Materials Science Forum Vol. 1187

Abstract: Complex geometry components fabricated through Fused Filament Fabrication in polyether ether ketone exhibit very interesting performances, but they are very difficult to predict. Non-standard mechanical tests allow for estimating a global structural response and do not provide local information about the failure evolution. This work investigates the integration of a Digital Image Processing method with non-standard mechanical test to improve the knowledge of the component performance through the tracking and the analysis of local failures. This way, a targeted redesign of the component can be provided: in this work the component was modified at manufacturing stage by changing the Fused Filament Fabrication infill, and at optimization stage by employing a stress line approach for locally densifying the interior.

Abstract: This work introduces an initial finite element (FE) framework for modelling particle-substrate interaction during fluidized bed surface finishing of Laser Powder Bed Fusion (L-PBF) components. Due to the complexity of as-built surface morphology and the difficulty of experimentally observing high-speed particle impacts, the mechanisms governing material removal remain poorly understood. The proposed 3D explicit FE model simulates the impact of stainless-steel particles on representative AlSi10Mg asperities using Johnson-Cook plasticity model and damage formulations. Results show that erosion occurs mainly through localized brittle-like detachment rather than extensive plastic deformation. Sequential impacts and oblique trajectories significantly increase internal energy absorption, enhancing asperity fragmentation and the surface smoothing level. The framework provides a foundation for future optimization of Fluidized Bed Finishing (FBF) parameters for improved finishing of additively manufactured metal parts.

Abstract: PEEK is a thermoplastic polymer widely employed in the orthopedic field for the fabrication of prosthetic devices, owing to its Young’s modulus being comparable to that of cortical human bone. Surface functionalization through biomaterial micropatterning represents an effective strategy to enhance osteointegration. To this end, an innovative vibration-assisted surface embossing process was applied to PEEK samples. The surface patterning was performed using a square punch with a side length of 0.5 [mm], fabricated via CNC milling. The process is enabled by a linear actuator capable of generating controlled vibrations to induce localized sub-Tg heating of the polymer surface. After that, the application of a post-load is required for the embossing stage. This system allows frequency tuning in the range of 1–4 [kHz]. Finally, the patterned surfaces were sonicated through an ultrasound cleaner and characterized through contact angle measurements and white-light interferometry, confirming the feasibility of the process and demonstrating an increase in both the polar component of the surface free energy and the hydrophilicity compared with merely polished specimens. Enhancing the polar component of surface free energy is an effective strategy to improve biomaterial biocompatibility, confirming the relevance of the proposed surface modifications. Slightly hydrophilic surfaces promote preferential osteoblast adhesion and stable cytoskeletal organization, demonstrating the complementary roles of surface topography in shaping cellular responses.

Abstract: Present demands for weight reduction of vehicles to decrease the carbon footprint in the transport industry have increased the need for lightweight tubes. In this paper, composite tubes are drawn from two aluminum tubes and reinforcements with the aim of maximizing mechanical performance while maintaining low weight. The reinforcements are placed between the two aluminum tubes and are made from blanks of 22MnB5 steel or carbon fiber laid in different quantities and patterns. The compressive stresses in tube sinking are used to hold the reinforcements in the composites without the need for resins and energy-intensive heating or curing cycles. The composites are weighed, and their performance is evaluated by mechanical test. Bending tests reveal an increase in the bending strength of the reinforced tubes by 15% for both composites reinforced by carbon fiber and 22MnB5 steel. However, the composites made from carbon fiber have higher stiffness and lower weight. The bending strength and residual stresses of composites manufactured with different carbon fiber layouts and quantities are evaluated to determine their performance. Increasing the carbon fiber content did not improve the stiffness and ultimate tensile strength of the composites, indicating the compressive stresses from drawing and carbon fiber content should be optimized to achieve the best mechanical performance.