An Experimental and Numerical Investigation Into the Fundamental Frequency Analysis of 3D-Printed PLA Beam With Delamination

This report consists of experimental and Finite element-based numerical modal analysis of a 3D printed PLA cantilever beam with a nonuniform delamination of 0.5mm, carried out as part of an MEng project. Experimental modal analysis is performed on four different samples of different delamination thicknesses, including the one with a delamination of 0.5mm, to obtain the system's bending fundamental frequency. Numerical analysis, however, is focused and conducted on only the defective specimen with a non-uniform delamination of 0.5mm. In this case, the delamination is sketched with the help of an electronic microscope which takes the images of the delamination zone. These images are then used to plot the non-uniform delamination on the 3D model, focusing on obtaining the model that is as close as possible to the manufactured specimen. The experimental frequencies are subsequently compared with the numerical values obtained from the Finite Element Analysis (FEA) of the 3D model. In numerical analysis, a progressive approach was used to create two sophisticated models referred to as refined and further refined models. The numerical fundamental frequency obtained from these last models are compared with that of the PLA beam with uniform delamination of 0.5mm. It is observed that by applying progressive refinement in the FEM model, the numerical fundamental bending frequency increasingly converges to the experimental one. Appendix A consists of the images taken by the microscope, which show the non-uniform geometry of the delamination zone.