Quasi-static indentation analysis on three-dimensional printed continuous-fiber sandwich composites

Abstract

Fiber reinforced sandwich structures are widely used as structural elements due to their lightweight and high load-bearing capacity. In this paper, effort is taken to fabricate fiber facesheet (0°/90° orientation) and corrugated cores (trapezoidal vertical pillared, core-1 and sinusoidal vertical pillared, core-2) of the sandwich structure using fused filament fabrication and Inkjet printing techniques, respectively. Firstly, the quasi-static indentation properties of the additively manufactured facesheet, cores, and sandwich structures were investigated. In addition, acoustic emission signals were monitored during quasi-static indentation testing and the resulting hits data were correlated with quasi-static indentation test results. The quasi-static indentation test results showed that sinusoidal sandwich structures have the highest load-bearing capacity of 1.79 kN until crack initiation and a total energy-absorption capacity of 20.05 J. Acoustic emission hits recorded in the range of 1–30, 30–100, and above 100 represented crack initiation, crack propagation, and specimen failure, respectively. Lastly, micro-computed tomography analysis was performed on the sandwich structures at intermediate indentation displacements, thus leading to the identification of hard to detect failure points and damage propagation. Fracture surface morphology of the sandwich structures showed that fiber pullout and core shear were the dominant damage mechanisms.

Quasi-static indentation and sound-absorbing properties of 3D printed sandwich core panels

“…The above-mentioned studies focused on the acoustic aspect of the 3D printed periodic structures without investigating the mechanical performance of the 3D printed structures. In our previous work, we focused on the compressive properties [27] and quasi-static indentation [28] of the 3D printed composite sandwich panels. Sinusoidal vertical pillared sandwich structures were found to have higher load-bearing and energy absorption capacity in comparison to trapezoidal vertical pillar structures.…”

Damage Assessment of Glass-Fibre-Reinforced Plastic Structures under Quasi-Static Indentation with Acoustic Emission

“…For the laminate specimens, region I was identified as the initiation of damage at the microscopic stage (matrix cracking), region II represents the initiation of macroscopic damage such as fibre/matrix debonding, and finally region III indicates the start of damage propagation until failure of the structure (fibre breakage/rupture) [39]. On the other hand, two additional damage processes could be identified (regions IV and V) for samples, and the earlier damage points discussed were similar to those of the face sheet of the GS samples [17]. Region IV represents the core/face sheet debonding and delamination, while region V indicates the fracture of the bottom face sheets.…”

Simplified local infill size optimization for FDM printed PLA parts

“…Apart from the conventional infill types, by forming the inner structure of the parts, they can be better perform under special conditions. Furthermore, several previous research has investigated the lightweight structures considering different aspects and using different techniques [6][7][8] .…”