WO1994011064A1

WO1994011064A1 - Hybrid stringing arrangement of main and cross strings with enhanced performance characteristics for use in a sports racket

Info

Publication number: WO1994011064A1
Application number: PCT/US1993/005382
Authority: WO
Inventors: Harry M. Ferrari; Ronald H. Carr; Raymond P. Harrington; Charles N. Vietmeier
Original assignee: Ferrari Importing Company
Priority date: 1992-11-06
Filing date: 1993-06-07
Publication date: 1994-05-26
Also published as: AU4598893A

Abstract

For a sports racquet (10) including a frame (12) with a head portion (14) encompassing an open region (24), a hybrid stringing arrangement (26) is defined by a plurality of main strings (28) and a plurality of cross strings (30) composed of dissimilar materials that are applied under tension to the head portion (14) and extended across the open region (24) thereof in an interwoven grid pattern. All of the strings of the one plurality of the main strings (28) and cross strings (30) of the stringing arrangement (26) are composed of a metallic structural material, such as a stainless steel alloy, coated externally with an outer player of synthetic non-structural material, such as a suitable polymer. All of the strings of the other plurality of main strings (28) and cross strings (30) of the stringing arrangement (26) are composed of one or the other of an animal gut structural material or a synthetic structural material, such as a suitable polymer.

Description

HYBRID STRINGING ARRANGEMENT OF MAIN AND CROSS STRINGS WITH ENHANCED PERFORMANCE CHARACTERISTICS FOR USE IN A SPORTS RACQUET

This application is a continuation-in-part of copending

U. S. patent application Serial No. 07/788,979, filed

November 7, 1991, and entitled "Sports Racquet With Hybrid Stringing Arrangement Of Dissimilar Longitudinal And Cross

Strings", by Harry M. Ferrari et al.

Technical Field

The present invention generally relates to stringing arrangements for racquets used in sports games and, more particularly, is concerned with a hybrid stringing arrangement of main and cross strings of dissimilar structural materials exhibiting different resiliency and wear compatibility characteristics so as to optimize the playability and durability of the stringing bed.

Background Art

A conventional sports racquet, such as a tennis racquet, has a frame which includes a head portion, a throat portion and a handle portion formed as an integral structure. Typically, the racquet frame is fabricated of composite-type material composed of high modulus fibers such as graphite fibers or glass fibers in a matrix of an epoxy resin. Alternatively, racquet frames have been fabricated from other materials, such as aluminum, wood and plastics.

The head portion of the racquet frame typically has a round or oval configuration and contains a plurality of holes aligned in a common plane. A grid pattern of stringing extends through the holes and is applied under tension across the head portion to provide a ball striking area of the racquet. The handle portion of the racquet frame is usually covered with an outer sheath for facilitating gripping of the racquet by the user's hand. Commonly, stringing for sports racquet is made of structural materials including animal gut, synthetic materials, or in rare instances metallic wire and generally the vertical main strings and the horizontal cross strings are made of the same material.

Animal gut stringing is normally made from the twisting together of a plurality of strips of beef or sheep intestines bonded together with an adhesive and then protected with a non- structural resin coating. The strips of intestine provide the structural support in the string. Animal gut is generally considered to have optimum playing characteristics for racquet sports. However, it is costly, affected adversely by weather, has a relatively short play life, and breaks easily.

Synthetic stringing for sports racquets, normally made from a single strand, or a plurality of strands of polymeric materials, such as nylon, polyester, or other engineered polymer composites which are twisted together and bonded with adhesive resins. The strand or strands of polymeric material provides the structural support in the strings. Certain synthetic materials, such as nylon, polyester or polyolephine, can be engineered to provide good playing characteristics. Other synthetic polymeric strings, such as strings made from a plurality of high strength aramid fibers twisted together, bonded with an adhesive resin, and protected by an outer resin coating can also be made. The high strength aramid fibers provide the structural support in the strings. Synthetic strings made from aramid fibers can be engineered to provide good durability. However, there is not a synthetic material that provides an optimum combination of playability and durability.

Metallic stringing for sports racquets is normally made from a single strand or a plurality of strands composed of ferrous alloys, such as steel, or a stainless steel alloy, or other metallic alloys which are twisted together and then coated with a non-structural friction reducing material. The metallic strand or strands provide the structural support in the strings. If properly designed, metallic strings provide good durability; however, they are too stiff to provide an acceptable level of playability. They also produce high levels of shock and vibration which are damaging to the racquet frame and are hazardous to the wrist and arm of the player.

Generally, the playability of the string bed is determined by the stiffness and resiliency of the strings. The stiffness affects the feel of the racquet and the resiliency effects the power. Lower stiffness provides a softer feel and higher resiliency provides greater power. On the other hand, the durability of the string bed is determined by the wear compatibility of the stringing which is determined by the abrasion resistance of the strings. The main strings typically exhibit the most severe wear since these strings become notched due to sliding back and forth over the cross strings. Consequently, the main strings are usually the first strings to break in the stringing.

By using a high strength structural material for the strings, such as steel or aramid fibers, greater string durability can be achieved, however, in general these high strength materials are extremely stiff and result in high impact forces and unacceptable racquet playability. In addition, stiff strings transfer the impact energy of the ball substantially undampened which is damaging to the racquet frame and the players wrist and arm. If the tension of these stiff strings is reduced to make the string bed more flexible, then they lack the resiliency required to accept the impact energy of the incoming ball and rebound it at an acceptable velocity to keep it in play.

It is known in the art to use different structural materials for the main strings and cross strings. One example of such teaching is seen in the Hutchinson (US 1,252,576) patent wherein the cross strings 9 and the outer portions of the main strings 8 are comprised of catgut or other fibrous string material and wherein the intermediate or central portion of the main strings have been substituted with flat metal rods 10 that are bent into a sinusoidal shape and are individually installed with pins 12 and threaded connectors 13. The purpose of the metallic rods 10 are to provide a means for re- tightening or stiffening the string bed, after the initial stringing, to maintain the desired string bed stiffness. It is also stated that the individual metallic rods 10 add strength to the string bed and are specially designed with a flat profile so as to prevent damage to the ball and the catgut strings. Another example of using different structural materials for the main strings and cross strings can be seen in the Soong (US 4,437,662) patent wherein there is disclosed a racquet having transverse nylon (cross) strings and longitudinal Kevlar (main) strings. The racquet frame was specifically designed such that the main strings have a length which are at least 30% longer than the cross strings and which also require a stringing tension that is at least 30% higher than the cross strings. In utilizing main strings having a length 30% longer than the cross strings and with a tension 30% higher than the cross strings, Soong intended to form a stringing bed wherein the strings would have a low stiffness characteristic and be of a high tensile strength. In other words, this combination of string length and tension was intended to reduce the energy loss in the strings by reducing the strain in the strings, and thus, the internal friction or hystersis loss due to geometric and force relationships. Due to the extra length of the main strings in Soong's design, Kevlar, a high strength synthetic material produced by DuPont, was selected purely on the basis of the high strength requirements placed on the main strings, however, Kevlar has a high stiffness characteristic and thus his selection thereof is contrary to what he teaches. It would appear that the teaching of the Soong patent is limited to Soong's design of a racquet having its main strings being 30% longer than the cross strings and with the tension being 30% greater than the cross strings.

Consequently, a need still exists for improvement of racquet stringing so as to optimize the playability and durability of the racquet strings.

Disclosure of Invention

The present invention provides a hybrid stringing arrangement for sports racquets designed to satisfy the aforementioned needs by optimizing the combination of playability and durability of racquet stringing. Accordingly, the present invention relates to a hybrid stringing arrangement for a sports racquet having a frame having a head portion encompassing an open region. The hybrid stringing arrangement comprises a plurality of main strings and a plurality of cross strings adapted to be applied under tension to the head portion of the frame and extending across the open region in an interwoven grid pattern in defining a stringing bed for providing a striking area of the racquet. One of the plurality of main strings or cross strings has a resiliency factor at least 2 times greater than the resiliency factor of the other plurality of main or cross strings in the stringing. Further, in another embodiment, the main and cross strings have a wear compatibility such that the notching wear is eliminated in the structural material comprising the main strings resulting in longer string life.

More particularly, in one embodiment, the main strings have a resiliency factor of greater than 2 times the resiliency factor for the cross strings, whereas, in a second embodiment, the cross strings have a resiliency factor of greater than 2 times the resiliency factor for the main strings. In the one embodiment, the structural material for all of the main strings of the stringing arrangement is a metallic material and the structural material for all of the cross strings of the stringing arrangement is a non-metallic material, preferably a synthetic material or an animal gut material. In the second embodiment, the structural material for the cross strings is a metallic material and the structural material for the main strings is a non-metallic material.

The metallic material composing the main strings in the one embodiment is a metal selected from the group consisting of ferrous alloys, such as steel or stainless steel, or non- ferrous metals or alloys, such as titanium or nickel alloys. Also, the metallic material is preferably coated externally with an outer layer of a low friction, abrasion resistant, synthetic material.

The synthetic material composing the cross strings in the one embodiment and the outer layer surrounding the metallic material of the main strings in the same embodiment is a polymer material, such as a polyamide, such as nylon and ara ids, polyester, polyolephine, polyetheretherketone, or polyethylene.

These and other features and advantages of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings wherein there is shown and described an illustrative embodiment of the invention.

Brief Description of Drawings

Fig. 1 is a plan view of a prior art tennis racquet to which can be applied a hybrid stringing arrangement in accordance with the present invention.

Fig. 2 is an enlarged fragmentary plan view of the hybrid stringing arrangement in accordance with one embodiment of the present invention.

Fig. 3 is an enlarged cross-sectional view of a cross string of the hybrid stringing arrangement taken along line 3—3 of Fig. 2.

Fig. 4 is an enlarged cross-sectional view of a main string of the hybrid stringing arrangement taken along line 4—4 of Fig. 2. For illustrated purposes, the cross section is depicted with a single strand of structural material 32, however, the structural material 32 could also be composed of multiple strands of the material.

Fig. 5 is an enlarged fragmentary plan view of the hybrid stringing arrangement in accordance with another embodiment of the present invention.

Fig. 6 is an enlarged cross-sectional view of a cross string of the hybrid stringing arrangement taken along line 6—6 of Fig. 5. For illustrative purposes, the cross section is depicted with a single strand of structural material 32', however, the structural material 32' could also be composed of multiple strands of the material.

Fig. 7 is an enlarged cross-sectional view of a main string of the hybrid stringing arrangement taken along line 7—7 of Fig. 5. For illustrative purposes, the cross section is depicted as a single strand of material, however, it can also be composed of multiple strands of material.

Best Mode for Carrying Out the Invention

Referring now to the drawings, and particularly to Fig. 1, there is shown a prior art tennis racquet, generally indicated by the numeral 10. While the present invention is illustrated in Figs. 2-7 and described below in conjunction with the tennis racquet 10, the present invention is believed to be applicable to the racquets used in playing other sports comparable to tennis, such as squash and badminton. Thus, the reference hereafter to a tennis racquet 10 should be construed in a generic sense as applicable to other sports racquets. In its basic construction, the tennis racquet 10 has a frame 12 which includes a head portion 14, a handle portion 16 and a throat portion 18 extending between and interconnecting the head and handle portions 14, 16. The racquet frame 12 typically is fabricated of a composite-type material composed of high modulus fibers such as graphite fibers or glass fibers in a matrix of an epoxy resin. Alternatively, the racquet frame 12 can be fabricated from other materials, such as aluminum, wood and plastics.

The handle portion 16 of the racquet frame 10 typically includes an outer sheath (not shown) for facilitating gripping of the racquet by the user's hand. The throat portion 18 typically is in the form of a pair of shafts or legs 20 having a generally V-shaped configuration.

The head portion 14 of the racquet frame 12 typically has a round or oval configuration and contains a plurality of spaced stringing holes (not shown) extending between an inwardly facing surface 14A and along a narrow recess (not shown) formed in an outwardly facing surface 14B of the head portion 14. The stringing holes are aligned in a common plane. In a known manner, a conventional stringing 22 is applied under tension through the holes and across the open region 24 encompassed by the head portion 14 in an interwoven grid pattern to define a stringing bed that provides a striking area of the racquet 10 for a ball or other object.

Referring to Figs. 2-4, a hybrid stringing arrangement 26 of the present invention can be employed in the tennis racquet 10 instead of the conventional stringing 22. As used herein, a hybrid stringing arrangement is defined on the basis of the performance of the resiliency characteristic and the performance of the wear compatibility characteristic of the stringing materials when the main strings and cross strings are combined in a stringing bed. Thus, if two different strings, such as the main strings and cross strings, share the same basic resiliency or wear compatibility characteristic, then even though they may in fact be different materials their use together in the stringing bed would not be defined as a hybrid stringing arrangement as used herein. The hybrid stringing arrangement 26 is applied under tension to the head portion 14 and extends across the open region 24 in the same interwoven grid pattern as provided by the conventional stringing 22 to also define a stringing bed in providing a ball striking area of the racquet 10. However, unlike the conventional stringing 22, the hybrid arrangement 26 of stringing is comprised of a plurality of longitudinal main strings 28 and a plurality of horizontal cross strings 30 which are composed of different or dissimilar structural materials that exhibit superior resiliency and wear compatibility when combined to form the stringing bed. The resiliency is the ability of the stringing to rebound a ball with a high velocity and enhance the control and playability of a racquet whereas the wear compatibility increases the life of the stringing (durability) . in one embodiment of the present invention, as seen in Fig. 2, all of the vertical or longitudinal main strings 28 of the stringing arrangement 26 are composed of a metallic structural material 32. Preferably, the metallic structural material 32 of all the main strings 28 is coated externally with an outer layer 34 of a low friction, abrasion resistant, synthetic, non-structural material to facilitate stringing and reduce damage to the surface of the ball. All of the horizontal or cross strings 30 of the stringing arrangement 26 are composed of a non-metallic material, such as a synthetic structural material or an animal gut structural material.

In a second embodiment of the invention, as seen in

Figs. 5-7, the structural materials of the main strings and cross strings have been just reversed such that all of the horizontal cross strings 30' of the stringing arrangement 26' are composed of a metallic structural material 32' and coated externally with an outer layer 34' of a low friction, abrasion resistant, synthetic non-structural material and all of the vertical main strings 28' of the stringing arrangement 26' are composed of a non-metallic structural material, such as a synthetic structural material or an animal structural gut material. The major difference between the hybrid stringing arrangement 26 of the first embodiment seen in Fig. 2 and the hybrid stringing arrangement 26* of the second embodiment seen in Fig. 5 is that the stringing arrangement 26 offers greater power and durability whereas the stringing arrangement 26' offers lower impact and greater feel. However, both stringing arrangements 26 and 26' provide a unique combination of stringing materials that create a stringing bed that is more resilient and more durable due to a more compatible material combination for the intersecting strings.

More particularly, the metallic structural material composing the respective main strings 28 and cross strings 30' can be a ferrous alloy, such as stainless steel or another steel alloy, or a non-ferrous metal, such as titanium or nickel alloys. Other metallic materials can also be used due to the hardness, high strength, and resiliency of metallic materials. Preferably, the metallic structural material 32, 32' is stainless steel, a nickel alloy or titanium. The non- metallic material composing the cross strings 30, main strings 28' and the outer coating layer 34, 34* surrounding the main strings 28 and cross strings 30' can be a synthetic polymer, such as nylon, polyester, polyolephine, or an aramid. The non- metallic structural material composing the cross strings 30 or main strings 28' can also be animal gut.

In accordance with the present invention, the combination of the main strings 28 of metallic structural material and cross strings 30 of non-metallic structural material which comprise the hybrid stringing arrangement 26 of the first embodiment and the combination of the cross strings 30' of metallic material and main strings 28' of non-metallic material which comprise the hybrid stringing arrangement 26' of the second embodiment provide improved stringing durability and improved stringing playability. The durability of the hybrid stringing arrangement 26 is vastly improved since string movement caused by impact with the ball is reduced as a result of the stiffer metallic main strings 28, which in turn, reduces string wear. In addition, due to the hardness of the metallic material in the main strings 28, being much harder than the non-metallic cross strings 30, the notch wear in the main strings 28 is limited to the wear of the non-structural coating 34. Due to the hardness of the metallic material, there is virtually no wear in the structural material of the main strings 28 since the string movement resulting from impact of a ball is in a direction such that the cross strings 30 remain virtually still while the main strings 28 move back and forth in a direction perpendicular to the major axis of the string, thus the wear in the cross strings 30 is spread over a larger surface area of the string. Therefore, the time required to reach a critical wear depth is extended such that string breakage is forced to occur in the cross strings 30, resulting in an extended time period for string breakage.

The durability of the hybrid stringing arrangement 26' is also improved over conventional stringing 22 due to the reduced string movement provided by the stiff metallic cross strings 30*. The reduced string movement limits the abrasive action between the non-metallic main strings 28' and the metallic cross strings 30'. The result is that the amount of time required to reach a critical wear depth in the non-metallic main strings 28 is extended. As with the hybrid stringing arrangement 26, the wear in the metallic cross strings 30' of hybrid stringing arrangement 26* is limited to the non- structural coating 34', and thus, no breakage of the cross strings 30' .

Further, when compared to a stringing arrangement formed of metallic main and metallic cross strings, metal-to-synthetic material (such as nylon) contact, as in the case of the invention, has a much lower coefficient of friction, than metal-to-metal contact (0.2 compared to 0.8) which translates into less wear for the metal-to-synthetic material contact.

As described above, for optimizing the playability and durability of racquet strings, the inventors have selected a metallic structural material for the stringing of one of the sets of strings (main or cross) and a non-metallic structural material for the stringing of the other set of strings (main or cross) which make up the hybrid stringing arrangements 26 and 26' of the present invention. Contrary to the "stiffness" and "strength" characteristics advocated by the prior art teachings discussed above, the present invention examines the "resiliency" and "wear compatibility" characteristics of the stringing materials and defines the hybrid stringing arrangement on the basis of these characteristics when the main and cross strings are combined in the stringing bed. From a "resiliency" and "wear compatibility" standpoint, it has been found that by combining metallic and non-metallic structural materials in the stringing, the resiliency and wear compatibility are far superior to that of a stringing or stringing bed composed of all metallic or all non-metallic materials. To quantify the resiliency and wear compatibility of different stringing structural materials, the inventors examined the dynamic Young's modulus compared to the dynamic loss modulus (Table I) and performed dynamic wear tests (Table II) on various strings composed of various structural materials and combinations of these structural materials for evaluating wear compatibility.

Resiliency tests were performed by exciting a mass attached to a string under tension and monitoring its response. The results obtained are dynamic stiffness (dynamic Young's modulus) and dynamic loss (energy loss in string material) and the relationship between the stiffness and loss is defined as the resiliency factor. The results of the tests are as follows: TABLE I

Racquet String Dynamic Stiffness/Dynamic Loss (Material) (Resiliency Factor)

Nylon 3.7

Natural Gut 5.8

Kevlar 4.2

Coated Steel 18.9

As can be easily seen from the above test results, Nylon, Kevlar and Natural Gut (all conventional non-metallic structural materials used for stringing) all have similar values (3.7-5.8) with regards to resiliency, whereas, steel (a representative metallic structural material) coated with nylon has a value of 18.9 which is 3.3 to 5.1 times better than these non-metallic structural materials from a resiliency standpoint. In combining the metallic and non-metallic structural materials in the stringing, since there is a substantial difference in the "resiliency" characteristics between metallic and non-metallic materials, the net result will be a stringing having a resiliency factor which is at least 2 times greater than a stringing composed of all non- metallic structural materials.

Dynamic wear tests were also performed for different stringing materials by stringing a test racquet with various strings at a predetermined tension and then striking tennis balls off the stringing bed. The number of ball impacts were recorded until breakage of the stringing occurred. The results of these tests are as follows:

TABLE II

Racquet Stringing Dynamic Wear Test

As can be easily seen from the above test results, natural gut alone, nylon alone, coated steel alone or nylon and Kevlar strung together have similar results (170, 270, 174 and 350 impacts respectively) , however, coated steel and nylon provided results of 600 impacts which is significantly better than Kevlar and nylon. It should be noted here that the steel was coated with an outer layer of nylon in accordance with the invention. Based on the main and cross strings of nylon structural material being the benchmark for comparison purposes, it can be easily seen that main strings and cross strings of coated steel/nylon and nylon/coated steel have a wear compatibility of approximately 1.5 to 2 times better than the wear compatibility of the benchmark structural material.

To further quantity the resiliency and wear compatibility of different stringing structural materials, on- court play tests have been performed. These on-court tests measure the durability of the hybrid stringing arrangement 26 of the present invention for comparison with that of the prior art. The results are summarized in Table III. These tests involved a cross section of advanced players using various racquet stringing under routine playing conditions, and measuring the amount of time required for the stringing to break.

TABLE III >

Stringing Combination Equivalent Hours of Match (Main/Cross) Play Before Strand Breakage

Animal Gut/Animal Gut 6

Nylon/Nylon 9 Coated Steel/Coated Steel 6

Coated Steel/Nylon 24

Coated Steel/Animal Gut 9

These tests were conducted using a stainless steel alloy coated with nylon for the main strings 28, as being representative of highly resilient metallic structural materials, and nylon or animal gut material for the cross strings 30, as being representative of the non-metallic structural materials.

The playability of the hybrid stringing arrangement 26 of the present invention is also vastly improved over all-metallic or all-non-metallic stringing. The resiliency provided by the metallic main strings 28 and the elasticity provided by the non-metallic cross strings 30 in the hybrid stringing arrangement 26 results in reduced vibration and much better energy transfer to the struck ball (greater ball velocity) . Tests have also been performed to measure the playability of the hybrid stringing arrangement 26 and compare it to that of the prior art. The results are summarized in Table IV. These tests involved measurement of rebound ball velocities while keeping incoming ball velocities relatively constant. These tests were conducted using stainless steel coated with nylon for the main strings 28, as being representative of highly resilient metallic structural materials, and nylon, Kevlar, or animal gut material for the cross strings 30, as being representative of the non-metallic structural materials.

TABLE IV

Stringing Combination Velocity of Struck Ball (Main/Cross) (Miles Per Hour)

Animal Gut/Animal Gut 49

Nylon/Nylon 48

Coated Steel/Coated Steel 39

Coated Steel/Nylon 46 Coated Steel/Animal Gut 46

From the court-play tests conducted, the combined ranking of durability and playability is best with a combination of metallic main strings 28 and non-metallic cross strings 30 as provided in the hybrid stringing arrangement 26 of the present invention.

An added advantage to the present invention is the ability to reduce the diameter of the metallic main strings 28 of stringing arrangement 26 and cross strings 30' of stringing arrangement 26'. This is due to the elimination of wear in the metallic structural material of the main strings 28 in combination with the non-metallic structural material of the cross strings 30 (stringing arrangement 26) and main strings 28' (stringing arrangement 26'). The smaller diameter strings provide more penetration into the surface of the ball, thus providing for more ball control and spin. The diameter reduction can be greatly improved over that of prior art stringing by at least ten percent.

It is thought that the present invention and many of its attendant advantages will be understood from the foregoing description and it will be apparent that various changes may be made in the form, construction and arrangement of the parts thereof without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the form hereinbefore described being merely a preferred or exemplary embodiment thereof.

Claims

1. A hybrid stringing arrangement for a sports racquet including a frame having a head portion encompassing an open region, said hybrid stringing arrangement comprising: a plurality of main strings and a plurality of cross strings adapted to be applied under tension to said head portion and extending across said open region in an interwoven grid pattern in defining a stringing bed for providing a striking area of said racquet, one of said plurality of main strings and cross strings having a resiliency factor of at least 2 times greater than the resiliency factor for the other one of said plurality of main strings and cross strings.

2. The stringing arrangement as recited in Claim 1, wherein one of said plurality of main strings and cross strings is composed of a metallic structural material and the other one of said plurality of main strings and cross strings is composed of a non-metallic structural material.

3. The stringing arrangement as recited in Claim 2, wherein said metallic structural material composing said one plurality of main strings and cross strings is a metal selected from the group consisting of ferrous alloys, non-ferrous metals, or non-ferrous alloys.

4. The stringing arrangement as recited in Claim 3, wherein said metallic structural material composing said one plurality of main strings and cross strings is a metal selected from the group consisting of stainless steel, steel alloy, titanium and nickel alloy.

5. The stringing arrangement as recited in Claim 2, wherein said metallic structural material composing said one plurality of main strings and cross strings is a stainless steel alloy.

6. The stringing arrangement as recited in Claim 2, wherein all of said one plurality of main strings and cross strings are further composed of an outer layer of a non- metallic, non-structural synthetic material surrounding and externally coating said metallic structural material of said strings.

7. The stringing arrangement as recited in Claim 6, wherein said non-metallic, non-structural synthetic material composing said outer layer surrounding said metallic structural material of said one plurality of main strings and cross strings is a polymer.

8. The stringing arrangement as recited in Claim 7, wherein said non-metallic synthetic material composing said outer layer surrounding said metallic structural material of said one plurality of main strings and cross strings is a polymer selected from the group consisting of polyamides, polyester, polyolephine and polyetheretherketone.

9. The stringing arrangement as recited in Claim 2, wherein said non-metallic structural material composing said other plurality of main strings and cross strings is a synthetic structural material.

10. The stringing arrangement as recited in Claim 9, wherein said synthetic structural material composing said other plurality of main strings and cross strings is a polymer selected from the group consisting of polyamides, polyester, polyolephine, polyetheretherketone and polyethylene.

11. The stringing arrangement as recited in Claim 2, wherein said non-metallic structural material composing said other plurality of main strings and cross strings is an animal gut structural material.

12. The stringing arrangement as recited in Claim 1, wherein all of said main strings are composed of a metallic structural material and all of said cross strings are composed of a non-metallic structural material, said main strings having a resiliency factor of greater than 2 times the resiliency factor of said cross strings.

13. The stringing arrangement as recited in Claim 1, wherein all of said cross strings are composed of a metallic structural material and all of said main strings are composed of a non-metallic structural material, said cross strings having a resiliency factor of greater than 2 times the resiliency factor of said main strings.

14. A hybrid stringing arrangement for a sports racquet having a frame including a head portion encompassing an open region, said hybrid stringing arrangement comprising: a plurality of main strings and a plurality of cross strings adapted to be applied under tension to said head portion and extending across said open region in an interwoven grid pattern in definging a stringing bed for providing a striking area of said racquet, said main strings and cross strings being composed of different structural materials from one another, said structural material of said main strings being significantly harder than said structural material of said cross strings such that there is substantially no notching wear in said structural material of said main strings which would cause breakage of said main strings compared to wear of said structural material of said cross strings while said racquet is in play so as to extend the life of said stringing bed.

15. The stringing arrangement as recited in Claim 14, wherein all of said main strings are composed of a metallic structural material coated externally with an outer layer of synthetic non-structural material and all of said cross strings are composed of a non-metallic structural material.

16. The stringing arrangement as recited in Claim 15, wherein said metallic structural material composing said main strings is a metal selected from the group consisting of ferrous alloys, non-ferrous metals, and non-ferrous alloys.

17. The stringing arrangement as recited in Claim 15, wherein said metallic structural material composing said main strings is a stainless steel alloy.

18. The stringing arrangement as recited in Claim 15, wherein said synthetic non-structural material composing said outer layer surrounding said metallic structural material of said main strings is a polymer.

19. The stringing arrangement as recited in Claim 15, wherein said synthetic non-structural material composing said outer layer surrounding said metallic structural material of said main strings and composing said structural material of said cross strings of said stringing arrangement is a polymer selected from the group consisting of polyamides, polyester, polyolephine, polyetheretherketone and polyethylene.

20. The stringing arrangement as recited in Claim 14, wherein one of said plurality of said main strings and cross strings has a resiliency factor of greater than 2 times the resiliency factor for said other plurality of main strings and cross strings.

21. A hybrid stringing arrangement for a sports racquet having a frame including a head portion encompassing an open region, said hybrid stringing arrangement comprising: a plurality of main strings and a plurality of cross strings adapted to be applied under tension to said head portion and extending across said open region in an interwoven grid pattern in definging a stringing bed for providing a striking area of said racquet, said main strings and cross strings being composed of different structural materials from one another, said structural material of said cross strings being significantly stiffer than said structural material of said main strings for limiting movement of said cross strings and main strings relative to one another during play of said racquet so as to reduce wear and breakage of said strings in extending the life of said stringing bed.

22. The stringing arrangement as recited in Claim 22, wherein all of said cross strings are composed of a metallic structural material coated externally with an outer layer of synthetic non-structural material and all of said main strings are composed of a non-metallic structural material.