you will want something more powerful than SW to do the fea

There are lots of different ways to do it. The hard part will be predicting core shear

could you elaborate on "if every thing is under control you are going to slow." ? I don't quite understand that one. Also, we recently obtained licensing for use of Altair's hyperworks software, do you have any advice as to how we should use this software? any teams out there using altair to design their monocoques?

quote:

could you elaborate on "if every thing is under control you are going to slow." ?

That's a quote of Mario Andretti. In other words, if you're completely in control then you are not pushing hard enough...

ok....So thanks to Rellis, we now know that solidwork's FEA is not powerful enough to analyze laminate structures, so we contacted Altair Engineering in Korea, and obtained a copy of their hyperworks program. Of course there are no classes and no books on the damn program so we turn to forum members once again to ask advice. To my understanding we can model and test the carbon monocoque structure all on Altair hyperworks. Is this correct? Or do we use shells from a CAD modeler like SW and import it into Altair's software to analyze it? Does anyone have experience using Altair's Hyperworks to analyze composite structures? Thanks so much once again.


fsae.kaist.ac.kr
Aaron Park
KAIST

Hi,
Hyperworks can be quite frustrating at times and I can understand any frustration you are experiencing, but in my experience it is well worth it.
You could try using 2D elements, so a shell sounds about right (my uni uses pro/e so excuse my solidworks ignorance).
In the 2D panel on hyperworks you will find your greatest friend for composite structures in the Hyperlaminate module. It is fairly intuitive so I will leave it to you to learn about it.
Also, there are some pretty good tutorials that are included with Hyperworks and I would strongly advise going through these.

thanks a bunch

by the way how did you guys get your 2009 car ready so quickly????

Aaron, the car we have recently finished (well, not quite finished, but getting there) is our 2008 car. Because we build for the Australasian competition in November/December our build cycle basically follows a calendar year, so we started our design mid-January, so we had just under 9 months from beginning design work to having a running car. However, we built the car to be compliant with the 2009 chassis rules (or those that were proposed around this time last year) so that following the Australasian competition, we can take it further abroad, (Germany or UK being likely candidates) if the car is competitive (ie scoring over 800 points) and if finances allow.

I would do some test layups to compare to your FEA results.

greetings!!!

our team is registered for west w00t....number 27, looking forward to meeting all you in person. Just got a question though, for the monocoque, with the outside skin laid down, core placed in, and inside skin being laid down, how do you make the two skins meet/bond???? I've been building it my head for several weeks now and I just cant figure out how it is done...anyone got a quick tip on how to do this?? Once again, how to make the outside skin of the monocoque meet the inside skin with the honeycomb in the middle. Thanks a bunch

you dont put your honeycomb all of the way to the edge you need some overlap for you plies to meet back up.

If you are asking questions like this you may want to reconsider a composite tub. Might I suggest a seat first

PS great number

that was my racing number of choice if I couldn't get that one I was 127

thanks rellis, i am learning more and more how hard composite tubs are to make, and to be honest am reconsidering. Only if I could see a tub just once I would be happy. And it would answer a lot of questions, but i guess i have to try before giving up. Can any of you suggest reading or learning material on this subject? I cant seem to find anything specific to composites in automotive applications

What's wrong with bringing the outside skin over the core and then overlapping that skin with the inside skin?

We call these "close out". You have built a moulds to incorporate these have you not? If not, nothing a little bog can't conceal.

H_HH
H|#|
H|#||
H|#|`
H|#|

Where:
H - Mold
# - Core
| - Outter Skin
| - Inner Skin

Regards
Fred

quote:

Originally posted by Fred G:
What's wrong with bringing the outside skin over the core and then overlapping that skin with the inside skin?

We call these "close out". You have built a moulds to incorporate these have you not? If not, nothing a little bog can't conceal.

H_HH
H|#|
H|#||
H|#|`
H|#|

Where:
H - Mold
# - Core
| - Outter Skin
| - Inner Skin

Regards
Fred

Easier to get voids and wrinkles more complex molds and no core taper requires extremely precise core placement

Im not saying it cant be done but that would be my reason for not doing it

"I strongly discourage you from doing carbon tub for your first year. I just cant see how you can modify or fix the carbon tub in case something happens at, during or before the competition, at least in a quick way."

Repairs are easy enough but you should really consider small panel test construction first.

rob, you should elaborate more on your comment. Im interested to know and learn how to make quick and easy repairs just as i would with welding steel tubes.

Remember, some ppl out there rather buy gallons of bondo but wont spend a dime on the bondo spreader.

RiNaZ,

There are loads of books on composite repair. Granted, I haven't had enough experience or read enough of them to say that it's quick and easy, but I have my hands on Advanced Composites, by Cindy Foreman, and it overviews way to repairing composites, mostly geared towards boats and small aircraft.

Welding repairs would require at least a welder, and composite repairs would require a vacuum pump. Both require skill and experience. I guess the cure time eliminates the possibility of a "quick" repair, though, if you're already at comp and something fails.

Zhefei, yes, i know composite repair. My comment was for rob to share his experience based on his comment that repairs are easy enough.

My experience is telling me that no matter how good you are in composite, you're still at the mercy of the material and i just couldnt see how fixing composite can be faster than welding tubes.

And the context of this is in the FSAE world, not in some garage where you have all the equipment that you need to make repairs.