Clean Technologies Drive Automotive Parts
Some manufacturers are employing unique design methodologies that exploit the advantages of advanced materials to reduce part weight or control emissions. Others see a future where vehicles run on electricity.
By Mark Shortt
Editorial Director, Design-2-Part Magazine
There's a revolution going on in the automotive manufacturing world. Much of it is being driven by a combination of forces - namely, technological innovation and market economics - that have been activated by concerns over environmental pollution, global warming, and dependence on foreign oil. The federal government has provided a push by funding research and development efforts to develop advanced vehicles and by passing legislation (the Energy Security and Independence and Security Act of 2007) that provides loan guarantees to manufacturers of parts for fuel-efficient automobiles. There's even a multimillion dollar competition open to teams from around the world to prove that they can design, build, and bring to market 100 miles-per-gallon or equivalent fuel-economy vehicles that people want to buy.
The X PRIZE Foundation (https://www.xprize.org/), an educational nonprofit prize institute, created the Automotive X PRIZE (AXP) competition “to inspire a new generation of viable, super-efficient vehicles to help break our addiction to oil and stem the effects of climate change.” Designed to incite innovation by tapping into competitive and entrepreneurial spirits, the X PRIZE has attracted dozens of competitors, including Aptera Motors, Desert Fuel, Phoenix Motorcars, and Tesla Motors, to name a few.
In this new automotive revolution, innovative companies are deploying unique software to exploit the advantages of advanced materials that can reduce part weight or control diesel exhaust emissions. Cleantech’s influence is also evident in the proliferation of high-power electronics that have contract manufacturers wrestling with the problems of heat management. In many cases, it’s about the use of specialty manufacturing processes that can cost-effectively and rapidly deliver the types of parts—conductive heat sinks, base plates, and diesel particulate filters—seeing increased demand for their ability to solve new issues or meet higher standards.
The automotive industry’s drive to achieve greater fuel economy and lower greenhouse gas emissions has created huge needs for lighter parts that don’t sacrifice strength. To meet these needs, carmakers are increasingly calling for parts manufacturing technologies that maximize the advantages of lighter, stronger materials, like carbon fiber or extruded aluminum. Virtually every major automaker is also now actively involved in developing a hybrid gas-electric vehicle, and many newer start-ups are pursuing the even more disruptive goal of putting on the road a battery electric vehicle that runs without the traditional internal combustion engine.
As these vehicles emerge, electric drive systems are intensifying the need for thermal management components, such as heat sinks and heat exchangers that aid in cooling high-power electronics. Electric drive systems are also powering another, different kind of race, one that’s taking place before any of the participants hit the road: the race to become the first company to mass produce, on a cost-competitive basis, a lithium-ion battery in the United States. Their performance proven in cell phones and laptops, lithium-ion batteries are widely viewed as a potentially game-changing technology for automotive manufacturing—one which, if safety issues are resolved, could jump-start the commercial production of hybrid and electric vehicles.
Already used widely in sports and recreation equipment, carbon fiber composites are emerging as a valuable advanced material for aerospace, medical, and automotive structural applications. Advanced carbon fiber composite materials provide a combination of high strength and light weight that can help automakers achieve their goals for reduced vehicle weight and fuel consumption. But they can also be produced with a number of other high-performance properties, including resistance to high-energy impact and corrosion, and the ability to be machined to close tolerances. DiMora Motorcar, a Palm Springs, California-based designer of luxury cars, is using them to build the chassis and roof assembly of its Natalia SLS 2 sport luxury sedan.
Contract Manufacturer Maximizes Advantages of Carbon Fiber Composites
Proprietary Analysis Methodology is Key to Developing Optimum Part Designs
Quatro Composites, (now AIM Aerospace) a division of Tec Industries L.L.C., is a contract manufacturer that designs, engineers, and manufactures carbon fiber composite components for various industries, including aerospace, medical, wind energy, and automotive. Headquartered in Orange City, Iowa, the company also has a technical development center in Poway, California, where it employs its proprietary OptiPart™ design process to optimize the structural performance of carbon fiber components. Quatro Composites uses a variety of processes, including bladder molding, compression molding, and autoclave and ultraclave™ processes, to engineer and manufacture parts with complex geometry.
Because carbon fiber composites have a higher stiffness-to-weight ratio than metals, they make for stronger, lighter parts that can increase fuel efficiency by up to 30%. They also provide design flexibility by enabling the manufacture of pliable parts as well as complex, detailed shapes that hold tight tolerances on structural interfaces. Examples of Quatro’s work for the automotive industry include two hollow bladder-molded parts: a carbon fiber strut brace for a BMW engine, and a carbon fiber cold air intake system. Both parts use prepreg material—the carbon fiber is “pre-impregnated” with an epoxy resin material.
Last year, Quatro Composites became a technology partner with DiMora Motorcar to support DiMora’s development of its Natalia SLS 2 sport luxury sedan. Quatro contributed a design parameter analysis that enabled DiMora to refine the design of its “radical chassis,” a carbon fiber-based structure that adds strength and substantial weight savings to the vehicle. At Quatro’s Technical Development Center, a series of finite element analysis (FEA) tests were performed on the Natalia chassis design. The company’s proprietary OptiPart™ methodology was then used to develop an optimum product design for improved performance characteristics for what is being called “the world’s first hand-built, $2 million, 16-cylinder production automobile.”
According to Quatro, the primary goal of the analysis was to achieve optimal torsional and bending stiffness of Natalia’s revolutionary chassis, while also minimizing weight. OptiPart™ was useful in identifying areas where the stiffness, strength, vibration characteristics, and crash performance properties could be improved.
“Quatro Composites has an impressive understanding of the properties of carbon fiber technologies and the innovations they facilitate,” said Alfred DiMora, founder and CEO, DiMora Motorcar, in a prepared statement. “Their experience in aircraft design is directly applicable to the Natalia SLS 2, as we integrate aerospace technology developments as much as automotive innovations. Their analysis both validated our design and identified places where a minor change would yield a major improvement in stiffness or other characteristics. They are an important part of the DiMora design development team.”
The OptiPart™ method “uses mathematical techniques to produce an optimized shape and material distribution for a given loading condition and for a variety of material models,” according to Quatro. To illustrate OptiPart’s effectiveness, the company’s development engineering manager, Rob Westberg, used an example of a carbon fiber composite part that provides a 60% weight saving versus a part made from 6000 series aluminum. While 40% of the weight savings comes from the conversion to a composite part, the other 20% is a result of the design optimization process, he said. OptiPart™ reinforces the advantages of carbon fiber composites by putting a higher percentage of load-bearing fibers in the direction of the load path.
“OptiPart™ contributes to weight reduction because it helps us to know where to put the material,” says Westberg. “It grows the structure to the loads. You don’t have areas of the structure that aren’t really being utilized. It’s driven by the loading conditions, the stiffness and strength requirements, and it tells us what the fiber angle should be.”
Instead of approaching the design process in a conventional way, beginning with CAD, Quatro performs finite element analysis (FEA) up front, before CAD. By making structural performance the design driver in the concept stage rather than later in the development process, OptiPart™ produces a part geometry “that’s been developed analytically, rather than intuitively,” says Westberg.
“The optimization may put fibers in places that you may not think are the best places,” he explains. “When you put all of the constraints and design goals on top of each other, it may come up with shapes and stiffness that you’re not expecting. But it will minimize the material in the areas that aren’t contributing.”
Quatro developed the OptiPart™ methodology in-house, using a combination of software and empirical design curves for certain loading conditions that the company uses, according to Ken Gamble, vice president of composites technology and co-founder with Doug Roberts, the company’s vice president of sales and marketing. “Some of it’s experience-based, some is driven by design curves,” says Gamble.
Looking toward the future, Gamble is enthusiastic about the strength and weight savings that can be achieved with carbon fiber composites. “The one barrier that’s going to be tough in automotive is price,” says Gamble. “The new material is expensive in price per pound. But we’re confident the industry is going in that direction. As fuel economy becomes more of an issue, it becomes easier and easier to justify these large weight savings.”
Creating a New Image for Electric Drive
The development of electric drive vehicles that are fun to drive could deliver the knockout punch needed for vehicles with little or no emissions to become commercially successful. San Carlos, California-based Tesla Motors, Inc., is striving to do that and more with its development of the Tesla Roadster, scheduled to go into production this year on a limited basis. The 100% electric Roadster is unlike most other electric vehicles: it’s a sleek-looking sports car that reportedly goes from 0 to 60 mph in under four seconds. The Tesla Roadster incorporates a lightweight extruded aluminum chassis, but its biggest innovation—and biggest challenge, according to the company—is its battery pack. Functioning as the car’s “fuel tank,” the lithium ion battery is said to be designed to provide multiple layers of safety. It’s also light, durable, and recyclable.
Lithium-Ion Battery Cell in Development for Chevrolet Volt
Battery will be used in E-Flex Electric Drive System
Under the terms of a contract announced last August, General Motors Corp. and A123Systems, Inc. will co-develop cells using A123System’s Nanophosphate™ battery chemistry, with the objective of obtaining a long-lasting, safe, and powerful battery for use in GM’s electric drive E-Flex system. The agreement is expected to expedite the development of batteries for both electric plug-in vehicles and fuel cell variants of the E-Flex architecture.
“Breakthrough battery technology will drive future automotive propulsion, and the company that aligns with the best strategic partners will win,” said Bob Lutz, GM vice chairman of Global Product Development, in a statement announcing the co-development agreement. “That’s what is so important about this deal. Whether you’re talking about the Chevy Volt, a fuel cell, or even a plug-in hybrid such as our planned Saturn Vue, we need to understand the fundamental battery cell performance.”
A123Systems, of Watertown, Mass., will develop battery cells to meet the specific requirements of GM’s E-Flex system. The company, a developer and producer of patent-pending Nanophosphate™ lithium ion batteries, is considered a forerunner in the development of nanophosphate-based cell technology, which, compared to other lithium-ion battery chemistries, is reported to provide higher power output, longer life, and safer operations over the life of the battery.
The E-Flex electric vehicle architecture was first shown in the Chevy Volt concept car revealed in 2007. For average commuters driving 40 miles, the Chevy Volt will use zero gasoline and produce zero emissions. According to GM, it “could nearly eliminate going to the gas station altogether.”
“The Chevy Volt will lead the automotive industry in a new direction,” Lutz said. “We see a future where vehicles run on electricity and are equipped with clever ways of making electricity on board, making us less dependent on gasoline. It’s the next great paradigm shift in our industry, an opportunity largely due to the rapid advancement in battery cell technology by companies such as A123Systems and LG Chem.”
In 2007, GM awarded two contracts for advanced development of battery packs, which require the integration of multiple battery cells, to Compact Power, Inc. (CPI), a subsidiary of Korean battery manufacturer LG Chem, based in Troy, Mich.; and Frankfurt, Germany-based Continental Automotive Systems, a division of Continental A.G., a tier one automotive supplier. Under these agreements, one contract was awarded to CPI, which will use battery cells developed by parent company LG Chem. A separate contract was issued to Continental, which will use the cells being co-developed by GM and A123Systems.
“A123Systems and LG Chem are both top-tier battery suppliers, with proven technologies,” said Denise Gray, director of GM’s Energy Storage Devices and Strategies. “We’re confident one, or possibly both of these companies’ solutions will meet our battery requirements for the E-Flex system.”
According to David Vieau, CEO and president of A123Systems, this type of battery will be advantageous in other transportation industries as well.
“We’re talking today about the Volt and implications that it will have on the electrification of passenger vehicles, but the technology goes a lot further than that,” Vieau said. “The weight, size, safety, and performance of these batteries have implications on all transportation, including hybrid buses, trucks, and aircraft.”
Founded in 2001, A123Systems currently manufactures over ten million cells annually, and is said to be the world’s largest producer of batteries with nanophosphate chemistry. Most of these cells are currently used in rechargeable power tools. The company’s proprietary nanoscale electrode technology is built on initial developments from the Massachusetts Institute of Technology. According to the company, its Nanophosphate™ technology enables its batteries to deliver previously unattainable levels of power, safety, and life. The batteries are applicable to a wide range of industries, and are said to remove many traditional technology constraints to provide OEMs expanded flexibility in system design.
Last October, A123Systems completed a $30 million round of funding that will be used to increase production capacity for new contract awards for hybrid electric, plug-in hybrid electric, and extended-range electric vehicle designs. Significantly higher demand for the company’s products within the past year has prompted A123Systems to open a new, state-of-the-art manufacturing site for the company’s Automotive Class Lithium Ion™ batteries. The new site was built to support TS-16949 quality systems in addition to the company’s leading-edge lithium ion manufacturing technology. It is also designed for large scale handling of nanomaterials, advanced particle control equipment, and the clean room environments needed to support the stringent manufacturing and quality requirements of the automotive market.
“We continue to scale our production-proven and cost-effective designs to meet demand as we expand our presence in the automotive, aviation, and hand-held power tool markets,” said Vieau. “We have vertically integrated production from key raw materials to finished cells, incorporating best practices at every level to deliver high quality products with superior performance.”
Design Methodology Speeds Nano-engineering of Materials for Emissions Control
In nations throughout the industrialized world, the consistent establishment of progressively stricter emissions-reduction standards has generated the need for a method to rapidly develop chemical catalysts that can be used to control emissions. One of the most innovative materials design methodologies currently being used is Nanostellar, Inc.’s Rational Catalyst Design methodology, which combines computational approaches with targeted experiments to accelerate the development of new emissions control materials. Rational Catalyst Design enables Nanostellar to obtain "a fundamental understanding of important chemical reactions and material properties under realistic operating conditions," according to Pankaj Dhingra, president and CEO of the Redwood City, California company. "This knowledge is then used to guide the creation of new products, addressing a variety of nanotechnology and chemistry-related issues with a sound fundamental understanding, less experimental resources, and higher speed," wrote Dhingra in an e-mail to Design-2-Part.
By helping Nanostellar gain a fundamental understanding of the surface chemistry and properties of nanomaterials, Rational Catalyst Design enables the company to develop, at unprecedented speeds, nano-engineered alloys that function as catalyst materials to reduce exhaust emissions and increase the effectiveness of precious metals in catalysts. The company's process employs a unique combination of algorithms, software, synthesis processes, and testing methodologies.
“Consumers are demanding cleaner air and more fuel-efficient methods of transportation, said Pankaj Dhingra, CEO of Nanostellar, Inc., in a statement released by the company. “As more automotive OEMs roll out clean-diesel vehicles in the next three to five years to address that demand, they’ll need catalyst materials that are both higher performing and more cost-effective than traditional materials.”
Nanostellar believes that the Rational Design methodology will fundamentally alter traditional materials research by enabling the rapid and cost-effective development of complex new materials. The methodology is not expected to be fully developed for another 10 years or more, according to Dhingra. But the company envisions that full development of the methodology will eventually enable chemists to computationally design materials that are targeted for specific application requirements, and predict their behavior through sophisticated simulation software.
"This will dramatically reduce the need for extensive lab work and, therefore, the time and cost required for materials design," Dhingra wrote in the e-mail. "The impact of Rational Design on the practice of chemistry is expected to be analogous to the impact that EDA (electronic design automation) has had on electronic circuit design (enabling complex circuits to be designed and tested computationally at a fraction of the time and cost required to do so by hand), or to the impact that fluid dynamics modeling has had on aircraft design (eliminating, for example, expensive, time-consuming wind tunnel testing)."
Nanostellar was one of 39 visionary companies from around the globe to be honored in January by the World Economic Forum as a 2008 Technology Pioneer. The company is following its founders' vision that the Rational Catalyst Design methodology would enable the use of less-expensive precious metals, such as palladium and gold, to control diesel exhaust emissions. Nanostellar is applying the technology to accelerate the development of new nano-engineered materials that replace the more expensive and scarce platinum materials traditionally used.
The company's first-generation product, launched in mid-2006 and based on a platinum and palladium alloy, reportedly achieved 25-to-30 percent higher performance than commercial pure-platinum catalysts. Customers have been using the product for several diesel aftermarket applications. In April of 2007, Nanostellar introduced a diesel emissions control material, NS Gold™, which independent testing determined to be "15-to-20 percent better than Nanostellar's first-generation platinum and palladium alloy catalyst," the company says. The NS Gold material, said to be the first use of gold as an oxidation catalyst in diesel emissions technology, combines the use of gold with the precious metals traditionally used for emissions reduction-platinum and palladium. But by reducing the requirements for these significantly more expensive metals, Nanostellar reduced the costs for the catalytic converters in which they are used, while capturing more than 20 percent higher noxious emissions
The company has initiated several programs with automotive manufacturers and has targeted commercialization for as early as this year. One global OEM has reportedly qualified Nanostellar products for its next-generation diesel vehicles in 2010. The company also recently stated that it plans on using Rational Catalyst Design for other applications, including catalysts for biofuels
"We have recently initiated activities to computationally model rhodium and molybdenum sulfide catalysts used to convert synthesis gas (which is the product of gasification of biomass, coal or natural gas) into ethanol," Dhingra stated in the e-mail. "The objective is to understand simpler reactions (e.g., ethanol catalysis) and then move on to more complex reactions required for conversion of synthesis gas into biodiesel."
Composite Base Plates Boost Reliability of High Power IGBT Modules
CPS Technologies Corporation (Norton, Massachusetts) manufactures aluminum silicon carbide (AlSiC) metal-matrix composite base plates for the insulated-gate bipolar transistors (IGBTs) used in high-power traction, power control, and hybrid electric vehicle (HEV) power systems, as well as fly-by-wire applications. The company also manufactures AlSiC pin-fin coolers for liquid cooling in hybrid electric vehicle IGBT applications. Both parts—base plates and pin-fin coolers—are used to manage thermal load and heat output to keep electronic systems functioning reliably.
The low isotropic coefficient of thermal expansion (CTE) value of AlSiC-9 (8 ppm/°C: 30 – 100°C) is compatible with the thermal expansion value of the die or substrate used in IGBT applications. Because AlSiC's substrate-compatible CTE reduces mechanical stresses on the IGBT die and substrates that are induced by thermal power cycling, it improves reliability of substrate attachment and reduces die cracking failures.
“We manufacture a lot of these parts for IGBTs, all related to energy management,” says Mark Occhionero, senior research scientist and vice president of sales and marketing, CPS Technologies. “They go to traction, or anything related to electric motion. A lot our parts go into transportation, high-speed rail, and subway systems. They are also used in hybrid electric and fuel cell vehicles.”
The device-compatible thermal expansion coefficient of AlSiC also eliminates the need for stress compensation material layers that are required in copper (CTE = 17ppm/°C) baseplate assemblies. By eliminating this need, the AlSiC baseplate simplifies assembly and reduces the thermal resistance for AlSiC systems. As a result, AlSiC systems have equal or improved thermal dissipation over copper baseplate assemblies, the company says.
“Copper is a great thermal conductor, often used for dissipating heat,” says Occhionero. “But it has a very high thermal expansion coefficient. So it makes it very difficult to put your dies on top of the substrate because it will cause the substrate—or die—to crack.” In high-power applications (> 1200 V/ 400 A), IGBT modules that are assembled with AlSiC baseplates are found to have a service reliability of “many tens of thousands of thermal power cycles over copper equivalent systems.”
Its light weight (1/3 that of copper) makes AlSiC a suitable cooling material for weight-sensitive IGBT applications. AlSiC also has higher strength and stiffness than copper, which, combined with its lightweight nature, makes AlSiC assemblies more tolerant of shock and vibration.
CPS Technologies employs a near net-shape fabrication process to produce the AlSiC composite material and fabricate the product geometry, allowing for the design of IGBT base plates with a dome profile. By improving thermal interface contact with cold plates and coolers, the geometry bolsters AlSiC’s advanced thermal management qualities.
For more information on Quatro Composites (now AIM Aerospace), visit https://www.aim-aerospace.com/.
For more on A123Systems, visit www.a123systems.com.
For more on Nanostellar, Inc., visit www.nanostellar.com.
For more information on CPS Technologies Corporation, visit www.alsic.com.
For more on DiMora Motorcar, visit www.dimoramotorcar.com.
For more on Tesla Motors, visit www.teslamotors.com.
This article includes information from newswires.
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