Thermomechanical Analysis and Numerical Simulations of Fused Filament Fabricated Polylactic Acid Parts

Abstract

This work aimed to investigate the thermal deformation of polylactic acid (PLA) samples 3D-printed by Fused Filament Fabrication. The irreversible thermal strain (ITS) and coefficient of linear thermal expansion (CLTE) of four sets of samples with various sizes and thicknesses of the layer in the three directions of the measurements were investigated. The thermomechanical analysis (TMA) was used for the investigation of thermal deformation. During the study, the dependencies of deformation on temperature were obtained. The samples' CLTE values at various ranges of temperatures were estimated using the obtained dependencies. ITS was observed after heating to 80 ℃ during the first TMA cycle. The values reached 8 – 9 %. The impact of layer thickness and the number of layers in the sample on ITS was noticed. Shrinkage in the X direction and expansion in the Z direction with almost the same values were observed. Finite element code ANSYS was used to simulate the distribution of temperature and accumulation of residual thermal stresses in the printed part. The correlation was obtained between the level of simulated residual thermal stresses for samples with different number of layers and layer thicknesses and measured ITS after annealing.