Ansys Learning Forum Forums Discuss Simulation General Mechanical Seeking Advice on FEM Analysis for Bike Frame Model in Ansys Reply To: Seeking Advice on FEM Analysis for Bike Frame Model in Ansys

peteroznewman
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If you take a 3d surface model of the tubes that make up the frame, and you slice it in the center plane and support the cut edges in that plane with a Symmetry object and region in Mechanical, then you would apply only half the force because you have only half a frame.

Pinned is not the correct boundary condtion for a frame on wheels since the wheel can roll as the frame is loaded at the seat.  The correct BC to apply at the rear axle is simply Y=0 leaving X free assuming the XY plane is the plane of symmetry.

The force going into the seat would more correctly be modeled as a remote force scoped to some elements at the top of the seat tube at the height of the seat above the frame. The force would have the weight of the rider with a negative sign in the Y component and there would be no X component if the rider is just sitting on the seat with no weight on the pedals.

Another load case is with the rider standing on the two pedals equally. That would be a Y component applied at the pedal axle.

A more severe load case is with the rider applying force to just one pedal. This cannot be done on a symmetry model becuase the load is not symmetric. When the rider pushes down on the right side pedal, they push down on the left side handle bar while pulling up on the right side handle bar. You don't need the handlebars to apply this load, you can have the front tube fixed. The load on one pedal has the effect of twisting the 3D frame.