Fracture mechanical characterization and lifetime estimation of near-homogeneous components produced by fused filament fabrication. (April 2018)

• Record Type: Journal Article
• Authors: Arbeiter, Florian; Spoerk, Martin; Wiener, Johannes; Gosch, Anja; Pinter, Gerald
• Is Part Of: Polymer testing. Volume 66(2018)
• Page Start: 105
• Page End: 113
• Publication Date: 2018-04
• Subjects: Fused filament fabrication -- Additive manufacturing -- Polylactic acid -- Homogeneous properties -- Fracture mechanics -- Lifetime-model; Polymers -- Testing -- Periodicals; Polymères -- Tests -- Périodiques; 620.1920287
• DOI: 10.1016/j.polymertesting.2018.01.002
• Languages: English
• ISSNs: 0142-9418

Abstract

Abstract: It has been widely believed that components produced by fused filament fabrication (FFF) experience weak mechanical properties due to weld lines. However, recent studies disproved this finding by reaching strength values almost identical to those of compression-molded plates by optimizing the printing parameters. Hence, the present work investigates different fracture mechanical properties on specimens produced by FFF under optimized conditions dependent on the strand orientation. For monotonic loading conditions, tests on compact tension (CT) and single edge notched bending (SENB) specimens resulted in rather similar results for specimens produced in 0°, 0°/90° and 90° strand orientation. Surprisingly, the 90° orientation, in which the strand interface is directly loaded, even outperformed the 0° orientation in certain cases. Fatigue tests on CT-specimens proved a similar independency of the strand orientation for both crack initiation and crack propagation laws, which can be used for lifetime estimation of components produced by FFF. Highlights: 3D-printed PLA specimens are produced using optimized printing parameters and show near homogeneous properties. Fracture properties of 3D-printed specimens are investigated using linear-elastic and elastic plastic fracture mechanics. Fracture properties were found to be nearly identical, regardless of orientation during printing. Fatigue of 3D-printed specimens is examined with regard to orientation. A lifetime-model for components based on fracture mechanics is proposed.