• Check the metadata sheet to make sure that the header information, especially author names and the corresponding affiliations are correctly shown. • Check the questions that may have arisen during copy editing and insert your answers/corrections. • Check that the text is complete and that all figures, tables and their legends are included. Also check the accuracy of special characters, equations, and electronic supplementary material if applicable. If necessary refer to the Edited manuscript. • The publication of inaccurate data such as dosages and units can have serious consequences. Please take particular care that all such details are correct. • Please do not make changes that involve only matters of style. We have generally introduced forms that follow the journal's style. Substantial changes in content, e.g., new results, corrected values, title and authorship are not allowed without the approval of the responsible editor. In such a case, please contact the Editorial Office and return his/her consent together with the proof. • If we do not receive your corrections within 48 hours, we will send you a reminder. Please note Your article will be published Online First approximately one week after receipt of your corrected proofs. This is the official first publication citable with the DOI. Further changes are, therefore, not possible.

No abstract

The present study evaluates the manufacturing parameters effects on the tensile properties of material composed by polylactic acid (PLA) with wood fibers known as Timberfill.The specimens were built through fused filament fabrication (FFF). The influence of four printing parameters (Layer height, Fill density, Printing velocity, and Orientation) are considered through a 27 Taguchi orthogonal array in order to reduce experimental runs. Tensile test is applied to obtain the response variable used as output results to perform the ANOVA calculations. Fill density is the most influential parameter on the tensile strength, followed by building orientation and layer height, whereas the printing velocity shows no significant influence. The optimal set of parameters and levels is found, being 75% fill density, 0 ○ Z-axis orientation, 0.4 mm layer height, and 40 mm/s velocity as the best combination. Applying this combination showed 9.37 MPa in maximum tension.Lastly, five solid Timberfill specimens manufactured via injection molding technology were also tested and the results compared to the printed samples. The values of the elastic modulus, elastic limit, and maximum tension of the injected samples were almost twofold of those were obtained for the FFF samples, but the maximum elongation of injected specimens was fell sharply.

Additive manufacturing (AM) or 3D printing offers a new paradigm for designing and developing chemical reactors, in particular, prototypes. The use of 3D printers has been increasing, their performance has been improving, and their price has been reducing. While the general trend is clear, particular applications need to be assessed for their practicality. This study develops and follows a systematic approach to the prototyping of Advanced Oxidation Processes (AOP) reactors. Specifically, this work evaluates and discusses different printable materials in terms of mechanical and chemical resistance to photo-Fenton reactants. Metallic and ceramic materials are shown to be impracticable due to their high printing cost. Polymeric and composite materials are sieved according to criteria such as biodegradability, chemical, thermal, and mechanical resistance. Finally, 3D-printed prototypes are produced and tested in terms of leakage and resistance to the photo-Fenton reacting environment. Polylactic acid (PLA) and wood–PLA composite (Timberfill®) were selected, and lab-scale raceway pond reactors (RPR) were printed accordingly. They were next exposed to H2O2/Fe(II) solutions at pH = 3 ± 0.2 and UV radiation. After 48 h reaction tests, results revealed that the Timberfill® reactor produced higher Total Organic Carbon (TOC) concentrations (9.6 mg·L−1) than that obtained for the PLA reactor (5.5 mg·L−1) and Pyrex® reactor (5.2 mg·L−1), which suggests the interference of Timberfill® with the reaction. The work also considers and discusses further chemical and mechanical criteria that also favor PLA for 3D-printing Fenton and photo-Fenton reactors. Finally, the work also provides a detailed explanation of the printing parameters used and guidelines for preparing prototypes.

No abstract

Fused Filament Fabrication (FFF) is one of the most common additive manufacturing (AM) technologies that has arisen interesting from industry in a wide range of applications. In this paper, the mechanical properties of FFF 3D printed wood-PLA (Timberfill®) parts are investigated both experimentally and computationally to predict the mechanical characteristics of this material. Firstly, experimental tensile test is carried out to achieve the properties of the material. Secondly, the obtained parameters (Young’s modulus, Poisson’s ratio and yielding stress) will be use as input data in the ANSYS software to simulate a 4-point bending test. Finally, in order to validate the obtained model, the simulation results are compared to an experimental flexural test results indicating the correspondence between them. The main result of this work is an appropriate model to predict the behaviour of a 3D-printed piece formed by an internal structure with certain characteristics suitable for the manufacturing process and surrounded by a skin, which is subjected to certain external load.

This paper deals with the improvement of the material surface state of friction stir welding paths modified in situ by plastic deformation through ball burnishing. The metallurgical and topological states of materials joined by this welding technique are typically detrimental to the ulterior performance of the workpiece, and it is believed that ball burnishing can improve these states to enhance functioning. This study is divided into two phases. The first one is experimental and consists of welding aluminum AA2024-T3 plates while combining different tool rotations and welding speeds. Then, the welding line is deformed locally by ball burnishing. The improvement of the topology and deep hardness distribution is measured and discussed, and the evolution of mechanical properties is assessed through tensile tests. The second phase is oriented towards estimating the residual stresses by combining two pre-existing models of friction stir welding and burnishing developed by the same authors using ANSYS®. Friction stir welding experimentation and measurements show a decrease in the values of all measured mechanical properties compared to the original material. The dominant factor affecting the properties and texture of the materials is the rotational speed of the tool, with the rupture point in the tensile test located in the distinct zone with the lowest value of microhardness on the advancing side. The higher the ratio of the rotational speed to the welding speed, the lower the roughness value. Finally, ball burnishing is proven to be an effective method to enhance the surface integrity of friction stir welded joints in light of the results, achieving a reduction of 11% to 36% in average roughness and an increase of about 22% in hardness profile, along with an integrated numerical model estimation of a remarkable effect on compressive residual stresses in-depth on the retreating side of the welded samples. However, in some tests, this treatment reduced some characteristics (yield stress and failure strain).

No abstract