Category Archives: Tensile Strength

What’s The Difference?

As tennis players, you must constantly ask “what’s the difference” when it comes to tennis racquets and string! Well, as racquet technicians we ask the same questions!

This post is intended to showcase the differences of string in testing, not playing, however, some of the data may be noticeable to the player in certain situations.

What this graph shows us, in addition to our trying to save a tree by printing on the back of previously used paper, is that each of these stings will provide almost the same performance. This is indicated by the curve and how closely related the strings are.

Tensile Strength Comparison

The differences you do see here can be attributed to the gauge, or diameter, of the string, with the largest diameter (Tour Bite) having the highest tensile strength.  Down in the “hitting” displacement range (way below the 39.9mm!), there is very little difference.

The tensile strength can be a factor as the string begins to “notch” or otherwise come apart.  Each of the strings in this graph is monofilament so notching would be the failure mode in a racquet.

 

What Can Pictures Tell Us About String?

It is said that “a picture is worth a thousand words,” which may be true as long as the picture tells a story.

This story is about natural gut string, and the pictures will show what we can achieve, informationally, with our testing equipment. The two (2) strings are Babolat VS Touch 17 and Luxilon Natural Gut 125.

Both are awesome products, and we use a lot of both of them, but for different reasons, we may be able to understand by the pictures!

Our Questron software scales the images to suit the data so the graphs will not be the same size.

Babolat VS Touch 17

Our testing loads the string from 0 pounds force to 50 pounds and back to zero then up to 50 pounds three (3) times.  This is the “stress/strain” curve.  Fifty (50) pounds is arbitrary and because we are using the same methodology for all string materials it is a good number.  The closer these lines are together the better.

The farther it takes to reach 50 pounds the “higher elongation” the string is.  In this case it is about 44mm.

The important property of this string is the linearity!  That is the “straightness” of the line from beginning to end.  This indicates predictability, stability, and consistency.

This picture tells us the tensile strength and the knot strength.  In this case the knot strength is 52.3 pounds and takes a stretch to very close to 60mm before failure.

Luxilon Natural Gut 125

What is, probably, the first thing you notice about this “picture”? Could it be the squiggly lines? What could be causing this?

We believe it is the “break-in period” players associate with Luxilon gut! We have heard it from the players but have not been able to “see” it! It could be the bonding agents realigning as the load is applied.

You will notice a couple of things: the similarity of the “stress/strain” curve and the displacement to “knot strength” of the two strings. This string will feel a little less “soft” than the Babolat VS Touch 17. The linearity is quite good up to failure.

So, based on these pictures, could you make a recommendation? If so, let us hear them!

And The Winner Is…

If you know anything about Tecnifibre yo know they make some of the best multifilament strings in the business!

 

The winner is Tecnifibre MultiFeel 17!

This string, MultiFeel, is a very “soft” polyurethane bonded construction that offers playability and a good value!

Tecnifibre MultiFeel !7 Gauge

This graph shows the high elongation and nice elasticity of this string.  The fairly linear slope up to failure would indicate some consistency of shot all the way up to breakage!

The knot strength is pretty good for a thin multifilament and we can say from experience that the know is going to be fine when property “tightened” and large enough to not slip bak into the grommet barrel.

If you are considering a multifilament this would be a good one to try!

And the winner is…Head FXP 17

 

Head FXP is a string that seems to be largely overlooked and I am surprised after seeing the results of the installation and testing!

String NameCategoryGaugeUltimate Tensile Strength/LbsKnot Strength/LbsCountry of Origin
Head FXPMultifilament - Nylon17165.993.4Japan

Both the tensile strength and knot strength are exceptional and the graph shows that this string is very “elastic” which is a good thing for tennis racquet string but sometimes just not considered.

Head FXP 17

The area under the solid red lines is considered a stress-strain curve and indicates the “elasticity” of string by how close the lines fit from 0 to 50 three (3) times.  A perfectly elastic material would be one line even though it went through three (3) cycles.  What you see here is quite good and one of the reasons it is the winner!

And the winner is…overview

Racquet Quest is going to add a “winner” of the week to our website as a way to develop a fun way to look at string!

Each week we will select a string that has exhibited outstanding properties from one of five (5) major categories:

    • Synthetic Gut
    • Mulit-filamanet
           Nylon
           PEEK
    • Natural gut
    • PEEK Monofilament
    • Polyester Monofilament

The winning string must have been installed in the most recent week either in a client or demo racquet.

We will include as much information as possible including graphs and the country of origin.

We will try to post “And the Winner is…” on Friday so take look!