A Study of Fracture Mechanisms and Related Quantifications in 3D Printed Short Carbon Fiber Reinforced Polylactic Acid Composites

Bing Li, Purdue University


In this research, a study on fracture mechanism is carried out for single side cracked 3D printed panel under tension. The purpose of this project is to reveal specialties of fracture behavior in 3D printed structure and provide guidance on safety design of parts and structures manufactured by fused deposition molding. In the introduction session, comparison between thermoplastic and thermoset polymers is provided, and strength for thermoplastic material to be used in aerospace and astronautics industry is summarized. For those manufacturing methods compared in this research, fused deposition molding possess strength in time efficiency and capacity of manufacturing structures and parts with complicated geometry, which is suitable for the increasingly popular personalized manufacturing. For quantification of mechanical property of 3D printed sheet, structure parameters (normal and shear stiffness) are used as Young’s modulus of homogenized material for numerical simulation purpose. For simplification of structure property description, plane stress assumption and orthotropic symmetry are proved for the structure. Size effect on structure stiffness is also discussed. For description of Poisson’s effect, tensile test of 45° oriented sample and microscope observation of transverse deformation provide different result and the reason is discussed. Finally, panel with single side crack is loaded under tension, and crack propagation is investigated under microscope. Bridging is observed at crack rear region and its effect on resistance of structure to fracture is discussed. Load- displacement relation from experiment is compared with prediction from numerical method with homogenized material property derived before to verity the strategies used. Critical energy release rate of the panel is evaluated with J-integral.




Tomar, Purdue University.

Subject Area

Mechanical engineering|Materials science

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