Vibration Isolation vs. Shock Isolation

I also hope to know their difference.

I guess vibration is a small attenuation oscillation and shock is large amplitude oscillation

just guess, dont be serious

Duration of event ? (unless the latter is electrical )

Vibration is effectively repetitive shocks.

An arrangement which will damp or absorb an occaisional shock could easilly fail under constant equivalent vibration.

Resonance is much more important with vibration, as this can be very destructive.

Vibration is a continuous set of mechanical shocks often generated by rapidly moving objects, a speaker cone with a low bass note playing can be said to vibrate, if you get annoyed and find a hammer to hit the speaker this will be a blow or shock, but if it has a thick soft rubber coating this will deaden the blow giving shock isolation. Resonance is when some thing is excited by another object or sound wave the first could be a tuning fork the second when a window breaks because you found its point of resonance. Resonance can be highly destructive the Tacoma narrows bridge was destroyed because of resonant effects.

it seems my guess is right.

So, can rubber feet act as a shock isolator and at the same time good for vibration isolation?

Yield is the main factor for shock , and resonant frequency is the factor for vibration. A compromise would probably be inevitable. Sounds like 'annoyance' of a continual problem versus 'disater' consequence of a single problem. A bit like rumbling seat on a train versus crash effect.

What do you mean by yield is the main factor for shock?

So, how do we know that the rubber feet installed is good for shock?

wether the rubber buffer is a good insulator to provent from shock or vibration depend on it feature. its a two order ordernary differential equation. most of us must be familiar with it when I list below.

M*X'' + B*X' + K*X =F

where x position shift an F is outside force, it can be periodic or not, say, impulse force etc. M quality B damp coefficient and k spring coeficient.

adjust these parameters, we can get the satisfactory result.

fast rise, over rise, or slow rise, etc.

or rewrite as

X'' + B/M * X' + K/M * x = F(t)/M

its generation solution is of its homogenerous equation

and special solution use right value.

if we go a little far from here, we can write is as Laplace form

X = F(s)/M /(s^2 +B/M *s +K/M)

we can evaluate it by control theory.

we can add zero or pole point on the quation to get our target.

thsi is just a theory analysis, the practical action will be more complex. it wil l depend on your practice experience.

If you crash you're car , an air bag that yields is helpful. For you journey comfort you want rubberized mountings to smooth vibration. Do it the wrong way round and you will have an unpleasant trip that may have a fatal outcome if you crash.

A friend of mine several years ago worked in a facility using many presses (frequent shock loads). He found that wood can be a very good shock isolator (absorber).

In some applications yes.

I have worked on products where the shock was generally far greater than the mechanical vibration so an additional suspension system was necessary. Also to damp vibration you need to be very tuned into the hysteresis rate of your damper. I've found damping shock (no repetition) tends to be more flexible as to how you achieve your goal.

I don't know if cattle-grids are used elsewhere in the world (grid with bars a few inches apart to keep stock from leaving fields ) , but driving over them at the right speed makes a big difference. Too fast or too slow and you really notice it. It's a fairly good way to rate a cars shock and vibration resistance I'd have thought (either side of optimum speed will test each).

Vibration=AC.Can be handled to live with.Like living next to Diesel Genset, Truck, Jetplane

Shock=Impulse-Unpredictable and most likely to cause heavy Damages --like Tornado/Earthquake

en mis analisis clasifico "shock" como una onda con un alto indice de ataque y un release prolongado, en el caso de "vibration" el ataque es sinuidal con release corto, esta diferencia es muy importante tenerla en la cuenta para efectos de aislamiento mecanicos y acusticos ya que los materiales a utilizar presentan diferentes comportamientos a estos procesos; no es lo mismo el comportamiento por ejemplo del cristal bajo esfuersos a "shock" o a "vibration" aun bajo paramentros de la misma energia aplicada.

Frenchman, at first congratulate to your country has a new, younger, handsome president.

second could you translate your paragraph into english so that I can read adn be comprehensive

I studyed only one year french and forget all only but a article un

I think you have studied Sanish or Portugese by mistake cnpower !

a, Im ashamed!

its a lesson!

No shame cnpower ! you asked a good question when nobody else did. If I see someone on CR4 who may be able to translate I shall ask them.

I hve to blame myself! I presume its french but its not!

there are many people speak portugal in China Macao.

No blame , No blame !!

Anyway , I sent a mail asked someone listed on the spanish members group to have a look . It will get fixed eventually , so no problem. Have you noticed the other Chinese members here now ? It's good to see.

Hello, I translated what the spanish man wrote. Sorry my poor english because I speak portuguese.

"in my analysis I classify "shock" as a wave with a high index of attack and release prolonged, in the case of "vibration" the attack is sinuidal with release short, this difference is very important to have it in the account for mechanical and acoustic effects of isolation since the materials to use present different behaviors from these processes; it is not the same the behavior for example of the crystal under esfuersos to "shock" or "vibration" even under paramentros of the same applied energy."

Érika

Welcome Erika - you are a star and really have the spirit of CR4 ! Helping people so soon after joining is the mark of a truly public spirited person. I salute you !

Thank you!

I know only a man from Singapora and I list out a formula for his reference and find nobody from china here only but me.

I find several chinese in the past, they will offer their products to post. some of them live abroad now. but seems only me is active now here. I believe, most of them are watching. and laze to post any thread.

I concern content of threads without conscious where they are from and their nation. most of them didnt marked their nation.

I noticed most of the roommates are from USA and your europe. a lots from India. singapore, indonisia and philipine and south america.

but no korea and japanese here, it sticks me odd. maybe they are all going to some IT wet site forum.

IT web sites; not wet site

I've seen several people recently who have a chinese location under their name , but nobody has joined the " User Group.... China" yet. I am usually cautious , My location of UK is true (Soth East England to be more exact) but Etherville is just a fun name I made up. I think I saw one person from Korea . Maybe Japan has a good forum in Japanese language (though I have met many Japanese before who speak English well).

The globalspec web site has an office in China, I seem to watch their advertise in some website. they have their representatives as well. it may be their advertise sent to my mailbox that guid me to the forum.

Most of chinese who come to here are pure businessmen. but some of them have less special engineering knowledge, they can speak very good english. and familiar domestic and international market.

both in japan and china have very good forum. Most of us go to there for seeking help and seeking kowledge. after all they are using our mother tongue language.

this room is not as cool as ours somewhere and less people here than ours

It would be fascinating to see other forums if I spoke the language.

I like the new flag . How come you're globe is showing the Americas , I only just noticed !

I dont know, the picture is offered by the site itself.

I cannt see it clearly. it seems there are some bubbles around it.

I can change one more better picture later.

now I joint china user group, only myself one now.

its time to lunch now, I shall come back soon.

If an uneven distribution of rotary masses, like bent shaft or imbalance, the equipment vibrates. As indicated by many it is mostly repetitive if not further aggravating.

In some reciprocating machines like engines and compressors certain amount of imbalance do exist naturally from the day one. In such cases where prevention is not possible/worthwhile the vibration has to be isolated by one or more means. This include mass, spring and or dashpot. Or simply resilience materials like a piece of rubber boot.

Shock on the other hand is sharp, high amplitude but only for spontaneous duration. Good example would be a damage on the ball or raceway of a ball bearing. Every time the damages contact undesirably, such shocks generate. Could be repetitive. Even sobers on running further. If such shocks are not intentional (hammer mill, jack hammer etc) there is no merit in managing then by isolation. They are to be treated/rectified at the root cause level.

Nice graphics at the yesyen site !