Growing age and different conditions often require the replacement of orthoses, and FDM-based 3D printing can produce them quickly with less investment. In today’s market for orthotics, these characteristics are highly desired. Therefore, this study is fully focused on the optimization and strength analysis of FDM 3D-printed ankle–foot orthoses (AFO) fabricated using PLA and PLA reinforced with carbon fiber (PLA-C). An increase in ankle plantar-flexor force can be achieved by reinforcing thermoplastic AFOs with CFs. Specially designed mechanical strength tests were conducted at the UTM to generate force–displacement curves for stored elastic energy and fracture studies. The mechanical behavior of both AFOs was predicted with the help of an FEA. The model predictions were validated by comparing them with mechanical strength testing conducted under the same loading and boundary conditions as the FEA. In both the prediction and experimental analysis, the PLA-C-based AFOs were stiffer and could withstand greater loads than the PLA-based AFOs. An area of high stress in the simulation and a fracture point in experimentation were both found at the same location. Furthermore, these highly accurate models will allow the fabrication of AFOs to be improved without investing time and resources on trials.

Direct Ink Writing (DIW) opens new possibilities in three-dimensional (3D) printing of carbon-based polymeric ink. This is due to its ability in design flexibility, structural complexity, and environmental sustainability. This area requires exhaustive study because of its wide application in different manufacturing sectors. The present article is related to the variant emerging 3D printing techniques and DIW of carbonaceous materials. Carbon-based materials, extensively used for various applications in 3D printing, possess impressive chemical stability, strength, and flexible nanostructure. Fine printable inks consist predominantly of uniform solutions of carbon materials, such as graphene, graphene oxide (GO), carbon fibers (CFs), carbon nanotubes (CNTs), and solvents. It also contains compatible polymers and suitable additives. This review article elaborately discusses the fundamental requirements of DIW in structuring carbon-doped polymeric inks viz. ink formulation, required ink rheology, extrusion parameters, print fidelity prediction, layer bonding examination, substrate selection, and curing method to achieve fine functional composites. A detailed description of its application in the fields of electronics, medical, and mechanical segments have also been focused in this study.

Limb injuries frequently necessitate orthotic bracing, and the utilization of material extrusion (MEX) additive manufacturing (AM) or 3D printing offers a rapid and cost-effective means of producing orthoses. These characteristics are highly sought after in today’s orthotic market. The study focused on the mechanical strength analysis of the wrist-hand orthosis (WHO) made of PET-G filament. Experimental testing and simulation were employed to assess the properties of individualized wrist orthoses fabricated through the MEX AM process. Standard three-point bending samples were manufactured using PET-G filament on a low-cost MEX 3D printer, alongside orthotic fragments and complete orthosis. Experimental testing was performed using a universal testing machine, and results were juxtaposed with those from a finite element simulation model created in the Abaqus environment. This comprehensive research approach facilitates the comparison of the modulus of elasticity of the fabricated components, enabling a comparison between the mechanical properties of the complete wrist-hand orthosis (WHO) product and those of a conventional bending sample.

This study presents a practical method of print fidelity evaluation for an extrusion-dependent technique of 3D printing. Simulation through computational fluid dynamics (CFD) tool has been used for evaluating the fidelity of printing. The polyvinyl alcohol (PVA) based hydrogel was prepared with deionized (DI) water and PVA powder using a magnetic stirrer at 90 °C for 3D printing. Rheological tests were carried out for checking the viscosity at various shear rates. CFD simulation was done by employing the Bird-Carreau modelusing rheological values. Velocity, pressure, shearing rate, and viscosity distributions through nozzle were obtained. From the shear rate and viscosity results, the increase in shear rate and decrease in gel’s viscosity for both the nozzles prove that the material can be extruded. It was seen that the nozzle with a diameter of 0.51mm shows better results than the 0.41mm diameter, which was concluded from the values of maximum shear rate at the edges of the nozzles. The maximum shear rate value has reached a maximum of up to 326.5102s ^–1 whereas for a 0.41 mm diameter nozzle, it is 623.8037s ^–1 increasing the chances of developing wavy edges in a 0.41mm diameter nozzle than a 0.51mm diameter nozzle concluding that the nozzle with 0.51mm diameter gives far better results than the 0.41mm diameter nozzle.