Pub Date : 2024-06-11DOI: 10.1108/rpj-12-2023-0446
Shakeel Dilawar, Ahsan Khan, Asif Ur Rehman, Syed Zahid Husain, S. Jaffery
Purpose The purpose of this study was to use bridge curvature method (BCM) to quantify stress, while multiscale modeling with adaptive coarsening predicted distortions based on experimentally validated models. Taguchi method and response surface method were used to optimize process parameters (energy density, hatch spacing, scanning speed and beam diameter). Design/methodology/approach Laser powder bed fusion (LPBF) offers significant design freedom but suffers from residual stresses due to rapid melting and solidification. This study presents a novel approach combining multiscale modeling and statistical optimization to minimize residual stress in SS316L. Findings Optimal parameters were identified through simulations and validated with experiments, achieving an 8% deviation. This approach significantly reduced printing costs compared to traditional trial-and-error methods. The analysis revealed a non-monotonic relationship between residual stress and energy density, with an initial increase followed by a decrease with increasing hatch spacing and scanning speed (both contributing to lower energy density). Additionally, beam diameter had a minimal impact compared to other energy density parameters. Originality/value This work offers a unique framework for optimizing LPBF processes by combining multiscale modeling with statistical techniques. The identified optimal parameters and insights into the individual and combined effects of energy density parameters provide valuable guidance for mitigating residual stress in SS316L, leading to improved part quality and performance.
{"title":"Breaking the tradeoff: multiscale optimization for lower cost, lower residual stress LPBF of SS316L","authors":"Shakeel Dilawar, Ahsan Khan, Asif Ur Rehman, Syed Zahid Husain, S. Jaffery","doi":"10.1108/rpj-12-2023-0446","DOIUrl":"https://doi.org/10.1108/rpj-12-2023-0446","url":null,"abstract":"Purpose\u0000The purpose of this study was to use bridge curvature method (BCM) to quantify stress, while multiscale modeling with adaptive coarsening predicted distortions based on experimentally validated models. Taguchi method and response surface method were used to optimize process parameters (energy density, hatch spacing, scanning speed and beam diameter).\u0000\u0000Design/methodology/approach\u0000Laser powder bed fusion (LPBF) offers significant design freedom but suffers from residual stresses due to rapid melting and solidification. This study presents a novel approach combining multiscale modeling and statistical optimization to minimize residual stress in SS316L.\u0000\u0000Findings\u0000Optimal parameters were identified through simulations and validated with experiments, achieving an 8% deviation. This approach significantly reduced printing costs compared to traditional trial-and-error methods. The analysis revealed a non-monotonic relationship between residual stress and energy density, with an initial increase followed by a decrease with increasing hatch spacing and scanning speed (both contributing to lower energy density). Additionally, beam diameter had a minimal impact compared to other energy density parameters.\u0000\u0000Originality/value\u0000This work offers a unique framework for optimizing LPBF processes by combining multiscale modeling with statistical techniques. The identified optimal parameters and insights into the individual and combined effects of energy density parameters provide valuable guidance for mitigating residual stress in SS316L, leading to improved part quality and performance.\u0000","PeriodicalId":20981,"journal":{"name":"Rapid Prototyping Journal","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141360112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-05-20DOI: 10.1108/rpj-06-2023-0207
Kimia Abedi, Hamid Keshvari, Mehran Solati-Hashjin
Purpose This study aims to develop a simplified bioink preparation method that can be applied to most hydrogel bioinks used in extrusion-based techniques. Design/methodology/approach The parameters of the bioprinting process significantly affect the printability of the bioink and the viability of cells. In turn, the bioink formulation and its physicochemical properties may influence the appropriate range of printing parameters. In extrusion-based bioprinting, the rheology of the bioink affects the printing pressure, cell survival and structural integrity. Three concentrations of alginate-gelatin hydrogel were prepared and printed at three different flow rates and nozzle gauges to investigate the print parameters. Other characterizations were performed to evaluate the hydrogel structure, printability, gelation time, swelling and degradation rates of the bioink and cell viability. An experimental design was used to determine optimal parameters. The analyses included live/dead assays, rheological measurements, swelling and degradation. Findings The experimental design results showed that the hydrogel flow rate substantially influenced printing accuracy and pressure. The best hydrogel flow rate in this study was 10 ml/h with a nozzle gauge of 18% and 4% alginate. Three different concentrations of alginate-gelatin hydrogels were found to exhibit shear-thinning behavior during printing. After seven days, 46% of the structure in the 4% alginate-5% gelatin sample remained intact. After printing, the viability of skin fibroblast cells for the optimized sample was 91%. Originality/value This methodology offers a straightforward bioink preparation method applicable to the majority of hydrogels used in extrusion-based procedures. This can also be considered a prerequisite for cell printing.
{"title":"Extrusion-based bioprinting: considerations toward gelatin-alginate bioink","authors":"Kimia Abedi, Hamid Keshvari, Mehran Solati-Hashjin","doi":"10.1108/rpj-06-2023-0207","DOIUrl":"https://doi.org/10.1108/rpj-06-2023-0207","url":null,"abstract":"Purpose\u0000This study aims to develop a simplified bioink preparation method that can be applied to most hydrogel bioinks used in extrusion-based techniques.\u0000\u0000Design/methodology/approach\u0000The parameters of the bioprinting process significantly affect the printability of the bioink and the viability of cells. In turn, the bioink formulation and its physicochemical properties may influence the appropriate range of printing parameters. In extrusion-based bioprinting, the rheology of the bioink affects the printing pressure, cell survival and structural integrity. Three concentrations of alginate-gelatin hydrogel were prepared and printed at three different flow rates and nozzle gauges to investigate the print parameters. Other characterizations were performed to evaluate the hydrogel structure, printability, gelation time, swelling and degradation rates of the bioink and cell viability. An experimental design was used to determine optimal parameters. The analyses included live/dead assays, rheological measurements, swelling and degradation.\u0000\u0000Findings\u0000The experimental design results showed that the hydrogel flow rate substantially influenced printing accuracy and pressure. The best hydrogel flow rate in this study was 10 ml/h with a nozzle gauge of 18% and 4% alginate. Three different concentrations of alginate-gelatin hydrogels were found to exhibit shear-thinning behavior during printing. After seven days, 46% of the structure in the 4% alginate-5% gelatin sample remained intact. After printing, the viability of skin fibroblast cells for the optimized sample was 91%.\u0000\u0000Originality/value\u0000This methodology offers a straightforward bioink preparation method applicable to the majority of hydrogels used in extrusion-based procedures. This can also be considered a prerequisite for cell printing.\u0000","PeriodicalId":20981,"journal":{"name":"Rapid Prototyping Journal","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140961848","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-05-13DOI: 10.1108/rpj-08-2023-0299
Fay Rhianna Claybrook, Darren John Southee, Mazher Mohammed
Purpose Cushioning is a useful material property applicable for a range of applications from medical devices to personal protective equipment. The current ability to apply cushioning in a product context is limited by the appropriateness of available materials, with polyurethane foams being the current gold standard material. The purpose of this study is to investigate additively manufactured flexible printing of scaffold structures as an alternative. Design/methodology/approach In this study, this study investigates triply periodic minimal surface (TPMS) structures, including Gyroid, Diamond and Schwarz P formed in thermoplastic polyurethane (TPU), as a possible alternative. Each TPMS structure was fabricated using material extrusion additive manufacturing and evaluated to ASTM mechanical testing standard for polymers. This study focuses attention to TPMS structures fabricated for a fixed unit cell size of 10 mm and examine the compressive properties for changes in the scaffold porosity for samples fabricated in TPU with a shore hardness of 63A and 90A. Findings It was discovered that for increased porosity there was a measured reduction in the load required to deform the scaffold. Additionally, a complex relationship between the shore hardness and the stiffness of a structure. It was highlighted that through the adjustment of porosity, the compressive strength required to deform the scaffolds to a point of densification could be controlled and predicted with high repeatability. Originality/value The results indicate the ability to tailor the scaffold design parameters using both 63A and 90A TPU material, to mimic the loading properties of common polyurethane foams. The use of these structures indicates a next generation of tailored cushioning using additive manufacturing techniques by tailoring both geometry and porosity to loading and compressive strengths.
{"title":"Mechanical evaluation of elastomeric thermoplastic polyurethane additively manufactured triply periodic minimal surface area lattice structures for adjustable cushioning properties","authors":"Fay Rhianna Claybrook, Darren John Southee, Mazher Mohammed","doi":"10.1108/rpj-08-2023-0299","DOIUrl":"https://doi.org/10.1108/rpj-08-2023-0299","url":null,"abstract":"\u0000Purpose\u0000Cushioning is a useful material property applicable for a range of applications from medical devices to personal protective equipment. The current ability to apply cushioning in a product context is limited by the appropriateness of available materials, with polyurethane foams being the current gold standard material. The purpose of this study is to investigate additively manufactured flexible printing of scaffold structures as an alternative.\u0000\u0000\u0000Design/methodology/approach\u0000In this study, this study investigates triply periodic minimal surface (TPMS) structures, including Gyroid, Diamond and Schwarz P formed in thermoplastic polyurethane (TPU), as a possible alternative. Each TPMS structure was fabricated using material extrusion additive manufacturing and evaluated to ASTM mechanical testing standard for polymers. This study focuses attention to TPMS structures fabricated for a fixed unit cell size of 10 mm and examine the compressive properties for changes in the scaffold porosity for samples fabricated in TPU with a shore hardness of 63A and 90A.\u0000\u0000\u0000Findings\u0000It was discovered that for increased porosity there was a measured reduction in the load required to deform the scaffold. Additionally, a complex relationship between the shore hardness and the stiffness of a structure. It was highlighted that through the adjustment of porosity, the compressive strength required to deform the scaffolds to a point of densification could be controlled and predicted with high repeatability.\u0000\u0000\u0000Originality/value\u0000The results indicate the ability to tailor the scaffold design parameters using both 63A and 90A TPU material, to mimic the loading properties of common polyurethane foams. The use of these structures indicates a next generation of tailored cushioning using additive manufacturing techniques by tailoring both geometry and porosity to loading and compressive strengths.\u0000","PeriodicalId":20981,"journal":{"name":"Rapid Prototyping Journal","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140985261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-05-08DOI: 10.1108/rpj-01-2023-0005
Vishal Kumar, Amitava Mandal
Purpose Wire-arc-based additive manufacturing (WAAM) is a promising technology for the efficient and economical fabrication of medium-large components. However, the anisotropic behavior of the multilayered WAAM-fabricated components remains a challenging problem. Design/methodology/approach The purpose of this paper is to conduct a comprehensive study of the grain morphology, crystallographic orientation and texture in three regions of the WAAM printed component. Furthermore, the interdependence of the grain morphology in different regions of the fabricated component with their mechanical and tribological properties was established. Findings The electron back-scattered diffraction analysis of the top and bottom regions revealed fine recrystallized grains, whereas the middle regions acquired columnar grains with an average size of approximately 8.980 µm. The analysis revealed a higher misorientation angle and an intense crystallographic texture in the upper and lower regions. The investigations found a higher microhardness value of 168.93 ± 1.71 HV with superior wear resistance in the bottom region. The quantitative evaluation of the residual stress detected higher compressive stress in the upper regions. Evidence for comparable ultimate tensile strength and greater elongation (%) compared to its wrought counterpart has been observed. Originality/value The study found a good correlation between the grain morphology in different regions of the WAAM-fabricated component and their mechanical and wear properties. The Hall–Petch relationship also established good agreement between the grain morphology and tensile test results. Improved ductility compared to its wrought counterpart was observed. The anisotropy exists with improved mechanical properties along the longitudinal direction. Moreover, cylindrical components have superior tribological properties compared with cuboidal components.
{"title":"A critical investigation of the anisotropic behavior in the WAAM-fabricated structure","authors":"Vishal Kumar, Amitava Mandal","doi":"10.1108/rpj-01-2023-0005","DOIUrl":"https://doi.org/10.1108/rpj-01-2023-0005","url":null,"abstract":"Purpose\u0000Wire-arc-based additive manufacturing (WAAM) is a promising technology for the efficient and economical fabrication of medium-large components. However, the anisotropic behavior of the multilayered WAAM-fabricated components remains a challenging problem.\u0000\u0000Design/methodology/approach\u0000The purpose of this paper is to conduct a comprehensive study of the grain morphology, crystallographic orientation and texture in three regions of the WAAM printed component. Furthermore, the interdependence of the grain morphology in different regions of the fabricated component with their mechanical and tribological properties was established.\u0000\u0000Findings\u0000The electron back-scattered diffraction analysis of the top and bottom regions revealed fine recrystallized grains, whereas the middle regions acquired columnar grains with an average size of approximately 8.980 µm. The analysis revealed a higher misorientation angle and an intense crystallographic texture in the upper and lower regions. The investigations found a higher microhardness value of 168.93 ± 1.71 HV with superior wear resistance in the bottom region. The quantitative evaluation of the residual stress detected higher compressive stress in the upper regions. Evidence for comparable ultimate tensile strength and greater elongation (%) compared to its wrought counterpart has been observed.\u0000\u0000Originality/value\u0000The study found a good correlation between the grain morphology in different regions of the WAAM-fabricated component and their mechanical and wear properties. The Hall–Petch relationship also established good agreement between the grain morphology and tensile test results. Improved ductility compared to its wrought counterpart was observed. The anisotropy exists with improved mechanical properties along the longitudinal direction. Moreover, cylindrical components have superior tribological properties compared with cuboidal components.\u0000","PeriodicalId":20981,"journal":{"name":"Rapid Prototyping Journal","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141001911","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-05-07DOI: 10.1108/rpj-11-2023-0415
J. Wambua, Fredrick Mwema, Stephen Akinlabi, Martin Birkett, Ben Xu, Wai Lok Woo, Mike Taverne, Ying-Lung Daniel Ho, Esther Akinlabi
Purpose The purpose of this paper is to present an optimisation of four-point star-shaped structures produced through additive manufacturing (AM) polylactic acid (PLA). The study also aims to investigate the compression failure mechanism of the structure. Design/methodology/approach A Taguchi L9 orthogonal array design of the experiment is adopted in which the input parameters are resolution (0.06, 0.15 and 0.30 mm), print speed (60, 70 and 80 mm/s) and bed temperature (55°C, 60°C, 65°C). The response parameters considered were printing time, material usage, compression yield strength, compression modulus and dimensional stability. Empirical observations during compression tests were used to evaluate the load–response mechanism of the structures. Findings The printing resolution is the most significant input parameter. Material length is not influenced by the printing speed and bed temperature. The compression stress–strain curve exhibits elastic, plateau and densification regions. All the samples exhibit negative Poisson’s ratio values within the elastic and plateau regions. At the beginning of densification, the Poisson’s ratios change to positive values. The metamaterial printed at a resolution of 0.3 mm, 80 mm/s and 60°C exhibits the best mechanical properties (yield strength and modulus of 2.02 and 58.87 MPa, respectively). The failure of the structure occurs through bending and torsion of the unit cells. Practical implications The optimisation study is significant for decision-making during the 3D printing and the empirical failure model shall complement the existing techniques for the mechanical analysis of the metamaterials. Originality/value To the best of the authors’ knowledge, for the first time, a new empirical model, based on the uniaxial load response and “static truss concept”, for failure mechanisms of the unit cell is presented.
{"title":"Optimisation of printing parameters of fused filament fabrication and uniaxial compression failure analysis for four-point star-shaped structures","authors":"J. Wambua, Fredrick Mwema, Stephen Akinlabi, Martin Birkett, Ben Xu, Wai Lok Woo, Mike Taverne, Ying-Lung Daniel Ho, Esther Akinlabi","doi":"10.1108/rpj-11-2023-0415","DOIUrl":"https://doi.org/10.1108/rpj-11-2023-0415","url":null,"abstract":"Purpose\u0000The purpose of this paper is to present an optimisation of four-point star-shaped structures produced through additive manufacturing (AM) polylactic acid (PLA). The study also aims to investigate the compression failure mechanism of the structure.\u0000\u0000Design/methodology/approach\u0000A Taguchi L9 orthogonal array design of the experiment is adopted in which the input parameters are resolution (0.06, 0.15 and 0.30 mm), print speed (60, 70 and 80 mm/s) and bed temperature (55°C, 60°C, 65°C). The response parameters considered were printing time, material usage, compression yield strength, compression modulus and dimensional stability. Empirical observations during compression tests were used to evaluate the load–response mechanism of the structures.\u0000\u0000Findings\u0000The printing resolution is the most significant input parameter. Material length is not influenced by the printing speed and bed temperature. The compression stress–strain curve exhibits elastic, plateau and densification regions. All the samples exhibit negative Poisson’s ratio values within the elastic and plateau regions. At the beginning of densification, the Poisson’s ratios change to positive values. The metamaterial printed at a resolution of 0.3 mm, 80 mm/s and 60°C exhibits the best mechanical properties (yield strength and modulus of 2.02 and 58.87 MPa, respectively). The failure of the structure occurs through bending and torsion of the unit cells.\u0000\u0000Practical implications\u0000The optimisation study is significant for decision-making during the 3D printing and the empirical failure model shall complement the existing techniques for the mechanical analysis of the metamaterials.\u0000\u0000Originality/value\u0000To the best of the authors’ knowledge, for the first time, a new empirical model, based on the uniaxial load response and “static truss concept”, for failure mechanisms of the unit cell is presented.\u0000","PeriodicalId":20981,"journal":{"name":"Rapid Prototyping Journal","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141001798","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-05-07DOI: 10.1108/rpj-09-2023-0318
Nalinda Dissanayaka, Hamish Alexander, Danilo Carluccio, Michael Redmond, L. Vandi, James I. Novak
Purpose Three-dimensional (3D)printed skulls for neurosurgical training are increasingly being used due to the widespread access to 3D printing technology, their low cost and accuracy, as well as limitations and ethical concerns associated with using human cadavers. However, little is known about the risks of airborne particles or volatile organic compounds (VOCs) released while drilling into 3D-printed plastic models. The aim of this study is to assess the level of exposure to airborne contaminants while burr hole drilling. Design/methodology/approach 3D-printed skull samples were produced using three different materials (polyethylene terephthalate glycol [PETG], white resin and BoneSTN) across three different 3D print processes (fused filament fabrication, stereolithography [SLA] and material jetting). A neurosurgeon performed extended burr hole drilling for 10 min on each sample. Spot measurements of particulate matter (PM2.5 and PM10) were recorded, and air samples were analysed for approximately 90 VOCs. Findings The particulate matter for PETG was found to be below the threshold value for respirable particles. However, the particulate matter for white resin and BoneSTN was found to be above the threshold value at PM10, which could be harmful for long periods of exposure without personal protective equipment (PPE). The VOC measurements for all materials were found to be below safety thresholds, and therefore not harmful. Originality/value To the best of the authors’ knowledge, this is the first study to evaluate the safety of 3D-printed materials for burr hole surgical drilling. It recommends PETG as a safe material requiring minimal respiratory control measures, whereas resin-based materials will require safety controls to deal with airborne particles.
{"title":"How safe are 3D-printed skull models for neurosurgical simulation? Measurement of airborne particles and VOCs while burr hole drilling","authors":"Nalinda Dissanayaka, Hamish Alexander, Danilo Carluccio, Michael Redmond, L. Vandi, James I. Novak","doi":"10.1108/rpj-09-2023-0318","DOIUrl":"https://doi.org/10.1108/rpj-09-2023-0318","url":null,"abstract":"\u0000Purpose\u0000Three-dimensional (3D)printed skulls for neurosurgical training are increasingly being used due to the widespread access to 3D printing technology, their low cost and accuracy, as well as limitations and ethical concerns associated with using human cadavers. However, little is known about the risks of airborne particles or volatile organic compounds (VOCs) released while drilling into 3D-printed plastic models. The aim of this study is to assess the level of exposure to airborne contaminants while burr hole drilling.\u0000\u0000\u0000Design/methodology/approach\u00003D-printed skull samples were produced using three different materials (polyethylene terephthalate glycol [PETG], white resin and BoneSTN) across three different 3D print processes (fused filament fabrication, stereolithography [SLA] and material jetting). A neurosurgeon performed extended burr hole drilling for 10 min on each sample. Spot measurements of particulate matter (PM2.5 and PM10) were recorded, and air samples were analysed for approximately 90 VOCs.\u0000\u0000\u0000Findings\u0000The particulate matter for PETG was found to be below the threshold value for respirable particles. However, the particulate matter for white resin and BoneSTN was found to be above the threshold value at PM10, which could be harmful for long periods of exposure without personal protective equipment (PPE). The VOC measurements for all materials were found to be below safety thresholds, and therefore not harmful.\u0000\u0000\u0000Originality/value\u0000To the best of the authors’ knowledge, this is the first study to evaluate the safety of 3D-printed materials for burr hole surgical drilling. It recommends PETG as a safe material requiring minimal respiratory control measures, whereas resin-based materials will require safety controls to deal with airborne particles.\u0000","PeriodicalId":20981,"journal":{"name":"Rapid Prototyping Journal","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141001759","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-05-06DOI: 10.1108/rpj-11-2023-0400
Hansu Kim, Luke Crispo, Anuj Patel, Nicholas Galley, S. Yeon, Yong Son, Il Yong Kim
Purpose The lightweight design of aircraft seats can significantly improve fuel efficiency and reduce greenhouse gas emissions. Metal additive manufacturing (MAM) can produce lightweight topology-optimized designs with improved performance, but limited build volume restricts the printing of large components. The purpose of this paper is to design a lightweight aircraft seat leg structure using topology optimization (TO) and MAM with build volume restrictions, while satisfying structural airworthiness certification requirements. Design/methodology/approach TO was used to determine a lightweight conceptual design for the seat leg structure. The conceptual design was decomposed to meet the machine build volume, a detailed CAD assembly was designed and print orientation was selected for each component. Static and dynamic verification was performed, the design was updated to meet the structural requirements and a prototype was manufactured. Findings The final topology-optimized seat leg structure was decomposed into three parts, yielding a 57% reduction in the number of parts compared to a reference design. In addition, the design achieved an 8.5% mass reduction while satisfying structural requirements for airworthiness certification. Originality/value To the best of the authors’ knowledge, this study is the first paper to design an aircraft seat leg structure manufactured with MAM using a rigorous TO approach. The resultant design reduces mass and part count compared to a reference design and is verified with respect to real-world aircraft certification requirements.
目的飞机座椅的轻量化设计可显著提高燃油效率并减少温室气体排放。金属增材制造（MAM）可以生产出拓扑优化的轻质设计并提高性能，但有限的制造体积限制了大型部件的打印。本文的目的是利用拓扑优化（TO）和 MAM，在满足结构适航认证要求的前提下，设计一种轻质飞机座椅腿结构。对概念设计进行了分解，以满足机器的制造体积，设计了详细的 CAD 装配，并为每个组件选择了打印方向。进行了静态和动态验证，更新了设计以满足结构要求，并制造了一个原型。此外，该设计在满足适航认证结构要求的同时，还减少了 8.5% 的质量。原创性/价值 据作者所知，本研究是第一篇采用严格的 TO 方法设计飞机座椅腿结构的论文。与参考设计相比，该设计减少了质量和零件数量，并根据实际飞机认证要求进行了验证。
{"title":"Design of a metal additive manufactured aircraft seat leg using topology optimization and part decomposition","authors":"Hansu Kim, Luke Crispo, Anuj Patel, Nicholas Galley, S. Yeon, Yong Son, Il Yong Kim","doi":"10.1108/rpj-11-2023-0400","DOIUrl":"https://doi.org/10.1108/rpj-11-2023-0400","url":null,"abstract":"\u0000Purpose\u0000The lightweight design of aircraft seats can significantly improve fuel efficiency and reduce greenhouse gas emissions. Metal additive manufacturing (MAM) can produce lightweight topology-optimized designs with improved performance, but limited build volume restricts the printing of large components. The purpose of this paper is to design a lightweight aircraft seat leg structure using topology optimization (TO) and MAM with build volume restrictions, while satisfying structural airworthiness certification requirements.\u0000\u0000\u0000Design/methodology/approach\u0000TO was used to determine a lightweight conceptual design for the seat leg structure. The conceptual design was decomposed to meet the machine build volume, a detailed CAD assembly was designed and print orientation was selected for each component. Static and dynamic verification was performed, the design was updated to meet the structural requirements and a prototype was manufactured.\u0000\u0000\u0000Findings\u0000The final topology-optimized seat leg structure was decomposed into three parts, yielding a 57% reduction in the number of parts compared to a reference design. In addition, the design achieved an 8.5% mass reduction while satisfying structural requirements for airworthiness certification.\u0000\u0000\u0000Originality/value\u0000To the best of the authors’ knowledge, this study is the first paper to design an aircraft seat leg structure manufactured with MAM using a rigorous TO approach. The resultant design reduces mass and part count compared to a reference design and is verified with respect to real-world aircraft certification requirements.\u0000","PeriodicalId":20981,"journal":{"name":"Rapid Prototyping Journal","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141007015","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-05-06DOI: 10.1108/rpj-08-2023-0300
Mohammad Vahid Ehteshamfar, Amir Kiadarbandsari, Ali Ataee, Katayoun Ghozati, Mohammad Ali Bagherkhani
Purpose Stereolithography (SLA) additive manufacturing (AM) technique has enabled the production of inconspicuous and aesthetically pleasing orthodontics that are also hygienic. However, the staircase effect poses a challenge to the application of invisible orthodontics in the dental industry. The purpose of this study is to implement chemical postprocessing technique by using isopropyl alcohol as a solvent to overcome this challenge. Design/methodology/approach Fifteen experiments were conducted using a D-optimal design to investigate the effect of different concentrations and postprocessing times on the surface roughness, material removal rate (MRR), hardness and cost of SLA dental parts required for creating a clear customized aligner, and a container was constructed for chemical treatment of these parts made from photocurable resin. Findings The study revealed that the chemical postprocessing technique can significantly improve the surface roughness of dental SLA parts, but improper selection of concentration and time can lead to poor surface roughness. The optimal surface roughness was achieved with a concentration of 90 and a time of 37.5. Moreover, the dental part with the lowest concentration and time (60% and 15 min, respectively) had the lowest MRR and the highest hardness. The part with the highest concentration and time required the greatest budget allocation. Finally, the results of the multiobjective optimization analysis aligned with the experimental data. Originality/value This paper sheds light on a previously underestimated aspect, which is the pivotal role of chemical postprocessing in mitigating the adverse impact of stair case effect. This nuanced perspective contributes to the broader discourse on AM methodologies, establishing a novel pathway for advancing the capabilities of SLA in dental application.
{"title":"Chemical treatment in 3D dental model production for clear aligners via additive manufacturing: a comprehensive evaluation","authors":"Mohammad Vahid Ehteshamfar, Amir Kiadarbandsari, Ali Ataee, Katayoun Ghozati, Mohammad Ali Bagherkhani","doi":"10.1108/rpj-08-2023-0300","DOIUrl":"https://doi.org/10.1108/rpj-08-2023-0300","url":null,"abstract":"Purpose\u0000Stereolithography (SLA) additive manufacturing (AM) technique has enabled the production of inconspicuous and aesthetically pleasing orthodontics that are also hygienic. However, the staircase effect poses a challenge to the application of invisible orthodontics in the dental industry. The purpose of this study is to implement chemical postprocessing technique by using isopropyl alcohol as a solvent to overcome this challenge.\u0000\u0000Design/methodology/approach\u0000Fifteen experiments were conducted using a D-optimal design to investigate the effect of different concentrations and postprocessing times on the surface roughness, material removal rate (MRR), hardness and cost of SLA dental parts required for creating a clear customized aligner, and a container was constructed for chemical treatment of these parts made from photocurable resin.\u0000\u0000Findings\u0000The study revealed that the chemical postprocessing technique can significantly improve the surface roughness of dental SLA parts, but improper selection of concentration and time can lead to poor surface roughness. The optimal surface roughness was achieved with a concentration of 90 and a time of 37.5. Moreover, the dental part with the lowest concentration and time (60% and 15 min, respectively) had the lowest MRR and the highest hardness. The part with the highest concentration and time required the greatest budget allocation. Finally, the results of the multiobjective optimization analysis aligned with the experimental data.\u0000\u0000Originality/value\u0000This paper sheds light on a previously underestimated aspect, which is the pivotal role of chemical postprocessing in mitigating the adverse impact of stair case effect. This nuanced perspective contributes to the broader discourse on AM methodologies, establishing a novel pathway for advancing the capabilities of SLA in dental application.\u0000","PeriodicalId":20981,"journal":{"name":"Rapid Prototyping Journal","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141007474","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-05-03DOI: 10.1108/rpj-05-2023-0177
Cesar O. Balderrama-Armendáriz, Sergio Esteban Arbelaez-Rios, Santos-Adriana Martel-Estrada, A. Maldonado-Macías, Eric MacDonald, J. Aguilar-Duque
Purpose This study aims to propose the reuse of PA12 (powder) in another AM process, binder jettiinng, which is less sensitive to the chemical and mechanical degradation of the powder after multiple cycles in the laser system. Design/methodology/approach The experimental process for evaluating the reuse of SLS powders in a subsequent binder jetting process consists of four phases: powder characterization, bonding analysis, mixture testing and mixture characteristics. Analyses were carried out using techniques such as Fourier Transform Infrared Spectroscopy, scanning electron microscopy, thermogravimetric analysis and stress–strain tests for tension and compression. The surface roughness, color, hardness and density of the new mixture were also determined to find physical characteristics. A Taguchi design L8 was used to search for a mixture with the best mechanical strength. Findings The results indicated that the integration of waste powder PA12 with calcium sulfate hemihydrate (CSH) generates appropriate particle distribution with rounded particles of PA12 that improve powder flowability. The micropores observed with less than 60 µm, facilitated binder and infiltrant penetration on 3D parts. The 60/40 (CSH-PA12) mixture with epoxy resin postprocessing was found to be the best-bonded mixture in mechanical testing, rugosity and hardness results. The new CSH-PA12 mixture resulted lighter and stronger than the CSH powder commonly used in binder jetting technology. Originality/value This study adds value to the polymer powder bed fusion process by using its waste in a circular process. The novel reuse of PA12 waste in an established process was achieved in an accessible and economical manner.
{"title":"Recovery of residual polyamide (PA12) from polymer powder bed fusion additive manufacturing process through a binder jetting process","authors":"Cesar O. Balderrama-Armendáriz, Sergio Esteban Arbelaez-Rios, Santos-Adriana Martel-Estrada, A. Maldonado-Macías, Eric MacDonald, J. Aguilar-Duque","doi":"10.1108/rpj-05-2023-0177","DOIUrl":"https://doi.org/10.1108/rpj-05-2023-0177","url":null,"abstract":"\u0000Purpose\u0000This study aims to propose the reuse of PA12 (powder) in another AM process, binder jettiinng, which is less sensitive to the chemical and mechanical degradation of the powder after multiple cycles in the laser system.\u0000\u0000\u0000Design/methodology/approach\u0000The experimental process for evaluating the reuse of SLS powders in a subsequent binder jetting process consists of four phases: powder characterization, bonding analysis, mixture testing and mixture characteristics. Analyses were carried out using techniques such as Fourier Transform Infrared Spectroscopy, scanning electron microscopy, thermogravimetric analysis and stress–strain tests for tension and compression. The surface roughness, color, hardness and density of the new mixture were also determined to find physical characteristics. A Taguchi design L8 was used to search for a mixture with the best mechanical strength.\u0000\u0000\u0000Findings\u0000The results indicated that the integration of waste powder PA12 with calcium sulfate hemihydrate (CSH) generates appropriate particle distribution with rounded particles of PA12 that improve powder flowability. The micropores observed with less than 60 µm, facilitated binder and infiltrant penetration on 3D parts. The 60/40 (CSH-PA12) mixture with epoxy resin postprocessing was found to be the best-bonded mixture in mechanical testing, rugosity and hardness results. The new CSH-PA12 mixture resulted lighter and stronger than the CSH powder commonly used in binder jetting technology.\u0000\u0000\u0000Originality/value\u0000This study adds value to the polymer powder bed fusion process by using its waste in a circular process. The novel reuse of PA12 waste in an established process was achieved in an accessible and economical manner.\u0000","PeriodicalId":20981,"journal":{"name":"Rapid Prototyping Journal","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141016782","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-05-02DOI: 10.1108/rpj-09-2023-0314
Ali Hashemi Baghi, Jasmin Mansour
Purpose Fused Filament Fabrication (FFF) is one of the growing technologies in additive manufacturing, that can be used in a number of applications. In this method, process parameters can be customized and their simultaneous variation has conflicting impacts on various properties of printed parts such as dimensional accuracy (DA) and surface finish. These properties could be improved by optimizing the values of these parameters. Design/methodology/approach In this paper, four process parameters, namely, print speed, build orientation, raster width, and layer height which are referred to as “input variables” were investigated. The conflicting influence of their simultaneous variations on the DA of printed parts was investigated and predicated. To achieve this goal, a hybrid Genetic Algorithm – Artificial Neural Network (GA-ANN) model, was developed in C#.net, and three geometries, namely, U-shape, cube and cylinder were selected. To investigate the DA of printed parts, samples were printed with a central through hole. Design of Experiments (DoE), specifically the Rotational Central Composite Design method was adopted to establish the number of parts to be printed (30 for each selected geometry) and also the value of each input process parameter. The dimensions of printed parts were accurately measured by a shadowgraph and were used as an input data set for the training phase of the developed ANN to predict the behavior of process parameters. Then the predicted values were used as input to the Desirability Function tool which resulted in a mathematical model that optimizes the input process variables for selected geometries. The mean square error of 0.0528 was achieved, which is indicative of the accuracy of the developed model. Findings The results showed that print speed is the most dominant input variable compared to others, and by increasing its value, considerable variations resulted in DA. The inaccuracy increased, especially with parts of circular cross section. In addition, if there is no need to print parts in vertical position, the build orientation should be set at 0° to achieve the highest DA. Finally, optimized values of raster width and layer height improved the DA especially when the print speed was set at a high value. Originality/value By using ANN, it is possible to investigate the impact of simultaneous variations of FFF machines’ input process parameters on the DA of printed parts. By their optimization, parts of highly accurate dimensions could be printed. These findings will be of significant value to those industries that need to produce parts of high DA on FFF machines.
目的熔融长丝制造（FFF）是快速成型制造技术中不断发展的技术之一，可用于多种应用领域。在这种方法中，工艺参数可以定制，它们的同时变化会对打印部件的各种性能（如尺寸精度（DA）和表面光洁度）产生相互冲突的影响。本文研究了四个工艺参数，即打印速度、构建方向、光栅宽度和层高，它们被称为 "输入变量"。研究并预测了这四个参数的同时变化对打印部件 DA 的冲突影响。为实现这一目标，使用 C#.net 开发了遗传算法-人工神经网络（GA-ANN）混合模型，并选择了三种几何形状，即 U 形、立方体和圆柱体。为了研究打印部件的 DA，打印了带有中心通孔的样品。实验设计（DoE），特别是旋转中心复合设计方法，被用来确定要打印的零件数量（每个选定的几何形状为 30 个）以及每个输入工艺参数的值。通过阴影图精确测量了印刷部件的尺寸，并将其作为输入数据集，用于开发的 ANN 的训练阶段，以预测工艺参数的行为。然后，将预测值作为可取函数工具的输入，从而建立一个数学模型，优化选定几何形状的输入工艺变量。结果表明，与其他输入变量相比，印刷速度是最主要的输入变量。不准确度增加，尤其是圆形截面的零件。此外，如果不需要在垂直位置打印零件，则应将构建方向设置为 0°，以获得最高的 DA 值。最后，光栅宽度和层高的优化值改善了 DA，尤其是当打印速度设置为较高值时。 原创性/价值 通过使用 ANN，可以研究 FFF 机器输入工艺参数的同时变化对打印部件 DA 的影响。通过优化这些参数，可以打印出尺寸高度精确的零件。这些发现对于需要在 FFF 机器上生产高 DA 零件的行业具有重要价值。
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