Static Analysis of a Composite Propeller
Static Analysis of a Composite Propeller
(OP)
I am using FEMAP/NX NASTRAN to model a composite wind turbine propeller. The primary goal is to optimize the twist of the propeller blades at given rotational velocity. I will be applying shear, moment and centrifugal loads statically while adjusting the layup accordingly.
I am new to FEMAP and not sure if there are any unique features to help me model the loads correctly. I was planning to apply the loads with 10 bands of elements equally spaced from the center to the tip (to start anyway..)
Also, any considerations from those who would know how to do this really well with FEMAP would be greatly appreciated.
Thanks you
I am new to FEMAP and not sure if there are any unique features to help me model the loads correctly. I was planning to apply the loads with 10 bands of elements equally spaced from the center to the tip (to start anyway..)
Also, any considerations from those who would know how to do this really well with FEMAP would be greatly appreciated.
Thanks you





RE: Static Analysis of a Composite Propeller
RE: Static Analysis of a Composite Propeller
RE: Static Analysis of a Composite Propeller
personally i'd link the blade pitch controller to a speed governor (decreasing the pitch should depower the blade).
RE: Static Analysis of a Composite Propeller
What do you think...?
RE: Static Analysis of a Composite Propeller
i guess you're trying to tailor the elatic axis of the blade so that the blade will deflect to depower the itself (like they've done with forward swept wings). very trcky design ... and with a fixed pitch blade ?? (mechanically simple, but diminished operating efficiency
anyways, your question was about loads .. your CFD should have given you pressures, which you can apply to each element ... interpolate onto nodes or element cg ... i suspect you'll probably need something like excel for this.
RE: Static Analysis of a Composite Propeller
I'm finding that this thing will need to be extremely flexible to achieve enough twist.
RE: Static Analysis of a Composite Propeller
the other thing to consider is if you are making a flexible blade, and the CFD was done with a rigid blade (likely, if you'd don't have a structure) then how good is the CFD ?
RE: Static Analysis of a Composite Propeller
Besides what you are trying to do requires a fluid-structure interaction analysis where you would have to couple both your CFD analysis and your Static analysis.
Ansys has a publication on composite lay-up optimisation based on FSI analysis using a Wind Turbine as a case study. Unfortunately I cant lay my hands on the publication at the moment. It might be worth searching and reading through.
RE: Static Analysis of a Composite Propeller
Thanks for the input. I will look for that ansys publication but feel free to let me know if you find it...
I do not think stretch twist is going to add much since the rpm, mass and length is very small.
I am not getting much bend twist from the aero loads but I am getting good twist from bending due to inertia. In other words, the eccentricity of the blade geometry is creating bending and twist.
Thanks
RE: Static Analysis of a Composite Propeller
The next problem you will encounter with very flexible vanes is flutter instability...whee!
(sorry if my terminology is backwards, but I'm thinking/writing here using fixed-wing conventions.)