@article{FischerPeterMoeini2025, author = {Fischer, Georg and Peter, Grass and Moeini, Ghazal}, title = {Influence of electron beam modulation on deposition characteristics in directed energy deposition-electron beam additive manufacturing (DED-EB) of titanium}, series = {Welding in the World}, volume = {2025}, journal = {Welding in the World}, number = {Volume 69, Issue 12}, edition = {Modified publication 2025}, publisher = {Springer Nature}, issn = {1878-6669}, doi = {10.1007/s40194-025-02271-4}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:1010-opus4-49006}, pages = {15}, year = {2025}, abstract = {Directed energy deposition-electron beam (DED-EB) additive manufacturing is a highly promising process for the fabrication of titanium components, offering high deposition rates and precise process control under vacuum conditions. However, optimizing the deposition characteristics, such as dimensional accuracy, surface quality, and layer uniformity, remains a key challenge, partly due to the complex dynamics of heat input and melt pool behavior. This study examines the influence of electron beam modulation on these deposition characteristics by systematically varying beam deflection parameters, including frequency and pattern, during the wire-based additive manufacturing of titanium. The effects of beam modulation on wire melting, melt pool stability, layer formation, and overall build geometry were thoroughly evaluated. The results demonstrate that carefully controlled electron beam modulation enables significant improvements in deposition stability, surface finish, and control over geometric features, thereby enhancing process reliability and enabling the production of near-net-shape titanium components. Notably, a parameter set consisting of a circular beam deflection at an oscillation frequency of 500Hz and an overfocus setting of + 40 mA effectively minimized surface ripples and waviness, thereby enhancing process stability and yielding defect-free components. These insights contribute to advancing DED-EB as a viable solution for applications where high geometric accuracy and process efficiency are demanded.}, language = {en} } @article{ArdeljanFrunzaverdeCojocaruetal.2025, author = {Ardeljan, Deian Dorel and Frunzaverde, Doina and Cojocaru, Vasile and Turiac, Raul-Rusalin and Bacescu, Nicoleta and Ciubotariu, Costel-Relu and Marginean, Gabriela}, title = {The Impact of Elevated Printing Speeds and Filament Color on the Dimensional Precision and Tensile Properties of FDM-Printed PLA Specimens}, series = {Polymers}, volume = {2025 (Special Issue Mechanical Behaviour of Polymeric-Based Systems Used in Engineering Applications, 2nd Edition)}, journal = {Polymers}, number = {17(15)}, publisher = {MDPI}, doi = {10.3390/polym17152090}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:1010-opus4-48255}, pages = {17}, year = {2025}, abstract = {This study examines the effect of elevated printing speeds (100-600 mm/s) on the dimensional accuracy and tensile strength of PLA components fabricated via fused deposition modeling (FDM). To isolate the influence of printing speed, all other parameters were kept constant, and two filament variants—natural (unpigmented) and black PLA—were analyzed. ISO 527-2 type 1A specimens were produced and tested for dimensional deviations and ultimate tensile strength (UTS). The results indicate that printing speed has a marked impact on both geometric precision and mechanical performance. The optimal speed of 300 mm/s provided the best compromise between dimensional accuracy and tensile strength for both filaments. At speeds below 300 mm/s, under-extrusion caused weak layer bonding and air gaps, while speeds above 300 mm/s led to over-extrusion and structural defects due to thermal stress and rapid cooling. Black PLA yielded better dimensional accuracy at higher speeds, with cross-sectional deviations between 2.76\% and 5.33\%, while natural PLA showed larger deviations of up to 8.63\%. However, natural PLA exhibited superior tensile strength, reaching up to 46.59 MPa, with black PLA showing up to 13.16\% lower UTS values. The findings emphasize the importance of speed tuning and material selection for achieving high-quality, reliable, and efficient FDM prints.}, language = {en} } @article{BurgioMoeini2025, author = {Burgio, Vito and Moeini, Ghazal}, title = {Laser Powder Bed Fusion Additive Manufacturing of a CoCrFeNiCu High-Entropy Alloy: Processability, Microstructural Insights, and (In Situ) Mechanical Behavior}, series = {Materials}, volume = {2025}, journal = {Materials}, number = {18(13), Special Issue Additive Manufacturing and Microstructure Characteristics of Metallic Material}, publisher = {MDPI}, doi = {10.3390/ma18133071}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:1010-opus4-48140}, pages = {1 -- 18}, year = {2025}, abstract = {High-entropy alloys are known for their promising mechanical properties, wear and corrosion resistance, which are maintained across a wide range of temperatures. In this study, a CoCrFeNiCu-based high-entropy alloy, distinguished from conventional CoCrFeNi systems by the addition of Cu, which is known to enhance toughness and wear resistance, was investigated to better understand the effects of compositional modification on processability and performance. The influence of key process parameters, specifically laser power and scan speed, on the processability of CoCrFeNiCu-based high-entropy alloys produced by laser powder bed fusion additive manufacturing was investigated, with a focus of low laser power, which is critical for minimizing defects and improving the resulting microstructure and mechanical performance. The printed sample density gradually increases with higher volumetric energy density, achieving densities exceeding 99.0\%. However, at higher energy densities, the samples exhibit susceptibility to hot cracking, an issue that cannot be mitigated by adjusting the process parameters. Mechanical properties under optimized parameters were further evaluated using Charpy impact and (in situ) tensile tests. These evaluations were supplemented by in situ tensile experiments conducted within a scanning electron microscope to gain insights into the behavior of defects, such as hot cracks, during tensile testing. Despite the sensitivity to hot cracking, the samples exhibited a respectable ultimate tensile strength of 662 MPa, comparable to fine-grained steels like S500MC (070XLK). These findings underscore the potential of CoCrFeNiCu-based high-entropy alloys for advanced applications. However, they also highlight the necessity for developing strategies to ensure stable and reliable processing methods that can mitigate the susceptibility to hot cracking.}, language = {en} } @article{KunkelSauerIsaacsetal.2025, author = {Kunkel, Maria Elizete and Sauer, Alexander and Isaacs, Carlos and Alc{\^a}ntara Ferreira Ganga, Thabata and Fazan, Leonardo Henrique and Keller Rorato, Eduardo}, title = {Teaching Bioinspired Design for Assistive Technologies Using Additive Manufacturing: A Collaborative Experience}, series = {Biomimetics}, volume = {2025}, journal = {Biomimetics}, number = {10(6), Special Issue Bioinspired Designs for Additive Manufacturing in Advanced Engineering Applications}, publisher = {MDPI}, doi = {10.3390/biomimetics10060391}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:1010-opus4-48123}, pages = {1 -- 22}, year = {2025}, abstract = {Abstract Integrating bioinspired design and additive manufacturing into engineering education fosters innovation to meet the growing demand for accessible, personalized assistive technologies. This paper presents the outcomes of an international course, "3D Prosthetics and Orthotics", offered to undergraduate students in the Biomimetic program at Westf{\"a}lische Hochschule (Germany), in collaboration with the 3D Orthotics and Prosthetics Laboratory at the Federal University of S{\~a}o Paulo—UNIFESP (Brazil). The course combined theoretical and hands-on modules covering digital modeling (CAD), simulation (CAE), and fabrication (CAM), enabling students to develop bioinspired assistive devices through a Project-based learning approach. Working in interdisciplinary teams, students addressed real-world rehabilitation challenges by translating biological mechanisms into engineered solutions using additive manufacturing. Resulting prototypes included a hand prosthesis based on the Fin Ray effect, a modular finger prosthesis inspired by tendon-muscle antagonism, and a cervical orthosis designed based on stingray morphology. Each device was digitally modeled, mechanically analyzed, and physically fabricated using open-source and low-cost methods. This initiative illustrates how biomimetic mechanisms and design can be integrated into education to generate functional outcomes and socially impactful health technologies. Grounded in the Mao3D open-source methodology, this experience demonstrates the value of combining nature-inspired principles, digital fabrication, Design Thinking, and international collaboration to advance inclusive, low-cost innovations in assistive technology.}, language = {en} } @article{MoeiniMerghanyVogelsangetal.2023, author = {Moeini, Ghazal and Merghany, Mohamed and Vogelsang, Joerg and Sajadifar, Seyed Vahid and Tenkamp, Jochen and Niendorf, Thomas and Walther, Frank}, title = {Integrity Assessment of Electron-Beam-Welded Joints of Additively Manufactured AlSi10Mg Components}, series = {Advanced Engineering Materials}, volume = {26 (2024)}, journal = {Advanced Engineering Materials}, number = {Issue 2, Artikel Nr. 2301401}, issn = {1438-1656}, doi = {10.1002/adem.202301401}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:1010-opus4-47066}, pages = {12 Seiten}, year = {2023}, abstract = {Abstract Laser-based powder bed fusion of metals (PBF-LB/M) is found to be a promising processing method for the fabrication of components with no limits of complexity by adding layers upon layers of material. However, drawbacks such as pro- ductivity and dimension limitations adversely affect the employment of com- ponents processed by additive manufacturing (AM) in envisaged applications. This brings welding and joining techniques into play to integrate AM metal parts into larger assemblies. In the present study, electron beam welding is used to join the AlSi10Mg specimens, fabricated via two different manufacturing processes, that is, PBF-LB/M and casting. The main focus is to study the quasistatic and fatigue behavior of similar and dissimilar welded joints in different combinations, namely AM-AM, AM-cast, and cast-cast, alongside thorough microstructure analysis, to investigate the correlation between the microscopic and macroscopic properties. Dissimilar welded joints demonstrate inferior material strength. This fact can be attributed to the inherent coarse microstructure of the cast material. Although similar welded joints of AM components suffer from high porosity in the weld zone, they are characterized by a better fatigue life, which can be attributed to the equiaxed eutectic microstructure in the welded area.}, language = {en} } @article{RajanKrochmalWegeneretal.2023, author = {Rajan, Aravindh Nammalvar Raja and Krochmal, Marcel and Wegener, Thomas and Hartmaier, Alexander and Niendorf, Thomas and Moeini, Ghazal}, title = {Micro-macro modeling of tensile behavior of a friction stir welded hybrid joint of AlSi10Mg parts produced by powder bed fusion and casting}, series = {Welding in the World}, volume = {68}, journal = {Welding in the World}, doi = {10.1007/s40194-024-01775-9}, pages = {1693 -- 1705}, year = {2023}, abstract = {Additive manufacturing (AM) has gained considerable interest due to its ability to produce lightweight parts with hierarchical microstructures. However, the current constraints on the build chamber size in powder-bed fusion type AM processes limit its industrial application. A hybrid welded joint, consisting of an AM-processed and a conventionally manufactured part, can be employed to produce larger components. Due to the varying processing conditions, these hybrid welded joints contain a wide range of microstructural heterogeneities, which influences the mechanical properties of the joint. Using a numerical model to predict the mechanical behavior of welded joints by considering the microstructural variations is essential for the safe and reliable implementation of hybrid welded joints. This study aims to predict the local tensile behavior of each region of a hybrid friction-stir welded joint of AlSi10Mg produced by laser-based powder bed fusion and casting using a microstructure-sensitive model as well as the global tensile behavior by considering the properties of each region using a joint macroscopic model. The results from this modeling approach agree well with the experimental results. Therefore, this method can predict the mechanical behavior of hybrid welded joints and can establish the structure-property relationship in each weld region.}, language = {en} } @article{BrandMoeiniMarginean2023, author = {Brand, Marco and Moeini, Ghazal and Marginean, Gabriela}, title = {Corrosion behavior of 316L additively produced by Directed Energy Deposition-Arc}, series = {Materials Today: Proceedings}, volume = {2023}, journal = {Materials Today: Proceedings}, number = {78}, doi = {10.1016/j.matpr.2022.11.194}, pages = {242 -- 250}, year = {2023}, abstract = {Among all additive manufacturing processes, Directed Energy Deposition-Arc (DED-Arc) shows significantly shorter production times and is particularly suitable for large-volume components of simple to medium complexity. To exploit the full potential of this process, the microstructural, mechanical and corrosion behavior have to be studied. High stickout distances lead to a large offset, which leads to an instable electric arc and thus defects such as lack of fusion. Since corrosion preferentially occurs at such defects, the main objective of this work is to investigate the influence of the stickout distance on the corrosion behavior and microstructure of stainless steel manufactured by DED-Arc. Within the heterogenous structure of the manufactured samples lack of fusion defects were detected. The quantity of such defects was reduced by applying a shorter stickout distance. The corrosion behavior of the additively manufactured specimens was investigated by means of potentiodynamic polarization measurements. The semi-logarithmic current density potential curves showed a similar course and thus similar corrosion resistance like that of the conventionally forged sample. The polarization curve of the reference material shows numerous current peaks, both in the anodic and cathodic regions. This metastable behavior is induced by the presence of manganese sulfides. On the sample surface a local attack by pitting corrosion was identified.}, language = {en} } @article{FrunzaverdeCojocaruCiubotariuetal.2022, author = {Frunzaverde, Doina and Cojocaru, Vasile and Ciubotariu, Costel-Relu and Miclosina, Calin-Octavian and Ardeljan, Deian Dorel and Ignat, Emil Florin and Marginean, Gabriela}, title = {The Influence of the Printing Temperature and the Filament Color on the Dimensional Accuracy, Tensile Strength, and Friction Performance of FFF-Printed PLA Specimens}, series = {Polymers MDPI}, volume = {2022}, journal = {Polymers MDPI}, number = {14}, doi = {10.3390/polym14101978}, pages = {1978}, year = {2022}, abstract = {The printing variable least addressed in previous research aiming to reveal the effect of the FFF process parameters on the printed PLA part's quality and properties is the filament color. Moreover, the color of the PLA, as well as its manufacturer, are rarely mentioned when the experimental conditions for the printing of the samples are described, although current existing data reveal that their influence on the final characteristics of the print should not be neglected. In order to point out the importance of this influential parameter, a natural and a black-colored PLA filament, produced by the same manufacturer, were selected. The dimensional accuracy, tensile strength, and friction properties of the samples were analyzed and compared for printing temperatures ranging from 200 � C up to 240 � C. The experimental results clearly showed different characteristics depending on the polymer color of samples printed under the same conditions. Therefore, the optimization of the FFF process parameters for the 3D-printing of PLA should always start with the proper selection of the type of the PLA material, regarding both its color and the fabricant.}, language = {en} }