How do they prevent such things from happening?

 

Dampening and changing the resonate frequency if it's going to be seeing frequencies close to it's resonance I guess. I don't know what you would do in when engineering a structure, but when building a subwoofer box you add mass by using thicker MDF to bring the resonance frequency down, or you reduce the mass and make it stiffer to raise it.

 

Good to know. I shouldve clarified, how do they make sure you wont hit the resonance frequency in things like a jet engine, etc. I mean, you made it out to seem like its a common thing. Or, are some of these frequencies just so high/low that its not realistic that they would ever create them within normal operating conditions?

The way I understood resonance from chemistry was the frequency of energy needed to destroy the bonds between atoms withing an element or molecule. Say, water and microwaves, for example. Your typical microwave vibrates the water molecules and increases the energy (heat) of the food. Meh, I was going to continue on this... but Im not sure if Im wrong or right and have a headache... lol

 

Well with a jet, they know about what range of frequencies the turbines and fans putout and anythign else that may produce vibrations and make sure the resonance of the structure is outside of that range. I don't even have my AA yet and I never learned this in school so forgive me if I'm a bit off, everything I know was self taught so it's not always the best answer.

 

Jet engines have passive baffles in the various chambers to alter and help prevent resonance. Also, the throttle controls are set up to blip over the position that causes the resonance. For example, if 40% throttle caused the problem, the computer control wil let it go 37, 38,42, 43% ..... or something to that effect. I'll PM you a research project that I was involved in that is way too much to post here.

 

I think you could fit 87 pages in here....

 

Very interesting read, I've only just read a bit but it seems most to come is going to be a bit over my head. My brother in laws brother is finishing up his PHD in thermal engineering at UofM, and he's been working with some company doing R&D on turbines, every time he comes over he's always got some really interesting facts on turbines and stuff.

 

I was referring more to the technical aspect ...... luckilly I did not have to write much of that ..... I was in charge of the easy stuff ..... piston / actuator design and custom manufacturing ....... yes, I built that entire rig. Honestly, the hardest part to build was the plastic test box; it was too big for the equipment that I made it on and had screws tapped into the edges of the plexi.

 

Polk Audio makes a really nice 12 inch sub. In something as small as an accord I would go with a good sealed box. Ported works alot better for vehicles with lots of space, for instance, I have 3 10's ported in an suv. And I'm from bama so I know the low frequency bass lines. I think some Polks would sound good with some Jeezy goin through 'em. I haven't done anything with my audio system yet, but I'm probably gonna go with Polk if not JBL.

 

I've never heard a polk sub, but JBL isn't all that at all. Their home audio stuff ins't bad, I have nice outdoor 3-way JBLs on my balcony that I really like. But their subs haven't been top notch for many years. Also I'm pretty sure the polk subs are SQs and not SPL which you are making them sound like.