beam elements?

You are using the wrong FEA tool. Try NEiWorks or NEiNastran. Even Cosmos/M will do beam elements. CosmosWorks is not for long slender thinwall parts.

i wish i could say that was good news to me, but considering that thi is for a research project and my deadline is fast approaching i ma have to try and be really creative with this. I wish I could giv nastran a shot, however having the funds of a typical student (ak being broke) i was lucky to purchase the student version o solidworks/cosmosworks....which by the way they assured me would mee my fea needs perfectly!!! With that said I hopped over to nastran' site and even if i were to find the extra $$ for the student version I don't think it could quite cover all the models I need t study....my school is of no help on this one either...as a physic major for some reason my department has a severe attitude when i comes to engineering topics....as a matter of fact I was EXTREMEL lucky to get my research approved (luckily one professor thought i was a good idea). In other words, since I'm not studyin superconductors or nuclear physics I get zero help from the school a far as resources go. Any suggestions on what direction to head fro here would be GREATLY appreciated

Well, as far as lessons go,you are getting a great value.

KEY POINTS: CAD expertise does not equate FEA expertise. Sales people are not good resources for analyzing your FEA needs.

The reason the mesh will not complete is probably related to running out of memory when trying to mesh the model at a super fine resolution or it may be having problems with aligning element nodes. I had similar issues with small IC device models until I learned more about what the FEA program was actually doing.

CosmosWorks recommends using shell elements for thin features such as your tubular frame and in fact that method would be recommended by anyone for this particular problem. The reason being that you don't need a volume mesh to come up with a good plot. You can shell the entire frame and specify the different thicknesses on different shell areas. A good FEA Modeler/Engineer is always trying to optimize the mesh model so that it's efficient (research "FEA convergence"). You don't want too much unecessary elements because this increases the amount of resources you need to solve it and also increase the chance of errors due to a more complex mathmatical problem. I would suggest starting a study using shells only and use a rough setting for the mesh resolution. If that works, run the study and identify the areas in which the stresses show up. You can then go back and use mesh control to make those particular areas a denser mesh and get more accurate plots. You can also send me your model and I can let you know if I have any success with meshing it. Just let me know and I can give you my gmail address.

-Jeff

p> I am having a definte problem within cosmos works when it comes to

Thanks for the tip. You're abolutely correct about the memory. It i to the point where I simply can't create any finer of a mesh due t memory limitations and for that reason i had previously explore shell meshing. Now, having only previous FEA experience with an ol student version of ANSYS in which the number of elements wa extremely limited, the idea of attempting shell meshing seeme itimidating, but on the contrary it was easy enough to follow th principles and techniques used by COSMOS. However the problem wit the shell mesh lies in the fact that while most of the frame meshe well, even with a relatively large global element size, some member simply do not mesh at all and "disappear". The members in questio are mostly areas in which there are bends, or members tangent to ben members (i.e. the portion of the member directly before or after th bend). Attempting to correct this I applied mesh controls to th areas that were not meshing, and also tried applying contols to th members that were not meshing as well as any adjoining members....en result....nothing changes....the pieces that wouldn't mesh stil won't. Could this have to do with some type of gap condition? Theoretically there shouldn't be any gap, but being new to solidwork I suppose it's possible I have done somethign else wrong. An insight? By the way thanks for the offer to look at my frame mes for me, I just may have to take you up on it if I can't sort thi out.....I suppose I'd at least like to know if I'm going about thing all wrong

If you're stuck with solid mesh and running out of memory, you might still have options.

Run your analysis with a coarse mesh to get an idea of you hotspots. Consider carefully both areas of high stress AND areas with high stress gradient (large change over small distance). Then refine your mesh in the hotspots.

Every time you refine, resulting stress values will most likely increase. Keep refining until the resulting stress values taper off. Many of the big-boy FEA packages can do this automatically. Very important. It's called "convergence".

Believe it or not there are some free FEA codes that will do what you want. By the way, what is the goal of your study?

I have attempted to refine the mesh to find some convergence in th numbers. Problem is.....thus far i can't even establish a goo enough mesh in the first place. Either it is too fine of a mesh t create or some members are left out etc... The ultimate goal of th study is actually rather simple...see which frame members/section se a signifigant stress under a set of static load conditions. Jus attempting to spot a trend in the load patterns of the members, mayb determine if some would be more well suited if they ha thicker/thinner walls, different material type etc...All in all th results don't have to be super accurate, it would just be nice to se some reasonable stresses and deflections

When you have singularities in your mesh, refining will only make them worse. The tool you have really isn't appropriate for what you are trying to do.

TOP is right - the tool you have is not the right tool for the job. Jointed tubes are best analysed as beams, plain and simple.

Try googling for =A3free fea software". Anything that analyses trusses or frames could do the job.

Martin

I typically do FEA on solid models (engine parts) but when I do a race car chassis I use beam elements.

If you are going to do the surface analysis in CosmosWorks, make sure you have "split" all the surfaces where surfaces intersect (see Solidworks help, "split lines"). It's a pain in the tukos, but the only way I have found to check that all surfaces are split correctly, is to split as many as you can find, then mesh the part and look along all the edges to see where the meshes do not align on surfaces joining at an edge. If they do not align, then the surface meeting the edge of another, needs to be split. You also need to watch where edges end in the middle of a surface. That surface needs to be split so there is a point where the other edge ends. Another way to check that the mesh aligns at all edges is to run the analysis every once in a while and check where surfaces pass through stiffeners (easier to see if you scale up deflection appearance). This will also show you where surfaces need to be split.

I believe this is the reason why you are seeing surfaces disappear after meshing.

If this has confused you, I can send a part that I have had to split all over the place to get it to mech correctly. This could give you an example of what I'm talking about.