Fabrication and Characterization of Fiber-Reinforced Composite Sandwich Structures Obtained by Fused Filament Fabrication Process

Abstract

The application of fused filament fabrication processes is rapidly expanding in many domains such as aerospace, automotive, medical, and energy, mainly due to the flexibility of manufacturing structures with complex geometries in a short time. To improve the mechanical properties of lightweight sandwich structures, the polymer matrix can be strengthened with different materials, such as carbon fibers and glass fibers. In this study, fiber-reinforced composite sandwich structures were fabricated by FFF process and their mechanical properties were characterized. In order to conduct the mechanical tests for three-point bending, tensile strength, and impact behavior, two types of skins were produced from chopped carbon-fiber-reinforced skin using a core reinforced with chopped glass fiber at three infill densities of 100%, 60%, and 20%. Using microscopic analysis, the behavior of the breaking surfaces and the most common defects on fiber-reinforced composite sandwich structures were analyzed. The results of the mechanical tests indicated a significant influence of the filling density in the case of the three-point bending and impact tests. In contrast, the filling density does not decisively influence the structural performance of tensile tests of the fiber-reinforced composite sandwich structures. Composite sandwich structures, manufactured by fused filament fabrication process, were analyzed in terms of strength-to-mass ratio. Finite element analysis of the composite sandwich structures was performed to analyze the bending and tensile behavior.

Compression and Bending Properties of Short Carbon Fiber Reinforced Polymers Sandwich Structures Produced via Fused Filament Fabrication Process

“…The composite sandwich specimens were analyzed microscopically on the sections perpendicular to the XY plane (cross section) and according to the construction direction-Z axis (longitudinal section) with a magnification of 100×. On the microscopic analysis, typical defects of short fiber-reinforced composites were found, similar to the ones in other studies [7,23,30,[60][61][62]. The defects are rectangular and triangular voids formation, inter-layer voids, voids found in the matrix or filament, and poor adhesion between the fiber and the matrix.…”

“…The finite element model was analyzed according to the properties of the wing sections, showing an infill density of 100%. In the finite element analysis of the wing sections, some simplifying hypotheses were established, and used in other studies [ 60 , 66 , 67 , 68 ]: the constituents have a linear elastic behavior, the matrix (polyamide) has isotropic properties; short micro-carbon fibers are transverse isotropic; the fiber matrix has a perfect adhesion and has no voids or defects. The value of the modulus of elasticity was 8386 MPa, assumed to be that of the composite filament, and the Poisson’s ratio had the value of 0.3 [ 66 , 68 ].…”

Finite Element Analysis of Upper Limb Splint Designs and Materials for 3D Printing

“…The scanning duration, as well as practicality, mobility, and adaptability, are the most important scanner criteria in orthotics [ 12 ]. Likewise, AM enables the comparatively simple realization of very complex digitally produced models with little or no human intervention in the manufacturing process or in-depth material expertise [ 13 ]. With the help of an organized, layer-by-layer build process, objects can be constructed in complicated configurations that would otherwise be impossible to create using conventional manufacturing techniques [ 14 ].…”

“…The design and production of orthotic devices that conform precisely to the anatomical features of patients can enhance their quality of life by providing personalized shape, performance, function, and aesthetics [ 11 ]. The process of creating custom handmade orthoses through manual fabrication using low-temperature thermoplastic material, as recommended by the International Committee of the Red Cross, can be a challenging, laborious, and time-intensive task [ 13 ]. Additionally, this method carries the potential risk of minor skin burns or irritations owing to direct exposure to heated material [ 17 ].…”

A Novel Manufacturing Concept of LCP Fiber-Reinforced GPET-Based Sandwich Structures with an FDM 3D-Printed Core

“…However, the obtained results do not show a significant advantage of the CFC-FDM technique. A different concept of the work assumes using a ready-made fabric reinforced prepreg and combining it with a 3D-printed composite core using the adhesive technique [ 43 , 44 , 45 ]. The advantage of this solution is the possibility of using a wide range of printing methods, including printing photocurable materials or thermosets.…”