K2 Sports Takes FEA to the Extreme for Designing Outdoor Sports Gear
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K2 Sports (a division of K2 Inc. [NYSE: KTO]) is a leading maker of outdoor sporting goods including ski equipment, snowboards, snowshoes, inline skates and mountain bikes. When the company upgraded its computer-aided engineering tools, they chose finite element analysis (FEA) software from ALGOR, Inc. of Pittsburgh, Pennsylvania to help design products that can handle the rigors of extreme use. "First and foremost, we want to make a product that doesn't break so that people don't get hurt," said Bruce Jahnke, Director of Testing for K2 Sports. "Secondly, we want the product to be performance-oriented and as lightweight as possible because our customers are sports enthusiasts who use our gear frequently. Using ALGOR FEA helps us to ensure that we have a strong product - one that won't fail - and that people won't get hurt during its lifetime of use."
In particular, K2 Sports uses ALGOR's Mechanical Event Simulation (MES) software to simulate the kinds of dynamic events that often occur during use of extreme sports gear. MES differs from traditional FEA in that it provides nonlinear, multi-body dynamics with large-scale motion, large deformation and large strain with body-to-body contact, which allows engineers to see motion and its results, such as impact, buckling and permanent deformation. "The world is not static," observed Jahnke. "People are riding off jumps on our skis, snowboards, skates and mountain bikes. ALGOR MES allows us to thoroughly evaluate such mechanical events and verify the best design and materials for the application."
Simulation and Testing at K2 Sports
In 1961, K2 Sports founders Bill and Don Kirschner produced their first pair of fiberglass skis. Since that time, the K2 Sports name has become synonymous with high-quality outdoor gear. Today, at the company's research and development facility in Vashon, Washington, Jahnke directs a team of engineers and technicians in testing and verifying K2's innovative product designs, including use of an on-site test laboratory and computer-aided design (CAD) and engineering software tools.
"Our product developers come up with a design in CAD using SolidWorks or Pro/ENGINEER," explained Jahnke. "I then open the CAD model in ALGOR and analyze it to improve and finalize the design. Next, a prototype of the product is manufactured and then tested in the lab to verify that it's strong enough to meet the customer's needs. Once it passes physical testing, the product will go into full manufacturing."
Simulating an Impact Test for a Mountain Bike Frame
One of Jahnke's first MES applications was to simulate an impact test for an aluminum mountain bike frame. "This was an exercise to see if we could set up and perform a simulation and get results that would correlate to a lab test that we had already done," said Jahnke. The lab test had been performed for the Razorback hardtail mountain bike to demonstrate that the frame met safety requirements as specified by a European standard (CEN/TC333/WG2). During the test, a 22.5-kilogram steel mass was dropped onto the front wheel axle in order to replicate the kind of loading scenario that would occur if the bike was being ridden along an outdoor trail and it hit a rock or log at the front wheel. The Razorback frame did not break and its permanent deformation was less than the maximum allowed (10 millimeters), thus it successfully passed the laboratory impact test.
To simulate the impact test with ALGOR software, Jahnke opened the Pro/ENGINEER CAD model of the Razorback frame. "It was a seamless operation," said Jahnke. "I was very impressed that a model could be easily transferred between the CAD and FEA packages. This was important to me because I receive a lot of model files and I need to be able to turn them around quickly."
Jahnke set up the analysis in ALGOR's easy-to-use single user interface, FEMPRO, by defining the element types, material properties and constraints. He specified the event duration and capture rate and then allowed the software to automatically calculate the effects of dropping the steel mass from a height of 360 millimeters onto the frame's front axle, based on gravity and Newton's laws of motion. The analysis results verified that the displacement and stresses in the frame were less than the material yield point, thus confirming the safety of the design. "The deflection calculated by ALGOR MES was very close to the test measurement," said Jahnke, "with less than 10 percent difference."
In addition to verifying the displacement test criteria, Jahnke noted, "The main benefit of MES was that it allowed me to look at the stress levels in the bicycle frame and determine how close we were to failure. The design had passed the physical test, but that didn't tell me how close we came to the material yield point. The simulation results verified that we had an acceptable margin of error and the product was safe."
Gaining a better understanding of the strength of the design was important to Jahnke. "In mountain bike design, weight is critical," Jahnke said. "Second only to safety, the strength-to-weight ratio is the most important design criteria. Computer simulation helps us to determine if the design is strong and reliable without being overly heavy."
Future Plans for FEA
"Generally, I try to use ALGOR analysis as an up-front design tool so we can cut down on design iterations," said Jahnke. "We make design modifications based on the simulation results. Physical testing is done as a check of the final design."
Jahnke has used ALGOR software to analyze several other K2 Sports products including MES of a snowshoe and linear static stress analyses of snowboard bindings and the buckle of a winter sports goggle. Jahnke added, "I'm very happy with the software and the customer support. The software certainly meets my needs and I rely on it heavily."
Bruce Jahnke is the Director of Testing for K2 Sports in Vashon, Washington. He earned a B.S. in Mechanical Engineering at the University of Wyoming. Previously, he worked as a Stress Analyst for The Boeing Company. For more information about K2 Sports, visit www.k2sports.com.
Julie Halapchuk
Marketing Communications
ALGOR, INC.
150 Beta Drive
Pittsburgh, PA 15238-2932 USA
Phone: 1.412.967.2700
Fax: 1.412.967.2781
E-mail: info@ALGOR.com
URL: www.ALGOR.com
