<p>3D printing manufacturing method gains significant attractions from industries due to its advantages over other production methods. Polylactic Acid (PLA), a biodegradable feedstock in 3D printing and one of the major filaments in the market, is investigated. Impulse Excitation Technique (IET) is used to obtain Young’s modulus of 3D-printed PLA specimens. The results are then compared with those achieved through experimental tensile testing. Displacement laser sensors, attached on the vertical base along cantilever 3D printed PLA cantilever beam samples, are used to capture the fundamental flexural frequencies of the beams, and are compared with those obtained from ANSYS FEM models. The effect of through-the-thickness cracks on the fundamental frequency of the defective samples is also studied, both experimentally and numerically. Samples including deliberately printed cracks of different depths and locations were examined through experiment and simulation. Results showed that the crack distance from the fixed-end has a more pronounced effect on fundamental frequency than the crack size. Finally, variation of numerically calculated fundamental frequency of defective beam models vs. crack depth and location are presented, which could be used as a database and pave the road to more elaborate crack identification techniques.  </p>

<p>3D printing manufacturing method gains significant attractions from industries due to its advantages over other production methods. Polylactic Acid (PLA), a biodegradable feedstock in 3D printing and one of the major filaments in the market, is investigated. Impulse Excitation Technique (IET) is used to obtain Young’s modulus of 3D-printed PLA specimens. The results are then compared with those achieved through experimental tensile testing. Displacement laser sensors, attached on the vertical base along cantilever 3D printed PLA cantilever beam samples, are used to capture the fundamental flexural frequencies of the beams, and are compared with those obtained from ANSYS FEM models. The effect of through-the-thickness cracks on the fundamental frequency of the defective samples is also studied, both experimentally and numerically. Samples including deliberately printed cracks of different depths and locations were examined through experiment and simulation. Results showed that the crack distance from the fixed-end has a more pronounced effect on fundamental frequency than the crack size. Finally, variation of numerically calculated fundamental frequency of defective beam models vs. crack depth and location are presented, which could be used as a database and pave the road to more elaborate crack identification techniques.  </p>

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