Airsoft CAD project

[TurtleFace]

Hey guys,
I'm going to be doing an informal CAD project for one of my courses, and was thinking about doing something airsoft related because it'd be interesting.
Current ideas (so you understand the kind of thing I'm doing):
Analyzing stresses on metal piston teeth and determining where/why they fracture. Then, post analysis, suggesting an alternative material that is sufficiently strong to withstand forces, or alternative design that prevents areas of high stress concentration.
Or perhaps something like looking at reaction forces on the piston head as it slams into the front of the cylinder.

That's the kind of stuff I'll be doing. I'm just fishing for ideas here, but if anyone has some real good suggestions then I'll roll with that. Perhaps there's some part of your AEG you want analyzed?
If there's interest then I'll post the final report on here, with pretty pictures and everything.

[phiz]

Maybe something about angular momentum transfer to an accelerated sphere depending on the coefficient of friction. Calculate the force / velocity where the coefficent of friction goes from static to dynamic for the hop up rubber. Non-linear with gamma being a function of V, since the rubber deforms. You would have to solve it numerically or by approximation methods.

[LiberalPacifist]

design an airsoft grenade fuse that doesn't suck.

[TurtleFace]

Maybe something about angular momentum transfer to an accelerated sphere depending on the coefficient of friction. Calculate the force / velocity where the coefficent of friction goes from static to dynamic for the hop up rubber. Non-linear with gamma being a function of V, since the rubber deforms. You would have to solve it numerically or by approximation methods.

That may be an interesting project, and possible, though I probably should have specified that I need to be analyzing either static or at least quasistatic loadings.
However, I did have some ideas for a future project applying simple fluid dynamics to predict airsoft BB trajectories based on different velocities/amount of hop.

[phiz]

bbbastard did a good job with hop / trajectories, http://msed.bbbastard.com/

[TurtleFace]

bbbastard did a good job with hop / trajectories, http://msed.bbbastard.com/

The ATP is my primary inspiration for my future project, so I know it's been done before. But I just wanted to do it for myself for fun, because I guess I have an odd definition of "fun".

[Nocte]

bbbastard did a good job with hop / trajectories, http://msed.bbbastard.com/

Wow, I was just beginning work on extremely similar research. Thanks for posting this.

[Airsoft_Rezidentura]

Analyzing dynamic stresses on a complicated assembly is quite beyond the scope of an "informal" cad study... to have any accurate result you would need to start with a full analysis of all relevant dimensions, their tolerances and so on. Then you would need to characterize the force of a non-linear spring, build a motor torque curve, etc. As you can see, the task quickly becomes quite daunting.

Depending on the FEA/Tolerance analysis requirements of your course, some ideas could be:

mp5 receivers and why they like to break at the barrel mount (hint, they are cantilevered)

Analysis of forces on sears of bolt rifle of your choice, and redesign to lower them (only need spring force at one point)

Design a quick release and / or adjustable preload spring guide.

What CAD/FEA package will you be using?

Good Luck!

[TurtleFace]

I'll be using SolidWorks to do my modeling and ALGOR for the FEA.
I actually like your idea about analyzing stresses on bolt sears, as that would be a purely static load and perhaps a more applicable problem for me (since I usually use a bolt).
Currently my proposed project involves adding a fillet to the base of piston teeth to avoid stress concentrations when the gears are first engaged. Like you said, this is a complicated problem to model accurately, and the amount of simplifying I would do doesn't make it very useful outside of getting a grade on the assignment.