I created a new simulation project called 'Wing Structure Demo':
More of my public projects can be found here.
Refining a Wing structure
Using FEA and a Wing Structure Script
The idea of this project is to use the scripts I created in OnShape and FEA in SimScale to iteratively refine the structure of a wing. The script used are the new Profile Generator Script, Multi-Spline and the new Wing Structure script. All three of these scripts can be found here. Please use the new Profile Generator, it includes the old Profile Generator and the old NACAXXX scripts with many improvements.
The process I’ll be using is one which involves performing a CFD simulation to obtain the pressure values to import as load values into the FEA simulations. I will perform a set of different basic designs evaluate the strengths and use these to predict the best design. I will then further refine the geometry with lightening features (such as removing material from the ribs) to get my final design.
3D Model in OnShape
The first step to this is to create the wing. this can be done by drawing the wing shape, then placing aerofoil profiles in key points and using multispline to loft between them:
Finally, I used a boolean operation to create the cut which is for the aileron. At this stage, I duplicated the part studio as this was the geometry I wished to use for my CFD simulation.
Next, I wanted to create a base structure design, this gives me a starting point and something to compare the other designs too. The general steps to create the wing structure is:
- Key point the Ribs
- Multi-Rib between the key pointed Ribs
- Add Stiffeners (I-beams, Box spars and Bars)
- Finish the design (boolean, delete, fillet and lighten as required)
With this base setup, I can add to and modify it to produce the design iterations.
CFD Simulation for Load Conditions
To simulate the load of the wing I am putting it through three flight conditions, starting with straight level flight, then take-off load and finally manoeuvring at max load (the force we want to be able to bank at without the wings falling off).
Since this write-up focuses on the structural design I will just show the results but you are more than welcome to check out the project for more info on how it was meshed and simulated.
The first thing to note when taking the results is the convergence, although residual convergence was very good we can see that the actual convergence looking at the result control item for force was less pleasing:
I, therefore, needed to increase the termination residuals to simulate until the result control items steadied.