Mesh and Force

[joes]

Hi

 

Still struggling a bit with simulation studies in solidworks. As in my last post (Materials) I have a dome structure that I want to apply a pressure to. I dont want this to be uniformly distributed as it has to simulate wind pressure at a certain point.

 

so my questions are: -

 

1. How can I apply a pressure to one area (do i have to sketch the area on the part first)

 

2. I want to create a mesh for the dome with the mesh being 'fine' around the areas most likely to be effected by the stress and 'coarse' around the other areas. Not sure how to do this.

 

Again any help would be appreciated

 

Thanks

[shift1313]

Which version are you running? If you are running SimulationExpress you are able to make changes to mesh but its for the entire part and not one area.

 

1. The feature "Split Line" is what you want to look into. You can use the split line tool to create divisions on your part making selectable faces of the part rather than the whole part. In your case a projection split line will probably be the best, you will need to create a line or sketch that would be perpendicular to the direction of force and use the projected split line. Ive uploaded an image where you can see the sketch(dashed line) and the projected split plane on one face which is now selected(so you can see it better). This face would now be selectable in an analysis and you would use the plane as a reference for direction. (note: setting your load as a pressure will assume the force is perpendicular to the face so in this case on a dome you would not be accurately modeling this, plane reference for force direction is only available with force and not pressure). For your split line i would just draw a single line in your top plane that bisects the dome and project this as a split line. It will "split" your dome in half.

 

2. the second and third screen shot show you some simXpress windows. when you are prompted to run with default settings you need to click no, this is how you change the mesh size with simXpress.

 

If you are dealing with the full version of the simulation and flow software you can do aero studies where you put the entire mast assembly in a wind environment and it can spit out an FEA model. I do not have this nor have i used it so if thats what you have i cant help.

 

 

I suggest you go to your help menu, Solidworks tutorials, then click on design analysis and simulationxpress. This will give you the basics. I have seen tutorials on simulations online but i dont remember where that was, ill have to dig for it.

 

 

edit, didnt have to dig that far:

 

http://www.solidworksmedia.com/SimulationXpress/index.html

[joes]

Thanks again that was really helpful. I have managed to sketch an area and project it on to the face of the dome.

 

My version of simulation does seem to be a little different though, i have come across a way to generate the mesh with something called mesh controls.

 

I have not run the study yet but hopefully it will be a step in the right direction.

 

Thanks for your help!

[shift1313]

what version do you have? When you open up a simulation the first page on the pop up is a welcome page. There should be a link on that page to online help tutorials which will walk you through all the basic steps.

 

SW08 used Cosmos

SW09 will be simulationXpress (these are the lower level simulation packages)

 

The next level is called SimulationProfessional i think.

[joes]

I must have simulation professional I dont thinnk it is xpress. I have found the online tutorials though, so will give them ago.

[shift1313]

If you do have Pro i would recommend that you do a flow study. You can place your mast in a "wind tunnel" environment and get a more accurate analysis.

[joes]

when I start a new study i have these options: -

 

static

frequency

buckling

thermal

drop test

optimization

nonlinear

linear dynamic

pressure vessel design

 

I am running a static study at the moment. Is the wind tunnel simulation a sub option from one of the above. If not i dont think i have it, shame.

[shift1313]

do me a favor and go to your tools menu, then down to add-ins and show my what add-ins you have available. You should have simulationPro and FlowPro I think. Like i said i dont have these so im not real farmiliar with them.

[joes]

File Attached of tools - add ins options.

 

I dont think i have the option to run simulation flow?

Doc1.doc

[shift1313]

hmm, when you drop down your tools menu, what do you click on to start your simulation(or do you have the sim toolbar open?) Because i have the 1st level i have flowXpress and simXpress.

[joes]

Yes when i drop the tools menu down i have found floXpress. I have had a quick look at it and it does not look as though i can apply a wind pressure externally to the object.

 

I'll see if i can find any tutorials on it and try and work it out.

 

Thanks for your continued help.

[joes]

After looking a bit further into it i think i would have to draw a contained enviroment for my dome to represent the wind tunnel?

 

I am using floXpress (i believe there is another version called floworks?)

 

Not had any luck finding tutorials in solidworks, do you know of any? if not are there any external tutorials out there?

[shift1313]

flowxpress is the lower version. You are only allowed 1 inlet and 1 outlet, there needs to be a pressure drop between these. The resolution for this isnt great either. Its designed for things like flow through a valve. FlowWorks is the one I was talking about with the "wind tunnel" type testing. FlowXpress will only give you flow traces and tell you things like max speed, but will not give you any forces.

 

So you will need to calculate the forces your part will see and run a study in your SimulationPro

[joes]

Ok thanks. I have managed to draw up a wind tunnel and place my part inside it. I have run flowexpress and as you say it does not calculate forces acting upon my part.

 

You dont know of anyway to obtain the floworks add in do you?

[shift1313]

contact your solidworks retailer directly. I work for an educational institution and the package is very reasonable for me but if you work for a non educational institution expect a few thousand for the package.

 

One issue that happens with the "wind tunnel" thing in flowXpress is interation with the walls. As you probably found out it will only plot up to 50traces. If you make the "tunnel" too larger you get very poor resolution around your part, if you make it too small then you get interaction with the walls which is not a realistic scenario.