Why do some metals ring when struck while others don’t?
In: Physics
Depends on their stiffness.
Any material, plastic bag Vs a plastic bottle. A tight drum skin Vs a loose drum skin, will vibrate depending on its siffness. The stiffer the item the more it vibrates.
The shape of the item and how it relates to air makes the sound you hear. So a bell made of lead will ring louder than a ball of copper half buried in sand. Even though a copper bell is louder than a lead one.
It also is affected by the size and shape of the object. A long skinny metal rod will ring way better than a screw, because at the end of the day that ringing sound is just the metal vibrating fast enough to cause pressure waves in the air.
Some metals even ring differently when molded differently, for example, forged steel will ring easily when suspended and struck but cast steel will make more of a “thud.” This has to do with domain alignment in the steel when shaping it, but I’m not an expert.
Metals and other materials ring is call resonance. The pitch at which the resonance occurs is caused by the amount of deflection of the object (stiffness) along with the mass (weight). For the case of a guitar string, you will notice the larger strings play a lower note, this is because the weight of the string and how tight it is pulled. The reason a heavier string is used is because you can apply more tension to the string and get the same resonance. If you used a small string and tried to tune it to low E, the string would be so loose it would strike the fretboard and cause buzzing. Because a heavier string will deflect less at the same tension, you can achieve the resonance frequency you desire with deflection within tolerance; however a heavier string will give you different harmonics.
Harmonics are additional frequencies that are heard in addition to the main resonance frequency but that have less power than the resonance frequency. These frequencies combine to give you a full picture of a sound. This is how you can tell the difference between a piano or a guitar even though they may be playing the same note and also help you judge distance and direction of a sound.
Some metals do not make a sound because they are not stiff enough or have too much deflection to be audable.
It also has to do with how the metal is being held/mounted. For example if you hold a long metal rod in the middle and then hit it, it will usually ring pretty well. But if you move your hand away from the middle a bit you’ll notice it won’t ring as well. This is because the waves traveling though the material wants to be split into perfect fractions (1/2, 1/4…) and in the engineering world we like call these points nodes. By holding the rod somewhere that isn’t a node you will be making the materials waves decay much faster or in other words it won’t ring very well.
Theres more to it then just that, but it would take forever to talk about all the different ways something can vibrate. So I’ll just leave it at that.
Doesn’t crystalline structure also have something to do with it? Ie a single crystal will ring much longer than a multicrystalline structure?
I read this as some metal rings, not metals ring, and I was like why does this have 570 likes it doesn’t make ANY sense lol As for the question I have no clue, just thought it was funny that I stared at the question for 5 minutes trying to figure out what you were asking
When it comes to iron and steel, I think it’s related to the microcrystalline structure. Iron is a “dead metal”, does not resonate. High carbon steel, properly hardened and tempered, rings long and clear. Those old high quality knife blades sound like a tuning fork when struck.
There’s is no better acoustic sound than when you bang a 12 foot 6″ inch round bar of steel or aluminum a bit. The vibration makes it last for soooo long and it feels so good on the ears.
Eyyy something I actually know the answer too… well at least in iron. Metallurgist here.
It has to do with the crystal structure of the matrix. Certain irons such as gray iron (brake rotors) have flake like carbon within the matrix.. these carbon flakes muffle the sound/vibration which is why they make good brake rotors.
Ductile iron is formed with with magnesium which caused the carbon to form spherical/nodular grains in the lattice matrix. This in turns strengthens the iron but these nodes don’t absorb the vibration so if struck it will vibrate and ring.
I’m assuming a similar explanation could be used across all metals. Depending on the alloys composition the metal will ring and vibrate more or will dampen the vibration causing a dull thud sound
Latest Answers