Ansys - Explicit Dynamics Meshing/Solver help

[RDelaCourt513]

Hi all,

I am a relatively new Ansys user and am currently analysing a space frame chassis with means of exploring the structure deformation upon impact of rigid surface.

I have created the chassis by using the 'weldment' feature on Solidworks and imported the Solidworks assembly (chassis and wall) into ANSYS Mechanical. (For the initial study I have only included a section of the Rollcage so I can understand what it is that I am doing first before I go deeper).

Why is my mesh in the form that is shown in picture 2 where a combination of mesh elements are used? Is there a better way to set up the mesh? (tubes are hollow (30mm OD,2.5 Thick)). Would it be easier to shell model the chassis?

Lastly (and I really would appreciate this a response to this) Can someone explain to me how I should set up the 'step controls' (max no. of cycles, End Time, Initial time step, Min time step and max time step.

Currently my solver times are ridiculous, For the entire Rollcage geometry in this explicity dynamics solver with everything set to 'programme controlled', the study is expected to take 100 hours.

AMD FX(tm) - 8350 Eight core processor
16Gb Ram


velocity is going to be set to 50,000mm/s

Thank you guys in advance and I apologise, In the past I have always researched what to do before seeking help but I am in a rush with this and time is starting to get the better of me.

Thank you,

Ryan.

 

[FEA way]

Your mesh doesn't look good. You should make it more regular. Shell approximation is a very good idea. Remember that in explicit analyses element size may influence computational requirement significantly. The same applies to the analyzed time period. It's usually advised to speed up events artificially whenever possible. Finally, make sure that you use parallel processing so that your computational resources are fully utilized.
You may also consider using mass scaling.

 

[RDelaCourt513]

Thanks for the advice, I have enabled parallel processing so that My CPU is using more available processors.

As for the meshing side of things...I will need to do some more research on the subject.

I have found that by modifying the geometry (Solidworks weldments) in "Spaceclaim" the mesh is much more uniform.

Thank you for the advice FEA Way.