Modal analysis

[saikum]

what should be done to reduce the frequencies from the engine.?

[DougMilliken]

Originally posted by saikum:
what should be done to dampen the frequencies from the engine.?
Why would you want to make your engine frequencies all wet?
* dampen, dampening = making wet
* damp, damping = removing energy from a system

[Simon Dingle]

what should be done to dampen the frequencies from the engine.?

I think you might have to put a little more detail into your question before you'll get any sensible replies.

Which frequencies? From which part of the engine? Which parts of your car do you want to isolate (this might not be the right term...) from these frequencies? Why are you trying to "dampen the frequencies from the engine"?

I might not be able to help, but at least if you give some detail, I will know if I can help or not.

[BillCobb]

Hey Doug, that's funny !

Meanwhile:
You need to determine whether the vibration you are troubled by is from a bounce or a rocking mode or modes. This is a measurement process (or try using a strobe light and video). You will need to run an rpm (frequency) sweep to analyze this properly. Then you design a motor mount system to attenuate the transfer function you measure. No, you don't need 10 mounts, but a 10 female on you team will get you some buzz. (a ten you ate, get it?)

A good engineering project title list might include 'Torque Axis Mounting System Design', 'Hydraulic Motor Mount Tuning', and maybe 'Design of an Active Order Reduction Engine Mounting System for a Small Race Application'.

So, what else is dampening? If the octane rating of your gazzoil is 2 low, it will ping from pre-ignition. To fix the dammed ping, add some octane booster.

[saikum]

When the frequencies of engine match with natural frequencies of chassis there may be a chance that chassis vibrate with higher amplitude causing considerable damage to the weld joints.I am not very sure about this.I need some help from you..Forgive me for my mistakes in the previous post.We are a group of guys(TEAM UNWIRED) doing our B.tech and this is the first time that we are entering FS..Thanks in advance..

[Owen Thomas]

I think he means dampening the vibration from the engine through the motor mounts. I don't know why you would ever bother in our application; but I guess if you run a thumper it would be good practice.

Look in to the various damping properties of different materials which you have access to (steel, aluminum, brass, plastics, etc), and fashion a "washer" out of your selected material. Place between chassis and engine, much like you would with a normal washer. This might not do much, but it's certainly a better solution than a mess of rubber bands and bungie cords constraining your engine.

[Chris Texas]

The vibrations of a 1-cylinder can put out very high fatigue stresses on your chassis. In fact, I've seen it shear off wing mounts, and crack engine mount welds. I do a lot of the Vibration testing on big diesel engines, which are completely different then this application. You could run an FEA of your engine and chassis system, but you need to get some sort of reference acceleration to determine how much acceleration you need to excite the system. Also, its a very complex model, and the restraints are very hard to model without testing. The way we do it is we do an initial analysis and then validate that analysis with a vibration test. I think this testing is pretty advanced and complicated for an FSAE team, but never the less it is all about learning.

[Drew Price]

Originally posted by BillCobb:
Hey Doug, that's funny !

Meanwhile:
You need to determine whether the vibration you are troubled by is from a bounce or a rocking mode or modes. This is a measurement process (or try using a strobe light and video). You will need to run an rpm (frequency) sweep to analyze this properly. Then you design a motor mount system to attenuate the transfer function you measure. No, you don't need 10 mounts, but a 10 female on you team will get you some buzz. (a ten you ate, get it?)

A good engineering project title list might include 'Torque Axis Mounting System Design', 'Hydraulic Motor Mount Tuning', and maybe 'Design of an Active Order Reduction Engine Mounting System for a Small Race Application'.

So, what else is dampening? If the octane rating of your gazzoil is 2 low, it will ping from pre-ignition. To fix the dammed ping, add some octane booster.



If you are ever in LA, please let me treat you to a beer or three.

[Z]

Originally posted by DougMilliken:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by saikum:
what should be done to dampen the frequencies from the engine.?
Why would you want to make your engine frequencies all wet?
* dampen, dampening = making wet
* damp, damping = removing energy from a system </div></BLOCKQUOTE>
Doug,

When I first started reading this thread I though he might be trying to damp his electromagnetic (emf) radiation.

In which case some "dampening" would work a treat! http://fsae.com/groupee_common/emoticons/icon_smile.gif

Z

[Frank]

I see nothing wrong with his use of the word dampen.


http://oxforddictionaries.com/...lish/dampen?q=dampen (http://oxforddictionaries.com/definition/english/dampen?q=dampen)

make less strong or intense:

nothing could dampen her enthusiasm

reduce the amplitude of (a sound source):

slider switches on the mixers can dampen the drums



Americans correcting the use of the English language, fancy that…

[Edward M. Kasprzak]

Just curious: Did you also look up the definition of damping? I think you'll notice a difference, as damping is a technical term. Dampening is not.

[Frank]

The word used was dampen.

[Frank]

The original question was:
"What should be done to dampen the frequencies from the engine?"

Look at these two verbs:
dampen is an intransitive verb
damp is a transitive verb

Shall we continue, and discuss the transitivity and valency of the verb?

[Max Trenkle]

Grammar contest go.