Chapter 10. Design and Materials in Ice Hockey

D
D
D
D
′
X
X
Y
Z
Y
Z
X
Z
Y
C
C
C
C
′
D
′
D’
C
′
C’
Shaft
Hosel
(A)
(B)
(C)
(C)
Figure 10.6 The basic design components of a hockey stick as seen from the (A)
front; (B) top and (C) side views.
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the ice and viewed directly from above (Fig. B. Various forms of blade twist or torsion patterns along the blades long axis exist
(
Fig. C. The concave curvature of the blade allows greater control of the puck both in terms of stick handling possession and shooting accuracy
(lift and spin. Conversely, blade curve compromises shooting and passing with the backhand.
Players hold the stick either left (the right hand gripping the top of the stick shaft) or right (the left hand on the top of the stick shaft, and the concave curve will typically be oriented forward. Factors determining initial left-versus-right laterality selection vary with intrinsic and extrinsic context variables, but at higher skill levels, ones stick side becomes strongly interrelated to playing position, such as left or right wing or playing side on the rink surface (
Puterman, Schorer, & Baker, 2010
). As a general guide, lower lie angle sticks are used for players who skate lower to the ice and carry the puck out in front, whereas lies of 7 and 8 are for players who skate upright and carry the puck close to their skates Stick Materials and Construction
The materials and construction of hockey sticks have changed considerably since their origin in the s. Initially, whole sticks were cut from one piece from wood timbers or bolts. Local industries arose in conjunction with existing carpentry and furniture stores. Wood stocks were harvested so that the form and grain followed the general stick and blade shape. Hardwoods such as rock (or cork) elm were first used given their
Figure 10.7 Example of shaft-to-blade lie angles 4, 5, and 6 degrees.
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durability, although they tended to be heavy (about 1 kg) and stiff. Top end sticks were free of knots or grain irregularities. The shapes of wood bolts were then modified using a combination of steam and clamps and then kiln dried to approximately 8% moisture content. Blade ends were dipped in varnish to prevent cracking (
Dowbiggin, 2001
). Such steamed sticks were prone to gradually reverting to their original shape in wet and warmer conditions consequently, players often used electrical tape around their blade ends to reduce warping (a tradition persisting to this day for different reasons. As elm wood stocks became scarce, alternative woods and construction techniques evolved around 1920. Softer woods such as white ash became popular substitute materials due to their plentiful availability, decreased weightless than 800 g, and greater shaft flex. In addition, to overcome grain limitations in acceptable wood bolts, two- part sticks were developed consisting of a blade inserted and glued into amortise joint on the heel of the shaft (
Dowbiggin, 2001
). By the 1950s,
three-part sticks were developed consisting of a separate heel joint about cm long glued to the base of the shaft.
By the sands, laminates (for example, 14 21 multiply wood
“wafer” or sandwich strips held together with epoxy) and fiberglass composites became more and more prevalent. These newer materials diversified the available properties of stick flexibility and responsiveness as well as permitting greater consistency in mechanical properties. To further lighten sticks (to approximately 600 g, some manufacturers hollowed the shafts. Wood hybrid sticks were introduced with blades and/or shafts of wood (aspen or birch) cores wrapped in fiberglass or Kevlar/aramid,
reinforced cloth (or laminates, and resin. Variations in weaving patterns,
laminate densities, and epoxy resins have allowed manufacturers greater control over engineering the mechanical behavior of the stick. Aluminum shafts with wood laminate or plastic blade inserts were also introduced in the s but failed to hold a substantial market share due, primarily, to problems with vibration and
“ringing” in players hands, and they were superseded by the next generation of materials graphite (carbon fiber)
composites in the s. Composite sticks became popular despite being substantially more expensive than wood laminate models because they offered further lightness and material fatigue resistance to bending. The major criticism of composites is their susceptibility to brittle fracture.
In terms of composite sticks, various construction techniques are used such as resin transfer molding (RTM), preimpregnated (prepreg), full- wrap, and sandwich structures. RTM involves dry fibers placed, then
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compressed, while resin and a catalyst are injected under low pressure.
Prepreg involves carbon or fiberglass fibers placed in a mold impregnated with resin. This process uses less resin than the RTM method and can make prepreg blades and shafts lighter. Full wrap refers to the outer layers of the blade or shaft being wrapped with carbon fibers. Lastly, the sandwich structure involves fibers being layered over each other but not wrapped. The orientation, number of layers, the continuity of layers, and the assembly process modulate the sticks bending and torsional stiffness.
Composite sticks maybe constructed as true one-piece or fused (two- piece) products. The former is one continuous structure from shaft to blade. The latter consists of a separate blade and shaft that are joined together during the manufacturing process and superficially appear as a one-piece stick. Since separate blades are inserted into the shafts, the hosel portion of a fused stick is a solid structure that has increased torsional stiffness compared to a
“true one-piece” stick. Stick blades can be replaced on aluminum alloy or composite sticks by heating the shaft at the end of the stick and removing the blade Evaluating Ice Hockey Stick Design
The stiffness, or flex, of a sticks shaft is important in determining control and performance. The general dimensions of the sticks cross section are rectangular (cm 1.9 cm or v 3 v, corresponding to the major and minor axes, respectively. Variation in materials and construction will determine the shafts (i.e., beams) effective stiffness. Bending primarily occurs about the sticks major axis. No industrial standard exists to describe quantitatively shaft stiffness. In general, most stick shafts come in flexes of medium, stiff, or extra stiff relative categories. Beginning players typically use alight stick with a medium stiffness rating, whereas larger and stronger players typically choose a stick with a stiffer flex. There is much variation in stick preferences indeed, many professional players choose low-flex sticks.
Shaft stiffness maybe determined in a number of ways. The simplest form is to apply known loads then measure the induced bend or rotational displacement (
Marino, 1998
). Stiffness maybe expressed as the coefficient of rigidity which corresponds to the applied force divided by the sticks displacement. For instance, if a blade were to bend 5 cm under a load of N, the resulting coefficient of rigidity would be 160/5 5 32 N/cm
(
Marino, 1998
). More sophisticated material testing systems can be used not
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only to control the magnitude of load (or displacement) perturbations but also to assess the effects of loading rate or fatigue properties due to multiple load cycles. Atypical means to determine shaft (beam) stiffness is a three- point bending test with central and/or cantilever loading. Deflections over the sticks length characteristically can range up to 5 cm without fracture.
Mechanical testing during stick design is essential to determine a stick shafts flexion rigidity and elasticity. Though industrial standards have not been established to quantify shaft stiffness or other properties (Bigford Smith, 2009), manufacturers categorize their sticks based on their own
“flex” rating. Shaft stiffness maybe estimated by controlled force and bend
(or displacement) of the shaft (
Marino & VanNeck, 1998; Simard, Roy,
Martin, Cantin, & Therrien, 2004
). Manufacturers produced sticks in a wide range of stiffness. In general, sticks range from 40 to 50 flex for youth and junior players, 60 to 75 flex for intermediate players, and 85 to flex for adults and more experienced players. It should be noted that cutting a sticks length to accommodate a player’s height and preferences effectively increases the flex rating by 5 10 points for each 2.5 cm shortened.
The resulting stiffness of stick shafts maybe determined in quasistatic loading tests. For instance, using a cantilever length of 1.17 m between clamp and blade load points, the effective stiffness (Young
’s moduli) of composite sticks has been found to range from 31 to 42 GPa compared to wood shafts at 10 12 GPa. The larger variation inelastic properties of composite materials depends in large part on the fiber material, the angle of the weave, as well as the geometry of the shaft cross-sectional area and wall thickness (
Marino & Cort, 2004
). Failure modes of sticks vary. Prior wood model sticks durability was found to decrease with age and duration of use. The most common failure modes during shots occurred at the hosel junction of blade and shaft, mid-shaft break or delamination, and blade break or delamination (
Hoerner, 1989
). Conversely, composite sticks retain greater mechanical flex stability with age however, accumulation of microfiber fractures due to wear from cyclic shot shaft flexion and/or stress point risers from nicks due to stick-to-stick collisions with the opponent players ultimately leads to catastrophic structural failure during high shot loading Performance Testing
Shooting tasks have been the most studied skills in ice hockey given that they are the primary tactical means of scoring (
Renger, 1994
). Players use
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a wide variety of shots during atypical game situation (e.g., slap, wrist,
snap, backhand, and sweep. The type of shot used is player and position specific (
Pileggi, Stolper, Boyle, & Stasko, 2012
). The ability to propel the puck at high speeds is the most common performance criterion measure. Puck speeds have been recorded using different techniques:
high-speed video, radar guns, light traps, infrared tracking, and accelero- meters (Alexander, Haddow, & Schultz, 1963; Doré & Roy, 1976,
1978; Chau, Sim, Stauffer, & Johannson, 1973; Pearsall, Montgomery,
Rothsching, & Turcotte, 1999; Wu et al., 2003
; Villaseñor-Herrera,
Turcotte, & Pearsall, et al., 2006). Puck velocities are typically greater for slap shots (80 160 km/h) than wrist shots (50 80 km/h). Shot velocities while skating are typically 20 30 km/h faster than shot velocities executed while standing.
All shot techniques involve a sequence of specific stick movement phases preloading (stick blade ice contact, loading (shaft deflection),
blade puck contact, and release (shaft recoil and release termination of puck contact) (
Fait et al., 2011; Pearsall et al., 1999; Villaseñor-Herrera et al., 2006; Lomond, Turcotte, & Pearsall, 2007
) (Fig. 10.8
). Slap shot
Figure 10.8 Study of shaft linear displacement and peak deflection angular (
ϴ) identifies dynamic bending behavior during different phases of the shot swing.
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phases include prior drawback and downswing phases of the stick to amplify energy input to the puck projection. The mechanical factors of importance during the slap shot are stick speed prior to puck contact, pre- loading bending of the stick, and puck blade contact time (
Marino,
1998
; Villaseñor-Herrera et al., 2004). The greater the stick blades tangential velocity and shaft bend prior to puck contact, the potentially greater energy transfer to the puck. With slap shots, this was demonstrated by
Lomond et al. (using D reconstruction from high-speed video records (1000 Hz) of slap shots (Fig. 10.8
). Across a wide range of player skill levels from recreational to elite subjects, stick blade velocity and shaft bend were closely related to recorded puck speed. To achieve these top speeds requires optimal body segment
“kinetic chain movement coordination to both rotate and bend the stick during ice and puck contact events.
Bending the sticks shaft allows stored elastic strain energy to be transmitted to the puck which augments shot speed due to stick rotation is augmented by bending (or preloading) of the sticks shaft (
Hache, 2002;
Worobets, Fairbairn, & Stefanyshyn, 2006; Kays & Smith, 2017
). In general, the players choice of stick stiffness rating should match their strength and body mass, as well as personal preferences for proprioceptive response.
To bend the stick the player must use three points of contact the (upper hand/top of stick (2) blade ice pressing backward against the stick;
and (3) the lower hand/mid-stick shaft pressing forward. This creates the transient bending moment to flex the stick shaft (
Michaud-Paquette,
Pearsall, & Turcotte, 2009; Michaud-Paquette, Magee, Pearsall, &
Turcotte, 2011; Zane, Michaud-Paquette, Pearsall, & Turcotte, Initially, the stick blade must obliquely impact the ice surface at an angle of approximately 35 degrees to the vertical to provide sufficient vertical reaction force (125 Nor B body weight) at point (2). Peak stick deflection angles may range up to 20 degrees during slap shots by elite players. Too upright a blades orientation yields insufficient ice contact reaction (20 N) due to low ice friction to bend the shaft (
Lomond et al.,
2007; Pearsall et al., 1999
). The latter is a common error shown by recreational players (Wu et al., Stick dynamic behavior is not easily extrapolated from static laboratory measures (Hunt & Russell, 2011; Marino, 1998; McQueen & McPhee,
2007
). For example,
Bigford and Smith (demonstrated that the impact properties (i.e., the effective coefficient of restitution COR) of the puck-to-blade are complex. Intrinsic stick shaft unloading (recoiling)
response may contribute as much as 30% to the outgoing puck velocity.
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Materials in Sports Equipment

However, impact characteristics were substantially affected by puck temperature, with COR varying from 0.27 at
24°C to 0.39 at C that, in turn, inversely affected the puck-to-stick reactive forces by 30 and 12 kN,
respectively (
Bigford & Smith, 2009
). In addition, given that manufacturing of carbon composite sticks permits full control of material and construction parameters, more sophisticated flexion-stiffness profiles along the shafts length are possible (as opposed to one uniform flex parameter. This has led to the introduction of sticks with varied flexion points such as mid-kick and low-kick points. By varying these properties, shot contact duration and release characteristics maybe tuned to match player preferences and/or perceptions (
Hannon, Michaud-Paquette, Pearsall, & Turcotte, 2011
).
10.6 CONCLUSION
This chapter examined the mechanical aspects of skate and stick design and construction in particular, methods for evaluating the physical interactions between equipment and player were presented as were representative biomechanical estimates. From this information, it becomes obvious that optimizing product development must involve coordinated human factors analysis.
Future efforts in ice hockey equipment should include research and development on the integration of smart sensor technologies into sports equipment. Examples can already be seen in speed skating wherein wireless force and inertial measurement units have been combined into the boot and blade construction to provide real-time output. This technological application is feasible in ice hockey skates (
Stidwill, Turcotte, Dixon, &
Pearsall, 2009
), sticks (
Hardegger et al., 2015
), and protective equipment
(
Wilcox et al., 2014
). This synthesis of equipment and measurement technology has the potential to greatly enhance athlete training as well as facilitate big data studies of team strategies.
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