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Written by: E. Maxwell Ernst
Written on: April 27th, 2011
Tags: sports & recreation, physics, material science
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About the Author
Max Ernst is a junior at USC studying Mechanical Engineering. He plays on the USC Ice Hockey Team, is the Frame Lead on the USC Formula SAE Racing Team and is an avid surfer.
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Volume XIII Issue II > Composite Technology and the Hockey Stick Revolution
Over the last decade, the game of hockey has changed significantly, especially due to advances in composite hockey stick technology. This paper discusses the progression of hockey stick composition throughout the years as well as important properties of hockey sticks and how the composition of sticks affects these properties. It also examines the slap shot, the most explosive action performed in hockey, and how it displays these stick properties. Composite hockey sticks are ideal because they combine many of the beneficial properties of other stick compositions, but there is still a significant amount of improvement that can be made to the technology.

Introduction

Across the sciences, people are always striving to use the latest and greatest technology. The same can be said for the sport of hockey. Composite carbon technology has been used in prosthetics, aerospace, car racing and now in hockey sticks. Material, manufacturing and structural advances in composite technology have allowed manufacturers to combine the best properties of previous wooden and aluminum hockey sticks while still adding new innovations that have made composite sticks ideal for today’s hockey players.

History of Hockey

When the game of hockey was first played on frozen ponds in the nineteenth century, players used sticks made from the wood of hardwood trees. In the 1940’s, laminated wood became the standard material (Fig. 1). These sticks were flexible for striking the puck with great force, yet durable and relatively inexpensive. The average wooden stick cost about $35 [1]. Since the technology and manufacturing practices have hardly changed, the price of wooden sticks has not substantially changed either. The main problem with wooden sticks is that they have a tendency to warp and become too flexible after too many hard shots [2]. When a stick loses some stiffness, it also loses accuracy and what players call "the feel of the stick" is compromised.
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Figure 1: The author carries the puck across the blue line during a USC hockey game. He is using a stick made of laminated wood, the current standard for flexibility, durability, and cost.
The stick’s feel is its ability to translate contact with the puck and the ice to the player’s hands [2]. Players prefer the stick to be stiff and stable when handling the puck because it feels as if the puck is on their finger tips instead of at the end of a stick. If the player can properly feel the puck on the stick, they will not need to look down while stick handling, allowing them to look for a teammate to pass to, an opponent to dodge, or taking a shot (Fig. 1).
In the early 1980s, many players, including Wayne Gretzky, the all-time leading scorer in National Hockey League (NHL) history, experimented with aluminum shafts with wooden blades [3]. These sticks gained popularity throughout the 80s and 90s due to their unmatched durability, stiffness and stability. The shaft was simply rectangular aluminum tubing with a replaceable wooden blade glued in [2]. Some stick shafts were so thick and heavy that they never broke or wore out and only the wooden blade needed to be replaced. Although the aluminum sticks were lighter, stronger, more durable and more stable than wooden sticks, they did not allow the player to feel the puck on the stick as well, which is why many players did not switch to aluminum sticks [4].
In the late 1990s, full composite sticks were introduced to the sport, changing the game forever [3]. These sticks were made from graphite fibers bound together by polymer resin, which made them extremely light. Composite hockey sticks “have soared in popularity the last four or five years and are used by more than 80 percent of players in the National Hockey League” [5]. Today, very few players in the NHL still use wooden sticks. Composite stick technology is ideal because it combines the flexibility of wood to generate hard shots, the stiffness and stability of aluminum for control and a lightness that is unmatched by wood or aluminum. Not only does the stick feel lighter in the player’s hands, but the player is be able to move the stick faster, which means quicker maneuvering of the stick and quicker release of the puck for passing and shooting [2]. This allows players to catch goalies and defenders off guard because they are able to release the puck more quickly off the blade of their stick.

Properties of the Hockey Stick

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Figure 2: USC player Ryan Manning uses the flex of his stick to generate a powerful shot from the blue line.
One main property of hockey sticks that contributes to shot velocity is the flexibility or flex of the stick (Fig. 2).
Manufacturers list the flex rating on each stick that corresponds to the amount of force (in pounds-force) that it takes to deflect or bend the shaft one inch [6]. For example, it would take 85 pounds of force to bend an “85 flex” stick one inch from its original resting position. The flex ratings of hockey sticks range from 50 to 120 flex, though most players age 16 and up use sticks with either 85 or 100 flex. Flex is important because the bending of the stick is where the shot derives all of its power. When the stick is bent by the player, it is loaded with potential energy, like a spring. This energy is then transferred from the stick into the puck, resulting in a high puck velocity [7].
When designing hockey sticks, manufacturers use a standard deformation equation to calculate the flex of the stick. The deformation equation,
F = 48EIδ/L3(1)
is used, where F is the force being applied at the center of the shaft of the stick, E is the Young’s Modulus of elasticity of the material, which depends on the type of material being used in the stick, I corresponds to the second area moment of inertia of the cross section of the shaft, δ is the deflection or amount of vertical deformation of the shaft when the force F is applied, and L is the length of the shaft [6]. Flex is especially important when attempting to maximize the velocity of a slap shot.
The slap shot is the most explosive and dynamic move in hockey and it demonstrates many stick properties. It is also the most common source of broken sticks. Many recent studies and research done on hockey stick technology cite a six-stage process for the slap shot which was first established by hockey scientists Pearsall, Montgomery, Rothsching and Turcotte in 1999. The six stages are backswing, downswing, pre-loading, loading, release and follow through (Fig. 3). The first stage of the slap shot is the backswing, where the stick is brought above the player’s head. The next stage is the downswing, where the stick is swung downwards toward the ice. The third stage, pre-loading, is one of the most overlooked stages of the slap shot. Many people who have never played hockey do not realize that the stick strikes the ice about a foot behind the puck before striking the puck. This is how the player is able to apply force to the stick and bend the shaft [8]. In this stage, the stick acts similarly to a three-point bending fixture. The player’s top hand and the ice act as the hinges which hold the shaft in place and the player’s hand that is holding the middle of the stick applies the force to the shaft. This leads into the next stage, loading.
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Figure 3: The author demonstrates the six stages of a slap shot:
a) backswing, b) downswing, c) pre-loading, d) loading, e) release, f) follow-through.
The bending of the shaft loads potential energy into the stick, similar to the way one would load a spring. The loading stage is extremely important to the shot because without the loading of the stick, the shot would be significantly slower, making it much easier to get stopped. Once the stick has been loaded, it continues along the ice until it touches the puck. The next stage is the release of the puck. This is the stage where the stick is in contact with the puck, in physics, this is known as an impulse. The impulse (I) is equal to the force (F) applied to the object multiplied by the total time (∆t) the force is applied to the object:
I = F∆t.(2)
In the release stage, all the potential energy that was stored in the stick due to flexing is transferred into the puck in the form of kinetic energy [8]. This is how the puck is able to fly through the air at such a high velocity. The final stage of the slap shot is the follow-through. The follow-through determines the direction that the puck will travel. If the stick follows through in an upwards direction, the puck will leave the ice and go into the air. If the follow-through is kept low, the puck will stay on the ice or fly a few inches off the ice. Players exploit the flex of the stick to fire pucks at speeds over 100 miles per hour [3].

Looking to the Future

Although hockey sticks have evolved due to advances in composite technology, there are still issues with composite hockey stick technology that need to be addressed. Such a significant change in technology has resulted in extreme price inflation and extremely short product cycles. A top of the line, year 2011, one-piece composite stick can cost up to $300.00, yet players of all skill levels continue to buy these high-tech sticks regardless of the fact that manufacturers have sacrificed durability for lightness [9]. A 1998 study performed at the University of Windsor and Louisville in Ontario, Canada showed that composite sticks break just as easily as wooden sticks (Fig. 4) [5].
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Figure 4: The author’s collection of broken sticks. Composite hockey sticks break just as easily as wood sticks, but players keep buying these expensive, high-tech sticks because they enjoy the performance.
After many years of innovation and price inflation, composite sticks still have the same life span as a wooden stick at over five times the cost. Hockey stick manufacturers have two ways to deal with this issue. They can either engineer a stick that combines the lightweight, yet flexible properties of present-day composite sticks with the durability of an aluminum stick, or they can develop new, low-cost materials that will have the same performance as composite sticks.

Conclusion

Advances in composite technology have revolutionized the hockey stick and the game of hockey. Today, almost every hockey player, novice to professional, uses a composite hockey stick. Composite sticks are ideal because they combine the feel and shooting flexibility of wood with the stiffness and stability of aluminum. Composite hockey sticks may be the best on the market today, but in the future, there will always be room for new technologies.

References

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    • [3] "Performance Superiority." Easton Hockey. Internet: http://eastonhockey.​com/the-difference/p​erformance-superiori​ty, [Apr. 04, 2011].
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    • [7] J.T. Worobets, J.C. Fairbairn, & D.J. Stefanyshyn. "The influence of shaft stiffness on potential energy and puck speed during wrist and slap shots in ice hockey." Sports Engineering, vol. 9(4), pp. 191–200, 2006.
    • [8] A. Villasenor, R.A. Turcotte, & D.J. Pearsall. "Recoil effect of the ice hockey stick during a slap shot." Journal of Applied Biomechanics, vol. 22(5), pp. 202–211, 2006.
    • [9] "Easton Stealth S19 Grip Sr. Composite Hockey Stick." Internet: HockeyMonkey.com, [Apr. 04, 2011].
    • [10] D.J. Pearsall, D. Montgomery, N. Rothsching, & R. Turcotte. "The influence of stick stiffness on the performance of ice hockey slap shots". Sports Engineering, vol. 2(1), pp. 3–11, 1999.
    • [11] D.J. Laliberte. "Biomechanics of Ice Hockey Slap Shots: Which Stick Is Best?" The Sport Journal. Available: http://www.thesportj​ournal.org/article/b​iomechanics-ice-hock​ey-slap-shots-which-​stick-best, 2009 [Mar. 20, 2011].