Pub Date : 2025-12-25DOI: 10.1016/j.addma.2025.105066
Dylan J. Balter , Colin McMillen , Alec Ewe , Jonathan Thomas , Samuel Silverman , Lalitha Parameswaran , Luis Fernando Velásquez-García , Emily Whiting , Steven Patterson , Hilmar Koerner , Keith A. Brown
Flexoelectricity is the electrical response that originates when insulating materials are subjected to a strain gradient. This effect is generally considered to be small but known to depend sensitively on material microstructure. This paper explores the hypothesis that the microstructure produced by additive manufacturing (AM) can strongly influence flexoelectricity. Surprisingly, it is found that minor changes to this microstructure produced using fused filament fabrication, a mainstream approach for additively manufacturing thermoplastics, can lead to enormous changes in the magnitude and polarity of the flexoelectric response of polylactic acid (PLA). To explain these changes, a layer dipole model (LDM) is proposed that connects the in-plane shear in each layer to the electrical polarization that it produces. This model explains three independent mechanisms that were identified and that collectively allow one to drastically increase the flexoelectric effect by 173 fold: (1) choosing printing settings to optimize the geometry of pores between extruded lines, (2) choosing the infill of each layer such that bending-induced strain produces productive in-plane shear stresses, and (3) post-deposition annealing of the printed material to increase its crystallinity. This understanding will enable future sensors in which the structural material is also responsible for electromechanical functionality.
{"title":"Giant flexoelectricity of additively manufactured polylactic acid","authors":"Dylan J. Balter , Colin McMillen , Alec Ewe , Jonathan Thomas , Samuel Silverman , Lalitha Parameswaran , Luis Fernando Velásquez-García , Emily Whiting , Steven Patterson , Hilmar Koerner , Keith A. Brown","doi":"10.1016/j.addma.2025.105066","DOIUrl":"10.1016/j.addma.2025.105066","url":null,"abstract":"<div><div>Flexoelectricity is the electrical response that originates when insulating materials are subjected to a strain gradient. This effect is generally considered to be small but known to depend sensitively on material microstructure. This paper explores the hypothesis that the microstructure produced by additive manufacturing (AM) can strongly influence flexoelectricity. Surprisingly, it is found that minor changes to this microstructure produced using fused filament fabrication, a mainstream approach for additively manufacturing thermoplastics, can lead to enormous changes in the magnitude and polarity of the flexoelectric response of polylactic acid (PLA). To explain these changes, a layer dipole model (LDM) is proposed that connects the in-plane shear in each layer to the electrical polarization that it produces. This model explains three independent mechanisms that were identified and that collectively allow one to drastically increase the flexoelectric effect by 173 fold: (1) choosing printing settings to optimize the geometry of pores between extruded lines, (2) choosing the infill of each layer such that bending-induced strain produces productive in-plane shear stresses, and (3) post-deposition annealing of the printed material to increase its crystallinity. This understanding will enable future sensors in which the structural material is also responsible for electromechanical functionality.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"116 ","pages":"Article 105066"},"PeriodicalIF":11.1,"publicationDate":"2025-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145923300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-25DOI: 10.1016/j.addma.2025.105068
Xiaodan Zhang , Hobyung Chae , Lisong Cao , E-Wen Huang , Jun Hyun Han , Soo Yeol Lee , Huamiao Wang
The deformation behavior and lattice strain evolution of additively manufactured (AM) stainless steel under tension are comprehensively investigated by using in-situ neutron diffraction and the elastic-viscoplastic self-consistent model incorporating phase transformation (EVPSC-PT). Two tensile specimens with distinct building orientations (AM-V and AM-H samples) are fabricated, and tensile tests are performed at both room temperature (300 K) and cryogenic temperature (100 K). The stress-strain response and lattice strains of the AM steels are analyzed based on experimental results and predictions from the EVPSC-PT model. The AM steels exhibit a unique microstructure and macroscopic deformation behavior depending on the building orientation and testing temperature. The lattice strains of the two samples demonstrate an orientation-dependent variation due to the material's elastic anisotropy, with the (200) orientation showing the lowest stiffness in both FCC and BCC phases. Phase transformation (PT) plays a critical role in the mechanical behavior of AM steel, and EVPSC-PT model further reveals that phase transformation accommodates plastic strain and delays stress accumulation in the early stage, while the high hardening capacity of the transformed martensite enhances overall work hardening after transformation completes.
{"title":"In-situ neutron diffraction and crystal plasticity modeling of additively manufactured 15–5PH stainless steel: Effect of temperature and building strategy","authors":"Xiaodan Zhang , Hobyung Chae , Lisong Cao , E-Wen Huang , Jun Hyun Han , Soo Yeol Lee , Huamiao Wang","doi":"10.1016/j.addma.2025.105068","DOIUrl":"10.1016/j.addma.2025.105068","url":null,"abstract":"<div><div>The deformation behavior and lattice strain evolution of additively manufactured (AM) stainless steel under tension are comprehensively investigated by using in-situ neutron diffraction and the elastic-viscoplastic self-consistent model incorporating phase transformation (EVPSC-PT). Two tensile specimens with distinct building orientations (AM-V and AM-H samples) are fabricated, and tensile tests are performed at both room temperature (300 K) and cryogenic temperature (100 K). The stress-strain response and lattice strains of the AM steels are analyzed based on experimental results and predictions from the EVPSC-PT model. The AM steels exhibit a unique microstructure and macroscopic deformation behavior depending on the building orientation and testing temperature. The lattice strains of the two samples demonstrate an orientation-dependent variation due to the material's elastic anisotropy, with the (200) orientation showing the lowest stiffness in both FCC and BCC phases. Phase transformation (PT) plays a critical role in the mechanical behavior of AM steel, and EVPSC-PT model further reveals that phase transformation accommodates plastic strain and delays stress accumulation in the early stage, while the high hardening capacity of the transformed martensite enhances overall work hardening after transformation completes.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"115 ","pages":"Article 105068"},"PeriodicalIF":11.1,"publicationDate":"2025-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145880749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-24DOI: 10.1016/j.addma.2025.105055
Natan Garrivier , Steven Van Petegem , Manuel Pouchon , Markus Strobl , Enrico Tosoratti , Adam Cretton , Ken Vidar Falch , Dario Ferreira Sanchez , Malgorzata Grazyna Makowska
Metal additive manufacturing is a promising route for producing complex, highly customized embedded structures for nuclear fusion environments, such as breeding blankets and divertors. These applications require steels with high thermomechanical stability and resistance to irradiation, yet AM processing often leads to undesired microstructural heterogeneities, including the formation of metastable phases. In this work, we investigate the formation and spatial distribution of retained austenite in Laser Powder Bed Fusion (PBF-LB/M) — processed ferritic–martensitic stainless steel (AISI 415) using multimodal synchrotron-based characterization. Micron-resolution 2D and 3D synchrotron X-ray Diffraction and X-ray Fluorescence mapping, combined with operando XRD during PBF-LB/M, reveal the presence of retained -phase in periodic mesostructures at concentrations up to 0.5 wt%, depending on scanning strategy. We demonstrated that this result, gained from volumetric measurements based on XRD scanning imaging, cannot be gathered by any surface-sensitive technique (e.g. EBSD) due to depth limitations and phase transformation artifacts during sample preparation. No correlation between -phase formation and elemental segregation was observed. Operando XRD measurements show that cooling rates critically affect phase evolution: wall-like geometries exhibit rapid cooling ( to K/s) and complete martensitic transformation, whereas bulk samples cool more slowly ( K/s), allowing up to 0.5 wt.% of -phase to be retained. These results demonstrate the strong influence of both scanning strategy and thermal history on phase stability in PBF-LB/M steels, supporting the qualification of AM-built components for nuclear applications.
{"title":"Multimodal synchrotron characterization of the formation and spatial distribution of retained austenite in PBF-LB/M-manufactured ferritic–martensitic steel","authors":"Natan Garrivier , Steven Van Petegem , Manuel Pouchon , Markus Strobl , Enrico Tosoratti , Adam Cretton , Ken Vidar Falch , Dario Ferreira Sanchez , Malgorzata Grazyna Makowska","doi":"10.1016/j.addma.2025.105055","DOIUrl":"10.1016/j.addma.2025.105055","url":null,"abstract":"<div><div>Metal additive manufacturing is a promising route for producing complex, highly customized embedded structures for nuclear fusion environments, such as breeding blankets and divertors. These applications require steels with high thermomechanical stability and resistance to irradiation, yet AM processing often leads to undesired microstructural heterogeneities, including the formation of metastable phases. In this work, we investigate the formation and spatial distribution of retained austenite in Laser Powder Bed Fusion (PBF-LB/M) — processed ferritic–martensitic stainless steel (AISI 415) using multimodal synchrotron-based characterization. Micron-resolution 2D and 3D synchrotron X-ray Diffraction and X-ray Fluorescence mapping, combined with operando XRD during PBF-LB/M, reveal the presence of retained <span><math><mi>γ</mi></math></span>-phase in periodic mesostructures at concentrations up to 0.5 wt%, depending on scanning strategy. We demonstrated that this result, gained from volumetric measurements based on <span><math><mi>μ</mi></math></span>XRD scanning imaging, cannot be gathered by any surface-sensitive technique (<em>e.g.</em> EBSD) due to depth limitations and phase transformation artifacts during sample preparation. No correlation between <span><math><mi>γ</mi></math></span>-phase formation and elemental segregation was observed. Operando XRD measurements show that cooling rates critically affect phase evolution: wall-like geometries exhibit rapid cooling (<span><math><mrow><mo>∼</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>5</mn></mrow></msup></mrow></math></span> to <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>6</mn></mrow></msup></mrow></math></span> K/s) and complete martensitic transformation, whereas bulk samples cool more slowly (<span><math><mrow><mo>∼</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>4</mn></mrow></msup></mrow></math></span> K/s), allowing up to 0.5 wt.% of <span><math><mi>γ</mi></math></span>-phase to be retained. These results demonstrate the strong influence of both scanning strategy and thermal history on phase stability in PBF-LB/M steels, supporting the qualification of AM-built components for nuclear applications.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"115 ","pages":"Article 105055"},"PeriodicalIF":11.1,"publicationDate":"2025-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837477","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-23DOI: 10.1016/j.addma.2025.105064
Yu Sun , Rongmao Du , Yanlong Fan , Hongtao Zhang , Junlin Pan , Xiaoya Tang , Jingwu Xu , Guo Yu , Xiaoli Wang , Qingxian Hu , Peng He
The growing demand for heterogeneous metal structures in aerospace and new energy vehicle industries has made the reliability of welding or additive manufacturing for such structures a critical industry focus. This paper proposes a hybrid solid-liquid phase additive manufacturing technique. The specific implementation involves first consolidating a niobium interlayer onto a aluminum alloy substrate via ultrasonic solid-phase additive manufacturing, followed by sequentially depositing titanium alloy structures using laser wire-feed additive manufacturing to achieve high-quality, rapid fabrication of Ti/Al dissimilar structures. During this hybrid manufacturing process, the ultrasonic technique induces strong mechanical interlocking through plastic deformation and atomic diffusion, while the subsequent laser deposition optimizes metallurgical bonding and suppresses brittle intermetallic formation via precise thermal control. The resulting dissimilar metal interface exhibits a unique hybrid microstructure combining solid-phase bonding and solidified liquid-phase reaction zones, significantly enhancing tensile and shear strength of the heterogeneous metal structures while effectively reducing residual stresses. Compared to direct additive manufacturing, the maximum tensile strength of the single-track ten-layer additive sample had reached to 127 MPa, an increase of 72 %; then the maximum interfacial shear strength was increased of 244.7 % to be 81 MPa when multi-track and multi-layer additive manufacturing was carried out, strengthened by interlocking chains between adjacent tracks on the interface. This solid-liquid phase hybrid additive manufacturing technology also provides an innovative solution for other cost-effective and high-performance dissimilar metal components.
{"title":"Novel method for achieving high-performance Ti/Al dissimilar structure via hybrid solid-liquid phase additive manufacturing","authors":"Yu Sun , Rongmao Du , Yanlong Fan , Hongtao Zhang , Junlin Pan , Xiaoya Tang , Jingwu Xu , Guo Yu , Xiaoli Wang , Qingxian Hu , Peng He","doi":"10.1016/j.addma.2025.105064","DOIUrl":"10.1016/j.addma.2025.105064","url":null,"abstract":"<div><div>The growing demand for heterogeneous metal structures in aerospace and new energy vehicle industries has made the reliability of welding or additive manufacturing for such structures a critical industry focus. This paper proposes a hybrid solid-liquid phase additive manufacturing technique. The specific implementation involves first consolidating a niobium interlayer onto a aluminum alloy substrate via ultrasonic solid-phase additive manufacturing, followed by sequentially depositing titanium alloy structures using laser wire-feed additive manufacturing to achieve high-quality, rapid fabrication of Ti/Al dissimilar structures. During this hybrid manufacturing process, the ultrasonic technique induces strong mechanical interlocking through plastic deformation and atomic diffusion, while the subsequent laser deposition optimizes metallurgical bonding and suppresses brittle intermetallic formation via precise thermal control. The resulting dissimilar metal interface exhibits a unique hybrid microstructure combining solid-phase bonding and solidified liquid-phase reaction zones, significantly enhancing tensile and shear strength of the heterogeneous metal structures while effectively reducing residual stresses. Compared to direct additive manufacturing, the maximum tensile strength of the single-track ten-layer additive sample had reached to 127 MPa, an increase of 72 %; then the maximum interfacial shear strength was increased of 244.7 % to be 81 MPa when multi-track and multi-layer additive manufacturing was carried out, strengthened by interlocking chains between adjacent tracks on the interface. This solid-liquid phase hybrid additive manufacturing technology also provides an innovative solution for other cost-effective and high-performance dissimilar metal components.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"115 ","pages":"Article 105064"},"PeriodicalIF":11.1,"publicationDate":"2025-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-23DOI: 10.1016/j.addma.2025.105065
North Beifang Deng , Sizhe Wang , Mingyang Li , Xiangyu Wang , Zhenbang Liu , Teck Neng Wong , Bak Koon Teoh , Ming Jen Tan
The reinforcement of 3D printed concrete structures remains a critical bottleneck hindering the widespread application of 3D printing technology in construction. To address this challenge, this study proposes a novel reinforcement strategy combining perforated strips and rebars to form three-dimensional frameworks for structural members. The reinforcement strategy is seamlessly integrated into the layer-by-layer concrete printing process and adaptable for complex geometries. To validate its feasibility and structural performance, large-scale 3D printed beams were fabricated and tested under flexural loading. The proposed strategy markedly enhanced the flexural performance of printed beams, with reinforced printed beams reaching over 100 % of the ultimate capacity and 90 % of the ductility of well-reinforced cast beams. Both experimental observations and finite element analysis confirmed that the failure mode corresponded to typical flexural failure of reinforced concrete beams. Moreover, existing design codes (such as Eurocode 2 and GB/T 50010–2010) were proved to be applicable in guiding the design of 3D printed members using this reinforcement strategy, facilitating practical engineering application of 3D printed concrete structures.
{"title":"A perforated strip-based three-dimensional reinforcement strategy for 3D printed concrete: Flexural testing of beams as a proof of concept","authors":"North Beifang Deng , Sizhe Wang , Mingyang Li , Xiangyu Wang , Zhenbang Liu , Teck Neng Wong , Bak Koon Teoh , Ming Jen Tan","doi":"10.1016/j.addma.2025.105065","DOIUrl":"10.1016/j.addma.2025.105065","url":null,"abstract":"<div><div>The reinforcement of 3D printed concrete structures remains a critical bottleneck hindering the widespread application of 3D printing technology in construction. To address this challenge, this study proposes a novel reinforcement strategy combining perforated strips and rebars to form three-dimensional frameworks for structural members. The reinforcement strategy is seamlessly integrated into the layer-by-layer concrete printing process and adaptable for complex geometries. To validate its feasibility and structural performance, large-scale 3D printed beams were fabricated and tested under flexural loading. The proposed strategy markedly enhanced the flexural performance of printed beams, with reinforced printed beams reaching over 100 % of the ultimate capacity and 90 % of the ductility of well-reinforced cast beams. Both experimental observations and finite element analysis confirmed that the failure mode corresponded to typical flexural failure of reinforced concrete beams. Moreover, existing design codes (such as Eurocode 2 and GB/T 50010–2010) were proved to be applicable in guiding the design of 3D printed members using this reinforcement strategy, facilitating practical engineering application of 3D printed concrete structures.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"115 ","pages":"Article 105065"},"PeriodicalIF":11.1,"publicationDate":"2025-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-23DOI: 10.1016/j.addma.2025.105063
Zhonghao Chen , Haochen Mu , Zhao Zhang , Lei Yuan , Donghong Ding , Hongtao Zhu , Ninshu Ma , Zengxi Pan
Recent advances in machine learning (ML) have enabled efficient modelling of process-structure-property relationships in metallic additive manufacturing (AM), offering promising alternatives to conventional simulation-based methods. However, most ML models rely on input-output regression paradigms, which limit their ability to generalize to unseen geometrical scenarios. This paper proposes a graph neural operator that integrates deep operator network (DeepONet) with graph neural networks (GNNs) to simulate the thermo-mechanical constitutive behaviour in metallic AM. The proposed DeepONet-GNN framework decouples the thermal and structural fields, leveraging sparse temperature measurements to predict full-field z-direction distortion across unseen geometries. Layer-wise evaluations across multiple structures indicate that the model maintains stable predictive accuracy, and robustness to variations in sensor distribution, with an RMSE of 0.0881 mm. Compared to a coupled GNN, DeepONet-GNN reaches convergence with similar accuracy using 50 % fewer training epochs. The proposed DeepONet-GNN model demonstrates the ability to generalize to unseen geometries while leveraging only 5 % of the temperature sensor data, highlighting the potential of graph neural operators as accurate and scalable surrogates for real-time prediction in AM processes.
{"title":"Graph neural operator: A DeepONet-based framework for learning thermo-mechanical distortion in metallic additive manufacturing","authors":"Zhonghao Chen , Haochen Mu , Zhao Zhang , Lei Yuan , Donghong Ding , Hongtao Zhu , Ninshu Ma , Zengxi Pan","doi":"10.1016/j.addma.2025.105063","DOIUrl":"10.1016/j.addma.2025.105063","url":null,"abstract":"<div><div>Recent advances in machine learning (ML) have enabled efficient modelling of process-structure-property relationships in metallic additive manufacturing (AM), offering promising alternatives to conventional simulation-based methods. However, most ML models rely on input-output regression paradigms, which limit their ability to generalize to unseen geometrical scenarios. This paper proposes a graph neural operator that integrates deep operator network (DeepONet) with graph neural networks (GNNs) to simulate the thermo-mechanical constitutive behaviour in metallic AM. The proposed DeepONet-GNN framework decouples the thermal and structural fields, leveraging sparse temperature measurements to predict full-field z-direction distortion across unseen geometries. Layer-wise evaluations across multiple structures indicate that the model maintains stable predictive accuracy, and robustness to variations in sensor distribution, with an RMSE of 0.0881 mm. Compared to a coupled GNN, DeepONet-GNN reaches convergence with similar accuracy using 50 % fewer training epochs. The proposed DeepONet-GNN model demonstrates the ability to generalize to unseen geometries while leveraging only 5 % of the temperature sensor data, highlighting the potential of graph neural operators as accurate and scalable surrogates for real-time prediction in AM processes.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"115 ","pages":"Article 105063"},"PeriodicalIF":11.1,"publicationDate":"2025-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837478","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-20DOI: 10.1016/j.addma.2025.105059
Zeqi Hu , Yongshuo She , Lin Hua , Kang Dong , Mingzhang Chen , Yitong Wang , Xunpeng Qin
The conventional planar layering paradigm of additive manufacturing (AM) has become a critical bottleneck, hindering the fabrication of high-performance components due to its inherent stair-stepping effect, mechanical anisotropy, and heavy reliance on support structures. Non-planar additive manufacturing (NPAM), by leveraging multi-axis motion systems and non-planar path planning, fundamentally overcomes these limitations, offering a transformative approach for the direct fabrication of parts with complex surfaces and optimized mechanical properties. This paper provides a comprehensive and systematic review of the latest research advancements in the NPAM field and innovatively establishes a core technology chain encompassing algorithm-system-process-quality. We delve into four key links: first, the non-planar slicing and path planning algorithms that form the technological core, covering strategies from support-free fabrication and performance enhancement to synergistic design with topology optimization; second, the multi-axis hardware systems that enable path execution, including robotic platforms, hybrid systems, specialized equipment, and their kinematic and dynamic control; third, the process physics and material behavior across polymers, composites, metals, ceramics, and functional inks; and finally, quality control to ensure manufacturing reliability, focusing on melt pool dynamics, geometric accuracy, microstructural evolution, and the crucial aspects of in-situ monitoring and closed-loop control. Furthermore, this paper systematically showcases the transformative applications of NPAM in aerospace, biomedical engineering, and conformal electronics. By elucidating the intrinsic connections between these technological links, this review aims to provide researchers with a structured knowledge framework, and prospect the future of intelligent design and manufacturing driven by artificial intelligence and digital twins.
{"title":"Non-planar additive manufacturing: A comprehensive review of path planning, system integration, process control, and applications","authors":"Zeqi Hu , Yongshuo She , Lin Hua , Kang Dong , Mingzhang Chen , Yitong Wang , Xunpeng Qin","doi":"10.1016/j.addma.2025.105059","DOIUrl":"10.1016/j.addma.2025.105059","url":null,"abstract":"<div><div>The conventional planar layering paradigm of additive manufacturing (AM) has become a critical bottleneck, hindering the fabrication of high-performance components due to its inherent stair-stepping effect, mechanical anisotropy, and heavy reliance on support structures. Non-planar additive manufacturing (NPAM), by leveraging multi-axis motion systems and non-planar path planning, fundamentally overcomes these limitations, offering a transformative approach for the direct fabrication of parts with complex surfaces and optimized mechanical properties. This paper provides a comprehensive and systematic review of the latest research advancements in the NPAM field and innovatively establishes a core technology chain encompassing algorithm-system-process-quality. We delve into four key links: first, the non-planar slicing and path planning algorithms that form the technological core, covering strategies from support-free fabrication and performance enhancement to synergistic design with topology optimization; second, the multi-axis hardware systems that enable path execution, including robotic platforms, hybrid systems, specialized equipment, and their kinematic and dynamic control; third, the process physics and material behavior across polymers, composites, metals, ceramics, and functional inks; and finally, quality control to ensure manufacturing reliability, focusing on melt pool dynamics, geometric accuracy, microstructural evolution, and the crucial aspects of in-situ monitoring and closed-loop control. Furthermore, this paper systematically showcases the transformative applications of NPAM in aerospace, biomedical engineering, and conformal electronics. By elucidating the intrinsic connections between these technological links, this review aims to provide researchers with a structured knowledge framework, and prospect the future of intelligent design and manufacturing driven by artificial intelligence and digital twins.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"115 ","pages":"Article 105059"},"PeriodicalIF":11.1,"publicationDate":"2025-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Laser powder bed fusion (L-PBF) of semi-crystalline polymers such as polyamide-12 (PA12) has found increasing use in various industrial applications. However, achieving high dimensional accuracy remains a significant challenge. Despite the seemingly straightforward layer-by-layer manufacturing concept, the L-PBF process involves complex thermal histories and strongly coupled multiphysics, making the evolution of stress and deformation mechanisms still not fully understood. To address this, a comprehensive three-dimensional thermo-mechanical modeling framework is developed to simulate the L-PBF process of PA12. The model for the first time incorporates transient heat transfer, phase transformation induced volumetric shrinkage, thermo-viscoelasticity, and a modified non-isothermal crystallization kinetics. To alleviate the computational burden of part-scale simulations, a dual-mesh strategy is employed to efficiently couple thermal and mechanical fields without compromising numerical accuracy, which also enables the framework to handle L-PBF simulations of arbitrarily complex three-dimensional geometries. Particular attention is paid to the role of mechanical and thermal boundary conditions. Specifically, the underlying powder bed is modeled as a fictitious viscous medium, providing support while permitting upward displacement. Additionally, a radiative heat loss boundary condition, which more closely approximates the actual physical process, is applied to the top powder surface. The incorporation of this radiation effect significantly enhances the crystallization rate and improves the agreement with experimentally measured warpage. The model is validated against experimental warpage data under various preheating temperatures. Furthermore, strain decoupling analysis for the first time reveals that displacement induced by phase transformation is approximately 10 times greater than that caused by thermal expansion, highlighting the dominant role of crystallization-induced shrinkage in warpage formation. Numerical tests also indicate that warpage is highly sensitive to the preheating target temperature of the PA12 powder bed, while the temperature of the newly recoated powder within the tested range has a limited effect. This work provides a predictive modeling foundation for future optimization of polymer L-PBF processes at part-scale, particularly in controlling deformation and improving dimensional accuracy.
{"title":"Deformation and stress evolution during laser powder bed fusion of semi-crystalline polyamide-12","authors":"Zhongfeng Xu , Wei Zhu , Lionel Freire , Noëlle Billon , Jean-Luc Bouvard , Yancheng Zhang","doi":"10.1016/j.addma.2025.105061","DOIUrl":"10.1016/j.addma.2025.105061","url":null,"abstract":"<div><div>Laser powder bed fusion (<span>L</span>-PBF) of semi-crystalline polymers such as polyamide-12 (PA12) has found increasing use in various industrial applications. However, achieving high dimensional accuracy remains a significant challenge. Despite the seemingly straightforward layer-by-layer manufacturing concept, the <span>L</span>-PBF process involves complex thermal histories and strongly coupled multiphysics, making the evolution of stress and deformation mechanisms still not fully understood. To address this, a comprehensive three-dimensional thermo-mechanical modeling framework is developed to simulate the <span>L</span>-PBF process of PA12. The model for the first time incorporates transient heat transfer, phase transformation induced volumetric shrinkage, thermo-viscoelasticity, and a modified non-isothermal crystallization kinetics. To alleviate the computational burden of part-scale simulations, a dual-mesh strategy is employed to efficiently couple thermal and mechanical fields without compromising numerical accuracy, which also enables the framework to handle <span>L</span>-PBF simulations of arbitrarily complex three-dimensional geometries. Particular attention is paid to the role of mechanical and thermal boundary conditions. Specifically, the underlying powder bed is modeled as a fictitious viscous medium, providing support while permitting upward displacement. Additionally, a radiative heat loss boundary condition, which more closely approximates the actual physical process, is applied to the top powder surface. The incorporation of this radiation effect significantly enhances the crystallization rate and improves the agreement with experimentally measured warpage. The model is validated against experimental warpage data under various preheating temperatures. Furthermore, strain decoupling analysis for the first time reveals that displacement induced by phase transformation is approximately 10 times greater than that caused by thermal expansion, highlighting the dominant role of crystallization-induced shrinkage in warpage formation. Numerical tests also indicate that warpage is highly sensitive to the preheating target temperature of the PA12 powder bed, while the temperature of the newly recoated powder within the tested range has a limited effect. This work provides a predictive modeling foundation for future optimization of polymer <span>L</span>-PBF processes at part-scale, particularly in controlling deformation and improving dimensional accuracy.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"115 ","pages":"Article 105061"},"PeriodicalIF":11.1,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-17DOI: 10.1016/j.addma.2025.105053
Chenghao Zhang , Zhanfei Zhang , Bo Zheng , Qixian Zhong , Fenghao Zhou , Huimin Xie , Zhanwei Liu
During laser-directed energy deposition (L-DED), the three-dimensional morphology and surface flow behavior of the melt pool is considered as critical physical fields which fundamentally determine the quality of fabricated components. Nevertheless, conventional in-situ monitoring systems have limitations in achieving synchronized observation of both morphological and flow characteristics. In this study, we develop an in-situ optical measurement system based on four-mirror module, enabling binocular vision imaging of the melt pool using a single high-speed camera. By incorporating deep learning-assisted feature extraction and matching algorithms, three-dimensional reconstruction of the melt pool morphology is accomplished. Simultaneously, digital image correlation techniques are employed to quantify surface flow fields. The dynamics evolution of melt pool morphology and surface flow are characterized under different process parameter combinations. On this basis, surrogate models correlating process parameters with melt pool characteristics are established. Sobol sensitivity analysis further reveals the influence of process parameters on the characteristics of melt pool. The obtained results demonstrate that the melt pool height is predominantly regulated by scanning speed and powder feed rate, whereas the melt pool width exhibits stronger dependence on laser power and scanning speed. The melt pool surface flow exhibits unsteady state, with turbulent kinetic energy concentrating predominantly in the central region. Marangoni convection is identified as the dominant mechanism governing melt transport along the scanning direction. This work provides a robust experimental framework for investigating multi-physics coupling phenomena in L-DED melt pools, offering technical support for process optimization and closed-loop control strategies of L-DED process.
{"title":"Probing melt pool dynamics in laser-directed energy deposition via optical metrology: Simultaneous mapping of 3D morphology and surface flow","authors":"Chenghao Zhang , Zhanfei Zhang , Bo Zheng , Qixian Zhong , Fenghao Zhou , Huimin Xie , Zhanwei Liu","doi":"10.1016/j.addma.2025.105053","DOIUrl":"10.1016/j.addma.2025.105053","url":null,"abstract":"<div><div>During laser-directed energy deposition (<span>L</span>-DED), the three-dimensional morphology and surface flow behavior of the melt pool is considered as critical physical fields which fundamentally determine the quality of fabricated components. Nevertheless, conventional in-situ monitoring systems have limitations in achieving synchronized observation of both morphological and flow characteristics. In this study, we develop an in-situ optical measurement system based on four-mirror module, enabling binocular vision imaging of the melt pool using a single high-speed camera. By incorporating deep learning-assisted feature extraction and matching algorithms, three-dimensional reconstruction of the melt pool morphology is accomplished. Simultaneously, digital image correlation techniques are employed to quantify surface flow fields. The dynamics evolution of melt pool morphology and surface flow are characterized under different process parameter combinations. On this basis, surrogate models correlating process parameters with melt pool characteristics are established. Sobol sensitivity analysis further reveals the influence of process parameters on the characteristics of melt pool. The obtained results demonstrate that the melt pool height is predominantly regulated by scanning speed and powder feed rate, whereas the melt pool width exhibits stronger dependence on laser power and scanning speed. The melt pool surface flow exhibits unsteady state, with turbulent kinetic energy concentrating predominantly in the central region. Marangoni convection is identified as the dominant mechanism governing melt transport along the scanning direction. This work provides a robust experimental framework for investigating multi-physics coupling phenomena in <span>L</span>-DED melt pools, offering technical support for process optimization and closed-loop control strategies of <span>L</span>-DED process.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"115 ","pages":"Article 105053"},"PeriodicalIF":11.1,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837745","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-16DOI: 10.1016/j.addma.2025.105058
Haoze Wang , Yuheng Tian , Yuxin Li , Leiyi Qi , Peng Chen , Chunze Yan , Yusheng Shi
Incorporating glass fibers (GF) into LPBF-printed PEEK enhances its mechanical and high-temperature load-bearing capacity while preserving the polymer’s electromagnetic transparency, enabling use in demanding environments that require heat resistance, heavy loads and excellent electrical insulation. This study investigates the effects of fiber length and content on the processability and mechanical properties of GF-reinforced PEEK composites. The results demonstrate that increasing GF content expanded the sintering window by up to 18 % and raised thermal degradation temperatures, thereby improving LPBF processability. The tensile modulus peaked at 4.80 GPa (31 % increase at 20 wt% for 250-mesh fibers), while longer fibers (125-mesh) exhibited better flexural modulus (5.21 GPa, 43 % increase at 20 wt% for 125-mesh fibers), as longer fibers help prevent crack propagation and reduce defect impact in bending. The storage modulus increased with both fiber content and length, reaching up to 182 % higher at 50 °C for 125-mesh fibers at 20 wt%. The dielectric constants of the PEEK/GF composites ranged from 2.48 to 3.53, with low dielectric losses, indicating excellent stability across 1–40 GHz, confirming suitability for lightweight insulation and radome applications.
{"title":"Enhancing processability and performance of laser powder bed fusion-fabricated poly-ether-ether-ketone composites: Influence of glass fiber length and content","authors":"Haoze Wang , Yuheng Tian , Yuxin Li , Leiyi Qi , Peng Chen , Chunze Yan , Yusheng Shi","doi":"10.1016/j.addma.2025.105058","DOIUrl":"10.1016/j.addma.2025.105058","url":null,"abstract":"<div><div>Incorporating glass fibers (GF) into LPBF-printed PEEK enhances its mechanical and high-temperature load-bearing capacity while preserving the polymer’s electromagnetic transparency, enabling use in demanding environments that require heat resistance, heavy loads and excellent electrical insulation. This study investigates the effects of fiber length and content on the processability and mechanical properties of GF-reinforced PEEK composites. The results demonstrate that increasing GF content expanded the sintering window by up to 18 % and raised thermal degradation temperatures, thereby improving LPBF processability. The tensile modulus peaked at 4.80 GPa (31 % increase at 20 wt% for 250-mesh fibers), while longer fibers (125-mesh) exhibited better flexural modulus (5.21 GPa, 43 % increase at 20 wt% for 125-mesh fibers), as longer fibers help prevent crack propagation and reduce defect impact in bending. The storage modulus increased with both fiber content and length, reaching up to 182 % higher at 50 °C for 125-mesh fibers at 20 wt%. The dielectric constants of the PEEK/GF composites ranged from 2.48 to 3.53, with low dielectric losses, indicating excellent stability across 1–40 GHz, confirming suitability for lightweight insulation and radome applications.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"115 ","pages":"Article 105058"},"PeriodicalIF":11.1,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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