In this study, the 3D printing technology was adopted to produce carbon fiber-reinforced polylactic acid and polyethylene terephthalate glycol composites. Fused deposition modeling process was conducted at different settings of printing parameters, specifically, raster angle, printing speed, and extrusion temperature. Each of the selected printing parameters has a key role in making the best-printed part in terms of layer-by-layer deposition quality and mechanical performance. To examine how these process parameters affect the behavior of the printed parts, tensile tests were performed and mechanical properties were assessed. It was reported that the printing orientation, characterized by the raster angle, can be identified as the determining factor to define the fracture mode. Composite parts printed with 0° raster angle, aligning with the tensile loading path, exhibit the highest levels of stiffness and ductility. Ductile and brittle fractures corresponding to 0° and 90° raster angles, respectively, were illustrated through optical observations of failure profiles. Furthermore, the tensile test indicates that higher printing speed leads to a significant deterioration in mechanical performances, notably reducing the stiffness of the printed structures. Scanning electron microscopy analysis confirmed that increasing the printing speed results in greater porosity within the structure, thereby weakening its mechanical strength. Regarding the extrusion temperature, it was shown that elevating it enhances the mechanical characteristics of the printed parts, particularly in terms of strength and ductility. Referring to microstructural observations, this outcome is attributed to the improved adhesion between the deposited layers and the reduction in porosity at high extrusion temperature.

In the frame of technology development, fused deposition modeling is adapted in this study to elaborate composite material from 20% short carbon fiber reinforced polyether ether ketone (CF/PEEK) filament. This printing technology has attached widespread intention as it provides a rapid prototyping parts with high performances in diverse fields. For this purpose, a set of experimental tensile and bending tests are carried out to focus on the effect of printing orientation on the mechanical properties of the designed samples. Three raster angles are considered in this investigation: 0°, ±45°, and 90°. The obtained results indicate that the printing orientation of 0°, which is parallel to the tensile loading path and perpendicular to the flexural one exhibits higher mechanical strength compared to the other orientations. Evolution of Young modulus, total elongation at failure, yield and ultimate strengths as well as deflection are also discussed. Experimental work is supported by numerical simulation and a good agreement is revealed. Microstructural analysis is performed in order to argue the observed mechanical behavior. Through the fractured section morphology, the effect of tensile loading on CF/PEEK microstructure, at various printing orientation is emphasized.

Numerical Analysis of Damage Thermo-Mechanical Models - Volume 7 Issue 5 - Hamdi Hentati, Ilyes Ben Naceur, Wassila Bouzid, Aref Maalej

Previous studies of the shearing process demonstrated that clearance and shear rate are the most influential parameters on the geometry of sheared billets. This paper illustrates a parametric numerical study of the impact of these parameters on the quality of the shear surface using the finite element simulation of shearing. In order to account for interactions between stress state evolution and the associated heating during shearing, a fully coupled thermo-mechanical simulation method was adopted. The influence of stress state, strain rate, and temperature on the material behavior were taken into account by using Johnson-Cook plasticity and ductile failure models. Many simulations were carried out involving diverse shear rates and shear clearances. The relationship between the parameters of shear surface geometry and the temperature was illustrated and proven. Contrary to the expectation of high-speed shearing performance, a burr free smooth shear surface was found using a low shear rate. This study illustrates a numerical strategy to determine the best shear clearance-rate set for aluminum alloy Al7075-T6 bars that minimizes the shear surface defects.

Design of experiments is a statistical approach from which an optimized number of experiments is determined. Taguchi design of experiments, applied on Erichsen tests, is chosen to be considered in this paper. The most important parameters in this forming process, Erichsen index ( IE), and maximum generated force ( F_max), are experimentally and theoretically determined. Three input factors are selected, at diverse levels, in order to study their influence on Erichsen output results. The considered input factors are sheet thickness, punch diameter, and friction coefficient. New mathematical models which take into account the effects of these factors and their interactions are developed. Moreover, the influence of Erichsen test on the S235 steel microstructural behavior is experimentally examined as function of the sheet thickness. A good agreement between experimental and theoretical findings proves that the proposed models provide a precise prediction and an exact estimation of the Erichsen output parameters ( IE and F_max). The efficiency of the adopted design of experiments via Taguchi method is well confirmed.

The use of 3D printing is expanding in manufacturing wind turbine blades for renewable energy. This study examines the relationship between geometric parameters, mechanical strength, and aerodynamic performance in blades made from short carbon fiber-reinforced PLA (SCFR-PLA) composites. To achieve this, it includes a comparative evaluation of innovative blade designs and materials, aiming to enhance both the energy efficiency and mechanical durability of horizontal axis wind turbines (HAWTs). The numerical model of the wind turbine blade is validated against experimental results, which employed a NACA geometry and ABS polymer. Building upon this validation, a design of experiments (DOE) analysis is employed to explore the influence of fused filament fabrication (FFF) parameters on the mechanical properties of SCFR-PLA composites. A novel blade design, referred to as HAWTSav, is numerically evaluated using 3D-printed SCFR-PLA composites. Numerical simulations are conducted to evaluate the energy efficiency and structural integrity of the HAWTSav blade. A comparative analysis is then performed, contrasting the performance of the conventional NACA blade in ABS with the HAWTSav blade in SCFR-PLA composites. The findings highlight the potential of SCFR-PLA composites in the development of efficient and durable wind turbine blades, highlighting their applicability, particularly in small-scale wind energy systems.