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About this Article
Written by: Brent Nash
Written on: March 30th, 2002
Tags: sports & recreation, entertainment, lifestyle
Thumbnail by: Charlesjsharp/Wikimedia Commons
About the Author
In spring of 2002, Brent Nash was a 20-year old Computer Engineering and Science major at the University of Southern California. As a student, he was an avid skier.
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Volume IV Issue III > Engineering a Smooth Ride: Creating the Perfect Ski Through Shaping and Vibration Damping
Although snow skis appear to be very basic products, the engineering behind them is surprisingly involved. The type of skiing and type of snow conditions dictate the required ski geometry. Avid skiers have longed for a high-performance, all-around ski. Vibration caused by high speeds and tough terrain has been a significant problem faced by engineers in the pursuit of such a design. Recently, however, engineers have developed skis that incorporate vibration control technology. This "Smart Ski" technology solves the vibratory problem through the use of piezoelectric ceramics. These ceramics detect vibration by sending an electrical signal to an on-board processing circuit, which then triggers mechanical actuators to cancel the unwanted vibration. Thus, the Smart Ski has demonstrated the complex technological intricacies hidden in the seemingly simple realm of ski engineering and manufacture.

Engineering a Smooth Ride: Shaping and Vibration Damping in Ski Design

Skis may appear to be relatively simple products without much room for high-tech engineering, but this is far from the truth [1]. Modern ski designers and engineers are on a never-ending quest to create a faster, lighter, more responsive and more durable product. These attempts have resulted in the creation of skis of all shapes and sizes using materials ranging from wood to synthetic fiber. The ski manufacturing process is an incredibly complicated science. Tests have shown that varying ski shapes and styles are more suited for different conditions [2]. Because each ski type possesses unique benefits and detriments in different conditions, a skier can be well suited for skiing conditions at one moment yet unprepared the next as snow conditions change. In addition, most ski designs must cope with an inability to eliminate unwanted vibrations that can compromise ski stability, one of the biggest problems facing the modern ski manufacturing industry. A new technology has emerged to overcome these limitations by utilizing a unique shape and the integration of piezoelectric sensors and an actuator control system.

Shaping the Smart Ski

Charlesjsharp/Wikime​dia Commons
Figure 1: Skier carving a turn in Méribel, France.
The first step in the creation of an all-purpose, all-mountain ski is to determine the shape characteristics of the ski. This shaping decision is no easy task for engineers due to the numerous benefits and detriments associated with different ski shapes. Longer skis provide greater stability and control at high speeds, but are harder to maneuver while shorter skis are easier to turn and maneuver, but are less stable (see Fig. 1). Wider skis ride better on soft, powdery snow while hourglass-shaped skis with a large sidecut turn better on hard snow and ice. Engineers ultimately decided to create a short, wide, hourglass-shaped ski. The wideness of the ski would allow for better riding on soft, powdery snow because the rider's weight would be more widely distributed over a larger area of the snow. This wider distribution would serve to create a buoyant riding effect, allowing the skier to almost "float" on top of the snow. In contrast, the hourglass shape of the ski would allow for a more smooth and controlled ride on hard-packed snow and ice. With their hourglass shape, the skis concentrate more of the skier's weight on the blade edge at the middle of the ski, allowing it to dig deeper and make sharper turns. Finally, the shortness of the ski allows for increased skier control. With a shorter ski, there is less ski surface to redirect when changing directions, making the skis easier to turn [2]. Recall the trendy "Bigfoot" short short skis of the 1980s, popular with beginners because they were easier to turn than longer skis.
By combining the hourglass shape, a wide base, and a shorter ski, engineers brought together the benefits of all three designs. The wider base and the hourglass shape of the ski complimented each other well because the former facilitated soft snow riding and the latter improved hard snow riding. Unfortunately, the shortness of the ski created a major maneuverability problem. All skis are subject to unwanted vibrations, especially at higher speeds, but testing has proven that shorter skis have a tendency to have more frequent and more powerful vibrations than longer skis [3]. At first glance, vibration as a problem does not seem incredibly difficult, but vibration and instability are actually very difficult to counteract.