Structural Rigidity, Anybody used structural foam? |
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Structural Rigidity, Anybody used structural foam? |
Beebo Kanelle |
Jan 12 2019, 06:24 PM
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#1
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Member Group: Members Posts: 248 Joined: 22-November 12 From: Houston, Texas Member No.: 15,177 Region Association: Southwest Region |
Has anybody here used structural foam on their 914 to increase structural rigidity?
Here is the original Abstract of that SAE paper 1999-01-1785 "Stability and structural integrity are extremely important in the design of a vehicle. Structural foams, when used to fill body cavities and joints, can greatly improve the stiffness of the vehicle, and provide additional acoustical and structural benefits.This study involves modal testing and finite element analysis on a Sport utility vehicle to understand the effect of structural foam on modal behavior. The modal analysis studies are performed on this vehicle to investigate the dynamic characteristics, joint stiffness and overall body behavior. A design of experiments (DOE) study was performed to understand how the foam's density and placement in the body influences vehicle stiffness. Prior to the design of experiments, a design sensitivity analysis (DSA) was done to identify the sensitive joints in the body structure and to minimize the number of design variables in the DOE Study." And the Conclusion: "The most sensitive area of the body were found to be the A-pillar, the D-pillar and their joints. With structural foam injected into this sensitive areas, the vehicle body was significantly stiffened, as shown by the increase in modal frequencies. The 1st torsional mode was most effected with an increase of 29.1% in modal frequency.The design sensitivity analysis and design of experiments described here, can be used to identify the sensitive ares of the body structure. This results are useful in the determining the best application locations for structural foam." |
mepstein |
Jan 12 2019, 06:33 PM
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#2
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914-6 GT in waiting Group: Members Posts: 19,518 Joined: 19-September 09 From: Landenberg, PA/Wilmington, DE Member No.: 10,825 Region Association: MidAtlantic Region |
Foam doesn’t have a good rep in our cars.
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Mark Henry |
Jan 12 2019, 06:34 PM
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#3
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that's what I do! Group: Members Posts: 20,065 Joined: 27-December 02 From: Port Hope, Ontario Member No.: 26 Region Association: Canada |
Peeps take the foam out of their 914's. (IMG:style_emoticons/default/popcorn[1].gif)
Rear/trunk and the rollbar have foam, consensus is it attracts rust (moisture). |
Beebo Kanelle |
Jan 12 2019, 06:47 PM
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#4
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Member Group: Members Posts: 248 Joined: 22-November 12 From: Houston, Texas Member No.: 15,177 Region Association: Southwest Region |
I understand that the foam originally used attracted moisture and was generally the cause of rusty mayhem.
This modern structural foam, appears to posses different characteristics... Amongst them, it does not retain but repels moisture. I've used commercial structural foam on large steel tanks, exposed to the elements and was amazed at its durability and performance. Then I saw the SAE paper and thought I'd ask the Gurus. Thanks for the input |
r_towle |
Jan 13 2019, 07:44 PM
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#5
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Custom Member Group: Members Posts: 24,624 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States |
Sounds interesting.
Could you post the full address to the paper? My phone wants to call that number above. |
mepstein |
Jan 13 2019, 07:52 PM
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#6
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914-6 GT in waiting Group: Members Posts: 19,518 Joined: 19-September 09 From: Landenberg, PA/Wilmington, DE Member No.: 10,825 Region Association: MidAtlantic Region |
I think it might be the same issue as trying to use adhesives instead of welding in our cars. The structure needs to be designed for the construction materials and meathods.
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mobymutt |
Jan 13 2019, 08:43 PM
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#7
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Senior Member Group: Members Posts: 553 Joined: 16-December 13 From: Kingston, Ontario, Canada Member No.: 16,770 Region Association: Canada |
In my opinion, this is something a modern OEM would do, in order to build a car as cheaply as possible. I don't see it being relevant to restoring an old Porsche -- metal is relatively inexpensive for us.
Maybe if there was a foam that absorbed rust... |
Beebo Kanelle |
Jan 13 2019, 08:44 PM
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#8
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Member Group: Members Posts: 248 Joined: 22-November 12 From: Houston, Texas Member No.: 15,177 Region Association: Southwest Region |
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Tdskip |
Jan 13 2019, 08:57 PM
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#9
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Advanced Member Group: Members Posts: 3,697 Joined: 1-December 17 From: soCal Member No.: 21,666 Region Association: None |
Thanks for posting.
Agree on foam being a source of horrors historically but I think this deserves a second look today. Sprayed inside a properly rust proofed cavity (with venting) I think this could be a viable option for people who don't weld. The structural improvements all the car makers are chasing can't be arrived at via more metal due to weight issues - I believe this is part of their solution. All that said - someone else can go first. Grin. |
Beebo Kanelle |
Jan 13 2019, 09:11 PM
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#10
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Member Group: Members Posts: 248 Joined: 22-November 12 From: Houston, Texas Member No.: 15,177 Region Association: Southwest Region |
I'm also looking for some articles by Mike Kojima - He foamed a 300ZX! Since then I've been reading more and more about the benefits... it appears that the 8# foam offers the best results.
On the matter of applying this technology to a 914, I think I'm going to try it. I just don't see any downsides... yet I also am going to get rid of the targa roof and replace it with a hard roof. The idea is to make the chassis as rigid as possible without the use of a roll-cage. |
Tdskip |
Jan 13 2019, 09:24 PM
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#11
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Advanced Member Group: Members Posts: 3,697 Joined: 1-December 17 From: soCal Member No.: 21,666 Region Association: None |
I'm also looking for some articles by Mike Kojima - He foamed a 300ZX! Since then I've been reading more and more about the benefits... it appears that the 8# foam offers the best results. On the matter of applying this technology to a 914, I think I'm going to try it. I just don't see any downsides... yet I also am going to get rid of the targa roof and replace it with a hard roof. The idea is to make the chassis as rigid as possible without the use of a roll-cage. Please keep us posted and document what you do. We should ideally come up with some independent and repeatable measure or it's all subjective. |
Beebo Kanelle |
Jan 13 2019, 09:44 PM
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#12
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Member Group: Members Posts: 248 Joined: 22-November 12 From: Houston, Texas Member No.: 15,177 Region Association: Southwest Region |
Well firstly, I just settled with the USPS (after 2+ years!) and can now straighten my car and put it back to factory specs. Then we will head into the great unknown. I'll be sure and keep everybody abreast of anything and everything.
BTW, There was a dark blue 914 that had a hardtop (w/sunroof!) from a 944 grafted on. Does anybody here own that car? When last I read about it, it was for sale in Las Vegas, I believe.. It would be interesting, from a historical perspective, to see how that 914 has held up. and maybe do an A-B comparison, if possible. Anyway, if anybody finds out anything please post it, as I read these forums constantly. |
Dave_Darling |
Jan 13 2019, 10:05 PM
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#13
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914 Idiot Group: Members Posts: 15,048 Joined: 9-January 03 From: Silicon Valley / Kailua-Kona Member No.: 121 Region Association: Northern California |
The build was (sort of) documented here. I say "sort of" because some parts were skipped...
Here's the thread: http://www.914world.com/bbs2/index.php?sho...=76305&st=0 It has been sold on here a number of times; TC seems to keep buying it back and then re-selling it. Here is a thread about AA fabricating a 916 type roof: http://www.914world.com/bbs2/index.php?sho...c=66687&hl= --DD |
Beebo Kanelle |
Jan 13 2019, 10:10 PM
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#14
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Member Group: Members Posts: 248 Joined: 22-November 12 From: Houston, Texas Member No.: 15,177 Region Association: Southwest Region |
The build was (sort of) documented here. I say "sort of" because some parts were skipped... It has been sold on here a number of times; TC seems to keep buying it back and then re-selling it. --DD Is there any data / observations as to how its dynamics differ from a conventional 914? Anybody here driven it? Is it for sale? I'd love to hear about it. Thanks! |
falcor75 |
Jan 14 2019, 12:26 AM
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#15
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Senior Member Group: Members Posts: 1,579 Joined: 22-November 12 From: Sweden Member No.: 15,176 Region Association: Scandinavia |
Modern car bodies are built from steel that is already rust protected from the mill and then the fully welded chassis is dipped in an ED coat bath to further protect it and seal all welds etc. I think that any foaming operations are performed after the ED coat which means that to do it on a 914 with the same level of protection you'd need to acid dip and e-coat the chassis. The foam wont perform as intended if all it bonds too is surface rust which sadly coats the inner panels on most of our cars.
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carr914 |
Jan 14 2019, 06:09 AM
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#16
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Racer from Birth Group: Members Posts: 121,107 Joined: 2-February 04 From: Tampa,FL Member No.: 1,623 Region Association: South East States |
BTW, There was a dark blue 914 that had a hardtop (w/sunroof!) from a 944 grafted on. Does anybody here own that car? When last I read about it, it was for sale in Las Vegas, I believe.. It would be interesting, from a historical perspective, to see how that 914 has held up. and maybe do an A-B comparison, if possible. I have owned it twice - the roof was the best part of the car. When I got it the 2nd time, the carbs had been gone thru my MotorScheister and it was a different car. It's in New Hampshire now or as far as I know |
Beebo Kanelle |
Jan 14 2019, 07:53 AM
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#17
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Member Group: Members Posts: 248 Joined: 22-November 12 From: Houston, Texas Member No.: 15,177 Region Association: Southwest Region |
BTW, There was a dark blue 914 that had a hardtop (w/sunroof!) from a 944 grafted on. Does anybody here own that car? When last I read about it, it was for sale in Las Vegas, I believe.. It would be interesting, from a historical perspective, to see how that 914 has held up. and maybe do an A-B comparison, if possible. I have owned it twice - the roof was the best part of the car. When I got it the 2nd time, the carbs had been gone thru my MotorScheister and it was a different car. It's in New Hampshire now or as far as I know Thanks for the info. I always thought that car was a brilliant interpretation of what the 914 was supposed to be, had production continued. Did you notice any difference in driving characteristics? Did the durability of the chassis / car change? Any other observations of note? |
Dave_Darling |
Jan 14 2019, 10:48 PM
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#18
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914 Idiot Group: Members Posts: 15,048 Joined: 9-January 03 From: Silicon Valley / Kailua-Kona Member No.: 121 Region Association: Northern California |
I have owned it twice ... Only twice? It seemed like more.... (IMG:style_emoticons/default/biggrin.gif) --DD |
jss297 |
Jan 15 2019, 06:35 PM
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#19
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Newbie Group: Members Posts: 5 Joined: 2-April 12 From: New Hampshire Member No.: 14,326 Region Association: North East States |
I have owned it twice - the roof was the best part of the car. When I got it the 2nd time, the carbs had been gone thru my MotorScheister and it was a different car. It's in New Hampshire now or as far as I know Yes, it is in NH - or technically in MA in storage. Bought it from TC with plans to put a 3.2 in it, but life got in the way. I bought another 914-6 conversion to keep me entertained until I have time to address this. |
Beebo Kanelle |
Jan 15 2019, 08:43 PM
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#20
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Member Group: Members Posts: 248 Joined: 22-November 12 From: Houston, Texas Member No.: 15,177 Region Association: Southwest Region |
I have owned it twice - the roof was the best part of the car. When I got it the 2nd time, the carbs had been gone thru my MotorScheister and it was a different car. It's in New Hampshire now or as far as I know Yes, it is in NH - or technically in MA in storage. Bought it from TC with plans to put a 3.2 in it, but life got in the way. I bought another 914-6 conversion to keep me entertained until I have time to address this. Can you share any differences in driving the hardtop? Anything noticeable? |
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