New to FEA and Mecway

MattBPhelps

I am excited about learning FEA and using Mecway. I am modeling hailstones impacting different surfaces. So I need to create different models of hailstones, which can be surprising complex, and I would like to build a library of different hailstones to impact a variety of roofing materials. I will also need to build a library of different roofing products. Each hailstone and roofing product will consist of different layers and each layer will have different engineering properties for Young's modulus, possion ratio, density and thermal coefficient.

Building these two libraries is one of my first objectives.

My next objective is to model the impact of one on the other. Hailstone impacts are driven by gravity, wind, and aerodynamic drag. I am unclear how to have the hailstones impact my various roofing surfaces and how to make the impact occur at different speeds. Typically we use terminal velocity which I can compute for specific hailstones in specific conditions. But how do I get Mecway to model this impact at the desired velocity? How do I model the results on the hailstone AND the roofing material? I have seen videos on YouTube of this being done with Solidworks.

Any help, suggestions or constructive criticizum would be most appreciated.

Thank you,

Matt

Victor

Hello Matt

For a library, you can use File -> Import to combine a 2nd model with one that's already open.

For a solid with multiple thin layers, it'll probably be best to have compatible meshes on adjacent layers so they can form a single mesh without bonded contact. For that, you may need to make the mesh manually if it's a simple shape (sphere?) or perhaps using a CAD model/assembly and the 3rd party Gmsh mesher.

If it's shell elements with layers, there's a laminate material type that allows you to specify layer properties on the same mesh.

For impact, use Nonlinear Dynamic Response 3D analysis type and the CCX solver.

Initial velocity isn't available through Mecway's UI but you can specify it by entering the CCX card by hand under CCX -> custom model definition with something like:

*INITIAL CONDITIONS,TYPE=VELOCITY
Node_Selection_Name,3,-1.234

Where 3 is the direction (Z axis) and -1.234 is the velocity in m/s.

MattBPhelps

Hello Victor,

Wonderful! Thank you very much. I am anxious to get started. I will post an update after I build my first model.

Thank you

MattBPhelps

I would like to add an element of a sphere with multiple concentric rings. Starting from the center and working outwards. I would like each layer to have different properties. Can I save the element to the existing "add element" shapes? Also, I have been looking for Nonlinear Dynamic Response SD and what I find is Nonlinear Static 3D. I do have Dynamic Response 3D, but not Nonlinear Dynamic Response 3D, in the analysis settings. Am I looking in the wrong place?

Thank you,

MattBPhelps

Opps, found it! Had to click CCX first!

Thank you,

Victor

You can't change the elements in Add element. For concentric rings or solid shells, you could either:

• Build them up from a spherical core using Mesh tools -> Extrude
  
• Mesh tools -> Revolve a straight line of line3 elements into a circle, then again into a sphere.
  
• Use Mesh tools -> Create -> Plate mesh -> Concentric circle with 2 quadrants then revolve into a sphere.
  

DaveStupple

Matt, I think you will have to set up a contact (Loads & Constraints>New contact) between the two surfaces. I initially assumed that two mesh entities would interact as they do in the real world, and I was surprised that they just pass through each other unless you tell them not to. Good luck with this, I'd be interested to see how it works.

Dave