Finite Element Analysis on Concrete Canoe Hull

[sjsucanoe]

Hello Everyone,
I'm on the hunt for someone who can import my AutoCAD dwg or dfx into their structural analysis program and perform some basic loading calculations for a concrete canoe and hopefully out put some nice graphics for the report!!
This is for San Jose State University, American Society of Civil Engineers, Concrete Canoe Team. Anyone who can help, please conctact me at sjsucanoe@hotmail.com so I can email you the file and loading details.
Thanks

[marshmat]

I don't think I've ever seen a detailed FEA simulation done on a concrete canoe before. Some of the teams do it to make pretty pictures but from what I've seen, there isn't a great deal of structural optimization that goes into these. After all, they do weigh 300-500 pounds....
Being at SJSU, I would think your engineering department would have at least one copy of either Algor or Ansys that you could play around with? With appropriate prep work, both can handle AutoCAD models.

[Raggi_Thor]

Does your concrete have any significant strength in tension at all? Do you have pre-stressed reinforcement?

[sjsucanoe]

Our concrete has very minimal tensile strenth. To over come this we use two layers of a carbon fiber mesh as our primary reinforcement. This year we will also be incorporating pre-tensioned cables.
Basically, we dont truely need FEA done to optimize the hull design. An analysis is required for the report to show that we actually engineered the reinforcement and rib placement.
This site has the top 5 national design papers if you care to take a look at them to see what they have on their analysis page.

http://www.engr.wisc.edu/studentorgs...ign_Papers.htm

[Raggi_Thor]

I looked at Wisconsin's pdf, quite impressive presentation :-)

I can only advice you to get some free or very low cost educational licenses.
Alibre Design Professional includes a version of Algor Designcheck, limited to analyze one part at a time. That may be good enough for your purpose.
I am not neutral here, since I sell Alibre in Norway :-)

[sjsucanoe]

I downloaded a demo version of alibre, the problem is that I don't know how to use it. I am very good at learning software so I should be able to figure it out, but I would rather find someone experienced so that the results come out fairly accurate and correct.

[Raggi_Thor]

Alibre is not the best hull modeller, but yu can draw a few sections as vertical sketches, insert a plane for each sketch, and then Loft the hull and the Shell it.
You can also make the hull in Rhino and open it in Alibre.
Or you can use Freeship or Delftship and export to Iges.

I don't think Algor is included in the trial version.
You should get some info from the nearest dealer, I think :-)

[Raggi_Thor]

I started to think about concrete and carbon and other reinforcement.
You probably have som rules regarding the minimum quantity of concrete you have to use?

[sjsucanoe]

There is no rule about the minimum thickness of our concrete. We already build it about as thin as we can with the set gradation curves. In order to achieve a strength that is durable enough for the stresses that the canoe is faced with, we typically build about 1/2" thick using 3 layers of concrete and two layers of reinforcement. We put a 1/8" layer of concrete, then carbon fiber, then a 1/4" layer of concrete, then carbon fiber, then 1/8" layer of concrete. We then sand it to reduce skin friction. We then apply about three or four layers of a concrete sealer. No paints are allowed because people used to build the entire thing about 1/4" thick and then use some military grade aircraft carrier paint to add strength with out adding much weight. The rule book is fairly long.

For the analysis, basically all I am looking for is for someone to take my surface model, apply loads of 4 people, 3 people, and 2 people, then say ok there is x amount of tensile and compressive stress at these locations and include a nice picture or chart.

Then I can take that and use it for the analysis section of our report.

[Raggi_Thor]

OK, I thought you would get a lighter boat with as much carbon as you can afford and then just a thin layer of concrete for cosmetics :-) But that would be cheating, I guess.

[sjsucanoe]

well, that can potentially work, but we used the carbon fiber as a fabric mesh, it wasn't hardened..but if we could harden it and make a carbon fiber hull, then just apply a thin layer of concrete...hmmm. I am going to have to read the rules very carefully on that one...

[UCDCanoe]

I'm from the Davis team, and I read up on your post. We're in a similar situation as well, and I'm looking for some good CFD programs. Personally I feel more analysis should go into the hull design, because we all know that two layers of carbon fiber @ 0.5" concrete works.

The prior post suggesting to use Rhino is a good one. Personally I use AutoCAD and Rhino to create the initial model. It looks very beautiful and is very fast.

I heard some SJSU people are going to Seattle. We will be too, I look forward to seeing you guys!

[nero]

Can you mix expanded polysteren beads into the concrete? This would allow for a thicker core to help spread the reinforcements.

This type of concrete is used in europe to insulate and provide a foundation for laying floor tile over wood floors. 1 bucket of cement + 1 bucket of river sand + 2 or 3 buckets of beads. Beads get mixed into the wet cement.

[Raggi_Thor]

I definitely think you need some rules saying how much concrete you have to use to call it a concrete canoe

[UCDCanoe]

There are specific rules on the proportions, gradations, etc.. the rules are pretty flexible though so there's room for innovation such as:

aggregates must meed ASTM C33 (anything conforming to that curve is an aggregate)

the rules can be found on concretecanoe.org

by the way.. would anyone know how to run a reliable CFD analysis on ANSYS?