we learned 2 things today

[_MIA_]

How fast does the vibration travel to the hands on balls hit off the sweet spot towards the end of the bat?

I would have to find out what the frequencies are of the transverse modes excited with sweet spot contact. I think it is in one of Nathan’s papers on the subject. I will look later.

 

[_MIA_]

I would have to find out what the frequencies are of the transverse modes excited with sweet spot contact. I think it is in one of Nathan’s papers on the subject. I will look later.

According to http://baseball.physics.illinois.edu/AJP-Nov2000.pdf
the group velocity of the elastic (transverse) waves is about 700 m/s.


Now I must say that the contact time of the ball with a bat may be a bit longer for a softball and the analysis done in the above paper was for a wood bat so the group velocity would be different (not by an order of magnitude but some difference) with a composite bat. It would be interesting for a similar analysis to be done using composite bat vibrational properties and a softball collision/contact time.

 

[ian]

According to http://baseball.physics.illinois.edu/AJP-Nov2000.pdf
the group velocity of the elastic (transverse) waves is about 700 m/s.


Now I must say that the contact time of the ball with a bat may be a bit longer for a softball and the analysis done in the above paper was for a wood bat so the group velocity would be different (not by an order of magnitude but some difference) with a composite bat. It would be interesting for a similar analysis to be done using composite bat vibrational properties and a softball collision/contact time.

And then do studies on 1 and 2 piece bats. And then different 2 piece bats because the connections and flexes are not the same. And if we wanted to be the slightest real world accurate we could take the measurements on moving bat grips instead of the silly way they fired a ball at a suspended stationary bat.

 

[_MIA_]

moving bat grips instead of the silly way they fired a ball at a suspended stationary bat.

I doubt this would make a difference. The bat properties are not significantly changed when it is moving at typical bat speeds and hence regardless of the amplitude of the wave (which would be larger with a moving bat), the velocity at which it propagates wouldn’t really change.

One piece vs 2 piece would change a few things. Outside of changing the modal properties (and hence the group velocity) I would think part of the wave would reflect back at the two piece connection but both that and the part of the wave which passes through would be reduced in amplitude because of the dampening properties of the connector(hence the reason you feel misshits less with two piece bats). I actually think for a two piece composite bat the chance of grip having an effect at contact would be less than the wood bat analyzed in that paper even when considering the possible increased contact/collision time for a softball.

I still doubt that grip matters at contact for composites but if it does then so what? Are you upset that an academic wrote a paper (where all the assumptions were clearly stated) which said it doesn’t? You are going to grip the bat at contact regardless of what his paper said…

Regardless this sort of stuff is interesting to me so thanks for the discussion. I did a project on this very topic (for aluminum bats) in my Vibrations class in graduate school way back in 2000 or 2001 (came to the same conclusion as Dr. Nathan but my analysis was a bit more rudimentary..lol)

 

[ian]

I doubt this would make a difference. The bat properties are not significantly changed when it is moving at typical bat speeds and hence regardless of the amplitude of the wave (which would be larger with a moving bat), the velocity at which it propagates wouldn’t really change.

One piece vs 2 piece would change a few things. Outside of changing the modal properties (and hence the group velocity) I would think part of the wave would reflect back at the two piece connection but both that and the part of the wave which passes through would be reduced in amplitude because of the dampening properties of the connector(hence the reason you feel misshits less with two piece bats). I actually think for a two piece composite bat the chance of grip having an effect at contact would be less than the wood bat analyzed in that paper even when considering the possible increased contact/collision time for a softball.

I still doubt that grip matters at contact for composites but if it does then so what? Are you upset that an academic wrote a paper (where all the assumptions were clearly stated) which said it doesn’t? You are going to grip the bat at contact regardless of what his paper said…

Regardless this sort of stuff is interesting to me so thanks for the discussion. I did a project on this very topic (for aluminum bats) in my Vibrations class in graduate school way back in 2000 or 2001 (came to the same conclusion as Dr. Nathan but my analysis was a bit more rudimentary..lol)

Yep we all came to the same conclusion. Grip matters on every swing. And grip matters on the overwhelming majority of in-game ball/bat collisions.

 

[_MIA_]

Yep we all came to the same conclusion. Grip matters on every swing. And grip matters on the overwhelming majority of in-game ball/bat collisions.

Lol..ok

 

[ian]

Lol..ok. You are a piece of work.

Thank you for your piece of work on bat vibrations LOL.

 

[ian]

I doubt this would make a difference. The bat properties are not significantly changed when it is moving at typical bat speeds and hence regardless of the amplitude of the wave (which would be larger with a moving bat), the velocity at which it propagates wouldn’t really change.

One piece vs 2 piece would change a few things. Outside of changing the modal properties (and hence the group velocity) I would think part of the wave would reflect back at the two piece connection but both that and the part of the wave which passes through would be reduced in amplitude because of the dampening properties of the connector(hence the reason you feel misshits less with two piece bats). I actually think for a two piece composite bat the chance of grip having an effect at contact would be less than the wood bat analyzed in that paper even when considering the possible increased contact/collision time for a softball.

I still doubt that grip matters at contact for composites but if it does then so what? Are you upset that an academic wrote a paper (where all the assumptions were clearly stated) which said it doesn’t? You are going to grip the bat at contact regardless of what his paper said…

Regardless this sort of stuff is interesting to me so thanks for the discussion. I did a project on this very topic (for aluminum bats) in my Vibrations class in graduate school way back in 2000 or 2001 (came to the same conclusion as Dr. Nathan but my analysis was a bit more rudimentary..lol)

Do you think handles and connections flex at contact?

 

[CoreSoftball20]

I can only say...OMG, why is this happening

 

[tim_s]

It's an old fashioned "mine is bigger than yours" stand-off, but thankfully both sides are keeping their pants on


For now