An Experimental Comparison for Compression of PLA Specimens Printed in In-Plane and Out-of-Plane Directions

Abstract

The present work proposes an experimental comparison between the in-plane and out-of-plane compressive behaviors of 3D printed PolyLactic Acid (PLA) specimens. These specimens are produced via the Fused Deposition Modeling (FDM) technique by using two different printing directions: the first printing direction in the xz plane allows experimental compression tests in the out-of-plane direction; the second printing direction in the xy plane allows experimental compression tests in the in-plane direction. The specimens are more rigid in the out-of-plane direction than in the in-plane direction. In the first case, a bigger linear compressive Young modulus has been found and both maximum stress and proportional limit stress were determined. In the second case, the linear compressive Young modulus is smaller and the specimens are less rigid but at the same time more resistant: in fact, no maximum stress and proportional limit stress have been obtained because the test machine has reached the maximum applicable load. This research demonstrates as the compressive behavior of 3D FDM printed polymeric elements depends on the printing and test directions and this feature is fundamental when such elements will be used for structural applications. The experimental tests performed in the present paper are accompanied by statistical and capability analyses for the dimensional parameters and for the mechanical properties in order to also evaluate the stability of the production process and the validity ranges for the mechanical characteristics.