Mechanical and failure behaviour of PLA FFF printed part under sweat absorption: Splint arm application

Abstract

This study focuses on the selection of printing parameters for arm splint to support forces under sweat exposure. We investigated the influence of varying infill density and raster angle on flexural properties after sweat diffusion. In particular, polylactic acid (PLA) beams were printed in the edge direction with different infill densities (60%, 80% and 100%) and raster angles (0°, 45° and 90°). We evaluated the flexural properties of the beams before and after aging in sweat, and analysed the failure mode based on the printing parameters. Additionally, we quantified the porosity of the samples and correlated it with sweat absorption and mechanical properties. Degradation of PLA in water and sweat is assessed by the Fourier transform infrared spectroscopy analysis. Our findings revealed that a higher strength and stiffness were achieved with a 45° raster angle and higher infill density. Interestingly, the parameters that resulted in optimal properties before and after sweat absorption aren’t the same. Sweat absorption depends on the architecture leads to the change in failure mode which initiated fracture. The findings provide valuable insights into the optimisation of printing parameters for arm splints, considering both mechanical performance and the impact of sweat interaction on fracture behaviour.