Mechanical behavior of polymer-based composites using fused filament fabrication under monotonic and fatigue loadings

The use of additive manufacturing has been widely developed in the industry due to its ability to make complex shapes. The use of reinforcing fibers has provided a wider design capability in this field. Due to the effect of the number of fibers reinforced used on the mechanical properties, the study of the obtained mechanical properties is of great importance. This paper presents the experimental findings of tensile loading and three points bending fatigue tests performed on polymer-based composites (Onyx (which is CF-PA6) and reinforced Onyx with continuous glass fiber (CF-PA6 + GF) using Fused Filament Fabrication. Tensile properties of various types of printing conditions (Solid, Triangular, Rectangular, and Hexagonal fill patterns) have been compared. The coupled frequency amplitude affects the nature of the overall fatigue response which can be controlled by the damage mechanisms accumulation and/or by the self-heating. For fatigue loading, self-heating has been observed and yielded a temperature rise to about 60°C which is more than the glass transition temperature of the polymer. Multi-scale damage analysis of the sample in fatigue showed that the first observed damage phenomenon corresponds to the debonding of the filaments which leads to the propagation of transverse cracks.