Elastic Asymmetry of PLA Material in FDM-Printed Parts: Considerations Concerning Experimental Characterisation for Use in Numerical Simulations

Abstract

The objective of this research is to characterise the material poly lactic acid (PLA), printed by fused deposition modelling (FDM) technology, under three loading conditions—tension, compression and bending—in order to get data that will allow to simulate structural components. In the absence of specific standards for materials manufactured in FDM technology, characterisation is carried out based on ASTM International standards D638, D695 and D790, respectively. Samples manufactured with the same printing parameters have been built and tested; and the tensile, compressive and flexural properties have been determined. The influences of the cross-sectional shape and the specimen length on the strength and elastic modulus of compression are addressed. By analysing the mechanical properties obtained in this way, the conclusion is that they are different, are not coherent with each other, and do not reflect the bimodular nature (different behaviour of material in tension and compression) of this material. A finite element (FE) model is used to verify these differences, including geometric non-linearity, to realistically reproduce conditions during physical tests. The main conclusion is that the test methods currently used do not guarantee a coherent set of mechanical properties useful for numerical simulation, which highlights the need to define new characterisation methods better adapted to the behaviour of FDM-printed PLA.

Surface Etching of 3D Printed Poly(lactic acid) with NaOH: A Systematic Approach

“…This is consistent with literature [10,16,21]. The E-modulus is around 4.5 ± 1.6 GPa, which is higher than reported in the literature [1,[29][30][31] but the same publications also state that here is a certain variation to these values. Because of our unique sample design, tensile testing cannot follow ISO or ASTM standard procedures.…”

The Influence of Raster Angle and Moisture Content on the Mechanical Properties of PLA Parts Produced by Fused Deposition Modeling

“…3D printing applications have been expanding rapidly due to the minimal cost of the production process, low supervision and maintenance cost, and simple material change [ 1 ]. Different 3D printing processes have been developed using numerous materials and methods [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. One of the most common 3D printing technologies is fused deposition modeling (FDM), which is a layer-by-layer technique using CAD and computer-aided manufacturing (CAM).…”

“…FDM is a manufacturing process that is affected by many parameters that may alter the quality and mechanical properties of the part. Many researchers have investigated multiple parameters to improve the performance of the 3D-printed parts and components [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. Chacón et al [ 21 ] investigated how the strength and the ductility of PLA specimens are affected by the layer thickness.…”

Novel Synthesis of Core-Shell Biomaterials from Polymeric Filaments with a Bioceramic Coating for Biomedical Applications

“…In contrast, the deformation of the TPU samples occurred in the incipient part of the filament and was subsequently transferred to the adhesive-filament interface. This uneven behavior can be explained based on the different elasticity modules of the PLA, TPU and the chosen adhesive (the PLA has an elasticity module of approximate three times higher than the adhesive, while the TPU values are close to those of the adhesive) [71][72][73][74].…”