Designing a Flexural Fatigue Machine for Characterization of 3d Printed Materials: An Approach Using the Third Law of Newton

In this study, a novel flexural fatigue testing apparatus was designed to evaluate the fatigue behavior of 3D-printed materials. The machine was validated using polylactic acid (PLA) 3D-printed samples and fiber-reinforced thermoformed polypropylene (PP). The investigation focused on the effects of varying infill percentages of PLA and fiber reinforcement in PP under constant deflection, in accordance with Newton’s third law. The results provided significant insights into the fatigue life of these materials, including stiffness degradation and damage accumulation, thereby confirming the machine’s efficacy. This research contributes to a deeper understanding of 3D-printed material behavior under cyclic loading and enhances the machine’s capability to assess both conventional and specialized plastics. Furthermore, we compared the indirect measurement of elastic modulus obtained from fatigue testing with direct measurements for various percentages of reinforced PP, demonstrating the feasibility of deriving elastic modulus from fatigue testing.