Both hierarchical and auxetic structures have shown unusual mechanical properties and draw great attention for multiple engineering applications. Recently, a triangular 2nd order of hierarchy has been successfully integrated into re-entrant honeycomb, one specific type of auxetic structures, by the emerging additive manufacturing method. The resulted hierarchical re-entrant honeycomb (H-ReH) outperforms the conventional re-entrant honeycomb (C-ReH) in stiffness, initial buckling strength, densification strain and specific energy absorption capacity (SEA). However, the optimized designs of the cell structures in H-ReH are still elusive and yet to be explored, which is critical for advanced safety applications. The mechanical performance and deformation mode of H-ReH are mainly determined by the geometric parameters of the structure, among which the cell-wall angle is one of the most critical design parameters. To this end, we designed H-ReHs with three different cell-wall angles, i.e. 60°, 75° and 90°. C-ReHs with the same three angle designs were processed through the same 3D-printing method as reference samples. The mechanical performance of the fabricated specimens was characterized by the uniaxial quasi-static compression tests. The evolution of the strain field in all the samples was measured and analyzed by the Digital Image Correlation (DIC). The results show that the angle designs have significant influences on the elastic modulus, strength, structural stability, and SEA of H-ReH. By increasing the angle from 60° to 75°, the densification strain and the SEA are increased by 60% and 75%, respectively. This is due to the altered deformation modes of the H-ReHs with different cell-wall angles. By contrast, the C-ReHs are found to be nearly inert to the angle change, due to its bending-dominated behavior regardless of the cell-wall angle change. When further increase the cell-wall angle to 90°, both H-ReH and C-ReH exhibit notable enhancement on the elastic modulus and the strength, but at a much-compromised structural stability. The vertical member of both structures buckles and fractures at a small strain. In conclusion, this study has demonstrated that the mechanical properties of H-ReH is sensitive to the cell-wall angle. Furthermore, the H-ReH has much better mechanical tunability over C-ReH through the angle designs due to its unique deformation mechanisms. These findings will guide the future design of H-ReH and other types of lightweight robust materials and structures.
{"title":"Effect of Cell-Wall Angle on the Mechanical Properties of 3D-Printed Hierarchical Re-Entrant Honeycomb","authors":"Chi Zhan, Mingzhe Li, Weiyi Lu","doi":"10.1115/imece2022-93988","DOIUrl":"https://doi.org/10.1115/imece2022-93988","url":null,"abstract":"\u0000 Both hierarchical and auxetic structures have shown unusual mechanical properties and draw great attention for multiple engineering applications. Recently, a triangular 2nd order of hierarchy has been successfully integrated into re-entrant honeycomb, one specific type of auxetic structures, by the emerging additive manufacturing method. The resulted hierarchical re-entrant honeycomb (H-ReH) outperforms the conventional re-entrant honeycomb (C-ReH) in stiffness, initial buckling strength, densification strain and specific energy absorption capacity (SEA). However, the optimized designs of the cell structures in H-ReH are still elusive and yet to be explored, which is critical for advanced safety applications. The mechanical performance and deformation mode of H-ReH are mainly determined by the geometric parameters of the structure, among which the cell-wall angle is one of the most critical design parameters.\u0000 To this end, we designed H-ReHs with three different cell-wall angles, i.e. 60°, 75° and 90°. C-ReHs with the same three angle designs were processed through the same 3D-printing method as reference samples. The mechanical performance of the fabricated specimens was characterized by the uniaxial quasi-static compression tests. The evolution of the strain field in all the samples was measured and analyzed by the Digital Image Correlation (DIC). The results show that the angle designs have significant influences on the elastic modulus, strength, structural stability, and SEA of H-ReH. By increasing the angle from 60° to 75°, the densification strain and the SEA are increased by 60% and 75%, respectively. This is due to the altered deformation modes of the H-ReHs with different cell-wall angles. By contrast, the C-ReHs are found to be nearly inert to the angle change, due to its bending-dominated behavior regardless of the cell-wall angle change. When further increase the cell-wall angle to 90°, both H-ReH and C-ReH exhibit notable enhancement on the elastic modulus and the strength, but at a much-compromised structural stability. The vertical member of both structures buckles and fractures at a small strain.\u0000 In conclusion, this study has demonstrated that the mechanical properties of H-ReH is sensitive to the cell-wall angle. Furthermore, the H-ReH has much better mechanical tunability over C-ReH through the angle designs due to its unique deformation mechanisms. These findings will guide the future design of H-ReH and other types of lightweight robust materials and structures.","PeriodicalId":146276,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization and Applications; Advances in Aerospace Technology","volume":"384 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116484568","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Justin D. Valenti, Joseph Barolai, J. Cole, M. Yukish
The objective of this study is to characterize the trade space for the structural design of small uncrewed aerial vehicle wings fabricated using Material Extrusion Additive Manufacturing, specifically the trade-off between maintaining the wing external shape while minimizing its internal structure. Beam bending analysis shows that the structural requirements associated with flight loads are easily met with a single perimeter extrusion monocoque construction, however this approach leads to large, unsupported, thin-walled structures that can deform during the build process, creating a potential need for additional structure to maintain wing shape. To characterize the relationship between structure/weight and wing deformation, wing sections were fabricated with varying internal structures for two airfoil shapes. Weight and 3-D laser measurements were taken of the printed parts to capture the final as-built geometry. The as-built geometries were then compared to the as-designed geometries to quantify the deformation, and a coupled viscous-inviscid flow solver was used to determine the aerodynamic effects. The results indicate that while significant aerodynamic performance penalties exist for the monocoque construction, a small amount of well-placed internal structure provides sufficient improvement at minimal weight penalty. Results also showed that less internal structure is required to minimize deformation for an airfoil with larger initial curvature.
{"title":"Additive Manufacturing Process-Induced Wing Skin Deformation and Effects on Aerodynamic Performance","authors":"Justin D. Valenti, Joseph Barolai, J. Cole, M. Yukish","doi":"10.1115/imece2022-96569","DOIUrl":"https://doi.org/10.1115/imece2022-96569","url":null,"abstract":"\u0000 The objective of this study is to characterize the trade space for the structural design of small uncrewed aerial vehicle wings fabricated using Material Extrusion Additive Manufacturing, specifically the trade-off between maintaining the wing external shape while minimizing its internal structure. Beam bending analysis shows that the structural requirements associated with flight loads are easily met with a single perimeter extrusion monocoque construction, however this approach leads to large, unsupported, thin-walled structures that can deform during the build process, creating a potential need for additional structure to maintain wing shape. To characterize the relationship between structure/weight and wing deformation, wing sections were fabricated with varying internal structures for two airfoil shapes. Weight and 3-D laser measurements were taken of the printed parts to capture the final as-built geometry. The as-built geometries were then compared to the as-designed geometries to quantify the deformation, and a coupled viscous-inviscid flow solver was used to determine the aerodynamic effects. The results indicate that while significant aerodynamic performance penalties exist for the monocoque construction, a small amount of well-placed internal structure provides sufficient improvement at minimal weight penalty. Results also showed that less internal structure is required to minimize deformation for an airfoil with larger initial curvature.","PeriodicalId":146276,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization and Applications; Advances in Aerospace Technology","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128583637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lakshman Rao Kolla, A. Gupta, D. Mathur, A. Bhardwaj
Lightweight alloys play a significant role in different manufacturing applications in the aerospace, automobile, and medical industries. Among other light alloys, 7075 aluminum alloy (AA7075) is widely utilized due to its excellent mechanical strength, low weight to strength ratio, and good corrosion resistance. One of the prominent ways to improve the alloy’s properties is grain refinement, which is easily accomplished by severe plastic deformation (SPD) techniques. Among different SPD techniques, constrained groove pressing (CGP) is one of the prominent SPD techniques, particularly for the sheet/plate material. In this work, AA7075 alloy was subjected to the CGP process at 300°C with various heat treatments. The repetitive shear. Grain refinement of CGPed samples was observed through an optical microscope to measure the average grain size of the specimen. SEM and XRD were used to investigate the precipitation and crystallography of the processed alloy. Results indicate that the heat treatment significantly affects grain growth as precipitates are segregated along grain boundaries.
{"title":"Experimental Investigation on Severe Plastic Deformation of AA7075 Alloy at Elevated Temperature","authors":"Lakshman Rao Kolla, A. Gupta, D. Mathur, A. Bhardwaj","doi":"10.1115/imece2022-95017","DOIUrl":"https://doi.org/10.1115/imece2022-95017","url":null,"abstract":"\u0000 Lightweight alloys play a significant role in different manufacturing applications in the aerospace, automobile, and medical industries. Among other light alloys, 7075 aluminum alloy (AA7075) is widely utilized due to its excellent mechanical strength, low weight to strength ratio, and good corrosion resistance. One of the prominent ways to improve the alloy’s properties is grain refinement, which is easily accomplished by severe plastic deformation (SPD) techniques. Among different SPD techniques, constrained groove pressing (CGP) is one of the prominent SPD techniques, particularly for the sheet/plate material. In this work, AA7075 alloy was subjected to the CGP process at 300°C with various heat treatments. The repetitive shear. Grain refinement of CGPed samples was observed through an optical microscope to measure the average grain size of the specimen. SEM and XRD were used to investigate the precipitation and crystallography of the processed alloy. Results indicate that the heat treatment significantly affects grain growth as precipitates are segregated along grain boundaries.","PeriodicalId":146276,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization and Applications; Advances in Aerospace Technology","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128635420","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Commercial applications of polymer nanocomposites for materials used in offshore settings is continuously touted as a potential solution to expand the material property envelope of polymers used in high pressure and temperature environments. In this regard, polyurethane urea (PUU) has been successfully used in such environments, however, they are limited in terms of their ability to offer multifunctional behavior i.e., thermal conductive behavior with mechanical properties. This gap offers the opportunity for their properties to be enhanced as an advanced multi-functional polymer. Hence, in this study, polyurethane urea/graphene nanocomposites were synthesized using commercial Polyurethane urea (Task 12), and graphene nanoplatelets (GnP). The graphene nanoplatelets were dispersed in one part of the polyurethane urea component using facile dispersion methods. The properties of the new PUU nanocomposite materials were studied using SEM, mechanical and thermal analysis techniques (DMA and Hot Disk), to examine the development of the multifunctional properties in the PUU nanocomposite. Our analysis describes the influence of graphene nanoplatelets at ultra-low concentrations on multi-functional properties of the PUU nanocomposites. The developed nanocomposites recorded a 16% increase in the tensile strength and an 8% increase in the thermal conductive values. The property improvements are credited generally to the high aspect ratio of graphene nanoplatelets, dispersion and filler-polyurethane interactions at the interface. The impartation of multi-functional behavior, in enhancing the thermal conductivity whilst maintaining the mechanical properties makes it a potentially valuable for subsea applications.
{"title":"Investigating the Thermal and Mechanical Properties of Polyurethane Urea Nanocomposites for Subsea Applications","authors":"C. Okolo, A. Elmarakbi, M. Birkett","doi":"10.1115/imece2022-95623","DOIUrl":"https://doi.org/10.1115/imece2022-95623","url":null,"abstract":"\u0000 Commercial applications of polymer nanocomposites for materials used in offshore settings is continuously touted as a potential solution to expand the material property envelope of polymers used in high pressure and temperature environments. In this regard, polyurethane urea (PUU) has been successfully used in such environments, however, they are limited in terms of their ability to offer multifunctional behavior i.e., thermal conductive behavior with mechanical properties. This gap offers the opportunity for their properties to be enhanced as an advanced multi-functional polymer.\u0000 Hence, in this study, polyurethane urea/graphene nanocomposites were synthesized using commercial Polyurethane urea (Task 12), and graphene nanoplatelets (GnP). The graphene nanoplatelets were dispersed in one part of the polyurethane urea component using facile dispersion methods. The properties of the new PUU nanocomposite materials were studied using SEM, mechanical and thermal analysis techniques (DMA and Hot Disk), to examine the development of the multifunctional properties in the PUU nanocomposite. Our analysis describes the influence of graphene nanoplatelets at ultra-low concentrations on multi-functional properties of the PUU nanocomposites. The developed nanocomposites recorded a 16% increase in the tensile strength and an 8% increase in the thermal conductive values. The property improvements are credited generally to the high aspect ratio of graphene nanoplatelets, dispersion and filler-polyurethane interactions at the interface. The impartation of multi-functional behavior, in enhancing the thermal conductivity whilst maintaining the mechanical properties makes it a potentially valuable for subsea applications.","PeriodicalId":146276,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization and Applications; Advances in Aerospace Technology","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131097412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the present work is made an overview of the use of hydrogen in aviation, the modifications needed to convert a conventional gas turbine to use hydrogen and a CFD simulation of an existent gas turbine burning hydrogen. The CFD simulation was done in a CFM56-3 combustor burning Jet A (as a reference standard) and hydrogen, with the intention of evaluate the viability of conversion of existent gas turbines to hydrogen, in a combustion point of view, by analyzing the emissions through ICAO’s LTO cycle while burning this fuel. ANSYS Fluent 2020R2 was the software used to perform the numerical study. The RSM was the viscous model used. Only the NOx emissions were assessed as pollutant once the hydrogen combustion products are reduced to water vapor and NOx. These emissions were evaluated through a detailed mechanism and the NOx model available on ANSYS to get a better concordance with the ICAO’s values. During this study, several sensibility studies were carried out for hydrogen burn, for instance, the analysis of the air flow with/without swirl in the primary zone and different inlet pressure and temperature for fuel.
{"title":"CFD Analysis of the Combustion of Hydrogen Fuel on a CFM56-3 Combustor","authors":"R. Domingues, F. Brójo, Pedro Oliveira","doi":"10.1115/imece2022-95371","DOIUrl":"https://doi.org/10.1115/imece2022-95371","url":null,"abstract":"\u0000 In the present work is made an overview of the use of hydrogen in aviation, the modifications needed to convert a conventional gas turbine to use hydrogen and a CFD simulation of an existent gas turbine burning hydrogen. The CFD simulation was done in a CFM56-3 combustor burning Jet A (as a reference standard) and hydrogen, with the intention of evaluate the viability of conversion of existent gas turbines to hydrogen, in a combustion point of view, by analyzing the emissions through ICAO’s LTO cycle while burning this fuel. ANSYS Fluent 2020R2 was the software used to perform the numerical study. The RSM was the viscous model used. Only the NOx emissions were assessed as pollutant once the hydrogen combustion products are reduced to water vapor and NOx. These emissions were evaluated through a detailed mechanism and the NOx model available on ANSYS to get a better concordance with the ICAO’s values. During this study, several sensibility studies were carried out for hydrogen burn, for instance, the analysis of the air flow with/without swirl in the primary zone and different inlet pressure and temperature for fuel.","PeriodicalId":146276,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization and Applications; Advances in Aerospace Technology","volume":"94 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131771077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Sierra, H. Scott, Darwin Pray, Z. Polus, P. Iglesias
Friction and wear are inherent problems in mechanical systems, leading to about 23% world’s total energy usage. However, energy losses could be reduced by up to 40% using high-performance lubricants. In order to meet these objectives, Ionic liquids have been studied for more than two decades. Ionic liquids are a class of synthetic salts with melting points below 100 °C due to their asymmetric chemical structure. This feature confers them remarkably interesting physicochemical properties. Moreover, the delocalized charge in their functional groups enables them to react with metal surfaces through the formation of protective layers that prevent them against contact. Ionic liquids are generally categorized based on the nature of their cation into aprotic ionic liquids and protic ionic liquids. Even though aprotic ionic liquids have been proved as neat lubricants and additives with great performance, their applicability is limited as a consequence of the complexity of their synthesis. On the contrary, protic ionic liquids can be easily obtained through proton transfer from a Brønsted acid to a Brønsted base. In this study, two borate-based PILs, N-methylethanolamine 1,2-dodecanediolborate and N’N-dimethylethanolamine 1,2-dodecanediolborate, were synthesized, with same anion and different ammonium cation. Their lubricating abilities were investigated as neat lubricants on steel-steel contact at room temperature, using a custom-designed ball-on-flat reciprocating tribometer. Each protic ionic liquid was tested using ground and polished steel disks and two levels of normal force and frequency. Results showed that the surface finish have an important influence on the lubricating performance of these ordered fluids. In addition, frequency was found to have an influence on the wear mechanisms on steel surfaces.
{"title":"Effects of Surface Finish and Molecular Structure on the Lubricating Ability of Borate-Based Protic Ionic Liquids","authors":"A. Sierra, H. Scott, Darwin Pray, Z. Polus, P. Iglesias","doi":"10.1115/imece2022-95163","DOIUrl":"https://doi.org/10.1115/imece2022-95163","url":null,"abstract":"\u0000 Friction and wear are inherent problems in mechanical systems, leading to about 23% world’s total energy usage. However, energy losses could be reduced by up to 40% using high-performance lubricants.\u0000 In order to meet these objectives, Ionic liquids have been studied for more than two decades. Ionic liquids are a class of synthetic salts with melting points below 100 °C due to their asymmetric chemical structure. This feature confers them remarkably interesting physicochemical properties. Moreover, the delocalized charge in their functional groups enables them to react with metal surfaces through the formation of protective layers that prevent them against contact. Ionic liquids are generally categorized based on the nature of their cation into aprotic ionic liquids and protic ionic liquids. Even though aprotic ionic liquids have been proved as neat lubricants and additives with great performance, their applicability is limited as a consequence of the complexity of their synthesis. On the contrary, protic ionic liquids can be easily obtained through proton transfer from a Brønsted acid to a Brønsted base.\u0000 In this study, two borate-based PILs, N-methylethanolamine 1,2-dodecanediolborate and N’N-dimethylethanolamine 1,2-dodecanediolborate, were synthesized, with same anion and different ammonium cation. Their lubricating abilities were investigated as neat lubricants on steel-steel contact at room temperature, using a custom-designed ball-on-flat reciprocating tribometer. Each protic ionic liquid was tested using ground and polished steel disks and two levels of normal force and frequency.\u0000 Results showed that the surface finish have an important influence on the lubricating performance of these ordered fluids. In addition, frequency was found to have an influence on the wear mechanisms on steel surfaces.","PeriodicalId":146276,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization and Applications; Advances in Aerospace Technology","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125614209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Patrick Ehi Imoisili, E. Nwanna, George Enebe, T. Jen
Sound is produced by the fluctuation of oscillation waves caused by variations in pressure in a medium containing various frequency ranges, which can be detected by either an animal or a human auditory apparatus and then transferred to the brain for analysis. Noise can be diminished and controlled by using absorptive materials. This is necessary because noise has a negative effect on public health, sharing of knowledge, and serenity, and it is getting worse every day as a result of urbanization and increased affiliated functions. Utilization of natural and synthetic reinforced polymer composites in noise pollution control is an emerging area of research. Natural fibers could potentially replace synthetic fibre reinforced composites due to their low impact on human health and environmental friendliness, according to research. Though academics have been excited about studying their mechanical features, little attention has been paid to quantifying their sound reduction behaviours. Natural fibers, when interacting with a variety of sound frequency and intensity, the varied structures of sound absorbing materials, such as porous structure, hollow structure, multi-dimensional size and length structure, or solid composite materials, having their own distinctive sound absorbing capabilities. This study aims to develop and examine the void content, impact, hardness and acoustic properties of a natural fibre reinforced biocomposites. Natural fibre was extracted from plantain (Musa paradisiacal) fibre (PF), using the water retting method. Extracted fibre wasd used to prepare a fibre reinforced biocomposite using an epoxy resin as the matrix. Biocomposite with 5, 10, 15 and 20 (Wt. %) PF content were fabricated. Impact, hardness and void content analysis was conducted on prepared biocomposite in triplicate. Surface morphology of the fracture surface of prepared biocomposite was examine using a scanning electron microscope (SEM). Porosity and sound absorption coefficient properties of the fibre reinforced biocomposite were also investigated. Test analysis shows that impact, hardness and void content of the biocomposite, increases as PF content increases. Maximum hardness and impact strength were observed at 15 (w %). SEM analysis, shows the existence of cavities on the fracture surface, together with rough fibre surfaces that easily trap air, and this feature tends to boost the biocomposite’s sound absorption qualities.The sound absorption coefficient shows improvement as fibre volume increases in the bio composite. Results suggest that of PF reinforced biocomposites could be less costly, feasible and ecologically superior alternatives to synthetic fibre composites for acoustic applications in areas like building architecture and automotive industries.
声音是由含有不同频率范围的介质中压力变化引起的振荡波的波动产生的，这种波动可以被动物或人类的听觉器官检测到，然后转移到大脑中进行分析。使用吸声材料可以减少和控制噪音。这是必要的，因为噪音对公共健康、知识共享和宁静有负面影响，而且由于城市化和附属功能的增加，噪音日益恶化。利用天然和合成增强聚合物复合材料控制噪声污染是一个新兴的研究领域。根据一项研究，由于天然纤维对人体健康的影响较小，而且对环境友好，因此它们有可能取代合成纤维增强复合材料。虽然学术界一直热衷于研究它们的力学特性，但很少有人关注它们的减音行为的量化。天然纤维在与各种声音频率和强度相互作用时，吸声材料的各种结构，如多孔结构、中空结构、多维尺寸和长度结构，或固体复合材料等，都具有各自独特的吸声能力。本研究旨在开发和研究天然纤维增强生物复合材料的空隙含量、冲击、硬度和声学性能。采用水蒸馏法从车前草(Musa paradacal)纤维中提取天然纤维。提取的纤维用于制备以环氧树脂为基体的纤维增强生物复合材料。制备了PF含量分别为5、10、15和20 (Wt. %)的生物复合材料。对制备的生物复合材料进行了冲击、硬度和孔隙含量分析。用扫描电镜观察了制备的生物复合材料断口表面形貌。研究了纤维增强生物复合材料的孔隙率和吸声系数。试验分析表明，随着酚醛含量的增加，生物复合材料的冲击强度、硬度和孔隙率均有所增加。最大硬度和冲击强度为15 (w %)。扫描电镜分析显示，在断裂表面存在空洞，以及粗糙的纤维表面，容易捕获空气，这一特征倾向于提高生物复合材料的吸声质量。生物复合材料的吸声系数随着纤维体积的增加而提高。结果表明，在建筑和汽车工业等声学应用领域，酚醛增强生物复合材料可能是合成纤维复合材料成本更低、可行且生态更优越的替代品。
{"title":"Investigation of the Acoustic Performance of Plantain (Musa Paradisiacal) Fibre Reinforced Epoxy Biocomposite","authors":"Patrick Ehi Imoisili, E. Nwanna, George Enebe, T. Jen","doi":"10.1115/imece2022-94773","DOIUrl":"https://doi.org/10.1115/imece2022-94773","url":null,"abstract":"\u0000 Sound is produced by the fluctuation of oscillation waves caused by variations in pressure in a medium containing various frequency ranges, which can be detected by either an animal or a human auditory apparatus and then transferred to the brain for analysis. Noise can be diminished and controlled by using absorptive materials. This is necessary because noise has a negative effect on public health, sharing of knowledge, and serenity, and it is getting worse every day as a result of urbanization and increased affiliated functions. Utilization of natural and synthetic reinforced polymer composites in noise pollution control is an emerging area of research. Natural fibers could potentially replace synthetic fibre reinforced composites due to their low impact on human health and environmental friendliness, according to research. Though academics have been excited about studying their mechanical features, little attention has been paid to quantifying their sound reduction behaviours. Natural fibers, when interacting with a variety of sound frequency and intensity, the varied structures of sound absorbing materials, such as porous structure, hollow structure, multi-dimensional size and length structure, or solid composite materials, having their own distinctive sound absorbing capabilities. This study aims to develop and examine the void content, impact, hardness and acoustic properties of a natural fibre reinforced biocomposites. Natural fibre was extracted from plantain (Musa paradisiacal) fibre (PF), using the water retting method. Extracted fibre wasd used to prepare a fibre reinforced biocomposite using an epoxy resin as the matrix. Biocomposite with 5, 10, 15 and 20 (Wt. %) PF content were fabricated. Impact, hardness and void content analysis was conducted on prepared biocomposite in triplicate. Surface morphology of the fracture surface of prepared biocomposite was examine using a scanning electron microscope (SEM). Porosity and sound absorption coefficient properties of the fibre reinforced biocomposite were also investigated. Test analysis shows that impact, hardness and void content of the biocomposite, increases as PF content increases. Maximum hardness and impact strength were observed at 15 (w %). SEM analysis, shows the existence of cavities on the fracture surface, together with rough fibre surfaces that easily trap air, and this feature tends to boost the biocomposite’s sound absorption qualities.The sound absorption coefficient shows improvement as fibre volume increases in the bio composite. Results suggest that of PF reinforced biocomposites could be less costly, feasible and ecologically superior alternatives to synthetic fibre composites for acoustic applications in areas like building architecture and automotive industries.","PeriodicalId":146276,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization and Applications; Advances in Aerospace Technology","volume":"105 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115853788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. P. Smith, P. Cavallaro, Jacob O'Donnell, Eric A. Warner, Nicholas A. Valm, Nick Gencarelle
This research study investigated the flame-smoke-toxicity (FST) behaviors of water-based, nontoxic, and lightweight coating materials as thermal insulation for fiber-reinforced polymer (FRP) composites. Material experiments were conducted to evaluate the thermal and mechanical performances of these materials in two forms, namely as coatings on and matrices in structural composites. The present research evaluated the thermal protection performance of a nontoxic, aqueous coating material (SBS-1607[1]) demonstrated on carbon- and glass fiber-reinforced epoxy composites. The SBS-1607 coating is a ceramic particulate-filled thermoset material. The SBS-1607 coating does not produce toxic gases during a burn event and can be used as novel matrix material. The SBS-1607 material was applied as thin coatings on glass fiber (GF) and carbon fiber (CF) epoxy laminated plates. The dimensions of both laminates were 8 inches by 8 inches by 0.197 inches (203.2 mm by 203.2 mm by 5.00 mm). The thickness of the SBS-1607 coating was 0.025 inches (0.67 mm). The maximum temperatures measured from the thermocouple for the uncoated GF and CF samples were 158.7°F and 431.1°F, respectively; the inclusion of the SBS-1607 coating on the GF and CF samples reduced their maximum temperatures to 144.6°F and 227.2°F, respectively. Residual tensile strengths and elastic moduli were used as indicators of thermal damage in the matrix. Visible damage zones were approximated using surface measurements. The coated GF and CF burned composite specimens respectively had 71.85% and 151.14% higher UTS than their uncoated counterpart; the GF and CF specimens with the SBS-1607 coating therefore sustained less damage after the thermal event test.
本研究研究了水基、无毒、轻质涂层材料作为纤维增强聚合物(FRP)复合材料隔热材料的火焰-烟雾毒性(FST)行为。通过材料实验，评价了这些材料在结构复合材料中作为涂层和基体两种形式的热力学性能。本研究评估了一种无毒的水性涂层材料(SBS-1607[1])在碳和玻璃纤维增强环氧复合材料上的热防护性能。SBS-1607涂层是一种陶瓷颗粒填充的热固性材料。SBS-1607涂层在燃烧过程中不会产生有毒气体，可以用作新型基体材料。将SBS-1607材料作为薄涂层应用于玻璃纤维(GF)和碳纤维(CF)环氧复合板上。两种层压板的尺寸均为8英寸× 8英寸× 0.197英寸(203.2 mm × 203.2 mm × 5.00 mm)。SBS-1607涂层的厚度为0.025英寸(0.67毫米)。未涂覆的GF和CF样品热电偶测得的最高温度分别为158.7°F和431.1°F;在GF和CF样品上加入SBS-1607涂层后，其最高温度分别降至144.6°F和227.2°F。用残余拉伸强度和弹性模量作为基体热损伤的指标。使用表面测量近似可见损伤区域。包覆的GF和CF燃烧复合材料的UTS分别比未包覆的高71.85%和151.14%;因此，采用SBS-1607涂层的GF和CF试样在热事件试验后受到的损伤较小。
{"title":"Mechanical Characterization of Thermally Insulated Composites","authors":"M. P. Smith, P. Cavallaro, Jacob O'Donnell, Eric A. Warner, Nicholas A. Valm, Nick Gencarelle","doi":"10.1115/imece2022-95165","DOIUrl":"https://doi.org/10.1115/imece2022-95165","url":null,"abstract":"\u0000 This research study investigated the flame-smoke-toxicity (FST) behaviors of water-based, nontoxic, and lightweight coating materials as thermal insulation for fiber-reinforced polymer (FRP) composites. Material experiments were conducted to evaluate the thermal and mechanical performances of these materials in two forms, namely as coatings on and matrices in structural composites. The present research evaluated the thermal protection performance of a nontoxic, aqueous coating material (SBS-1607[1]) demonstrated on carbon- and glass fiber-reinforced epoxy composites. The SBS-1607 coating is a ceramic particulate-filled thermoset material. The SBS-1607 coating does not produce toxic gases during a burn event and can be used as novel matrix material.\u0000 The SBS-1607 material was applied as thin coatings on glass fiber (GF) and carbon fiber (CF) epoxy laminated plates. The dimensions of both laminates were 8 inches by 8 inches by 0.197 inches (203.2 mm by 203.2 mm by 5.00 mm). The thickness of the SBS-1607 coating was 0.025 inches (0.67 mm). The maximum temperatures measured from the thermocouple for the uncoated GF and CF samples were 158.7°F and 431.1°F, respectively; the inclusion of the SBS-1607 coating on the GF and CF samples reduced their maximum temperatures to 144.6°F and 227.2°F, respectively.\u0000 Residual tensile strengths and elastic moduli were used as indicators of thermal damage in the matrix. Visible damage zones were approximated using surface measurements. The coated GF and CF burned composite specimens respectively had 71.85% and 151.14% higher UTS than their uncoated counterpart; the GF and CF specimens with the SBS-1607 coating therefore sustained less damage after the thermal event test.","PeriodicalId":146276,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization and Applications; Advances in Aerospace Technology","volume":"1246 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125208926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The unsteady shock dynamics occurring in a numerically simulated unstarting scramjet isolator are examined using a novel model order reduction technique. The key challenges associated with the non-stationary nature of the phenomenon are overcome by leveraging a combination of Empirical Mode Decomposition (EMD) followed by time dependent snapshot shifting. The EMD method serves two purposes: to identify the oscillation modes of the unstarting shock train and to subsequently use the calculated non-stationary residual function to invoke a translating frame of reference that is co-moving with the unstarting shock system. Each snapshot is then shifted into the determined reference frame and subsequently windowed in space, creating a smaller, subset of snapshots from the original database. The windowing is informed by the physics of pseudo-shocks, and has the benefits of ensuring that each new snapshot contains the entire unstarting shock train, while simultaneously preventing the effects of circular shifting that have plagued other model order reduction techniques based on shift operators. When applied to the unstart problem, the shifting and windowing technique presents a more statistically stationary view of the unstarting shock dynamics in the frame of reference of the moving shock train. Dynamically relevant modes associated with upstream and downstream propagating pressure waves at the peak shock oscillation frequency in the boundary layers and separation regions are further extracted from the shifted and windowed snapshots using the sparsity promoting Dynamic Mode Decomposition algorithm.
{"title":"Model Order Reduction of Scramjet Isolator Shock Dynamics During Unstart","authors":"Jack Sullivan, D. Gaitonde","doi":"10.1115/imece2022-94316","DOIUrl":"https://doi.org/10.1115/imece2022-94316","url":null,"abstract":"\u0000 The unsteady shock dynamics occurring in a numerically simulated unstarting scramjet isolator are examined using a novel model order reduction technique. The key challenges associated with the non-stationary nature of the phenomenon are overcome by leveraging a combination of Empirical Mode Decomposition (EMD) followed by time dependent snapshot shifting. The EMD method serves two purposes: to identify the oscillation modes of the unstarting shock train and to subsequently use the calculated non-stationary residual function to invoke a translating frame of reference that is co-moving with the unstarting shock system. Each snapshot is then shifted into the determined reference frame and subsequently windowed in space, creating a smaller, subset of snapshots from the original database. The windowing is informed by the physics of pseudo-shocks, and has the benefits of ensuring that each new snapshot contains the entire unstarting shock train, while simultaneously preventing the effects of circular shifting that have plagued other model order reduction techniques based on shift operators. When applied to the unstart problem, the shifting and windowing technique presents a more statistically stationary view of the unstarting shock dynamics in the frame of reference of the moving shock train. Dynamically relevant modes associated with upstream and downstream propagating pressure waves at the peak shock oscillation frequency in the boundary layers and separation regions are further extracted from the shifted and windowed snapshots using the sparsity promoting Dynamic Mode Decomposition algorithm.","PeriodicalId":146276,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization and Applications; Advances in Aerospace Technology","volume":"41 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132389628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Traditional multiscale methods homogenize a beam-like structure into a material point in 1-D continuum with effective properties computed over a structure gene in terms of a cross-section or a 3D segment with spanwise periodicity. Such methods lose accuracy when dealing with real world beam-like structures usually not uniform or periodic along the spanwise direction. Thus, traditional multiscale methods cannot be rigorously applied to these cases. In our previous work, a new multiscale method was proposed based on a novel application of the recently developed Mechanics of Structure Genome (MSG) to analyze beam-like structures. Beam-like structures were homogenized into a series of 3-node Heterogeneous Beam Elements (HBE) with 18 × 18 effective beam element stiffness matrices, which were used as input for one-dimensional beam analyses. However, due to the shape function limitations, HBE could not handle transverse shear loads. In this work, the shape functions and the MSG theory are further modified to enable capabilities of HBE for transverse shear loads. Using the macroscopic behavior of the beam elements as input, dehomogenization can be performed to predict the local stresses and strains in the original structure. Two examples are used (a periodic composite beam and a tapered beam) to demonstrate the capability of this improved HBE.
{"title":"Heterogeneous Beam Element Based on Timoshenko Beam Model","authors":"R. Chiu, Wenbin Yu","doi":"10.1115/imece2022-94187","DOIUrl":"https://doi.org/10.1115/imece2022-94187","url":null,"abstract":"\u0000 Traditional multiscale methods homogenize a beam-like structure into a material point in 1-D continuum with effective properties computed over a structure gene in terms of a cross-section or a 3D segment with spanwise periodicity. Such methods lose accuracy when dealing with real world beam-like structures usually not uniform or periodic along the spanwise direction. Thus, traditional multiscale methods cannot be rigorously applied to these cases. In our previous work, a new multiscale method was proposed based on a novel application of the recently developed Mechanics of Structure Genome (MSG) to analyze beam-like structures. Beam-like structures were homogenized into a series of 3-node Heterogeneous Beam Elements (HBE) with 18 × 18 effective beam element stiffness matrices, which were used as input for one-dimensional beam analyses. However, due to the shape function limitations, HBE could not handle transverse shear loads. In this work, the shape functions and the MSG theory are further modified to enable capabilities of HBE for transverse shear loads. Using the macroscopic behavior of the beam elements as input, dehomogenization can be performed to predict the local stresses and strains in the original structure. Two examples are used (a periodic composite beam and a tapered beam) to demonstrate the capability of this improved HBE.","PeriodicalId":146276,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization and Applications; Advances in Aerospace Technology","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132462195","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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