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View Full Version : String breakage for the physics inclined

!<-_->!
03-17-2011, 09:52 AM
I was having this debate with a couple friends. Are strings breaking due more to the friction generated between the rubbing of strings or sheer force? I was in favour of the sawing motion creating friction while they claimed it was definitely attributed to sheer force moreso than friction. Can anyone shed some light on this?

Kevo
03-17-2011, 01:01 PM
Well, it's normally a combination of friction and tensional stress. The friction notches the strings until they get thin enough that the tensional stress from an impact breaks them.

Shear breaks tend to only occur from mishits.

At least that's my non-scientific observational take on the situation.

user92626
03-17-2011, 04:38 PM
I dunno what the point of your argument. There's no friction if there's no force. You need both to break string. As to which component contributes more, they're orange and apple to compare and measure. It's like asking what makes a pizza great -- the cheese or the tomato sauce! hehe

rich s
03-17-2011, 06:10 PM
the sawing action between the string causes notching and reduces the effective cross section of the string...

because/as the cross sectional area of the string is reduced the stress the string sees increases to the point that the string snaps upon a normal stroke.

Readers
03-17-2011, 07:06 PM
I dunno what the point of your argument. There's no friction if there's no force. You need both to break string. As to which component contributes more, they're orange and apple to compare and measure. It's like asking what makes a pizza great -- the cheese or the tomato sauce! hehe

First off, a strung stringbed do not need any outside force to have friction.

Second, why is so hard to understand, the force itself and the friction it caused are two different thing? A "super string", a string otherwise identical to say X-One could be completely frictionless, and it could still be broken, if that takes 10 to 100 times than it does with a real X-one, we can have an answer. But it's no so easy in real life.

BTW I have an answer to your pizza question!!! The CHEESE!!! I've ate great pizza with other sauce, but never one without cheese!!! :)

!<-_->!
03-17-2011, 09:51 PM
I guess the point was to ascertain which was the bigger factor in string breakage. Seems like from these posts that both play a big part and are about equal perhaps?

I don't know. My friends were bent on the idea of sheer force. I was claiming that it was friction. Guess we were all wrong since we were only claiming one aspect.

brownbearfalling
03-18-2011, 09:57 AM
I think of it this way. In my experience the string breaking heirarchy goes like this (assuming that they all play with the same racquets, strings and oppents)

1. Hard hitter with lots of top spin
2. Hard flat hitter
3. Moderate hitter with topspin
4. Moderate flat hitter

With this, It shows that both aspects contribute a great deal. But for triumph friction.

But then again the rule also goes that racquets that have bigger headsizes and more open string patterns break more often racquets with denser smaller headsizes.

In one case where I saw friction do most of the work in breaking strings is when a player I know broke a crosss string in the middle of the racquet in a pure storm limited. I assume it was from the constant sawing motion that did cut into the main string but the main string was sawing down the cross string.

franks
03-18-2011, 11:47 AM
With me it's sawing against one another.

ethebull
03-18-2011, 12:28 PM
friction leads to notching, notched strings = stress risers. Think of a 2x4 piece of wood, tuff and hard to break, until you saw a cross cut 1/4" deep, then you can snap it quite easily.

user92626
03-18-2011, 03:36 PM
I think it's the ball that attributes to breakage!
If you take the ball out of the equation, your string will last virtually forever regardless of whatever friction and force. Don't swing into a net pole though. If you do, then it's the net pole.

pvaudio
03-18-2011, 06:28 PM
It's a combination of both. You can shred a multifilament to feathery goodness before it snaps, but it only snaps because the tension on it is too great for the material to bear. At the same time, natural gut can break in your bag after stringing without you even hitting with it because just the tension can snap cheaply made natty.

kiteboard
03-18-2011, 06:42 PM
So why don't they make just mains, no crosses, just tight together? NO friction that way, only impact. Would have to string a lot tighter to keep the ball from going through the mains. Add stress to the frames. Stringing would be a lot faster.

Kevo
03-19-2011, 01:17 PM
The frames couldn't handle only mains. They would surely break. Maybe if science ever develops a way to build a carbon frame molecule by molecule, they might be able to create a frame similar to what we use now that could withstand the stress, but until then I think we will have to use cross strings.