Experimental Investigations of the Influence of 3D Printing at 100% Filling on the Elastic Properties of PLA Polymer Filament Samples

The article presents the results of experimental studies of how 3D printing with 100% filling influences the elastic properties of PLA filament polymer samples. The static and Thurston–Brugger methods simultaneously measure the dependence of strain and the relative change in the velocity of elastic waves on the applied mechanical stress (up to failure) for the initial and 3D-printed samples of the PLA polymer. Based on the measurement results, the linear and nonlinear Young’s moduli and second-order acoustic nonlinear parameter are calculated. It has been established that 3D printing leads to a deterioration in the strength and plastic characteristics of PLA. A different behavior of the nonlinear parameters of the initial and 3D-printed PLA samples in the loading and unloading region was revealed, associated with a change in the internal structure of the sample caused by 3D printing.