Progress in Additive Manufacturing

Tang, Qingchun; Zu, Hangyu; Zhang, Wanshun; Huang, Yukun; Chen, Fengjun; Wang, Yutao

doi: 10.1007/s40964-026-01799-1pmid: N/A

To investigate profile variation during laser cladding on curved substrates, this study established a thermo-mechanically coupled finite-element model for process-parameter analysis. First, 316L stainless steel was selected as the specimen material, and a clad component deposited along a spatial spiral laser-cladding trajectory on an annular curved substrate was taken as the research object. A thermo-mechanically coupled model was established by combining the element birth-and-death technique with a moving Gaussian heat source. Subsequently, the temperature field, thermal stress, and deformation under different combinations of laser process parameters were numerically analyzed, and the parameter combination with relatively low deformation was identified within the investigated parameter range. Finally, experiments were conducted using a four-axis laser cladding system. The post-cladding profiles were measured using an ultra-depth-of-field 3D digital microscope and compared with the simulated profiles. The experimental and simulated profiles showed similar variation trends. Both the experimental and simulated results showed that the maximum profile deviation increased with increasing laser power and decreased with increasing scanning speed. The maximum relative error between the experimental and simulated maximum profile deviation values was approximately 6.98%. These results indicate that the established thermo-mechanically coupled model can reasonably predict the profile variation trend during laser cladding on a curved substrate under a spatial spiral scanning path. This study can provide a reference for process parameter selection and shape control in laser cladding of curved components.

Raj, Tapish; Jain, Akash; Sahai, Ankit; Sharma, Rahul Swarup

doi: 10.1007/s40964-026-01783-9pmid: N/A

This study aims to develop an integrated experimental and machine learning framework for accurately predicting the tensile behaviour of high-content multi-walled carbon nanotubes (MWCNTs)-reinforced polylactic acid (PLA) composites fabricated using fused filament fabrication (FFF). The composite filaments were extruded using a single-screw process and 3D-printed under varied raster orientation, infill density, and layer height. Mechanical characterization through ASTM-standard tensile testing revealed a maximum tensile strength of 54.269 MPa, highlighting the critical influence of process parameters on interlayer bonding. X-ray diffraction analysis confirmed a crystallinity index increase from 36% (neat PLA) to 47.41% for PLA–MWCNTs composites, while SEM imaging demonstrated uniform MWCNTs dispersion without agglomeration. To predict tensile strength and reduce experimental iteration, five machine learning models—Linear Regression, Random Forest, AdaBoost, Ridge Regression, and K-Nearest Neighbors—were trained and evaluated. Among them, LR and RR achieved the highest accuracy with R2 = 0.99, outperforming ensemble and instance-based models. The proposed framework can be applied to optimize process parameters, reduce experimental effort, and support the design of high-performance polymer nanocomposites for applications in aerospace, automotive, and biomedical engineering.

Merkel, Markus; Hitzler, Leonhard

doi: 10.1007/s40964-026-01806-5pmid: N/A

Sarangi, Sweta Sarita; Priyadarsini, M. Jasmine Pemeena

doi: 10.1007/s40964-026-01629-4pmid: N/A

This work introduces a novel 3D-printed monolithic RF sensor based on a metamaterial absorber architecture, tailored for the precise characterization of liquid materials in the S-band frequency range. Additive manufacturing, commonly referred to as 3D printing, is used instead of subtractive manufacturing. By embedding a cavity within the dielectric substrate, the design ensures enhanced electromagnetic interaction between the sample and the sensing surface, enabling improved sensitivity and selectivity. The fully integrated structure, realized through a single-step additive manufacturing, eliminates traditional multi-layer assembly challenges and enables rapid, low-cost prototyping. To optimize absorption and sensing performance, the absorber’s resonance properties were fine-tuned using an equivalent circuit model and a thorough parametric analysis. The sensor works by identifying changes in the relative permittivity of test materials that result in shifts in the resonance frequency and reflection coefficient (\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$${\text{s}}_{11}$$\end{document}). The simulation results show that when the relative permittivity of the cavity is changed, distinct shifts in resonance frequency occur. Sensitivity to changes in dielectrics was verified using actual liquids (n-hexane, acetone, and acetonitrile) as well as their corresponding ideal dielectrics models in simulations, and the results indicate high sensitivity to dielectric properties.

Shi, Haoming; Yang, Haoqin; Shan, Zhongde; Yan, Dandan; Huang, Jian; Hu, Tianxiong; Wang, Jun; Yin, Yajun

doi: 10.1007/s40964-026-01787-5pmid: N/A

Reliable powder bed formation is fundamental to binder jet additive manufacturing, yet the particle-scale mechanisms governing complex spreading processes remain insufficiently understood, particularly for coarse and irregular particles. This study investigates sand-based binder jet manufacturing by combining powder spreading experiments with discrete element method simulations to systematically examine the effects of layer thickness, spreading speed, and roller rotation on particle behavior and powder bed quality. Results indicate that, during the transition from powder pile to powder layer, particle velocity and force states in the transitional region jointly control packing density and surface quality. Furthermore, particles in the pre-laid layer are reactivated under roller action and participate in the formation of new layers, with their buffering and constraining effects significantly influencing particle rearrangement and densification patterns. Distinct responses are observed for different sand types due to variations in particle size and roundness, revealing the coupled mechanisms between particle characteristics, process parameters, and powder bed quality. These findings provide insights for optimizing processes in sand-based and other coarse-particle powder bed additive manufacturing.

Banday, Zaheen; Fukanuma, T.; Otsuka, Yuichi; Kamaraj, M.; Amirthalingam, Murugaiyan

doi: 10.1007/s40964-026-01742-4pmid: N/A

Cold spray additive manufacturing (CSAM) enables fabrication of dense copper components without melting, but severe plastic deformation during particle impact introduces lattice defects that limit electrical conductivity to approximately 85% IACS. This study investigates the microstructural instability that arises during post-deposition annealing of high-purity electrolytic tough pitch (ETP) copper, specifically the formation of vacancy-induced voids at splat interfaces. Annealing at 350–950 °C for 1.5 h was combined with hot isostatic pressing (HIP) at 550 °C and 52.7 MPa. In un-HIPed samples, dislocation recovery releases excess vacancies that condense at high-energy splat interfaces, producing interfacial porosity that peaks at 1.45% at 750 °C and degrades conductivity below 80% IACS. The splat interiors remain void-free and fully softened (nanoindentation hardness \documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$${\sim }0.77$$\end{document} GPa), confirming that the conductivity loss originates from interfacial voiding rather than matrix contamination. HIP suppresses void formation by raising the nucleation barrier under isostatic pressure and converting splat interfaces into vacancy sinks through consolidation, maintaining porosity below 0.4%. Sequential annealing and HIP restore conductivity to approximately 100% IACS. These findings demonstrate that vacancy management, not simply defect removal, governs electrical performance recovery in cold-sprayed pure copper.Graphic abstract[graphic not available: see fulltext]

Naidu, Rahul; Jain, Neelesh Kumar; Rajak, Ashish

doi: 10.1007/s40964-026-01769-7pmid: N/A

This paper presents development and validation of ultrasonic solid-state additive manufacturing (USSAM) system for continuous bonding of multi-material laminates (MML) of foils and/or sheets of thermally challenging materials (having high thermal conductivity and/or diffusivity). The developed system integrates a novel horizontally rotating ultrasonic tool with the 3-axis computer numerically controlled worktable for continuous feeding of metallic foils or sheets under electro-pneumatically controlled compressive force to enable their good quality solid-state bonding without melting. The ultrasonic tool comprises of a piezoelectric transducer, booster, and sonotrode. Finite element simulations were used to ensure structural integrity of critical components under the applied loads thus confirming their safe operations. Functionality and performance of the developed system was validated by performing 27 full-factorial experiments by varying ultrasonic vibration amplitude, compressive force, and feed rate at 3 levels each and fabricating 27 MML of Al–Cu of 400 μm thickness. Analysis of variance and grey relational analysis identified optimum parametric combination of ultrasonic vibration amplitude, compressive force, and feed rate as 28 μm, 5000 N, and 0.38 m/s respectively. The corresponding MML yielded 60.82 N as maximum peel-off strength and 80.5% bonding efficiency. Its microstructural analysis revealed continuous and uniform interfacial bonding with minimal defects indicating high-quality metallurgical bonding. It is found that compressive force is the most influential parameter contributing 50% to the bonding strength. Developed USSAM system has potential to provide viable solutions to the thermally sensitive systems that require reliable and improved solid-state bonding such as embedded electronics, electromagnetic shielding, electric vehicles, solar panel, avionics.

Feng, Zhijian; Qiu, Yating; Zhu, Hankun; Han, Wei; Becker, Thorsten; Kong, Lingbao

doi: 10.1007/s40964-026-01777-7pmid: N/A

Laser powder bed fusion (LPBF) of SiO₂/AlSi10Mg composite powders offers a promising route for fabricating glass-metal hybrid structures with enhanced functionality. However, the large differences in thermal properties between ceramic and metallic phases present significant challenges in controlling melt pool behavior and interfacial bonding. In this study, a three-dimensional multiphysics numerical model based on the Volume-of-Fluid (VOF) method was developed to investigate the thermal-fluid dynamics during LPBF of SiO₂/AlSi10Mg composites. The model incorporates laser-material interaction, transient heat conduction, phase change, surface tension effects, and material-specific absorption characteristics. Simulation results reveal that AlSi10Mg melts earlier and preferentially migrates toward the melt pool boundaries due to its lower melting point and higher thermal conductivity, leading to compositional segregation. The effects of laser power, hatch distance, and powder distribution strategies were systematically analyzed. It was found that insufficient hatch overlap causes inter-track pores, while layered powder configurations with AlSi10Mg on top promote better melt continuity and interfacial bonding. Experimental results corroborate the simulation predictions, confirming melt pool shape evolution, metal-rich boundary formation, and melt spreading beyond the laser path. This work provides mechanistic insights into process-structure relationships in LPBF of dissimilar material systems and offers design guidelines for achieving dense, defect-free composite components.

Marchini, Luca; Abrami, Maria Beatrice; Gelfi, Marcello; Pola, Annalisa

doi: 10.1007/s40964-026-01764-ypmid: N/A

Lead-free biphasic brasses are attractive for fluid-handling components due to their environmental and regulatory advantages. However, the absence of lead reduces machinability, prompting the need for alternative strategies to optimize component design and performance. In this context, additive manufacturing offers new opportunities for geometrical customization and material efficiency. The present study evaluates the corrosion and cavitation-erosion performance of CuZn42 (CW510L) produced by laser powder bed fusion (LPBF), in comparison with conventionally extruded material. Microstructural characterization reveals a layered, anisotropic architecture with residual porosity and evidence of Zn depletion relative to the wrought bar, features that concentrate stress and influence the stability and distribution of the α and β phases. Under vibratory cavitation, both materials exhibit a similar delay before damage accelerates, yet the additively manufactured alloy transitions more readily to significant material removal, with damage paths guided by interlayer interfaces and pores. In chloride solution, corrosion appears highly localized. The build-direction section is the most electrochemically active condition, whereas the scan-plane section approaches the behavior of the wrought bar. Prolonged exposure promotes pit-centered dezincification and the development of zinc-rich corrosion products at pit peripheries, with a deeper affected layer in the additively processed material. Overall, the performance gap is governed primarily by process-induced heterogeneity rather than an intrinsic shortcoming of the alloy. The results offer guidance for the deployment of LPBF CuZn42 in components exposed to cavitation erosion or corrosion in salt water.

Han, Jisu; Ji, Seonghun; Nam, Kiwook; Kang, Dongseok; Yoon, Jongcheon; Yeon, Simo; Eo, Durim; Shin, Jaeho; Lee, Hyub

doi: 10.1007/s40964-026-01793-7pmid: N/A

Laser-wire Directed Energy Deposition (LW-DED) is a promising additive manufacturing process for fabricating large-scale metal structures with high material efficiency. However, the process inherently involves repeated energy input into localized volumes, which leads to thermal accumulation over successive layers. This thermal buildup is difficult to assess through conventional coaxial melt pool monitoring, which captures only top-view surface features and lacks access to subsurface thermal behavior. As a result, critical thermal variations—such as changes in melt pool size or bead geometry—can go undetected, increasing the risk of distortion or build failure. In this study, we experimentally validate that feedforward control based on thermal finite element method (FEM) can effectively suppress such cumulative heat effects in LW-DED, particularly for geometries with varying cross-sections. Using melt pool depth—a metric highly sensitive to thermal accumulation—as the control target, layer specific laser power profiles were computed via a FEM-embedded PD-type feedforward optimizer (with the integral gain tuned to zero) in the simulation stage and pre-applied to the toolpath. This approach successfully stabilized deposition across three Ti-6Al-4 V geometries (cylinder, upward-narrowing cone, and upward-widening cone), reducing bead width deviation from 1.9 mm to 0.3 mm and achieving full 30 layer builds. Moreover, we show that while coaxial monitoring failed to capture subsurface thermal changes that led to process failure, the FEM-guided feedforward strategy successfully mitigated these issues, demonstrating its practical advantage in thermal management for wire-based metal AM.