Pub Date : 2025-02-19DOI: 10.1016/j.addma.2025.104716
Hongtao Song , Michael J. Fogg , Mehran Tehrani , Carolyn Seepersad
Reactive Extrusion additive manufacturing (REAM) is an additive manufacturing (AM) process in which a liquid thermoset feedstock is deposited and cured in situ. The REAM process has many unique advantages such as the ability to fabricate parts with isotropic mechanical properties, initiate curing without external energy input, and utilize high extrusion rates. However, there are many complex factors such as curing kinetics, feedstock rheology, and thermal gradients that can influence the capabilities of the REAM system and the resulting dimensional accuracy and mechanical properties of the fabricated parts. Understanding the processing parameters of an AM process is crucial to resolving complex features and producing high-quality parts repeatably. While REAM has been documented in the literature, no in-depth studies investigating these processing parameters exist. In this work parameters such as the extrusion rate, deposition speed, and the elapsed time between layers are investigated, and their effect on resulting part properties are characterized. Additionally, the ability to fabricate unsupported overhangs and bridges is also studied as a function of different processing parameters. By understanding these variables and their effects, the system can be tuned to improve accuracy, repeatability, and feature resolution.
{"title":"Investigating the effects of processing parameters in reactive extrusion additive manufacturing","authors":"Hongtao Song , Michael J. Fogg , Mehran Tehrani , Carolyn Seepersad","doi":"10.1016/j.addma.2025.104716","DOIUrl":"10.1016/j.addma.2025.104716","url":null,"abstract":"<div><div>Reactive Extrusion additive manufacturing (REAM) is an additive manufacturing (AM) process in which a liquid thermoset feedstock is deposited and cured <em>in situ</em>. The REAM process has many unique advantages such as the ability to fabricate parts with isotropic mechanical properties, initiate curing without external energy input, and utilize high extrusion rates. However, there are many complex factors such as curing kinetics, feedstock rheology, and thermal gradients that can influence the capabilities of the REAM system and the resulting dimensional accuracy and mechanical properties of the fabricated parts. Understanding the processing parameters of an AM process is crucial to resolving complex features and producing high-quality parts repeatably. While REAM has been documented in the literature, no in-depth studies investigating these processing parameters exist. In this work parameters such as the extrusion rate, deposition speed, and the elapsed time between layers are investigated, and their effect on resulting part properties are characterized. Additionally, the ability to fabricate unsupported overhangs and bridges is also studied as a function of different processing parameters. By understanding these variables and their effects, the system can be tuned to improve accuracy, repeatability, and feature resolution.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"101 ","pages":"Article 104716"},"PeriodicalIF":10.3,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143519967","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}
Control over physical and chemical properties during additive manufacturing is highly advantageous for fabricating functional gradient materials (FGM) with diverse applications. Conventional methods like vat exchange or grayscale light projection are often limited in producing graded properties or compositional gradients and they suffer from slow speed and complicated setups. Here, we present the z-GrAdd (z-Gradient by Addition of a reagent) method, a facile method for Digital Light Processing (DLP)-based vat photopolymerization of FGMs in a single structure through the gradual addition of a resin component to the vat during printing. The z-GrAdd enables continuous alteration of resin composition during the printing, resulting in gradient properties in z-direction. We demonstrate FGM fabrication with gradients of surface energy, porosity, and hardness using a range of acrylate-based resins. Surface energy gradients (18–29 mN/m) and hardness gradients (19.2–29.6 shore D) were achieved by gradual variation of the hydrophilic monomer and crosslinker content, respectively. Porosity was modulated by gradual increase in porogen (non-solvent) which implied polymerization-induced phase separation, resulting in a pore size increase and a corresponding roughness between 52–401 nm (Sq). The versatility of the FGMs with wettability gradients was shown for passive droplet manipulation and liquid imbibition control. To further highlight the versatility of the z-GrAdd for fabricating different gradients, structures with ascending and descending hardness gradients by consecutive addition of two different reagents were produced. In conclusion, z-GrAdd is suitable for various acrylate-based compositions allowing for an easy cost-effective implementation, and fabrication of a wide variety of applications.
{"title":"z-GrAdd – Facile fabrication of various functional gradient materials by 3D printing using the gradual addition of reagents","authors":"Niloofar Nekoonam , Seyed Alireza Sheikholeslami , Silvio Tisato , Pang Zhu , Ramin Montazeri , Zahra Hosneolfat , Dorothea Helmer","doi":"10.1016/j.addma.2025.104713","DOIUrl":"10.1016/j.addma.2025.104713","url":null,"abstract":"<div><div>Control over physical and chemical properties during additive manufacturing is highly advantageous for fabricating functional gradient materials (FGM) with diverse applications. Conventional methods like vat exchange or grayscale light projection are often limited in producing graded properties or compositional gradients and they suffer from slow speed and complicated setups. Here, we present the z-GrAdd (z-Gradient by Addition of a reagent) method, a facile method for Digital Light Processing (DLP)-based vat photopolymerization of FGMs in a single structure through the gradual addition of a resin component to the vat during printing. The z-GrAdd enables continuous alteration of resin composition during the printing, resulting in gradient properties in z-direction. We demonstrate FGM fabrication with gradients of surface energy, porosity, and hardness using a range of acrylate-based resins. Surface energy gradients (18–29 mN/m) and hardness gradients (19.2–29.6 shore D) were achieved by gradual variation of the hydrophilic monomer and crosslinker content, respectively. Porosity was modulated by gradual increase in porogen (non-solvent) which implied polymerization-induced phase separation, resulting in a pore size increase and a corresponding roughness between 52–401 nm (S<sub>q</sub>). The versatility of the FGMs with wettability gradients was shown for passive droplet manipulation and liquid imbibition control. To further highlight the versatility of the z-GrAdd for fabricating different gradients, structures with ascending and descending hardness gradients by consecutive addition of two different reagents were produced. In conclusion, z-GrAdd is suitable for various acrylate-based compositions allowing for an easy cost-effective implementation, and fabrication of a wide variety of applications.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"101 ","pages":"Article 104713"},"PeriodicalIF":10.3,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143480218","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-18DOI: 10.1016/j.addma.2025.104711
Caterina Iantaffi , Chu Lun Alex Leung , George Maddison , Eral Bele , Samy Hocine , Rob Snell , Alexander Rack , Martina Meisnar , Thomas Rohr , Iain Todd , Peter D. Lee
The establishment of on-site autonomous manufacturing capabilities for a sustainable long term lunar base can benefit from additive manufacturing. While previous studies have demonstrated that laser powder bed fusion (LPBF) can manufacture lunar Regolith parts, significant challenges remain in fabricating large structural parts with consistent properties due to the complexities of LPBF process and the variability in the mineralogical composition of Regolith. This study examines process instabilities, melt flow dynamics and defect evolution during LPBF of lunar Mare Regolith simulant LMS-1, using in situ and operando synchrotron X-ray imaging and ex situ characterisation techniques across a range of processing parameters. Five processing regimes for LPBF of LMS-1 were identified: (i) no deposition, (ii) balling, (iii) sintering, (iv) vitrification, and (v) vaporization. The optimal LPBF parameters are 145 W laser power, 390 mm/s scan speed, and 0.25 mm hatch spacing. A laser re-scan strategy is used to further improve sample consolidation and minimise thermal stress accumulation in LMS-1 parts. Essential materials data and in situ X-rays images of melt pool geometry evolution for validating multiphysics numerical models of lunar Regolith laser melting are provided.
{"title":"Laser additive manufacturing of lunar regolith simulant: New insights from in situ synchrotron X-ray imaging","authors":"Caterina Iantaffi , Chu Lun Alex Leung , George Maddison , Eral Bele , Samy Hocine , Rob Snell , Alexander Rack , Martina Meisnar , Thomas Rohr , Iain Todd , Peter D. Lee","doi":"10.1016/j.addma.2025.104711","DOIUrl":"10.1016/j.addma.2025.104711","url":null,"abstract":"<div><div>The establishment of on-site autonomous manufacturing capabilities for a sustainable long term lunar base can benefit from additive manufacturing. While previous studies have demonstrated that laser powder bed fusion (LPBF) can manufacture lunar Regolith parts, significant challenges remain in fabricating large structural parts with consistent properties due to the complexities of LPBF process and the variability in the mineralogical composition of Regolith. This study examines process instabilities, melt flow dynamics and defect evolution during LPBF of lunar Mare Regolith simulant LMS-1, using <em>in situ</em> and <em>operando</em> synchrotron X-ray imaging and <em>ex situ</em> characterisation techniques across a range of processing parameters. Five processing regimes for LPBF of LMS-1 were identified: (i) no deposition, (ii) balling, (iii) sintering, (iv) vitrification, and (v) vaporization. The optimal LPBF parameters are 145 W laser power, 390 mm/s scan speed, and 0.25 mm hatch spacing. A laser re-scan strategy is used to further improve sample consolidation and minimise thermal stress accumulation in LMS-1 parts. Essential materials data and <em>in situ</em> X-rays images of melt pool geometry evolution for validating multiphysics numerical models of lunar Regolith laser melting are provided.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"101 ","pages":"Article 104711"},"PeriodicalIF":10.3,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143488176","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-18DOI: 10.1016/j.addma.2025.104714
Xiaochen Yu , Bohan Peng , Ajit Panesar
Lattice structures with multiple unit cell types diversify the property space by offering more design freedom, encouraging adaptation of metamaterials in engineering applications. It is essential to ensure structural connectivity and smooth transition among different cell types to avoid pre-mature failure. In this work, we propose a framework based on latent space operations to generate smoothly morphing and fully connected transition cells, addressing the current research gap in realising lattice designs of dissimilar unit cells. Latent embedding – a low-dimensional representation of the original microstructure – is obtained through a variational autoencoder. Different types of triply periodic minimal surface (TPMS) lattice were chosen as the targets to demonstrate the capability of the algorithm in handling complex 3D geometries within a physically restricted transition region. Both qualitative and quantitative evaluations are provided to illustrate the connectivity and geometric similarity of the generated transition. Benchmark comparisons against both analytical and existing machine learning (ML) based solutions indicate the superior efficacy and generality of the proposed framework.
{"title":"Smooth 3D transition cell generation based on latent space arithmetic","authors":"Xiaochen Yu , Bohan Peng , Ajit Panesar","doi":"10.1016/j.addma.2025.104714","DOIUrl":"10.1016/j.addma.2025.104714","url":null,"abstract":"<div><div>Lattice structures with multiple unit cell types diversify the property space by offering more design freedom, encouraging adaptation of metamaterials in engineering applications. It is essential to ensure structural connectivity and smooth transition among different cell types to avoid pre-mature failure. In this work, we propose a framework based on latent space operations to generate smoothly morphing and fully connected transition cells, addressing the current research gap in realising lattice designs of dissimilar unit cells. Latent embedding – a low-dimensional representation of the original microstructure – is obtained through a variational autoencoder. Different types of triply periodic minimal surface (TPMS) lattice were chosen as the targets to demonstrate the capability of the algorithm in handling complex 3D geometries within a physically restricted transition region. Both qualitative and quantitative evaluations are provided to illustrate the connectivity and geometric similarity of the generated transition. Benchmark comparisons against both analytical and existing machine learning (ML) based solutions indicate the superior efficacy and generality of the proposed framework.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"101 ","pages":"Article 104714"},"PeriodicalIF":10.3,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143464537","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-18DOI: 10.1016/j.addma.2025.104710
Simão Santos, Manuel F.R.P. Alves, Georgina Miranda , Susana M. Olhero
Hydroxyapatite (HAp) is a biocompatible, osteoconductive, and biodegradable material widely studied for tissue engineering applications. Additive manufacturing, particularly vat photopolymerization technologies, enable the manufacture of custom-made, highly precise solutions. In this work, a colloidal approach was used to develop a water-based photocurable HAp-loaded feedstock with low viscosity, high solid loading (45 vol%), and low amount of organic compounds (10 vol%). Two distinct types of dispersants were evaluated to modify the surface of the HAp powders to enhance stability and dispersion. Rheological experiments were conducted to determine the optimal dispersant concentration, solid-loading, and pre-polymer content. Photorheological experiments were also performed to identify the printing parameters suitable for the vat photopolymerization technology. This work’s approach, characterized by its low organic content, enabled a fast-debinding process (≈13.5 h) when compared to the conventional photocurable ceramic-based feedstock. Different sintering temperatures were tested (1150 °C → 1350 °C) and X-ray diffraction was used to evaluate the crystallographic composition at each temperature. Additionally, the relative density of the sintered parts was calculated and the compressive strength determined. The results demonstrated that sintering temperature enables high customization to meet specific end-user requirements. Architectured structures with interconnected porosity were successfully printed as a proof-of-concept of the potential printability of the developed aqueous-based feedstock. The eco-friendly photopolymerizable feedstock developed in this work should strongly impact the production cycle of resorbable bioceramic-based components.
{"title":"Water-based hydroxyapatite photocurable feedstock for the manufacture of architectured parts by vat photopolymerization","authors":"Simão Santos, Manuel F.R.P. Alves, Georgina Miranda , Susana M. Olhero","doi":"10.1016/j.addma.2025.104710","DOIUrl":"10.1016/j.addma.2025.104710","url":null,"abstract":"<div><div>Hydroxyapatite (HAp) is a biocompatible, osteoconductive, and biodegradable material widely studied for tissue engineering applications. Additive manufacturing, particularly vat photopolymerization technologies, enable the manufacture of custom-made, highly precise solutions. In this work, a colloidal approach was used to develop a water-based photocurable HAp-loaded feedstock with low viscosity, high solid loading (45 vol%), and low amount of organic compounds (10 vol%). Two distinct types of dispersants were evaluated to modify the surface of the HAp powders to enhance stability and dispersion. Rheological experiments were conducted to determine the optimal dispersant concentration, solid-loading, and pre-polymer content. Photorheological experiments were also performed to identify the printing parameters suitable for the vat photopolymerization technology. This work’s approach, characterized by its low organic content, enabled a fast-debinding process (≈13.5 h) when compared to the conventional photocurable ceramic-based feedstock. Different sintering temperatures were tested (1150 °C → 1350 °C) and X-ray diffraction was used to evaluate the crystallographic composition at each temperature. Additionally, the relative density of the sintered parts was calculated and the compressive strength determined. The results demonstrated that sintering temperature enables high customization to meet specific end-user requirements. Architectured structures with interconnected porosity were successfully printed as a proof-of-concept of the potential printability of the developed aqueous-based feedstock. The eco-friendly photopolymerizable feedstock developed in this work should strongly impact the production cycle of resorbable bioceramic-based components.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"101 ","pages":"Article 104710"},"PeriodicalIF":10.3,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143508390","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-17DOI: 10.1016/j.addma.2025.104709
Xing He , Reynier I. Revilla , Decheng Kong , Xiaoqing Ni , Wei Zhang , Kunjie Dai , Chaofang Dong
This study investigates the oxide films formed on the inner walls of lack-of-fusion (LOF) defects in Hastelloy X Ni-based alloy produced by laser powder bed fusion (LPBF) and their influence on corrosion behavior. Using X-ray CT and high-resolution transmission electron microscope, we revealed that these oxide films, located at the pore-matrix interfaces, exhibit an uneven thickness and play a significant structural role relative to the voids. The oxide film consists of a 6.3 nm NiO inner layer and a 1.2 nm amorphous outer layer, with the inner layer maintaining a coherent orientation with the matrix, minimizing interface strain. Electrochemical analyses showed that the existence of oxide films would reduce the diffusion coefficient of point defects and the concentration of dissolved metal cations in the passive film formed on the LOF defects while also boosting the outward diffusion rate of cations therein. This process diminishes the rate of dissolution associated with surface activity for LPBF Hastelloy X Ni-based alloy in corrosive mediums, ultimately promoting the repassivation process and improving the corrosion resistance properties.
{"title":"The nature of oxide films in process-induced lack-of-fusion defects on laser powder bed fusion-fabricated Hastelloy X Ni-based alloy","authors":"Xing He , Reynier I. Revilla , Decheng Kong , Xiaoqing Ni , Wei Zhang , Kunjie Dai , Chaofang Dong","doi":"10.1016/j.addma.2025.104709","DOIUrl":"10.1016/j.addma.2025.104709","url":null,"abstract":"<div><div>This study investigates the oxide films formed on the inner walls of lack-of-fusion (LOF) defects in Hastelloy X Ni-based alloy produced by laser powder bed fusion (LPBF) and their influence on corrosion behavior. Using X-ray CT and high-resolution transmission electron microscope, we revealed that these oxide films, located at the pore-matrix interfaces, exhibit an uneven thickness and play a significant structural role relative to the voids. The oxide film consists of a 6.3 nm NiO inner layer and a 1.2 nm amorphous outer layer, with the inner layer maintaining a coherent orientation with the matrix, minimizing interface strain. Electrochemical analyses showed that the existence of oxide films would reduce the diffusion coefficient of point defects and the concentration of dissolved metal cations in the passive film formed on the LOF defects while also boosting the outward diffusion rate of cations therein. This process diminishes the rate of dissolution associated with surface activity for LPBF Hastelloy X Ni-based alloy in corrosive mediums, ultimately promoting the repassivation process and improving the corrosion resistance properties.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"101 ","pages":"Article 104709"},"PeriodicalIF":10.3,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143428989","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 : 2025-02-17DOI: 10.1016/j.addma.2025.104707
Ismael E. Coello , Jennifer A. Glerum , Clement N. Ekaputra , Jon-Erik Mogonye , David C. Dunand
Microstructure and creep properties are studied in a eutectic AlSi10Mg alloy modified with Zr and Sc additions (Al-9.8Si-0.32Mg-0.70Zr-0.23Sc, wt%) manufactured through laser powder-bed fusion (L-PBF). Three types of Zr/Sc-bearing powders - elemental, master-alloy, and pre-alloyed - are employed in the fabrication process, with the pre-alloyed powders providing the highest incorporation of Zr and Sc in the Al matrix. The as-printed alloy exhibits a fine cellular Al-Si eutectic structure which fragments and coarsens into micron-sized Si particles during aging at 300 ºC, leading to a steady drop in alloy microhardness between 0.1 and 1000 h. Coarsening of the eutectic Si phase during aging is not measurably affected by Zr and Sc in solid solution, which precipitate during aging and increases strength, compensating weakening from Si coarsening between 1 and 200 h at 300 ºC. Atom-probe analysis in the peak-aged condition (96 h/300 °C) confirms the presence of Al3(Sc,Zr) secondary nano-precipitates with an average radius of 1.0 nm and some Si solubility. Micron-sized grains are present throughout the alloy, with ultra-fine-grained regions at the melt pool boundaries, neither of which coarsen during long-term aging at 300 ºC. Under creep conditions at 300 °C, the Zr/Sc-bearing alloy with Al3(Sc,Zr) nano-precipitates exhibits power-law behavior, with a high apparent stress exponent (na = 9) and a high threshold stress (σth = 43 MPa), exhibiting nearly double the strength of a Zr/Sc-free AlSi10Mg control alloy (σth = 22 MPa).
{"title":"Effect of Zr and Sc additions on coarsening- and creep resistance of AlSi10Mg fabricated by laser powder bed fusion","authors":"Ismael E. Coello , Jennifer A. Glerum , Clement N. Ekaputra , Jon-Erik Mogonye , David C. Dunand","doi":"10.1016/j.addma.2025.104707","DOIUrl":"10.1016/j.addma.2025.104707","url":null,"abstract":"<div><div>Microstructure and creep properties are studied in a eutectic AlSi10Mg alloy modified with Zr and Sc additions (Al-9.8Si-0.32Mg-0.70Zr-0.23Sc, wt%) manufactured through laser powder-bed fusion (L-PBF). Three types of Zr/Sc-bearing powders - elemental, master-alloy, and pre-alloyed - are employed in the fabrication process, with the pre-alloyed powders providing the highest incorporation of Zr and Sc in the Al matrix. The as-printed alloy exhibits a fine cellular Al-Si eutectic structure which fragments and coarsens into micron-sized Si particles during aging at 300 ºC, leading to a steady drop in alloy microhardness between 0.1 and 1000 h. Coarsening of the eutectic Si phase during aging is not measurably affected by Zr and Sc in solid solution, which precipitate during aging and increases strength, compensating weakening from Si coarsening between 1 and 200 h at 300 ºC. Atom-probe analysis in the peak-aged condition (96 h/300 °C) confirms the presence of Al<sub>3</sub>(Sc,Zr) secondary nano-precipitates with an average radius of 1.0 nm and some Si solubility. Micron-sized grains are present throughout the alloy, with ultra-fine-grained regions at the melt pool boundaries, neither of which coarsen during long-term aging at 300 ºC. Under creep conditions at 300 °C, the Zr/Sc-bearing alloy with Al<sub>3</sub>(Sc,Zr) nano-precipitates exhibits power-law behavior, with a high apparent stress exponent (<em>n</em><sub><em>a</em></sub> = 9) and a high threshold stress (<em>σ</em><sub><em>th</em></sub> = 43 MPa), exhibiting nearly double the strength of a Zr/Sc-free AlSi10Mg control alloy (<em>σ</em><sub><em>th</em></sub> = 22 MPa).</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"101 ","pages":"Article 104707"},"PeriodicalIF":10.3,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143464535","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 : 2025-02-17DOI: 10.1016/j.addma.2025.104704
Biaoqiang Liu , Bo Qian , Yuxin Liang , Peng Dai , Ruidi Li , Qingsong Wei
In traditional temperature control system of particle 3D printing extrusion device, it exists many issues such as slow response speed, large fluctuation, and poor anti-interference ability. The above issues cause the instability of the extruded PLA filament, affecting the mechanical properties and surface quality of the printed samples. Based on particle swarm optimization algorithm, this paper proposes a precise control method for temperature control system to iteratively optimize the quantization factor and proportion factor, finally it obtains the optimal weight factor. Compared with traditional PID control and fuzzy PID control, response speed has improved by 58.6 % and 40.0 % respectively, overshoot has reduced by 76 % and 35 % respectively, and steady-state time has shortened to 24 s. Comparison of experimental results: The tensile strength of the samples increases by 15.52 % and 7.47 % respectively, the bending strength increases by 17.93 % and 11.58 % respectively, and the internal pores are improved significantly. In summary, the method proposed in this paper can effectively solve the problems of the temperature control system for particle 3D printing, and improve the mechanical properties and surface quality of the samples. The printed prosthetic orthotic plate can well meet the fitness and comfort of the human body.
{"title":"Fast and accurate auto-disturbances-rejection temperature control system based on particle swarm optimized fuzzy control: Applied for particle three-dimensional (3D) printing prosthetic orthotic plate","authors":"Biaoqiang Liu , Bo Qian , Yuxin Liang , Peng Dai , Ruidi Li , Qingsong Wei","doi":"10.1016/j.addma.2025.104704","DOIUrl":"10.1016/j.addma.2025.104704","url":null,"abstract":"<div><div>In traditional temperature control system of particle 3D printing extrusion device, it exists many issues such as slow response speed, large fluctuation, and poor anti-interference ability. The above issues cause the instability of the extruded PLA filament, affecting the mechanical properties and surface quality of the printed samples. Based on particle swarm optimization algorithm, this paper proposes a precise control method for temperature control system to iteratively optimize the quantization factor and proportion factor, finally it obtains the optimal weight factor. Compared with traditional PID control and fuzzy PID control, response speed has improved by 58.6 % and 40.0 % respectively, overshoot has reduced by 76 % and 35 % respectively, and steady-state time has shortened to 24 s. Comparison of experimental results: The tensile strength of the samples increases by 15.52 % and 7.47 % respectively, the bending strength increases by 17.93 % and 11.58 % respectively, and the internal pores are improved significantly. In summary, the method proposed in this paper can effectively solve the problems of the temperature control system for particle 3D printing, and improve the mechanical properties and surface quality of the samples. The printed prosthetic orthotic plate can well meet the fitness and comfort of the human body.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"101 ","pages":"Article 104704"},"PeriodicalIF":10.3,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143428988","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 : 2025-02-17DOI: 10.1016/j.addma.2025.104706
Khai Yang Tan , Wen Siong Poh , Nor Azam Endot , Poi Sim Khiew , Chuan Yi Foo , Hong Ngee Lim
Vat photopolymerization (VPP) 3D printing is well suited for high-throughput production of intricate parts, making it ideal for soft electronics fabrication. This necessitates the development of VPP-printed stretchable-conductive nanocomposites (VPP-SCN), which currently exhibit limited conductivities (<0.1 mS cm−1) due to restricted conductive-filler concentration (CFC) to ensure resin’s printability and nanocomposite’s stretchability. Incorporating high aspect ratio (AR) conductive fillers can achieve superior conductivity at low CFC, but is hindered by ultrasonication-induced filler fractures in conventional dispersion methods. Herein, freeze drying is introduced to process high-AR silver nanowires, resulting in freeze-dried silver nanowires (f-AgNWs) that dispersible in resin via low-speed magnetic stirring, avoiding conventional ultrasonication. Due to their high AR, coplanar alignment of the f-AgNWs is induced during the layer-by-layer VPP process. This results in printed f-AgNW nanocomposites that exhibit anisotropic conductivity, with layer-perpendicular and layer-parallel conductivities of 5 mS cm⁻¹ and 110 mS cm⁻¹ respectively, demonstrating a significant enhancement over the existing VPP-SCN. The high AR of f-AgNWs facilitates the stated conductivity at low CFC of 5 wt%, preserving printability. Low CFC and AgNWs alignment also enable good stretchability (127 %), mechanical durability (32 %, 1000 cycles), and electrical stability (gauge factor = 1.38) of the nanocomposite. The achieved properties enable fully-printed functional applications, as demonstrated by a touch-detecting capacitive sensor, and a stretchable interconnect that maintains LED illumination under strain. This work provides valuable insights into achieving high conductivity without significantly compromising printability and stretchability, thereby enabling the potential utilization of VPP in the development and fabrication of soft electronics.
{"title":"Freeze-dried silver nanowire based resin formulation for vat photopolymerization 3D printing of stretchable and electrically conductive nanocomposites","authors":"Khai Yang Tan , Wen Siong Poh , Nor Azam Endot , Poi Sim Khiew , Chuan Yi Foo , Hong Ngee Lim","doi":"10.1016/j.addma.2025.104706","DOIUrl":"10.1016/j.addma.2025.104706","url":null,"abstract":"<div><div>Vat photopolymerization (VPP) 3D printing is well suited for high-throughput production of intricate parts, making it ideal for soft electronics fabrication. This necessitates the development of VPP-printed stretchable-conductive nanocomposites (VPP-SCN), which currently exhibit limited conductivities (<0.1 mS cm<sup>−1</sup>) due to restricted conductive-filler concentration (CFC) to ensure resin’s printability and nanocomposite’s stretchability. Incorporating high aspect ratio (AR) conductive fillers can achieve superior conductivity at low CFC, but is hindered by ultrasonication-induced filler fractures in conventional dispersion methods. Herein, freeze drying is introduced to process high-AR silver nanowires, resulting in freeze-dried silver nanowires (f-AgNWs) that dispersible in resin via low-speed magnetic stirring, avoiding conventional ultrasonication. Due to their high AR, coplanar alignment of the f-AgNWs is induced during the layer-by-layer VPP process. This results in printed f-AgNW nanocomposites that exhibit anisotropic conductivity, with layer-perpendicular and layer-parallel conductivities of 5 mS cm⁻¹ and 110 mS cm⁻¹ respectively, demonstrating a significant enhancement over the existing VPP-SCN. The high AR of f-AgNWs facilitates the stated conductivity at low CFC of 5 wt%, preserving printability. Low CFC and AgNWs alignment also enable good stretchability (127 %), mechanical durability (32 %, 1000 cycles), and electrical stability (gauge factor = 1.38) of the nanocomposite. The achieved properties enable fully-printed functional applications, as demonstrated by a touch-detecting capacitive sensor, and a stretchable interconnect that maintains LED illumination under strain. This work provides valuable insights into achieving high conductivity without significantly compromising printability and stretchability, thereby enabling the potential utilization of VPP in the development and fabrication of soft electronics.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"101 ","pages":"Article 104706"},"PeriodicalIF":10.3,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143464536","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 : 2025-02-16DOI: 10.1016/j.addma.2025.104701
Berkay Bostan, Shawn Hinnebusch, David Anderson, Albert C. To
Porosity critically impacts the reliability and performance of metal laser powder bed fusion (LPBF) parts, affecting properties like fracture toughness and fatigue life. This work proposes a deep learning (DL) framework to predict local porosity in LPBF Inconel 718 parts using in-situ infrared (IR) camera imaging where parts are produced under standard conditions, resulting in 0.03 % overall porosity. The framework achieves over 90 % balanced accuracy for detecting pores above 34 μm at a 360 μm sensor resolution. First, input features include six physics-based IR signatures (cooling rate, heat intensity, interpass temperature, relative melt pool area, spatter generation, and maximum predeposition temperature) and local scan vector length, all linked to porosity generation mechanisms. Second, the framework considers feature interactions across the current pixel and its 26 nearest neighbors. Third, special convolutional filters are developed to filter heat intensity and cooling rate features at edges and stripe boundaries, compensating for limited camera resolution in those regions. Ground truth data on pore size and locations are gathered through serial sectioning and optical microscopy. In unseen parts with varying geometrical features, the framework achieves a true positive rate above 88 % and a false negative rate below 4 % for pores over 34 μm. The proposed DL framework is rigorously compared to traditional machine learning models, demonstrating its superiority in terms of faster training, higher prediction speed, smaller size, and robust performance on unseen test blocks. Additionally, Shapley Additive Explanations analysis elucidates pore formation mechanisms, revealing complex feature interactions across different regimes. Results align well with known pore formation mechanisms, indicating that the developed algorithm interprets complex relationships between features and porosity. This work enhances in-situ porosity detection in LPBF and advances the understanding of pore formation mechanisms.
{"title":"Accurate detection of local porosity in laser powder bed fusion through deep learning of physics-based in-situ infrared camera signatures","authors":"Berkay Bostan, Shawn Hinnebusch, David Anderson, Albert C. To","doi":"10.1016/j.addma.2025.104701","DOIUrl":"10.1016/j.addma.2025.104701","url":null,"abstract":"<div><div>Porosity critically impacts the reliability and performance of metal laser powder bed fusion (LPBF) parts, affecting properties like fracture toughness and fatigue life. This work proposes a deep learning (DL) framework to predict local porosity in LPBF Inconel 718 parts using in-situ infrared (IR) camera imaging where parts are produced under standard conditions, resulting in 0.03 % overall porosity. The framework achieves over 90 % balanced accuracy for detecting pores above 34 μm at a 360 μm sensor resolution. First, input features include six physics-based IR signatures (cooling rate, heat intensity, interpass temperature, relative melt pool area, spatter generation, and maximum predeposition temperature) and local scan vector length, all linked to porosity generation mechanisms. Second, the framework considers feature interactions across the current pixel and its 26 nearest neighbors. Third, special convolutional filters are developed to filter heat intensity and cooling rate features at edges and stripe boundaries, compensating for limited camera resolution in those regions. Ground truth data on pore size and locations are gathered through serial sectioning and optical microscopy. In unseen parts with varying geometrical features, the framework achieves a true positive rate above 88 % and a false negative rate below 4 % for pores over 34 μm. The proposed DL framework is rigorously compared to traditional machine learning models, demonstrating its superiority in terms of faster training, higher prediction speed, smaller size, and robust performance on unseen test blocks. Additionally, Shapley Additive Explanations analysis elucidates pore formation mechanisms, revealing complex feature interactions across different regimes. Results align well with known pore formation mechanisms, indicating that the developed algorithm interprets complex relationships between features and porosity. This work enhances in-situ porosity detection in LPBF and advances the understanding of pore formation mechanisms.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"101 ","pages":"Article 104701"},"PeriodicalIF":10.3,"publicationDate":"2025-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143444337","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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