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The Next Big Thing(tm): Metal Foam!
January 31, 2010 8:51 PM   Subscribe

Afsaneh Rabiei has created a new steel foam and this stuff is going to be everywhere within our lifetimes. In the article: "inserting two pieces of her composite metal foam behind the bumper of a car traveling 28 mph, the impact would feel the same to passengers as impact traveling at only 5 mph"...at 1/3rd the weight of solid steel.
posted by swimming naked when the tide goes out (38 comments total) 13 users marked this as a favorite

 
I'm behind anything that damages the car rather than the passengers in the car...but will the auto industry pick up on this?

THAT is the big question.
posted by hal_c_on at 8:59 PM on January 31, 2010


Huh. People have been talking up metal foams since the 80's, I wonder what's different this time - the article says bubble size but doesn't give a lot of detail why it never worked before.
posted by GuyZero at 8:59 PM on January 31, 2010 [2 favorites]


That does seem like it could be used in everything. There's not much information about how it's made. Does anyone know if this could be made using recycled steel?
posted by Burhanistan at 8:59 PM on January 31, 2010


this stuff is going to be everywhere within our lifetimes

So many unanswered questions, no idea if this is commercially viable or not.
posted by stbalbach at 9:02 PM on January 31, 2010


Video on the foam.

Patent for the above.
posted by zabuni at 9:06 PM on January 31, 2010 [1 favorite]


It's aluminum with hollow steel spheres embedded in it.
posted by jjj606 at 9:14 PM on January 31, 2010


Here's an even more in depth video.
posted by zabuni at 9:15 PM on January 31, 2010


It's made of people!
posted by Artw at 9:17 PM on January 31, 2010 [3 favorites]


Actually, the patent indicates that it can be made with a wide range of metals and alloys.
posted by Burhanistan at 9:19 PM on January 31, 2010 [1 favorite]


The video says that this is hollow steel spheres in an aluminum matrix. It's an interesting mix. I think it is analogous to micro balloons(hollow glass spheres) in epoxy.
Aluminum honeycomb is the current energy absorber of choice for crash structures where the cost can be justified. I don't see something like this working very well in a car because it would still be too heavy to be just energy absorption and probably couldn't be relied on as a normal structural component for the long fatigue life a car needs. But that all comes from the test data. Why can't these reports give us the stress-strain curves? Then I could actually comment on its current usefulness.
posted by TheJoven at 9:24 PM on January 31, 2010 [1 favorite]


By Nate DeGraff, North Carolina State University Engineering Communications

Not saying this isn't cool, but I'm withholding judgment until there's an article about it that's not a press release from the communications staff of the engineering school Dr. Rabiei works at.
posted by Nothing... and like it at 9:32 PM on January 31, 2010 [1 favorite]


Not much meat in the press-releasy materials readily available, she's published several articles on the development over the course of five years going by her NSF award page, if you really want to dig into the research (and have access to a decent science library).
posted by nanojath at 9:34 PM on January 31, 2010


If I were Jaws from The Spy Who Loved Me, I would ask for my hollow steel spheres in an aluminium matrix to be served to me in a choc-mint flavour. It's the bubbles of nothing that make it really something!
posted by turgid dahlia at 9:36 PM on January 31, 2010 [1 favorite]


The confusion of energy and force in zabuni's in depth video bothers me, especially since it comes from someone who's actually developing the material. Their 'energy absorption test' appears to be just a hydraulic press which is a force device. It is true that they have something that is softer than a solid block of stainless, but a solid block of silly putty would have much better results in that test than even the metal foam. It is a pointless test that tells you nothing of the energy absorption properties of the material, just its yield strength. They should be doing drop tests onto the material(constant kinetic energy) and measuring the deflections to determine the average force exerted.
posted by TheJoven at 9:37 PM on January 31, 2010 [5 favorites]


I'm in favor of any technology that enables me to drive faster and more recklessly with no repercussions to myself or my property.
posted by Ritchie at 9:42 PM on January 31, 2010 [5 favorites]


Aluminium Foam?

That's the ticket, laddie.
posted by Esteemed Offendi at 9:51 PM on January 31, 2010 [6 favorites]


I thought she sounded Iranian.

Dr. Afsaneh Rabiei received her B.S. from the Department of Metallurgy & Material Science at Sharif University of Technology in Tehran, Iran in 1986.

Suck on that, people who like to tar all Islamic societies with the same women-aren't-allowed-to-do-anything brush.

/derail
posted by UbuRoivas at 10:03 PM on January 31, 2010 [2 favorites]


It is a pointless test that tells you nothing of the energy absorption properties of the material, just its yield strength. They should be doing drop tests onto the material(constant kinetic energy) and measuring the deflections to determine the average force exerted.

Absolutely, And it's only a third of the weight of steel - block steel, apparently. Are we supposed to translate that to a steel structure of comparable deflection under load? Or ability to prevent force transfer as implied (in a roundabout way)?

It is steel balls in some kind of aluminium matrix, so I don't see how it can be lighter than aluminium even to any significant degree (if at all). It's very confusing what it actually does that's so spectacular. Has it been compared to a steel rubbed structure as used in current vehicle design in terms of crash absorption? What about ease of working? Can it be formed into panels easily? What about in bending? Just filling a bumper with steel bubbles is a very low tech, backwards, step in crash safety.

Rough traffic accident calculations show that by inserting two pieces of her composite metal foam behind the bumper of a car traveling 28 mph, the impact would feel the same to passengers as impact traveling at only 5 mph.

What a pointless statement that is so totally open to interpretation as to be meaningless. A 5mph sudden stop is pretty damn big with no deformation. Whereas one that crushes the bumper is not so severe at all. How does this material integrate with the existing structure, and how can that be optimised? It sounds like they have just taken their energy absorption number and added it to an existing car accident pulse/trace and made a journalistic/optimistic leap, to me. So much so, that I call bullshit numbers without this being clarified. Using such a radically different material in terms of structural strength would involve a major redesign and so any tests or numbers not considering this element are worthless. Especially when you consider that there are no solid steel structures in a car (like being compared to here) it is all box structures and there is no information as to how useful or easy to work with in terms of pressings this material is.

If they find a way to easily recycle carbon (and similar) composite structures, those are a teeny fraction of the weight of a comparable steel structure and look more worthy of research in terms of vehicle (and especially aero) applications. I don't get why this steel bubble stuff would be better for a vehicle bumper, for example, over expanded foam with some honeycomb Aluminium/fibre structure in it or similar with a ribbed/complex steel structure behind it. Maybe I am missing something and the advantages will be more apparent later on.
posted by Brockles at 10:27 PM on January 31, 2010 [1 favorite]


It would be interesting to know how this material's strength, stiffness, weight, cost, crash energy absorption, recyclability, manufacturing energy cost and end-use design flexibility compare with those of fibre reinforced thermoplastics.
posted by flabdablet at 10:38 PM on January 31, 2010


It is steel balls in some kind of aluminium matrix, so I don't see how it can be lighter than aluminium even to any significant degree

The steel balls are hollow.
posted by flabdablet at 10:39 PM on January 31, 2010


Journalists doing a poor job of summarizing someone's research?

Unpossible!

Seriously, there are probably a scad of uses for this stuff, and while I've not go digging through all her papers, I'd imagine most of the research has gone into coming up with a controllable and economic way of producing the stuff. Nobody cares about that! It has to cure cancer, or kill terrorists, or something cool!
posted by Kid Charlemagne at 10:52 PM on January 31, 2010


The steel balls are hollow.

I realise that. But they are also ickle and tiny. So a small amount of steel (presumably enough to resist the casting process and retain the air gap) with a small amount of air inside is not going to be considerably lighter than aluminium unless there is much less than 1/3 the volume of steel in the space taken up by the ball and its air (aluminium is 3 times lighter than steel). You'd only achieve this with a relatively large ball.

But being as the article itself states it is 1/3 the weight of Block steel (so the same weight as Aluminium) you only have a slightly stronger Aluminium alternative - presumably because there is enough wall thickness in the steel balls to improve the crush strength.

So you have something that is good in crushing - but not necessarily good in terms of crash absorption - that is the same weight as Aluminium but not as workable. It's just not that impressive without some extra information or examples of REAL application. It is, at present, a block of 'stuff' that doesn't have the major advantages that it claims to have with only a slight investigation.

For example, if it did absorb the energy in a car crash as it claims, the occupants would still be injured because the stuff is too strong - the main reason for the crumple zone is to slow down the accident for the occupants by deforming large areas slowly to reduce the crash impules (ie max decelleration g). Stopping the car with less crush doesn't actually help the occupants in any way. Until they can show us a worked frame structure to mitigate this, then we can judge how impressive it is. Until then, it's a hearty 'meh'.
posted by Brockles at 11:08 PM on January 31, 2010 [2 favorites]


In the future, your home will be a chrome foam dome.
posted by Ratio at 11:56 PM on January 31, 2010


As I remember from physics class, the sphere is the strongest structure, or maybe it's an elliptical egg. Those forms resist deformation from the outside.
What is the (formable) structure that is EASILY collapsible? Energy absorption is the key to reducing force to the structure you don't want harmed, (the passenger compartment).

My Dad used to make frames for SPCA formula race cars. They had "boxes" of framed metal on the front and sides that were designed to collapse (and absorb energy) without damaging the main passenger frame.

I think that spheres, however hollow, would still move like they were solid in a high impact situation. If the strata (aluminum) was filled with aggregate (collapsible structures) that might be something to look in to. I'm just not sure what those structures might look like, and how you could form them without making them at a smaller (and more costly and technical) scale than making steel bubbles.
posted by Balisong at 12:05 AM on February 1, 2010


As I remember from physics class, the sphere is the strongest structure

From a pressure (ie uniform loading from all directions) perspective, yes. From directional loading? Nope. Not at all. This is why buildings aren't made of spheres, but usually a series of I-beams and triangles.

What is the (formable) structure that is EASILY collapsible? Energy absorption is the key to reducing force to the structure you don't want harmed, (the passenger compartment).

I don't understand the first bit, but energy absorption with respect to time is the key for crash safety. You can have all the energy absorbed by the crash structure, but if it does it incredibly quickly, the decelleration of the occupants (rather than that of the car) is not safe - your example of the racing car shows that; this is why racing drivers wear full, very tight, 2 or 3 inch 6-point harnesses and HANS devices to prevent their bodies moving around when these decellerations occur.

The issue arises in a passenger car that the occupants are not - in the proper sense - restrained to the vehicle effectively. So if you stop the car too quick (like restricting all the deformation to the bumper section with magic steel foam) then the seat belts and air bags won't be enough to stop the occupants having a 30mph impact with the dashboard or seats in front of them - the crash just happens to the occupants, rather than the car. Reducing the crash impulse (peak decelleration g) is more of an important aim than ultimate energy absorption.
posted by Brockles at 12:15 AM on February 1, 2010 [2 favorites]


For example, if it did absorb the energy in a car crash as it claims, the occupants would still be injured because the stuff is too strong

wah? Energy absorbed by the foam, think metal Styrofoam here, is energy that does not get imparted to the victims. These foams have been around for a long time. This particular advance seems aimed at reproducibility and density, ie. making very light weight foams consistently. So in a vehicle the foam is the crumple zone rather perhaps or in addition perhaps to designing weak points into the frame for controlled compression.
posted by caddis at 1:05 AM on February 1, 2010


wah? Energy absorbed by the foam, think metal Styrofoam here, is energy that does not get imparted to the victims.

Only up to a point. That point being how you manage to slow the occupants after you've absorbed all the energy in the structure. Engineered weaknesses allow a sufficiently slow decelleration to stop the occupants being rammed through the windscreen. The amount of damage that a car sustains (ie the entire front end being trashed) is actually a very good thing in terms of gradually decellerating the occupants - it's not just the ultimate energy absorbed, but the length of the crumple zone for a given force. There is a point at which a material is too strong to give adequate protection in terms of reducing the crash pulse.

There is nothing in this article to suggest any sort of improvement in crash safety from this stuff without significantly more demonstrated properties and characteristics - as several people have pointed out. At present it's all a bit witch doctor 'look how well it crushes' fancy videos with little presented substance or demonstration of engineering realism, so proclaiming the next great bumper structure is premature, to say the least.

Or, at least, it is only showing us a fraction of the story. In theory, a 'super absorbing strong foam' is awesome, on cursory glance, but it is not by any means a definite win. There's more to it.
posted by Brockles at 1:24 AM on February 1, 2010


It's not as strong as you think, and that is the point for energy absorption. I doubt it will replace your beloved engineered weakness type crumpling without adding undue volume to the vehicle. Wrap the whole vehicle in styrofoam to absorb impact forces, except in vehicle crash type forces styrofoam is a joke. Perhaps this stuff is not. I agree with your seeming frustration with this being pitched as a panacea. Yet it does also seem to offer some interesting engineering possibilities for energy absorption.
posted by caddis at 1:37 AM on February 1, 2010


It's not as strong as you think

Then perhaps comparing it to a 3 inch block of steel wasn't their best approach. I'd prefer this kind of product to be engineered to some degree to a compatible application, as that seems like a more realistic way to promote possible utilisations.

The wild claims here with little way of backing smacks of 'funding request propaganda' to me.
posted by Brockles at 1:55 AM on February 1, 2010


There is a grim calculus to vehicular impacts: a certain amount of energy has to be shed within a certain time (/distance), and the survival of the participants requires the peak power to be strictly limited. This is achieved by coupling the passengers tightly to the engineering structure (=car), then very carefully controlling the deformation rate of that structure. New materials are well and good, but their ability of absorb energy or deform is really not that important - if a single material doesn't offer the power-time curve you need you can always create a composite structure that does. The best a sexy new material can do is reduce the cost of creating appropriate deceleration profiles, which is nice for the auto industry, and even possibly for the consumer who gets a cheaper car, but not really much of an advance in the state of the crash-survival art.
posted by overyield at 4:17 AM on February 1, 2010


this stuff is going to be everywhere within our lifetimes.

Do you work for the manufacturer?tm?
posted by OmieWise at 4:45 AM on February 1, 2010


The way researchers tend to judge one another is thus.
What institution is the researcher at? North Carolina State - decent.
How many publications has the researcher had and in what journals? 28 published articles, 4 books in niche subjects - good for a mid-career researcher.
From what perspective is this announcement coming? Has several publications on composite metal foams, has two "Articles to appear" on this subject. Has several other research subjects in recent publications. Not too good a perspective. It seems as though the more important information about this is still forthcoming.
From what source is this announcement coming? A communication spokesman from her institution. These people are supposed to fluff up whatever research is going on at the institution for the positive publicity, for alumni and for donors. Nearly the worst possible source.
There could be something here. But it will have to survive the compression test of peers.
posted by dances_with_sneetches at 5:31 AM on February 1, 2010 [1 favorite]


I think this was posted because of the unstated human interest angle, that she is an Iranian immigrant woman who's making a contribution to our country.
posted by mert at 6:05 AM on February 1, 2010


What an odd assumption.

That would be patronising and presumptive on many levels. Why is it a contribution to your (presumably US) country, and nor just a material science discovery of general interest?
posted by Brockles at 6:25 AM on February 1, 2010 [2 favorites]


this stuff is going to be everywhere within our lifetimes.

Do you work for the manufacturer?tm?


No, and I don't know that you won't be hit by a bus next week.

Thanks for the snark, returned in kind.

...

I think this was posted because of the unstated human interest angle, that she is an Iranian immigrant woman who's making a contribution to our country.
posted by mert at 6:05 AM on February 1 [+] [!]


What an odd assumption.

That would be patronising and presumptive on many levels. Why is it a contribution to your (presumably US) country, and nor just a material science discovery of general interest?


It *is* an odd assumption. I read the article elsewhere without a pic of the researcher and didn't clue in she was female until I found a copy of the article on a more reputable site (the one I used). I posted it simply because it's a very cool tech. The "(tm)" was the only human interest angle, speaking to mass commercialization that I believe will follow this technology.
posted by swimming naked when the tide goes out at 7:12 AM on February 1, 2010


Rough traffic accident calculations show that by inserting two pieces of her composite metal foam behind the bumper of a car traveling 28 mph, the impact would feel the same to passengers as impact traveling at only 5 mph.

Yeah, but what they didn't mention is that at 29 mph, the impact would feel the same as a 28.5 mph one. And at 30 mph? Impact feels like 60 mph.

But seriously, one data point? That graph could look like anything.
posted by sentient at 8:43 AM on February 1, 2010


The only question I have is corrosion. Foam structures expose many thin-walled surfaces, and even a closed-cell aluminum matrix would be vulnerable. And once corrosion starts, it would just race through the foam. Unless they're intending that the foam would always be well-encapsulated.

Otherwise I think it's a great idea, and it could have alot of applications.
posted by Artful Codger at 10:22 AM on February 1, 2010


mert she is an Iranian immigrant woman who's making a contribution to our country.

That's not a completely empty assumption, but she did earn her PhD in Japan. She may have sentimental reasons (eg family, friends, lifestyle, familiarity of surroundings) to live in the USA, but like very many scientists, she seems to be a Citizen of the World. The reason why, is project funding.

The stereotypical professional life-cycle of a high-achieving academic scientist is more-or-less as follows (plenty of exceptions exist of course): they do an undergraduate degree at a single university, often with an exchange/study abroad semester, sometimes while doing paid and/or volunteer work that makes use of their academic knowledge. High achieving undergrads often seek out--and are sought out for--positions tutoring, doing lab work, and assisting more senior academics in various ways.

Having completed the undergrad degree they typically go on to a project-driven honors or masters or postgrad diploma (it's a bit more difficult to generalize postgrad study internationally - the typical Australian science academic does an honours year). This is where funding first becomes relevant; a more senior academic has applied for funding in some field, to investigate or produce something or other, and the project is considered to be within the scope of an honors etc student rather than a doctoral student.

This is another opportunity to change institution and change country. Students will have researched scientific areas of interest to them and/or where project funding is available and/or where they can afford (often by scholarship) and are willing to go and will attempt to balance these goals as best they can. This is a process which will repeat at each of the subsequent career levels.

Having completed honors etc, and developed further professional and academic network links, the student will go on to a doctorate. A doctorate is traditionally supervised closely by a small number of senior academics, and again is undertaken to advance an area of scientific enquiry where project funding is available for it.

Project funding is buffet, menu, and occasionally custom-cooked: senior academics will push to have projects funded which are then offered to interested doctoral students; third parties such as private industry will fund projects for which supervisors and students are found and matched-up by university administration; interested doctoral students will shop around to find senior academics who have or are able to find funding for projects the student is interested in; senior academics who don't have suitable project funding will seek out other senior academics to supervise the doctorates of their honors students; and some students are actually able to take the lead on finding funding for their own PhDs and shop around for a suitable supervisor. This last is most commonly done by scientists working in private industry, who intend to use their private industry projects as PhD material, and rightly so. Again, potentially in other institutions, potentially in other countries.

Teaching is an option pretty much from Honors upwards, though most science lecturers hold PhDs. A research-oriented academic with a fresh PhD will tend to look for work under a more senior academic (research assistance), and may teach classes and do tutoring. The funding search continues, the gaining of experience continues, and at some point the academic will be successful in a funding application and will be able to lead (or co-lead) their own project that students they supervise will assist.

In summary if you really want to be a top-flight academic researcher, especially in science, you must be prepared to move, often several times. You may be lucky enough to score a project where your friends and family live, or be sufficiently able to make that happen for yourself, but at some point as an academic researcher you must decide whether you'd prefer to stay where your family and friends are or you'd prefer to advance your career.
posted by aeschenkarnos at 2:49 PM on February 1, 2010 [2 favorites]


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