Effect of Resonant Vibration on Defects in Carbon Fiber Based Polymeric Composites Samuel Sellner, Mechanical Engineering Dr. Rani Elhajjar, Civil/Environmental Engineering

Objectives Determine the material properties of a carbon fiber composite bike frame and use this information to build a model to repeatedly predict defect propagation and resonant response in the frame. Investigate and characterize a new failure mode for defects within carbon fiber composite parts that have been exposed to resonant vibration. Investigate the distinct stages of composite fatigue failure related to initiation, propagation, and final growth.

Material Characterization Figure 2: Samples taken from bike Figure 1: CFRP composite bike frame cut into sections

Material Characterization Figure 3: Tensile test Figure 4: Three point bend test

Characterization Results Tension Stress Strain Bending Stress Strain Figure 6: Example of results for tensile test Figure 7: Results for three point bend test. Comparison of stiffness in different sections.

Future Work Verify material property results Apply material properties to finite element model of bike frame to predict failure

Figure 8: Forming a wrinkle Wrinkle Manufacture Use rods to form wrinkle in individual prepreg layers Stack prepreg layers Use vacuum bag to press prepreg layers together Figure 8: Forming a wrinkle

Figure 9: Design of experiment 24 samples to test 4 variables: Presence of wrinkle defect Vibration mode Composite thickness Fiber layup direction Figure 9: Design of experiment

Future Work Subject samples to resonant vibration Test samples to failure Determine affect of resonant vibration on the strength of the samples

Conclusion The goal of this study has not been met yet More experimentation is required to make a conclusion

Acknowledgements Rani Elhajjar UWM Office of Undergraduate Research College of Engineering and Applied Sciences