The materials used for lightweighting in transportation present different challenges, so selection requires careful choices, Ross Kozarsky, a LUX Research analyst and the report's lead author, told us. LUX Research conducted multiple decision-tree analyses to determine which materials are best used where, both now and 10 years from now. The decision-tree approach was designed to help automotive and aerospace companies, as well as suppliers and material developers. Kozarsky said:
Each material has its own portfolio of features, such as cost, environmental resistance, compatibility, tensile strength, thickness, corrosion, ability to absorb vibrations, and moldability. To best analyze an aircraft or an automobile, it needs to be broken down on the component level: what's the ideal material for each component?
Regardless of how much carbon fiber composites have entered into car designs such as Audi's, the biggest transportation lightweighting role in the near term will be played by high-performance metals like aluminum and advanced high-strength steel (AHSS), according to a new report from LUX Research. (Source: Audi)
AHSS and aluminum are on a similar part of the spectrum, said Kozarsky. "They are both the cheapest and offer the most incremental, rather than disruptive, performance changes. But for some applications, steel is better, and for others, aluminum is better." AHSS still offers high-volume automakers the lowest price and wide availability, so it continues to be the near-term leader. However, its limited ductility and welding can pose problems.
Because of the scale of its global giant producers, aluminum is second only to steel in cost and availability. On the report's structural materials spectrum its alloys occupy the middle ground. In many cases it's the best material for the short term, since it doesn't disrupt manufacturing patterns.
It has been interesting to see steel fight back against new materials. Legacy materials and systems benefit from technology as well as new materials. Another example is the internal combustion engine. It may get so efficient that it edges out hybrids and EVs for consumers wanting to go green.
Rob, good point. One of the "features" missing from the article is the fabrication difficulty. In aerospace and some high end applications, where the systems will last a long time, it is worth paying up front for more difficult fabrication. I think it was on this site that a new technique for welding titanium was discussed. This is just one example. Aluminum is also more difficult to weld than steel. Recall that most aircraft, which have used aluminum for a long time, are riveted. Jaguar started making the bodies of their high end XJs of aluminum. When they did that they save 500 pounds (on a 4,000+ pound vehicle). Many wondered if they would ever recover the cost of the production line changes that had to be made. As you mention, steel may end up getting better before price or process technology catches up for the other materials. In addition, steel and aluminum are eaisly recyclable.
Actually, fabrication difficulty is mentioned several times in the article, both directly and indirectly, as moldability, disruptive technology vs non-disruptive technology, as "3D components involve a more complicated, expensive molding technology" and "CFRPs are not only more expensive, but using them is also a step change difference, which is much greater than transitioning from using one metal to another metal." Regarding recyclability, it's interesting to note that Boeing has invested in composite recycling: http://www.designnews.com/document.asp?doc_id=235280
@Ann: Thank you, thank you, thank you for this article. There are some people who think that "lightweighting" means "make it out of plastic." This tends to go hand in hand with an idea that aluminum and steel are "old materials," while plastics and composites are "new materials."
The fact is that aluminum and steel technologies are hardly standing still. If you want evidence, just look at the new carburizing steels which QuesTek has developed. These alloys were developed from the ground up, starting with computational models. This is an exciting approach, which I think will bear even more fruit in the future.
Dave, thanks for the feedback. I was impressed with the thorough, detailed approach this study took to the materials decision making process. There's been a lot more news about composites than about metals and, in fact, many of the R&D efforts I've reported on are new materials. Also, I've had a tough time getting many metals companies to talk to me about lightweighting, especially in the steel industry, especially for automotive applications. So thanks for the info about carburized steel. What I'm especially interested in is structural applications and AHSS, as well as titanium and magnesium in aerospace and/or automotive apps.
Ann, is there an industry component to whether new composites or legacy metals tend to win the lightweight argument? Seems that aerospace likes components. In the auto industry is there more bias toward steel? Or am I reading this incorrectly?
Rob, there are definitely industry differences. Generally speaking, aerospace has been using composites, both glass and carbon fiber-based, for decades, first in military planes and more recently in commercial aircraft (as well as in spacecraft). Whereas in cars it's more recent and confined primarily to race or specialty cars. Regarding metals, steel doesn't figure much in aircraft because of its weight; the primo metal there is aluminum. Metals in most commercial planes still average over 50%. In Detroit cars, metals are a much higher proportion, primarily because of the cost of composites and the difficulty in adapting their manufacturing to highly automated, high-volume automotive production. All of this is a moving target.
The question still comes down to HOW STRONG IS IT? Researching a homebuilt car and the material requirements for structural strength and the weight savings aren't always there for lighter materials as you need more of the lighter material for the same strength. Cars and trucks need the strength to protect the passenger and deal with environmental factors (salt on the roads in the winter, accidents with other vehicles) while aircraft have used aluminum (and tubing ans cloth) and much more sophisticatd design to save weight ans still be strong. Imagine the cost of a Semi-Monoque car body built by riveting the layers together, but that is the approach aircraft use because weight is a controlling factor. In Automobiles weight is less of a concern, and durability and passenger protection as cars are more likely to be involved in an accident.
And how well would carbon fiber stand up to something trying to pierce it in an acceident? Steel, on the other hand, can deform and contain an object trying to piece the passenger compartment.
Smaller aircraft have used some of the composites, but a small savings on a 2000lb aircraft doesn't make much of a difference as compared to a 200,000lb aircraft so the savings does not always scale very well.
Another question is the repair of the vehicle - Stell is easy to cut and weld and repaint. Aluminum to cut and rivet ans paint. Would composites require a whole new section, and would it be available in 2 or 4 years?
And some of the chemicals rused in composites require special handling and present a whole new set of hazards to those handling them.
I'm not sure what composites you're researching, but they sound like glass fiber. Carbon fiber is another story and answers your strength questions: the strength-to-weight ratio is higher for carbon fiber than steel and even higher than aluminum. Also, I'd bet that any carbon fiber materials you're likely to be able to purchase as a home user are not the ones you can get for building military or commercial aircraft.
Ann: We have exhibited in the past few months at the following conferences and trade shows: ACMA 2012; SAMPE 2012; American Coatings Show 2012; ACS Rubber Division Energy Rubber Group Winter Conference; SPI NPE 2012; and SPE International Polyolefins 2012. So, it's just not fiberglass reinforced polyester. I am talking about all manner of inorganic and organic reinforcements used in thermosets and thermoplastics We manufacture since 1973 organometallic coupling agents based on titanium, zirconim, and aluminum chemistry - rather than silane chemistry. I have 29-U.S. Patents and 1 pending on their composition of matter and their application, and 375-ACS CAS abstracted works on the subject of the interface and their application in polymer compositions.
A class of neoalkoxy and coordinate titanates and zirconates can coordinate couple to any surface via its protons ever present on the inorganic/organic reinforcement - from carbon and aramid fiber to CaCO3 to PTFE - thus forming an impervious 1.5-nanometer chemical bridge between say the carbon fiber and epoxy. The fiber does not have to be pretreated, but can be coupled in-situ becase water of condensation is not needed as with silanes, which react with surface hydroxyls to form a silanol oligomer, which in turn condenses with the surface hydroxyl group to condense 3-moles of water, which must be removed.
The titanate or zirconate uses the resin phase to bring it to the interface and deposit 1.5-nanometer atomic monolayers thus bonding the resin to the reinforcement surface that subsequently resists aged deterioration under high pressure, high temperature, and severe environmental conditions such as 240-hr. water boil in 10% salt water. This mechanism works on all manner of carbonaceous substrates: carbon fiber; carbon black; carbon nano tubes; graphene; etc.
For example, carbon fiber reinforced methyl nadic anhydride cured epoxy composites produced by General Dynamics without zirconate will have a long-fiber tensile strength of 62 Joules, which will deteriorate to 21 Joules 240-hr. water boil in 10% salt water, while 4-parts per thousand of a zirconate [Ken-React(r) NZ(r) 97] added to the epoxy will yield 119 Joules Tensile initial and 113 Joules when similarly water boiled aged.
@sjmonte: A joule is a unit of energy, not tensile strength. Tensile strengths are customarily given in units of pascals; one joule per cubic meter is equal to one pascal. However, since one pascal is very small, it's common to use the megapascal, i.e. million pascals, as the base unit.
Could you please give us the tensile strength in either megapascals or pounds per square inch?
In any case, the strength increases you report (more than 2x dry and more than 5x wet) are very impressive. If you have been producing these coupling agents since the 1970s, why haven't they been more widely adopted? I'd expect the composites industry to be extremely enthusiastic about something like this.
The limitation of Carbon and Aramid and Glass reinforced materials - as well as nano-materials - is a lack of awareness of the ability to use zirconate and titanate and aluminate coupling agents to bond the interface of the fiber reinforcement to the polymer resin. Silanes - the material that made the Corvette possible (fiberglass reinforced peroxide cured unsaturated polyester) - have severe interfacial reaction and environmental aging issues due to the nature of their molecular bond formation.
Oak Ridge National Laboratory has developed a surface preparation method to improve joining carbon composites with aluminum, with potentially far-reaching ramifications for high-volume industrial applications.
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