Experimental and Numerical Investigation intoFree Vibration of Delaminated ۳D-Printed PLA Beams

The biodegradable Polylactic acid (PLA), is a versatile thermoplastic polymer and one of the mosteco-friendly materials widely adopted and used as the feedstock for ۳D printing and manufacturing ofelements used in various fields such as healthcare, textile, packaging, bio-medical devices, to name afew. PLA is also used in bio-composite materials. Research is being made for the low-cost applicationof PLA in the aerospace industry. With the exponential growth of ۳D printing applications, characterizationof the filaments, used as the feedstocks, and the printed parts is essential for determiningquality, controlling manufacturing processes, and making accurate model predictions of process andproduct performance. In this research project, the flexural vibration analysis and contact analysis ofthe ۳D-printed PLA beam specimens will be conducted.Experimental and FEM-based numerical free vibration analyses of defective ۳D-printed PLAcantilever beam specimens are presented. The experimental setup and PLA specimens are brieflydiscussed. Experimental fundamental frequency results for defective, cantilevered, PLA beam specimensare evaluated, and average fundamental flexural (bending) frequencies are reported. The defectis considered to be a single, symmetric, through-the-width, centrally located, delamination of variousthicknesses, covering one-third of the beam specimens’ length. The average frequency values arecalculated based on three different trials, conducted to ensure the accuracy of the obtained results.Numerical results, including fundamental frequencies and corresponding mode shapes, obtainedthrough simulations carried out using Finite Element Analysis (FEA) Software (Femap with NX Nastran)are also reported and discussed. The comparison is made between the numerical (FEM) and experimentalresults. It is observed that the natural frequency drops for a small-thickness delamination(e.g., ۰.۱ mm), associated with the reduction in the flexural rigidity of the beam while the mass remainsvirtually unchanged. However, when the delamination thickness is further increased, the systemnatural frequency increases. This can be explained by the fact that while, in this case, the system’sflexural rigidity and mass both lessen, with latter decreasing more significantly than the former.As a result, the system’s natural frequency increases with growing delamination thickness.