| This company's foam was used by Mike Kojima in an article in Sport Compact car magazine to "stiffen" the frame of an already (arguably) plenty stiff TT coupe. I have a VERY floppy framed convertible that everyone keeps saying I should spend the $150 or so on 5 "kits" of this stuff to completely fill my frame with foam to "improve it's handling and "stiffen the frame". I have a hard time believing this stuff works to actually "stiffen" a frame. Reduce noise, and vibration, yes, benefit? yes....stiffen? reduce frame flex? improve handling????????? I really think not. Especially in this case. Perhaps welding my doors all the way shut, might help some. a 10-point roll-bar, yeah, but some foam in my frame that's not within a 5-1 strength ratio??? why should I bother? I wrote an e-mail to the company and asked for the most qualified rep to comment on it's strength, and also to qualify how the testing was done-- to make it so they could claim on their website-- the foam was appropriate for "structural automotive" as well as NHV applications. here's the response:
>>>>>>>>>>>>>>>>>>>
"Michael, Your inquiry regarding Autoseal Foam has been directed to me. All the road
testing was done by Mike Kojima. The tensile strength is 46 psi (317 kPa)
and compressive strangth is 23 psi (158 kPa). Hope this helps. Art Goldman
ITW Foamseal
Sales Manager"
>>>>>>>>>>>>>>>>>>>>>>>>
I responded"
Thanks, so Autoseal was not orginally designed for structural, correct? _MWS"
>>>>>>>>>>>>>>>>>>
he sayeth: "Michael, AutoSeal is formulated as a 2K cavity fill foam system." (not as a "structural" foam system at his own omission _MWS)
>>>>>>>>>>>>>>>>>>>>>> Again, for you engineering nerds, no holds have been barred from my brother the shuttle designer's reponse to this, and if you can't understand what he's saying, then don't bother to respond (or grouse about the verbage). If you're into designing structural fiberglass and composite sandwiches and still don't understand what he's saying, then dust off your books, may the gloves come off... And if you can't handle my scientific approach to this and can't understand why I'd rather not squirt $150 worth of foaming jizz into my frame just because people say it works, and J-spec guys do it on the weekends becuase someone told THEM to do it, with NO proof, then you're missing the point of this friendly little excercise. Not one person has been able to comprehensively prove to me that a foam like ITW Foamseal, that states RIGHT on the package it's made ONLY for Noise Harshness and Vibration, can improve handling THROUGH the stiffening of the frame itself. You folks that squirted ITW into your frames have to be able to say you somehow TESTED your frame itself and it came up stiffer, AND it held up over time. here's my brother's reponse:
>>>>>>>>>>>>>>>>>>>>>>>>>> "The comment on a "2K cavity fill foam system" doesn't mean anything to me.
I guess cavity fill means it fills cavities. What does the 2k mean? (guve him a break guys, he doesn't build houses or cars, he builds aircraft -MWS) The strength quoted below sounds low for your application by a factor of 10 (!!!! -MWS)
or more. If I used that foam in applications I'm used to it would crumble.
I think that 2-3 sheets of what guage was it, 18 guage, steel would be far to stiff
to benifit from this foam. When I design an aircraft frame I have to size a
stiffener to be stiff enough to force a node in the frame or the frame will
buckle the stiffener and in turn the frame will buckle. If your friends are
quoting a benifit maybe it is accoustic. Maybe the foam dampens out certain
structural vibrational modes. I still maintian that if the frame bends
enough it will load up the foam and the foam will crumble. After a time it
will be dust. The dust will be trapped in the parts of the frame that
deflect the most. It will be trapped by the uncrumbled foam in the parts of
the frame that deflect the least. Are these guys touchy about being questioned? Some of these guys on lists
can really flame people who don't know ropes of the list and have no
patience for those who don't exercise the rigor they do. I haven't put any
rigor into my claims. I don't have enough information to do that anyway. Ask them what the ultimate and limit compressive allowables are for the
sheet steel being used? What is the thickness of the gage used? What is a
typical crossection? Could it be idealized as a circle? What diameter?
What do they claim the foam is doing for them? Ask Art Goldman whether the numbers he quoted were ultimate or limit? Good Hunting,
Tom"
Crash Test Dummy(tm)
"taking it on the chin so you don't have to..." |
