Chairs
Gary Michal
Dept of MS&E
Case Western Reserve Univ
Cleveland, OH 44106
216-368-5070
Steve Nolet
Fiberspar Inc.
W Wareham, MA 02576
508-291-2770
Frances Ross
IBM T.J. Watson Research Center
Yorktown Heights, NY 10598
914-945-1022
In sessions below "*" indicates an invited paper.
SESSION Y1: MATERIALS IN SAILING
AND WINDSURFING
Chairs: Frances M. Ross and Steve Nolet
Tuesday Afternoon, April 1, 1997
Nob Hill A
2:00 PM *Y1.1
CONSTRUCTION TECHNIQUES AND PERFORMANCE OF SAILS FOR YACHT RACING, David Starck, North Sails San Francisco, Alameda, CA.
The sailmaking industry has changed dramatically over the past decade largely due to the introduction of polyester mylar, kevlar and spectra into the construction of sails. With events such as the America's Cup and the Whitbread Around the World Race, sailmakers have refined sailshape and construction immensely. Sails built today using these low stretch fabrics are significantly lighter in weight and are able to hold their designed shape through a wider wind range. Another change which has taken place in sailmaking is the actual construction of sails. For centuries all sails have been designed, constructed and built by gluing and sewing shaped pieces of cloth together to form a sail. Today, North Sails has a patented process for molding sails called 3DL Three Dimensional Laminate). This allows us to build a one piece, seamless sail in which the fabric used (kevlar 49) is laid over a physical mold that has been "shaped" by input from the sail designer. In this presentation we will discuss construction vs. performance relationships as well as where the sailmaking industry is headed as the world prepares for the next America's Cup, to be held in Sydney, Australia in the year 2000.
2:30 PM *Y1.2
DYNAMIC TESTING OF ADVANCED COMPOSITE WINDSURFING MASTS AND RIGS, William Beland, Univ of Massachusetts, Lowell, MA; Steve Nolet, Fiberspar Inc., W Wareham, MA.
The sport of windsurfing has enjoyed tremendous growth in participation in the past ten years. The broad user base has led to the development of sophisticated equipment to meet the demands of high performance sailors. Current practice in the design of windsurfing masts and sails depends heavily on the static performance of the mast and the resulting sail shape. Mast bend curve shape and amplitude of deflection for a given load are most often used in determining the suitability of a mast for a given rig. The complex dynamic interaction of wind, surf, sailor and equipment illustrate the need to develop a better understanding of the dynamics of the windsurfing rig and provide insight into the design of next-generation masts leading to better response and further improve the performance of these systems. The results of a three tier dynamic test program will be presented. Results of laboratory level static and dynamic testing will be shown including full modal analysis results of cantilevered, free-free and boom clamped boundary conditions of several graphite/epoxy and hybrid graphite-glass/epoxy windsurfing masts. A modal analysis of the complete rig including sail, boom and mast was completed. Damping effects on the mast due to the sail and boom interaction are determined and the overall modal response of the rig for the lowest five natural frequencies were analyzed. In the third level of testing, a portable remote data acquisition system was developed and twelve different masts were each instrumented with axially oriented strain gage. Each mast was water tested with a compatible rig under demanding conditions in winds up to 30 knots. Thirty second data collection sorties were completed with a professional windsurfer and a predetermined tack. An accelerometer mounted on the board at the base of the mast recorded dynamic loading. Results of water testing including FFT analysis of data will be shown and the impact of the work on future testing and mast designs will be discussed.
3:30 PM Y1.3
A NEW TYPE OF REVERSIBLE AND FINITELY VARIABLE HYDROFOIL FOR SAIL POWERED MARINE VEHICLES, Simon B. Fagg, Bournemouth Univ, Bournemouth, UNITED KINGDOM.
The performance of sail-powered marine vehicles is highly dependent on the operational efficiency of its hydrofoil control surfaces, namely the keels, rudders and fins. Many of these devices need to operate on both sailing tacks which necessitates the utilization of symmetrically foiled cross-sections in the design. It is, however, normally the case that a symmetrical cross-section is inherently inferior in terms of ultimate hydrodynamic performance when compared with a cambered cross-section. Historically, a variable cambered cross-section can be achieved by incorporating trailing and leading edge flaps which are driven by separate activating mechanisms, although this approach is considered impractical for prolonged use in a highly saline marine environment. Therefore, a totally new type of cambered cross-section has been developed in which the camber is realized by using a combination of materials in which controlled structural deformations take place under the action of the external surface pressure forces acting on the section. This allows the cross-section to take on a cambered shape when in use in a manner analogous to the operation of traditional fabric sails. The paper discusses the historical nature of the problem as well as the material considerations and requirements of this new concept. In addition, the manner in which CAD and FEA tools have been employed to realize an operational prototype for the sport of windsurfing are detailed.
3:45 PM *Y1.4
DESIGN, EVOLUTION AND CATASTROPHIC MATERIAL FAILURE OF RECREATIONAL MARINE EQUIPMENT AS PORTRAYED IN THE CONTEMPORARY MEDIA, Paul Kamen, Surface Propulsion Analysis, Berkeley, CA.
Although it is clear that advances in material technology have always been prerequisites to innovative progress in maritime design, the public perception of design evolution tends to ignore this fact. An interesting dichotomy is evident when contemporary media portrayals of significant maritime failures are considered in this context: a close examination of relevant media samples almost invariably reviews material failures as underlying causative factors, while the lay public attributes technological advances to design innovation and individual inventive genius. This attitude persists even though the examples found in the media aimed at the same lay public always depict the factors limiting this progress to be rooted in the constraints imposed by the materials in use at the time. A number of explanations for this paradox are proposed. The media survey presented suggests an interesting paradigm for the role of modern media in the public perception of technological progress.
SESSION Y2: DEVELOPMENTS IN CARS
AND BICYCLES
Chairs: Gary M. Michal and Frances M. Ross
Wednesday Morning, April 2, 1997
Nob Hill A
9:00 AM *Y2.1
FASTER AND SAFER: BALANCING MATERIALS CHALLENGES FOR SPORTS AND RECREATIONAL APPLICATIONS, Ron Gronsky, Univ of California-Berkeley, Dept of Matls Sci & Min Engr, Berkeley, CA.
Beyond mechanical design, the engineering of vehicles for ground-based locomotion that meet the demanding needs of the sports enthusiast for speed and safety requires strict attention to materials selection. While every case for increased speed is based upon decreasing weight, especially in human-powered vehicles, ''lighter'' is sometimes compromised by ''safer,'' but not by large margins. Fiber reinforced composites and monolithic thermoplastic elastomers have been appearing in steadily increasing quantities in bicycles, off-road vehicles and ''fuelies'' for the past two decades, and the utilization of these materials range from skin treatments to fuel tanks to ''run-flat'' tire inserts that survive rough terrain and protect the passenger(s) from blow-out induced loss of control. Sophisticated alloys based upon many metals that are traded in the commodity markets at wildly fluctuating prices are also fair game for the sports market, where large retail differentials can be borne by demand for ultimate performance. Simple replacement of connecting rods, valve stems and valve retainers by Ti-1100 alloy has boosted red line by nearly 1000 rpm in OEM motorsports applications; Ti-6-4 is not far behind. Finally, the competition between the aluminum and steel industries rages on, primarily directed at the PNGV passenger vehicle market, but bringing obvious benefits to the sports vehicle market as well. When both speed and safety matter, the current trends in strength, toughness, R-curves, finish, manufacturability, and weldability signify exciting times ahead for the sports enthusiast.
9:30 AM *Y2.2
BASIC DESIGN CRITERIA AND MATERIALS SELECTION FOR THE BICYCLE, Eric Hjertberg, Wheelsmith Inc, Palo Alto, CA.
The bicycle's development over the past 100 years parallels the advance of structural materials. A bicycle's strict mechanical needs combine with its accessibility to make it a frequent testing ground for the latest materials. And if its popularity is any gauge of success then the nearly 1 billion bicycles that receive daily use are ample testimony to the successful application of materials. At their inception in the mid-1800s, bicycles utilized materials with outstanding strength to weight characteristics: wood, ivory and leather. The machines were strong and stable but not efficient or light enough to see widespread use. The breakthroughs that enabled the bicycle to flourish include the development of synthetic rubber and pneumatics (drastically reducing rolling friction), the invention of roller chains and variable speed transmissions (to get the most from human 1/8 hp), and the employment of tension via steel wire for wheel construction. These three enabled bicycles to become easy to pedal. Advances in tubular steel, applied first in bicycles, permitted significant frame weight reductions. Spinoffs from aeronautical materials advances included aluminum alloys which successfully challenged wood in the 1940s. Plastics largely replaced leather by the 1960s. By the seventies, carbon fiber structures rivalling steel made their appearance. And during the nineties, metal matrix composites and titanium have had profound impacts. Since it is largely unclear which materials will find acceptance, the industry is accustomed to many candidates for any one application. The disciplines of marketing and economics play as important roles as that of engineering in the lively contest for acceptance. The future of cycling holds great promise for materials suppliers. The bicycle's priority on light weight and its relative materials cost insensitivity makes the industry a very attractive market. However, before considering the relative merits of candidate materials, a thorough understanding of the basic design criteria of bicycles is required.
10:30 AM *Y2.3
BERYLLIUM ALUMINUM CASTINGS - A NEW ALLOY FOR THE HIGH TECHNOLOGY SPORTS AND RECREATIONAL INDUSTRY, Christopher E. Hinshaw, Beyond Beryllium Fabrications/Nuclear Metals Inc, San Jose, CA; Kevin R. Raftery, Nuclear Metals Inc., Concord, MA.
Beryllium-Aluminum (Be-Al) alloys, containing greater than 60 weight percent Be, are very attractive materials for lightweight and high stiffness applications. However, due to the inherent problems associated with casting these alloys, processing of Be-Al has generally been restricted to rolling or extrusion of pre-alloyed powder metal compacts. Nuclear Metals, Inc. (Concord, MA) has recently developed castable Be-Al alloys suited for the production of near net shape components via investment casting. These new alloys, identified as Beralcast, produce a fine grain homogeneous microstructure. Production of thin wall precision investment castings for aerospace applications has been demonstrated using this new alloy. In certain cases, where designs are being modified to take full advantage of the mechanical and thermal properties of Beralcast, component weight savings of up to 50 over conventional materials can be achieved.
11:00 AM *Y2.4
DESIGN AND MANUFACTURE OF RESIN TRANSFER MOLDED ADVANCED BICYCLE FRAMES, Frank Ko, Drexel Univ, Dept of Matls Engr, Philadelphia, PA.
(Abstract Not Available)
11:30 AM *Y2.5
TRENDS IN LIGHT METALS RESEARCH FOR AUTOMOBILE APPLICATIONS, Raja K. Mishra, General Motors R & D Center, Dept of Physics & Phys Chem, Warren, MI.
Lightweight alloys are enjoying progressively expanded use in the automotive industry, including application in drive train, body panels and other components traditionally manufactured from ferrous alloys. Existing manufacturing methods and alloy compositions are being stretched to the limit to produce materials to meet engineering specifications and market needs. Major research and development efforts are concurrently focusing on developing (i) new processing and manufacturing methods, (ii) new alloy compositions, and (iii) composites. In this paper, we will review recent developments in semisolid processing technology with specific emphasis on thixotropic aluminum and magnesium alloys. Using examples, we will illustrate how the challenges of superior material properties and inexpensive manufacturing methods are influencing research on Al and Mg alloys. Finally, we will discuss how the product-driven approach in the auto industry has placed microstructural investigation at the heart of light metals research.
SESSION Y3: SKIING, BASEBALL
AND OTHER ACTIVITIES:
INNOVATIVE MATERIALS AND DESIGNS
Chairs: Steve Nolet and Gary M. Michal
Wednesday Afternoon, April 2, 1997
Nob Hill A
2:00 PM *Y3.1
THE FUSION BAT - DESIGN AND DEVELOPMENT OF A HYBRID COMPOSITE ALUMINUM SOFTBALL BAT, Brian P. Feeney, Spalding Sports Worldwide, Chicopee, MA.
Current top of the line softball bats are all very similar in design, weight, balance and performance. These bats utilize Alcoa's C-405 series aluminum alloy tubes and have a barrel thickness of around 0.075. The major difference in most of the current bats is solely the name on the bat. Current bats have acceptable performance, but a tradeoff exists between performance and durability: the thinner the wall, the livelier the bat and the more likely it will dent. The use of hybrid composite and aluminum components in the Fusion bat overcomes the limitations of an all-aluminum bat and offers additional performance benefits. The Fusion bat incorporates a thinner aluminum tube in the barrel area. A composite (graphite/epoxy) structure is molded to form the handle of the bat, to form the transition area between the handle and barrel, and lastly to reinforce the inside of the aluminum barrel. With this hybrid construction the range of properties of the bat that can be varied is increased. Compared to a traditional all-aluminum bat, the result has reduced vibration, is lighter in weight, allows for increased bat speed, all while maintaining its moment of inertia and liveliness.
2:30 PM Y3.2
THE INFLUENCE OF MATERIALS SELECTION ON THE PERFORMANCE OF SPORTS EQUIPMENT, Gary M. Michal, Case Western Reserve Univ, Dept of MS&E, Cleveland, OH.
Advances in speed, distance and precision of a variety of popular sporting activities are directly dependent upon advances in sports equipment. A key element in the design of many types of sports equipment is their ability to acquire, store and recover energy with precise timing. Materials inherently have the ability to absorb and redirect the energy associated with sports activities ranging from jumping to collisions. Emphasis in this presentation will center upon how material properties are used in the design of the present generation of high performance equipment in order to control the transfer of energy during its use. This theme will be developed by examining the relationship between a player's action and the response of their equipment for specific sports. Included in the list of examples will be pole vaulting, tennis, and baseball.
2:45 PM Y3.3
ABOUT A NEW METHOD OF PROPERTIES CONTROL FOR COMPOSITE CONSTRUCTIONS CONTAINING RUBBER-LIKE MATERIALS, Andrei Koudine, Michel Barquins, ESPCI, PMMH, Paris, FRANCE.
We present a new unknown effect that is responsible for the stability breakage of detachment folds or Schallamach waves [1] which occurs in the contact area between a moving solid and the smooth flat surface of a soft elastomer sample. The direct dependence between the existence of detachment folds and the rubber sample thickness have been discovered experimentally. We carried out all tests on our laboratory installation that is described precisely in [2]. Our investigations show that Schallamach waves can be considered as a test indicator for study of skin friction in rubber-like materials [3, 4]. The obtained results can be useful for definition of critical wear for some kind of soft rubber covers used in different industrial equipments and for development of composite constructions containing rubber-like materials. The reliability of joints used for air or water-tightness as well as some joint fabrication problems are also discussed. As example, we consider the water penetration phenomenon to the ''waterproof'' watch and explain how to prevent thus nuisance.
3:30 PM *Y3.4
THE USE OF ADAPTIVE AND OTHER ADVANCED MATERIALS IN SPORTING GOODS APPLICATIONS, Dodd H. Grande, K2 Corporation, Matls Res Dept, Vashon, WA.
Recent applications of piezoelectric materials in skis, reverse thermal transition gel materials in inline skates, and composite materials in inline skates will be reviewed. Great advances have been made in the use of piezoelectric elements for damping and vibration control in snow skis. Past approaches for damping and vibration control of snow skis will be reviewed. An overview of K2's current use of piezoelectric elements on snow skis and recent vibration data will be presented. Fit and comfort are among the most important elements for inline skates. Reverse thermal transition gels, which undergo a transition to a more viscous state with increase in temperature, are an ideal material for achieving a comfortable high performance fit for inline skates. Anthropometric data will be presented which illustrates some of the challenges associated with providing superior fit for a skate product and the properties and uses of reverse thermal transition gels in inline skates will be reviewed. Continuous fiber carbon composite materials have found only limited applications in inline skates until recent years. Many components of inline skates can benefit from the use of these materials. A number of these applications will be presented and discussed.
4:00 PM *Y3.5
OPPORTUNITIES FOR CONTROL OF INJURIES DURING SNOW SKIING, C. D. Mote, Univ of California-Berkeley, Berkeley, CA.
The rate of injury while snow skiing has decreased from 7 injuries per 1,000 skiers per day in 1970 to about 2.5 in 1985 as a result of a broad, world-wide attack on the injury problem that has addressed equipment design, standards of various types for both equipment and practice, and instruction of professionals and practitioners alike about safety issues. The frequency and severity of most characteristic types of skiing injuries have decreased over this fifteen year period. Severe injuries to the knee have been the principal anomalous injury type which as increased substantially in severity and frequency: the characteristic significant skiing injury shifted from fractures of the leg and ankle prior to 1970 to severe ligamentous injuries at the knee after about 1985. Since 1985, injury rates and severity have not changed significantly leaving knee injury as the most serious of the common skiing injury problems and leaving researchers in a quandary about the solution to this problem. New thinking on causality and control of this injury is needed - no ready solution is apparent. The talk today will discuss some research directions for possible control of the knee injury problem. The first direction attempts to predict the loading generated at the knee during actual skiing by use of models of the leg and then it implements control of this loading at the need. This concept leads to hardware solution (including sensors, actuators and microprocessor controllers) needed to implement algorithms. The second direction determines the loading that is required to ski, establishes allowable limits in multidimensional force spaces, and then controls the loading to remain within these boundaries. The development of learning systems for the individual skier might also play a role in the future of skiing because the generation of forces on a limb during skiing is substantially more dependent on the skiing style of the individual than it is on the height, weight or ability of the skier.
4:30 PM Y3.6
EFFECT OF HYDROGEN IN TiNi, Brian Lee Pelton, David W. Harris, Charles Evans & Associates, Sunnyvale, CA; Alan G. Pelton, Ted Slater, Nitinol Devices & Components, Fremont, CA.
The shape memory properties of TiNi are experiencing increased use in medical and commercial products. Current applications include guidewires and stents for cardiovascular procedures, orthodontic devices, eyeglass frames, cellular telephone antennae, and fasteners. These finished components often require processing in hydrogen-containing environments, such as during electropolishing and electroplating procedures. TiNi alloys, similar to other Ti-based materials, are sensitive to hydrogen content. Bulk analysis suggests that hydrogen concentrations >100 ppm by weight may reduce ductility or embrittle the affected microstructure. The purpose of this paper is to document the mechanical and transformation properties of hydrogenated TiNi alloys and to relate these properties to the hydrogen content. A further aspect of this study is to clarify the role of hydrogen interaction and hydride formation in TiNi through both novel and conventional electron-beam microstructural analysis.
4:45 PM Y3.7
DESIGN AND DEVELOPMENT OF AN INTEGRALLY STIFFENED CARBON FIBER/EPOXY HOCKEY SHAFT, Steve Nolet, Fiberspar Inc., W Wareham, MA.
The use of composite materials is a recent development in lightweight high performance hockey shafts. The high specific properties of carbon fiber composites lead to a tremendous weight savings over conventional wooden shafts as well as newer aluminum design. For a given stiffness, a composite hockey shaft may be as much as 30 lighter than wood and 20 lighter than aluminum. The result is higher blade velocity and frequency response on shots leading to measurable increases in puck speed. The nearly perfect elastic bending behavior of the composite also provides a distinct advantage over aluminum products that exhibit short term yielding under operational bending loads and result in permanent warping of the shaft. Many different manufacturing methods have been employed in the manufacture of composite hockey shafts, including filament winding, pre preg roll and flag wrapping, pultrusion and resin-transfer molding. A multitude of laminate design variations have also been demonstrated, but a consistent trait of breakage at low impact loads compared to wood and aluminum designs has resulted in the limited use of these products by consumers. The basic cross-section of the shaft has seen little innovation by the industry. It has been demonstrated that the cross-section impact performance is enhanced in both the x and y direction if the unsupported region of the shaft's cross-section is reduced. The use of a novel integral reinforcement in a patented design has resulted in a 300 increase in impact energy before failure at only a 5 to 7 increase in weight. As a result of the effort to locate selective stiffening into the cross section of the shaft, more durable and longer lasting products have been introduced to both the NHL and consumer marketplace. Design methodology, test results and insights into manufacturing issues will be presented.