Bend It Like a Football Star – With SolidWorks Simulation

Watching my son play indoor 6-a-side football (or soccer, as some of you might call it), is both an exhilarating and nerve-racking experience. The father in me wants him to enjoy ‘the beautiful game,’ the competitor in me wants him to win, and the coach in me wants him to play well. One of the skills the boys on the team are learning is to get the ball to curl by imparting the correct amount of spin.

Now, I can talk until I’m blue in the face about how the spinning ball creates a region of low pressure on one side, resulting in a sideways force which creates the curl, but it’s the doing and seeing of it that made it real for the boys. I started to wonder if SolidWorks and SolidWorks Simulation could help out, and in a cosmic sense of kismet, a colleague in France sent me a simulation of the ‘Perfect Free Kick.’

Julien’s model is the perfect example of how you can use Design Studies with Motion to solve complex multi-physics problems.  If we consider the ball in isolation, there are three sets of forces acting on it.

1. The impact force which determines the initial velocity and spin of the ball
2. The aerodynamic forces, slowing the ball down and, partially, determining the path of the ball
3. Gravity, the other component that sets the path of the ball

Using the new motion function builder it is easy to apply the aerodynamic forces to the ball.

The motion analysis can now be run, and the ball dips and swerves over the defensive wall, beating the goalie and landing in the top left hand corner.

But that is only half the story. Using SolidWorks and Design Studies we can alter the both the position of the ball and the parameters of the ‘kick.’

The power of SolidWorks and Simulation is that you can run multiple versions of a design to determine the optimum configuration in the virtual world before you cut metal. But just as important as the optimum is the understanding of the design sensitivity, or how well your design performs ‘off optimum.’

The world isn’t perfect, and in the real world your design will have to perform over a wide range of loading conditions and environments.  The Design Study enables you to test for variation in geometric, environmental and loading conditions.  So in the case of the free kick, the robustness of the design can be measured by distance of ball center from the ‘ideal’ target center, and we can find many ‘correct’ solutions but only one robust solution.

By running an analysis on your design you not only gain insight to its current behavior but also its future behavior and how to improve it.  So I can now show my son how and why the ball bends, and that all he has to do is practice, practice, practice..

Stephen Endersby

Product Manager at SolidWorks