Sensitivity analysis and calibration leads to valid ski simulation models
Sector: Consumer goods/durable goodsSpecialist field: Structural mechanicsFor racing skiers, there is no better feeling than being fast. Hundredths of seconds decide between victory and defeat. So, the search for better equipment never ends. HEAD Sport uses Ansys software to adapt ski performance even more efficiently to requirements.
Summary
Task
Numerous prototypes and test runs are necessary in order to find an optimal design for the respective application in ski development. The layer structure of a ski is essential for its flexibility and performance. The use of simulation software should help shorten this lengthy process.
Solution
Since the properties of the material layers are often not known exactly, a calibration of the values in comparison with real tests was necessary for a valid simulation model. A sensitivity analysis resulted in eight influential parameters, which were adjusted so that the results of the simulations correlate with those of the tests.
Customer benefits
Thanks to the systematic identification of material values, simulation in the prototype phase has become an important basis for ski development at HEAD. This allows different ski designs to be built, analyzed and compared in a short time, thereby further reducing the number of real prototypes and test runs required.
Project Details
Task
Nowadays, skis are among the most high-tech products. They are built up in thin layers from different materials. The type of construction is essential for the ski’s performance, as it determines its flexibility. Numerous prototypes and test runs are therefore necessary in order to find an optimal design for the respective application in ski development. The renowned sporting goods manufacturer HEAD SPORT GmbH has been able to shorten this lengthy process by using Ansys simulation software in ski development for the verification and evaluation of digital prototype construction.
The combined use of Ansys Mechanical and Ansys optiSLang enables classic reverse engineering for the precise determination of material properties in the layer structure of a ski. HEAD is addressing the issue of simulation-driven development together with CADFEM and ANSYS Dynardo to ensure a secure foundation for the future development strategy: tests are saved due to digital development.
Customer Benefit
The systematic identification of material values was the basis for the further expansion of simulation-driven development at HEAD, thereby improving the understanding of the influence of diverse materials.
In the meantime, the simulation forms the basis for a general design of the layer materials in prototype construction. This allows different ski designs to be built in a short time and then analyzed and compared with Ansys.
One goal is to use simulations to compare established skis with new developments in order to better determine the skiing behavior of the new developments. On the one hand, this should eliminate some of the test runs that have been necessary up to now and, on the other hand, secure a major competitive advantage.
The most important advantages through the use of simulation:
- the material behavior and thus the driving behavior can be better estimated
- acceleration of development through simulation-based evaluation of digital prototypes
- the product quality (ski riding behavior) can be better predetermined and controlled
Solution
First, the stiffness behavior of the ski was mapped in a valid simulation model. Since the material properties of the thin layers are often not precisely known or do not lie within the specified scatter range, it was necessary to calibrate the values by comparing them with real bending and torsion tests.
Subsequently, the real tests were digitally mapped in Ansys Mechanical. Based on the CAD model, the individual layers were discretized with a continuous FEM mesh and assigned the correct material properties in each case. Since some components, such as the core with wood veneer layers, consist of a material with fiber directions, the orthotropic stiffness properties also had to be taken into account here. A total of 23 parameters were responsible for the model calibration.
The Ansys optiSlang software was used to evaluate the sensitivity and adaptation of the parameters. First, a sensitivity analysis was used to investigate the influence of the parameters. Since only eight parameters have a major influence on the stiffness of the ski, the calculation effort could be reduced considerably. These eight parameters were adjusted in the underlying scatter range of the material in such a way that the simulation results correlate as well as possible with the test results. .
Images: © HEAD Sport