The importance of print orientation in numerical modelling of 3D printed structures under impact loading

Anisotropy is commonly observed in 3D-printed polymer and composite parts, particularly when manufactured by fused filament fabrication (FFF). This anisotropy can lead to difficulty obtaining accurate material properties during mechanical characterisation. This study establishes a connection between the print parameters used in specimen characterisation and their influence on the accuracy of numerical models for 3D-printed cellular structures under impact. Material properties from only one of the characterisation variants studied, with a parallel infill, accurately represented the force response and physical damage of the experimental samples. In contrast, the default characterisation specimen with a +/- 45 degrees infill underpredicted the peak force and overpredicted the impact duration, potentially leading to underestimating impact severity. This discrepancy could result in greater damage to a person or structure being protected. It is recommended that the parallel infill pattern be used when characterising materials for use in FFF cellular structures under impact loading to ensure more reliable simulations and improved design of impact-resistant structures.