Re: barrel resonance
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: fewenuff</div><div class="ubbcode-body">Too many variables? OH contraire you can get close enough for government work, specifically 40mm cannons. (now i'm gonna have to kill anyone that reads this post, DAMN I HATE THAT WHEN THAT HAPPENS). Free free natural frequencies? floating barrel? Force frequency response? HEHEHE... <span style="font-weight: bold">often times when you break the physics down you find that you can toss out some of the TOO many variables as not contributing significantly to the result.</span> Also remember we are looking for magnitudes of change and not necessarily exact values given a change in the system.
Last week I did a quickie analysis of a mini-14 barrel that paralleled some test data I found. Yep cut 1.5 inches off of the old barrels and the harmonics start to behave ie groups closed up (for a mini-14, ha).
Told ya I bore you to death... C-; </div></div>
I've spent quite a bit of time doing optimization studies and variable reduction studies to figure out exactly what makes the most impact and what are the "asymptotic improvement variables" that we can ignore for the first 97% of the analysis.
You're exactly right IMHO, run the FEM, build some models and let them go on a computer. A frequency analysis, and a forcing function driven analysis like this is very simple and fast to run.
Someone want to get an idea of a barrel analysis, take some measurements for me, I'll make a model and put some results up tomorrow. We can all punch holes in it then. Who's got the actual dimensions of say, a Rem 700 barrel, 30 caliber, heavy varmint contour about 26" long. I'll run that against a straight bull barrel and a little spaghetti barrel for stiffness.
I think that would be a GREAT topic of discussion, let's get the engibeering nerds around here thinking!
My girlfriend doesn't understand my obsession with trickled loads, minute adjustments, punishing myself with recoil for the sake of "shooting groups" or the long hours I've spent sitting in front of my computer at home to