and magnesium. (©Audi AG)ALUMINUM


Because of aluminum’s use in aerospace and construction, scientists have a good understanding of its characteristics and processing. Manufacturers currently use it in vehicle hoods, panels, and powertrain components, but face barriers in cost and manufacturing. Manufacturers also face issues with joining, corrosion, repair, and recycling when they combine aluminum with other materials. A lighter, more expensive alternative to steel, aluminum is increasingly being utilized for hoods, trunk lids, and doors, and has the potential to reduce weight by up to 60 percent.

Pros: Technology is fairly mature; good stiffness, strength, and energy absorption.

Cons: Higher cost than steel, joining to other materials, and limited formability issues. MAGNESIUM


With the lowest density of all structural metals, magnesium alloys have the potential to reduce component by weight up to 70 percent. Magnesium is presently used in castings for power-trains or sub-assembly closures. The increased use of magnesium for automotive applications is limited by several technical challenges. Even though magnesium (Mg) can reduce component weight by more than 60 percent, its use is currently limited to less than 1 percent of the average vehicle by weight. Although incorporation of multiple, individually cast, or wrought Mg components into articulated sub-assemblies appears unlikely in the near-term, Mg will continue to have a role in vehicle lightweighting, predicated on its attractive features of low density, high specific stiffness, and amenability to thin-wall die casting and component integration.

Pros: High stiffness and strength, compatible with existing infrastructure for stamping.

Cons: Expensive, lack of availability from U.S. manufacturers in large quantities to meet automotive needs. Other challenges include ductility, joining, repair, recycling, and corrosion. Rare earth additives may also be needed to improve energy absorption to meet crash requirements. The Ford Escape features machined-aluminum wheels. (©The Ford Motor Company)CARBON FIBER COMPOSITES


While manufacturers use carbon fiber in high-performance vehicles, the expense of the input material and process to develop it are generally too high for use in popular models. Despite being half the weight of steel, carbon fiber composites are four times stronger and have the potential to reduce vehicle weight by up to 70 percent.

Pros: High stiffness, high strength, enables the manufacture of highly complex shapes, and offers tremendous weight savings.

Cons: High production cost of carbon fiber and difficulty joining into vehicles, along with associated challenges in modeling performance, infrastructure, and sufficient amounts of fiber to meet automotive needs. TITANIUM


This high-temperature metal is used in powertrain systems to reduce weight by up to 55 percent. Titanium is also used in valves, springs, suspensions, wheels, and gearbox housings.

Pros: High strength-to-weight ratio, can withstand high temperatures.

Cons: High cost of materials, and formability challenges. CONCLUSION


Lightweight structural materials — advanced high-strength steel, aluminum, magnesium, and carbon-fiber polymer composites — enable improvements in fuel economy by providing properties that are equal to or better than traditional materials, and by providing flexibility in design that enables additional lightweighting.

Although each lightweight structural material has strengths and weaknesses that render it more suitable for certain applications than others, the most effective way of reducing the overall weight of a vehicle is to use the right structural material for the right application. Multi-material crosscutting endeavors must include evaluations of both safety and cost.

[John]

Thanks you SheepDog. That is a very incisive article you found/posted.

Corvette reduced the weight of its SMC panels in 2014 when they decreased the amount of glass fibers from 25% to 21% of total content, then further reduced the SMC panels’ weight in 2016 (calling in now TCA Ultra Light). I wonder if the C8’s sheet molded composite (SMC) again shows a weight reduction. As shown in detail below, all of the Corvettes’ SMC panels are made by Continental Structural Composites.

Here some details on the 2016 SMC 9kg weight reduction for the C7.

Low-density SMC: Better living through chemistry

39
Proprietary sizing, special glass roving and microspheres strip 9 kilos of weight from Corvette body panels.

Case Study Post: 2/8/2016

PEGGY MALNATI

Low-density SMC: Five-year R&D payoff: Judges at two recent industry events agreed that Continental Structural Plastics’ (Auburn Hills, MI, US) TCA Ultra Lite sheet SMC, used to mold, for example, this very complex, one-piece Corvette right-front fender, is a winner. The CAMX 2015 steering committee gave it the Unsurpassed Innovation award during its October conference in Dallas, TX, US, and a month later, it topped the SPE Automotive Division’s Materials category and was the Grand Award winner at the 45th SPE Automotive Innovation Awards Gala in the Detroit suburbs. Source: SPE Automotive Div.

A new, low-density sheet molding compound (SMC), formulated and molded by Continental Structural Plastics (CSP, Auburn Hills, MI, US), is responsible for reducing mass by 9 kg on body panels for 2016 model year Chevrolet Corvette sports cars from General Motors Co. (GM, Detroit, MI, US). CSP calls the new material TCA (tough Class A) Ultra Lite. At a specific gravity (SG) of 1.2, it offers a 28% mass reduction vs. CSP’s mid-density TCA Lite (1.6 SG) grades, and a 43% reduction vs. conventional 1.9 SG grades of SMC. More importantly, TCA Ultra Lite not only offers mechanical performance comparable to TCA Lite (both feature a matrix of unsaturated polyester from AOC LLC, Collierville, TN, US), but also reportedly bonds more effectively to paint and adhesive. Although this first commercial use of TCA Ultra Lite is on painted Class A body panels, the company says it’s equally appropriate for fabrication of structural parts.

TCA Ultra Lite was introduced as a running change in the summer of 2015 to replace TCA Lite on all Corvette exterior body panels except the hood and roof, which are molded in carbon fiber-reinforced epoxy by another supplier. Notably, neither tooling, process adjustments nor part thickness changes were necessary during the material transition. “One day we were running TCA Lite, and the next day we were running TCA Ultra Lite,” explains Dr. Probir Guha, CSP’s VP, advanced R&D, “and there were no other changes.”

Aluminum is the real competition

Although the transition reportedly occurred without hiccups, the technology that made that smooth transition possible was five years in the making. Guha credits Frank Macher, who became CSP chairman in October 2010 and CEO in February 2011, with making TCA Ultra Lite’s invention possible.

“When he came on board, Frank said, ‘Stop everything and focus on R&D. Our competitor isn’t another composite, it’s aluminum,’” recalls Guha. “True to his word, he gave us the resources to dig deeper into the chemistry so we could under- stand what was going on at the molecular level.”

SMC already offered a host of benefits vs. steel and aluminum. It’s typically 40% lighter than metals in specification-comparable geometries. It also provides better low- and high-speed impact performance (energy management), so it brings safety benefits to vehicle occupants. Although it won’t rust or corrode and doesn’t need such treatment, it has the thermal and chemical resistance 
to survive the automotive electrophoretic (e-coat) deposition process used as a rust preventative on metallic chassis components. Hence, SMC parts can be attached to the body-in-white (the preferred assembly method) and don’t require special post e-coat assembly.

Far greater design flexibility is
another SMC advantage (especially
 vs. aluminum), and that’s a real boon
to automakers who favor the use
 of surfaces with compound curves,
 which are either difficult and costlyor impossible to duplicate in metals,
 owing to the deep draw. Parts-consoidation opportunities and insert 
molding enable previously multiple
 subcomponents to be molded as
 a single complex composite part,
 reducing the number of tools (dies) 
and post-mold assembly operations 
necessary to make the same part
 from metal. Even better, because it’s
 molded on compression presses, SMC
 offers this styling freedom at lower
 tooling costs than metals at both low
 and moderate production volumes
 (typically 50-70% tooling cost savings 
vs. steel or aluminum at build volumes 
of less than 150,000 per year). Historically, at higher volumes, the greater 
raw material cost of SMC vs. metals 
and the slower part production cycle 
cancel out SMC’s overall cost advantage: SMC takes 2.0-3.5 minutes vs. 
20-30 seconds for metals, despite the fact that that’s per die for a metal version of the part that requires multiple subcomponents, which need subsequent assembly. So the SMC molder must multiply the number of tools and machines to maintain competitive production rates at the higher volumes. This normally puts SMC out of the running in the per-part cost sweepstakes.

With aluminum as their target, CSP researchers focused on ways to make SMC cost-competitive at any production volume. The key was to target specific gravity: “We kept running the numbers and our calculations kept telling us that we could take on aluminum if we could get to 1.2,” explains Guha. “We got down to basics and started analyzing each component’s contribution.”

SMC typically contains resin, glass fiber, mineral filler and additives. One way the company reduced its product density was by replacing some percentage of its typical calcium carbonate (CACO3) filler with hollow glass microspheres (affectionately called “bubbles” in the industry). However,
 microspheres can crush easily during 
compounding or molding. “When that 
happened, our mechanicals would go
 south and our density would go up,”
recalls Guha. “We felt we needed both 
a tougher bubble and to do work on
the surface of the bubbles to improve 
interfacial adhesion.”

Chemistry is key

As luck would have it, part of the Macher-approved R&D investment included a state-of-the-art scanning electron microscope (SEM). Researchers lost no time mixing new formulations, molding and testing parts, then sectioning samples and looking at morphology via the SEM to try and understand how the structure they were seeing related to the performance they were measuring and the chemical tinkering they were doing. What they saw led to a three-pronged solution, and a number of different ways to improve the resin/reinforcement interface.

First, they looked at numerous types of microspheres, eventually switching to a tougher, higher performance microsphere from 3M (St. Paul, MN, US). Although CSP won’t divulge specifics, Guha does say the product has higher crush strength and has not been used previously in automotive composites applications with unsaturated polyester resins.
 Second, they strengthened the resin/ microsphere bond with a proprietary sizing that was developed and patented by CSP researchers, rather than using those offered by microsphere or additive suppliers. The sizing’s formulation is said to work with the free-radical reaction mechanism used in unsaturated polyester and vinyl ester. According to Guha, the difference between the new sizing and previous versions was “like night and day” — not only performance-wise, but also clearly visible on SEM images.

Serendipitously, as researchers dug deeper into the chemistry and physics of the resin/microsphere interface, they discovered that a longstanding issue with paint adhesion on certain SMC parts wasn’t the fault of a poor bond between paint and
 the surface of the composite, as everyone had assumed. SEM scans of part surfaces from which paint had flaked off revealed that not only the paint but the entire top layer of the composite’s resin matrix had detached from microsphere surfaces. CSP researchers discovered that their work on strengthening the resin/microsphere interface not only met or exceeded target mechanicals at lower density, the intended result, but also provided the additional benefit of improving the SMC’s capacity to bond well with paints and adhesives.

Third, researchers re-examined their options for glass rovings, selecting ME1975 multi-end glass roving, then newly formulated by Owens Corning (Toledo, OH, US) specifically for unsaturated-polyester SMC applications that require high strength and corrosion resistance. Here, too, the surface chemistry of this E-glass variant was the key contributor to performance improvements seen in surface finish and mechanicals.

Throughout the development process,
 as CSP researchers found something that seemed to improve performance, they evaluated the formulation not only by means
of standard, small-scale mechanical tests, but also with a lab-scale setup that simulated e-coat processing conditions. As
 their confidence grew with each formulation refinement, they took samples around to multiple automakers and did trials in OEM labs and factories. Eventually, with the formulation more or less set, they began looking for their first commercial application.

Vetting the technology

That first application, on GM’s flagship Corvette, now totals 21 body panel assemblies (depending on model), including doors, decklids (trunks), hatches, door surrounds, quarter panels, fenders, convertible tonneau assemblies, and coupé roof bows (read more online about how the the current Corvette also represents the first use of a new out-of-autoclave carbon composite production method in “Faster cycle, better surface: Out of the autoclave" under Editor's Picks at the right). The technology has fulfilled its promise to reduce costs vs. aluminum at all volumes: Life-cycle analyses done by CSP reportedly show that even at volumes as high as 350,000-400,000 vehicles per year, TCA Ultra Lite costs less per part than aluminum.

“In materials engineering, shaving off a single pound per car is a significant accomplishment,” notes Corvette chief engineer Tadge Juechter, “so saving 20 lb per car is monumental.”

Judges at two recent industry events seemed to agree. At CAMX 2015 in Dallas, TX, US, CSP won the conference’s Unsurpassed Innovation award. A month later, the SPE Automotive Division’s blue-ribbon judging panel selected TCA Ultra Lite as its Materials category and Grand Award winner as the year’s most innovative use of plastics at the 45th-annual SPE Automotive Innovation Awards Gala in Livonia, MI, US.

What’s next? Guha says the company is hard at work on new formulations of carbon fiber-reinforced SMC, as well as carbon composite prepreg and carbon material suitable for RTM. Key bogies are reducing offal, exploring the most efficient use of hybrid glass/ carbon reinforcement systems and finding a carbon-neutral way to recycle carbon fiber from scrap parts (that is, to
 recover fiber without burning).
 He predicts that in the not-too-
distant future, we’ll see carbon
 composites on high-volume,
moderate-cost vehicles, not just
 on high-cost, high-performance
 vehicles.

https://www.compositesworld.com/articles/low-density-smc-better-living-through-chemistry

Here are some pictures with more details showing how the 2016 changes improved the TCS Ultra Lite SMC Corvettes’ panels.

[AbqVic]

Thanks guys for the very exciting material above. The technology and its future seems to make a sub 3200# C8 very doable.

[Adrenaline Junky]

Hoping that the C8 is gonna be the lightest corvette yet


.........for a V-8