Design, Development, and Qualification of a Dual Purpose 3 and 4-point Flexural Fatigue Loading Fixture for Composite Testing

senior project cad pic

Fixture Design

Using multiple ASTM testing standards, this design was created to provide a dual purpose 3 and 4 point testing fixture for composite fatigue testing. The Composite test specimen is represented as the brown rectangular object in the figure to the left.


As a testing fixture was not commercially available, load to support spans from multiple ASTM documents needed to be taken into consideration. The Figure to the right outlines the importance of the support span and the design of the fixture. As the width and depth of the specimen changes, the contact points of the fixture on the test specimen needs to change as well.

3d printing
printed parts


Rapid prototyping techniques were implemented to achieve an approprioate tolerance along the guide rail track allowing variable supports in the test fixture. The figure to the left shows a support hinge being printed with HIPS plastic at a 1:2 scale.

CAM and CNC Machining

Using a combination of G-code and CATIA Prismatic machining, the Guide rail design outlined to the left was machined using a CNC machine. The entire design was coded such that it could be machined in one set-up

prismatic machining
guide rail

Final Fixture Assembly

Final Fixture Assembly

Questions Regarding the Project?

Send me an email an I would be happy to talk about my design and process.