i think so, i think 1lb ~= 25Hz or so. i updated the graph. another a couple of Hz drop after a today. so in total, for ZM62, it drops around 4-5% of the original string tension with zero use.
that's the plan. the racket has now pretty close to settled at around 1143-1145Hz. i will bring it to badminton tomorrow to see how much it drops after a few hours of play.
strange sudden drop of tension between 56 and 63 hours. the racket has not been used. will use it tonight and report back.
can anybody tell me what software thet use to measure the frequency? I have a laptop and USB-microphone and just can't find anything...
Setup : 2 x Ti 10s String: BG 65 White I guess my stringer cheated me.... LOL I asked stringer A to string my two Ti 10s at 26 lbs. ( Almost 2 weeks back ) I played a tournament just 4 days back, and ended up breaking the string of one of them. I gave it for re stringing at Stringer B and put 24 lbs. ( BG 65 white ) I compared one of my Ti 10 from Stringer A ( 26 lbs ) and the newly strung Ti 10 from Stringer B ( 24 lbs ). Note : The spare Ti 10 from A was barely used. To my surprise, the 24 lbs at Stringer B was actually more than the 26 lbs by Stringer A. Frequency Analysis Results : a. Ti 10 at Stringer A = 1230 Hz b. Ti 10 at Stringer B = 1289 Hz Now, if the difference of 50 Hz = 1 lb theory is true, then I have about 2 lbs of difference between the rackets. But, there is no way to verify if the tension " as said by the stringer " is same as the " Actual Tension ".
currently the theory is approx around 25Hz/lb. this will vary with different string types and probably different tension. the relationship between frequency and tension is not a straight line but instead square root. however, we are only interested in a vary narrow band so we can approximate it with linear difference.
after an hour or two of play with my ARC10+ZM62, the frequency dropped from ~1135Hz to 1106Hz. that's more than a pound drop in one evening with a newly strung racket.
i use something call iAnalyzerLite on the iPhone. i googled for "spectrum analyzer software" and quite a few came up. most are shareware that cost ~$10.
I suspect that 25 Hz = 1 lb is false theory. From Kwuns Data : Tension = 23.5 lbs Frequency recorded at 23.5 lbs = 1170 Hz The relation Frequency / Pound ( Hz / lb ) = 49.7 From my data of 24 lbs on Ti 10 Tension = 24 lbs Frequency recorded at 24 lbs = 1289 Hz Relation Hz/lb = 53.7 From the above 2 examples : I guess 25 Hz = 1 lb is FALSE. More accurate one would be ; 1 lb = 51 Hz ( +-2 )
i disagree. as i mentioned, theoretically, the relationship between tension and frequency is not linear but instead square root. therefore it is not correct to just divide the frequency with tension.
Found two related papers, Quote: It is shown that there is a small loss in tension with time after a racket is strung but there is a large decrease in tension during the stringing process. The tension immediately after stringing is typically about 30% lower than the pull tension. Additional experiments are described, showing that the large drop in tension is due to a combination of factors including stress relaxation, frame distortion and friction between the strings. http://www.physics.usyd.edu.au/~cross/CrossBower.pdf http://www.physics.usyd.edu.au/~cross/StringTension.pdf
here are some data that illustrate it: this is a graph of frequency (vertical axis) vs. tension (horiz axis). i measured it on a single piece of ZM62 (not a whole string bed). if you extend the line linearly, it won't intercept at the origin. i did a curve fit of a square root plot, and it fitted perfectly. the 25Hz/pound gradient is the gradient around where we are interested in, which is between 20-30lbs.
well, ok. i updated the graph after tonight's session. the graph should speak for itself what happened... sigh. .62mm don't last very long.
Why the sudden drop in frequency? Was there major wear and tear shown at that point when the huge drop happened?
the drop was from around 2hours of badminton. another big drop that went to 0 was because i broke the string. i didn't show that as that skewed the scale of the rest of the graph.
the drop was from around 2hours of badminton. another big drop that went to 0 was because i broke the string. i didn't show that as that skewed the scale of the rest of the graph.
