tool for stiffness measurement

Lately I am spending some spare time designing a tool that will allow me to measure chassis and swingarm stiffness. My intention is to design something relatively simple and cheap, but that will allow me to obtain precise data. The images that you can see below are just sketches, the final design will be probably quite different.
First image shows an arrangement to measure the chassis stiffness regarding torsion. The chassis is clamped in the swingarm pivot area, and a torque is applied around the steering head. The torque value is adjusted in a precise way adding steel discs (blue color in the drawing). A digital inclinometer will be placed over the lever arm to measure the torsion angle.
In order to measure the chassis stiffness with the engine assembled on it, it is possible to locate the green clamping parts in the external faces of the chassis.

chassis torsion

Second image shows an arrangement to measure the lateral stiffness of the chassis (flexion). In this case we just pull from the steering head, hanging a weight that is converted in lateral force through a pulley. Here it would be necessary to put an object under the chassis to avoid it to fall over the table (rotating over the swingarm pivot).

chassis lateral flexion

Third image shows an arrangement to measure the swingarm torsional stiffness. The arrangement to measure lateral stiffness would be similar to the one used for the chassis, using the same pulley.
I also want to use this tool to measure transversal torsional stiffness of the chassis, I mean, the stiffness that it has when we apply a load similar to the one that appears when we use the front brake.

swingarm torsion

I think that it is impossible to build a tool that could give you absolut stiffness values, the objective is to build a device to achieve values that will allow me to compare different chassis.

I want to use this table also to meassure chassis (general dimmensions, geometry, etc) and also to build chassis, using it as a base for my jigs.

Regarding stiffness meassurement, appart of general meassurement, I want to use extensometry to meassure local deformations on the chassis, in this way it will be possible to know the influence of each area of the chassis in the stiffness of the whole chassis. This could be very useful to validate and improve FEA models, trying to make these models more similar to reality.
I will keep you informed of this project progress in the blog.

[tags]bottpower, other projects, chassis, swingarm, stiffness, tool, extensometry, FEA[/tags]

3 thoughts on “tool for stiffness measurement”

  1. Hi, how did you get on with this? I am about to start a project on testing swingarms for torsional stiffness and would like to see how you got on.

    Thanks,

    Kieran.

  2. Hi Kieran,

    I built it, works very well. I changed the design a little bit trying to make it cheaper to build. The concept is very similar to these images anyway.
    Good luck with your project! 🙂

  3. Pingback: FZ-09 Superbike Build Begins - Page 8

Leave a Comment

Your email address will not be published. Required fields are marked *