The following article is based on a talk for Symposium X presented by Wolfgang Stoll, Chief Scientific Advisor and Consultant in Siemens, Germany, at the 1996 MRS Fall Meeting.

Since 1941 when Glenn Seaborg first isolated plutonium in milligram quantities, the total amount converted through neutron capture in U-238 has increased worldwide to about 1,200 tons and continues to grow about 70 tons/year. What was fissioned in situ in operating nuclear power stations is roughly equivalent to 5 billion tons of black coal, while the fission energy contained in those 1,200 tons unloaded in spent fuel is equivalent to another 2 billion tons of coal. About 260 of these 1,200 tons are ready to release their energy in about 4 kg-portions each in microseconds which is equivalent to 10,000 tons of coal. Most people believe this release of energy poses a major threat of the worldwide arsenal of weapons of mass destruction (WMD). The about 20-fold overkill stored in worldwide WMD is considered superfluous after the crumbling of the Soviet Union. Options are sought to dispose of this surplus in a safe, speedy, and controllable manner. While for highly enriched uranium (HEU) (the other nuclear weapons material) dilution into low-enriched uranium and utilization in current light water reactors (LWR) poses market adaptation problems only, and while the worldwide consensus on the elimination of chemical and biological WMD is still in an initial phase, the decision of both the United States (US) and the former Soviet Union (FSU) to remove most of the plutonium out of weapons looks as if it was a firm political decision.

The interplay between materials science and sports equipment takes many forms. Certainly a broad cross section of materials is used in sporting equipment to improve performance and safety, and to reduce cost. The new materials used in sports equipment originate from a long history of innovation, drawing from and contributing to other technologies. Amateurs and professionals play sports, so rules on the use of new technology vary immensely. This allows for a short circuit of new technology into the market-place in some cases and restriction or prohibition of opportunities in others. Also materials selection and development for sports equipment must stretch beyond consideration of the object itself to include the human interface and design of a system that best makes use of the materials. Sports after all are about human capability and interaction. The equipment is just a facilitator. Certainly more efficient ways exist of placing a ball into a hole than hitting it with a long metal stick from hundreds of yards away. This is perhaps the most unique element of materials development for sports. The rules governing materials development are not just laws of science and of government but rules put into place just for “sport.” Because of the connection of sports to the lives of so many people, either as participants or spectators, materials science of sporting equipment is also a great platform for educating students about materials selection and behavior.

“With a lighter but stiffer shaft and heavier clubhead the ball goes farther. Easier,” claims a 1975 advertisement for Shakespeare graphite irons. New materials such as graphite, boron, and titanium, have made sports equipment stronger yet lighter and thus more powerful. For athletes, sports have become, as the ad stated, easier. Serves over one hundred miles per hour are commonplace on the professional tennis tour, and athletes such as Tiger Woods are making par five golf holes obsolete. Sports organizations do not, however, always embrace these innovations that facilitate play. Major League Baseball retains its traditional mandate requiring only wood bats, the International Tennis Federation prohibited double strung tennis rackets, and the United States Golf Association banned asymmetrically dimpled golf balls. These technology regulations emerged to prevent the sport from becoming “easier,” protecting sport integrity.

The basic requirement golfers have about clubs is simple: “Help me to lower my score.” To the materials scientist, this means designs using the best materials. Golf clubs can be separated into three categories—woods (for long-distance hitting), irons (medium distance and accuracy), and putters (to get the ball into the hole on the green). In this article, we will discuss how material developments—in association with changes in design—have contributed to lower scores. It is very difficult to compare past achievements with those of today, perhaps with the exception of driving distances. However clubs have evolved tremendously, and it is difficult to imagine that Bobby Jones using hickory shafts could compete—at least in distance—with John Daly, Freddy Couples, or Tiger Woods, the present-day warriors armed with equipment often constructed from highstrength steel or graphite-epoxy shafts and an oversized hollow titanium head. Today professional golfers are driving farther, hitting greens with greater regularity, and sinking longer putts with the equipment they now have available attesting that the clubs constructed from advanced materials are contributing to better performance.

For the past seven years I have taught the Engineering Materials course (EM 380) at the United States Military Academy (USMA), Department of Civil and Mechanical Engineering (CME). The course has been modified to introduce modern materials technology to the cadets and to provide the opportunity to fabricate, design, test, and evaluate advanced materials in this course, in capstone design projects, and in independent-study projects. Theoretical and experimental studies of sporting equipment have been a sound and compelling basis to develop student ability in applied mechanics and to gain insight into the importance of materials choice. This article describes the methods and results of several of these projects.

The origins of the game of cricket are not known, but the first recorded game took place in London, England, on February 25, 1719. The basic rules of the game were formulated at a meeting of a self-appointed group of noblemen, held at the Star and Garter public house, Pall Mall, in 1774. These rules form the basis of the modern game.

Only under-arm bowling was allowed originally, and bats incorporated a curved blade to sweep the ball along the ground. Over-arm bowling where the ball was allowed to pitch or bounce was introduced late in the 18th century. This was quickly accepted and led to bats with straight blades to accommodate a variable bounce. Following a famous incident in 1793 in which a wide bat was used to completely cover the wickets, a new rule was quickly introduced to restrict the width of the blade to four and a quarter inches—a rule that survives to the present day.

The weight of the bat is not restricted by the rules, and the modern tendency is to use heavier bats. In the middle of the present century, a typical bat would weigh between 34 and 36 ounces. Currently bats of 40–44 ounces are widely available, and bats of 48 ounces and more are not uncommon among professional players. Although a heavier bat is widely believed to be capable of propelling the ball faster, there is a penalty. Heavier bats cause players to tire more quickly, and this affects their timing. Individual players tend to have a personal preferred weight of bat.

The evolution of the bicycle provides a good history of structural materials since the 1850s. The first machine that resembled a bicycle was made of a wooden beam with a wooden wagon wheel at each end. This presumably inspired the Hobby Horse, which had a forged iron beam for a frame, along with wooden wheels. The next step was the “boneshaker,” still with wooden wheels, but with the innovation of pedals, which allowed riders to keep their feet off the ground. Major reductions in weight came with the introduction of steel tubing for the frame and tensioned wire-spoke wheels, as in the high-wheelers of the 1880s. These breakthroughs came on the heels of the development of tube drawing and wire drawing in the new steel industry. With the introduction of the Humber “safety bicycle” in 1890, the evolution of the present-day diamond-frame configuration of the bicycle was completed. By this time, hardened steel components were available for the chain, cogs, bearings, and the chain wheel. In the previous year, John Dunlop had patented the pneumatic tire, and this invention took over the market for bicycle tires by 1895. The cotton-fiber-strengthened rubber-matrix tire was probably one of the earliest fabricated composite materials.

The use of brazing to join the cold-drawn steel tubes led to the development of the diamond frame. Lugs held the ends of the tubes in place. The brazing alloys were, and still are, based on Cu-40%Zn and on the Ag-Cu eutectic alloy. Wood and bamboo were tried as substitutes for steel tubes in diamond frames during the past century, but the lack of an available method for joining the pieces together defeated these attempts to save weight. The main materials developments in bicycles over the next 80 or 90 years after the Humber safety were the introduction of low-alloy steels for tubing, primarily the Cr-Mo-0.3%C 4130-type steel, the substitution of aluminum-alloy extrusions for steel tubing for wheel rims after the 1950s, and the use of stainless-steel spokes instead of carbon steel.

Over the past several years, the number of materials routinely employed for the fabrication of major bicycle components (e.g., frame, fork, and handlebar) has increased from one (steel) to at least five (steel, aluminum, titanium, fiber-reinforced polymers, and magnesium). Historically the primary driving force for implementation of new materials in bicycle manufacture has been the almost fanatical desire to reduce the weight of the bicycle. Although weight reduction of the bicycle will continue to be important, an old design paradigm—driven mostly by the recent popularity of bicycles designed to be ridden off-road (mountain bikes)—has re-emerged: the design of bicycles that minimize the amount of road/trail shock transmitted to the rider.