Hüseyin Karabiyik, Osman Eroglu, Muhammed Metin Eskimez, Berk Oncu Oncul, Muhammet Tayyip Yilmaz, İstemihan Gökdağ, R. Gorguluarslan
The most important need in the aviation industry is the realization of high-strength and lightweight designs. For this reason, topology optimization methods have become widespread recently. Besides, meeting the natural frequency requirements is one of the important design elements. However, topology optimization with stiffness maximization requires a static finite element analysis evaluation while the natural frequency calculation requires a modal analysis evaluation. Using these two different analysis procedures at the same time in the topology optimization process, on the other hand, is a challenging task. To address this challenge, a topology optimization methodology that accounts for the natural frequency constraint in a compliance minimization process is presented in this study. Since the commercial software can either minimize compliance or minimize the vibration frequency at one time, using these two different analysis procedures at the same time together stands out as an innovative aspect of this study. The applicability of the developed methodology is shown for two bracket designs; namely, the so-called GE bracket and a real-world satellite bracket with natural frequency and mass constraints. The prototypes of the designs are fabricated using the additive manufacturing technique.
{"title":"A Topology Optimization Methodology With Vibration Constraint for an Aerospace Bracket Design","authors":"Hüseyin Karabiyik, Osman Eroglu, Muhammed Metin Eskimez, Berk Oncu Oncul, Muhammet Tayyip Yilmaz, İstemihan Gökdağ, R. Gorguluarslan","doi":"10.1115/imece2022-95843","DOIUrl":"https://doi.org/10.1115/imece2022-95843","url":null,"abstract":"\u0000 The most important need in the aviation industry is the realization of high-strength and lightweight designs. For this reason, topology optimization methods have become widespread recently. Besides, meeting the natural frequency requirements is one of the important design elements. However, topology optimization with stiffness maximization requires a static finite element analysis evaluation while the natural frequency calculation requires a modal analysis evaluation. Using these two different analysis procedures at the same time in the topology optimization process, on the other hand, is a challenging task. To address this challenge, a topology optimization methodology that accounts for the natural frequency constraint in a compliance minimization process is presented in this study. Since the commercial software can either minimize compliance or minimize the vibration frequency at one time, using these two different analysis procedures at the same time together stands out as an innovative aspect of this study. The applicability of the developed methodology is shown for two bracket designs; namely, the so-called GE bracket and a real-world satellite bracket with natural frequency and mass constraints. The prototypes of the designs are fabricated using the additive manufacturing technique.","PeriodicalId":146276,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization and Applications; Advances in Aerospace Technology","volume":"140 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":"115757937","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 surge of growth in additive manufacturing (AM) has brought about increased interest in smart devices and advanced manufacturing. Fused Filament Fabrication (FFF) often presents itself as the starting equipment for industrial applications and hobby enthusiasts. The introduction of conductive polymer composites into FFF has brought about widespread capabilities, particularly in the areas of flexible sensors, printed electronics, and other multi-functional materials. Piezoresistive sensors have especially been of interest due to their use in wearable electronics and structural health monitoring coupled with the increasing commercial availability of conductive thermoplastic filaments. However, while much research has been devoted to the geometrical parameters in piezoresistive sensors in conventional manufacturing, little has been investigated with respect to additive manufacturing. Here, we present a unique method for tailoring the sensitivity of FFF produced flexible pressure sensors by altering the infill printing settings, therefore affecting the electromechanical response. Sensors were printed using common infill patterns (Concentric, Grid, Gyroid, Honeycomb, Lines, and Cubic) and low infill percentages (5–15%) capable of sensitivities of 2,010 kPa−1 under an applied pressure of up to 60 kPa and 530 kPa−1 under an applied pressure of up to 950 kPa. This work demonstrates the ease-of-fabrication and performance of flexible pressure sensors using an inexpensive and simple fabrication method.
{"title":"Effects of Infill on the Additive Manufacturing of Piezoresistive Pressure Sensors","authors":"James D. Banks, Meysam Khaleghian, Anahita Emami","doi":"10.1115/imece2022-91749","DOIUrl":"https://doi.org/10.1115/imece2022-91749","url":null,"abstract":"\u0000 The surge of growth in additive manufacturing (AM) has brought about increased interest in smart devices and advanced manufacturing. Fused Filament Fabrication (FFF) often presents itself as the starting equipment for industrial applications and hobby enthusiasts. The introduction of conductive polymer composites into FFF has brought about widespread capabilities, particularly in the areas of flexible sensors, printed electronics, and other multi-functional materials. Piezoresistive sensors have especially been of interest due to their use in wearable electronics and structural health monitoring coupled with the increasing commercial availability of conductive thermoplastic filaments. However, while much research has been devoted to the geometrical parameters in piezoresistive sensors in conventional manufacturing, little has been investigated with respect to additive manufacturing. Here, we present a unique method for tailoring the sensitivity of FFF produced flexible pressure sensors by altering the infill printing settings, therefore affecting the electromechanical response. Sensors were printed using common infill patterns (Concentric, Grid, Gyroid, Honeycomb, Lines, and Cubic) and low infill percentages (5–15%) capable of sensitivities of 2,010 kPa−1 under an applied pressure of up to 60 kPa and 530 kPa−1 under an applied pressure of up to 950 kPa. This work demonstrates the ease-of-fabrication and performance of flexible pressure sensors using an inexpensive and simple fabrication method.","PeriodicalId":146276,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization and Applications; Advances in Aerospace Technology","volume":"31 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":"121908877","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}
P. Shankar, P. Marayong, T. Strybel, V. Battiste, H. Nguyen, Justin Cheung, Jesús Viramontes
Urban Air Mobility (UAM) has the potential to transform the transportation landscape for movement of small number of passengers and good across citywide distances. However, the successful integration of such a concept into the National Air Space will require a significant effort focused on development and testing of both the vehicles and the supporting infrastructure. In this paper, the development of a virtual reality (VR) environment for testing urban air mobility operation concepts has been presented. The VR environment that is simulated in a CAVE system includes a quadcopter type vehicle that can transport passengers across citywide distances. The design features are primarily focused on cockpit input and display interfaces while the vehicle’s motion is sufficiently realistic. An experimental design to execute a mission in San Francisco city has been tested by participants with and without prior piloting experience. Preliminary analysis of the flight data collected indicates minimal impact of prior flight experience in completing the mission.
{"title":"Urban Air Mobility: Design of a Virtual Reality Testbed and Experiments for Human Factors Evaluation","authors":"P. Shankar, P. Marayong, T. Strybel, V. Battiste, H. Nguyen, Justin Cheung, Jesús Viramontes","doi":"10.1115/imece2022-95152","DOIUrl":"https://doi.org/10.1115/imece2022-95152","url":null,"abstract":"\u0000 Urban Air Mobility (UAM) has the potential to transform the transportation landscape for movement of small number of passengers and good across citywide distances. However, the successful integration of such a concept into the National Air Space will require a significant effort focused on development and testing of both the vehicles and the supporting infrastructure. In this paper, the development of a virtual reality (VR) environment for testing urban air mobility operation concepts has been presented. The VR environment that is simulated in a CAVE system includes a quadcopter type vehicle that can transport passengers across citywide distances. The design features are primarily focused on cockpit input and display interfaces while the vehicle’s motion is sufficiently realistic. An experimental design to execute a mission in San Francisco city has been tested by participants with and without prior piloting experience. Preliminary analysis of the flight data collected indicates minimal impact of prior flight experience in completing the mission.","PeriodicalId":146276,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization and Applications; Advances in Aerospace Technology","volume":"6 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":"128764920","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}
Electrospun multiwalled carbon nanotubes (MWCNTs)/epoxy nanofibers are placed between the layers of standard carbon fiber-reinforced polymer (CFRP) prepreg composites to improve their physical and mechanical properties. As epoxy resin is a thermosetting material, it must be electrospun carefully maintaining a specific viscosity of the epoxy, and optimizing all electrospinning parameters is both costly and time-intensive. Thus, prior to implementing the different experimental techniques, a modeling methodology is an effective tool for regulating the electrospinning process’s contributing factors. In this case, it is observed that having a smaller diameter of MWCNT/epoxy is very critical because MWCNTs stay aligned inside epoxy nanofibers with a smaller diameter than nanofibers with a bigger diameter. Those aligned MWCNTs can lead up to a 29% increase in the flexural strength of a CFRP structure. different Employing artificial neural networks (ANN) models, the present study investigates the effect of key parameters on the fiber diameter and uniformity of electrospun MWCNT/epoxy nanofibers. The goal of this work is to implement and differentiate the multilayer perceptron (MLP) feedforward backpropagation ANN, radial basis function neural network (RBFNN), and very commonly used support vector machine (SVM) methods in order to construct computational models for predicting diameter of MWCNT/epoxy nanofiber with high accuracy.
{"title":"Implementation of ANN Modeling Techniques and Genetic Algorithm in the Diameter Prediction of MWCNTs/Epoxy Nanofibers for CFRP Structures","authors":"P. Biswas, P. Zende, H. Dalir, Mangilal Agarwal","doi":"10.1115/imece2022-90499","DOIUrl":"https://doi.org/10.1115/imece2022-90499","url":null,"abstract":"\u0000 Electrospun multiwalled carbon nanotubes (MWCNTs)/epoxy nanofibers are placed between the layers of standard carbon fiber-reinforced polymer (CFRP) prepreg composites to improve their physical and mechanical properties. As epoxy resin is a thermosetting material, it must be electrospun carefully maintaining a specific viscosity of the epoxy, and optimizing all electrospinning parameters is both costly and time-intensive. Thus, prior to implementing the different experimental techniques, a modeling methodology is an effective tool for regulating the electrospinning process’s contributing factors. In this case, it is observed that having a smaller diameter of MWCNT/epoxy is very critical because MWCNTs stay aligned inside epoxy nanofibers with a smaller diameter than nanofibers with a bigger diameter. Those aligned MWCNTs can lead up to a 29% increase in the flexural strength of a CFRP structure. different Employing artificial neural networks (ANN) models, the present study investigates the effect of key parameters on the fiber diameter and uniformity of electrospun MWCNT/epoxy nanofibers. The goal of this work is to implement and differentiate the multilayer perceptron (MLP) feedforward backpropagation ANN, radial basis function neural network (RBFNN), and very commonly used support vector machine (SVM) methods in order to construct computational models for predicting diameter of MWCNT/epoxy nanofiber with high accuracy.","PeriodicalId":146276,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization and Applications; Advances in Aerospace Technology","volume":"37 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":"115892250","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}
Christopher Kasprzak, C. Hoffman, Ruey-Hung Chen, Liang Zhu, Ronghui Ma
This study investigates the directional solidification behavior and the effects of initial freezing temperature on the formation of porous structure. The aqueous suspension with 10 vol.% cupric oxide (CuO) particles is prepared by mixing CuO particles, polyvinyl alcohol, and polyvinylpyrrolidone in deionized water. Additionally, potassium hydroxide is used to adjust the pH values between 8–10. Based on the measurement of the suspension viscosity, the optimal amount of the dispersant and the range of pH values that enable a well dispersed and stable suspension is identified. The freezing curves of the suspensions are measured to obtain the freezing point of the suspension as well as the effect of the potassium hydroxide on the freezing behavior. The suspensions then undergo directional freezing under various initial freezing temperatures. After sublimation under a near vacuum pressure, the green samples are infiltrated with epoxy to facilitate visualization and characterization of the pore morphology and orientation using an optical microscope. We believe that the obtained relationship between the freezing conditions, and the structural specifics of freeze-cast porous CuO lays the groundwork for freeze-cast porous copper with desirable pore morphology and structures for thermal management and energy storage applications.
{"title":"Using Freeze-Casting Method to Create Lamellar Copper Structures – An Experimental Study of the Freezing Behavior of Cupric Oxide Colloidal Suspensions","authors":"Christopher Kasprzak, C. Hoffman, Ruey-Hung Chen, Liang Zhu, Ronghui Ma","doi":"10.1115/imece2022-88559","DOIUrl":"https://doi.org/10.1115/imece2022-88559","url":null,"abstract":"\u0000 This study investigates the directional solidification behavior and the effects of initial freezing temperature on the formation of porous structure. The aqueous suspension with 10 vol.% cupric oxide (CuO) particles is prepared by mixing CuO particles, polyvinyl alcohol, and polyvinylpyrrolidone in deionized water. Additionally, potassium hydroxide is used to adjust the pH values between 8–10. Based on the measurement of the suspension viscosity, the optimal amount of the dispersant and the range of pH values that enable a well dispersed and stable suspension is identified. The freezing curves of the suspensions are measured to obtain the freezing point of the suspension as well as the effect of the potassium hydroxide on the freezing behavior. The suspensions then undergo directional freezing under various initial freezing temperatures. After sublimation under a near vacuum pressure, the green samples are infiltrated with epoxy to facilitate visualization and characterization of the pore morphology and orientation using an optical microscope. We believe that the obtained relationship between the freezing conditions, and the structural specifics of freeze-cast porous CuO lays the groundwork for freeze-cast porous copper with desirable pore morphology and structures for thermal management and energy storage applications.","PeriodicalId":146276,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization and Applications; Advances in Aerospace Technology","volume":"138 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":"131576755","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}
Zipeng Guo, Ruizhe Yang, Jun Liu, J. Armstrong, Ruogang Zhao, Chi Zhou
A fast additive manufacturing (AM) protocol to fabricate multi-network hydrogels is reported in this work. The gas-permeable PDMS film creates a polymerization-inhibition zone, facilitating the continuous stereolithography (SLA) 3D printing of hydrogels. The fabricated multi-bonding network integrates the rigid covalent bonding and the tough ionic bonding. The elastic modulus and strength could be effectively tuned by varying the ratio between the covalent and ionic bonding networks to fulfill various loading conditions. The printed triply periodic minimal structures (TPMS) hydrogels demonstrated high compressibility for up to 80% recoverable strain. Moreover, the dried TPMS hydrogels show novel energy absorption properties. We fabricated uniform and gradient hydrogels and compared their energy absorption capability. The anisotropy and quasi-isotropy behavior of TPMS structures were analyzed using simulation studies, providing insights into designing and controlling the TPMS structures for energy absorption. The results showed that the gradient TPMS hydrogels are preferable energy absorbers and have potential applications in impact resistance and absorption.
{"title":"Continuous Stereolithography 3D Printing of Multi-Network Hydrogels in Triply Periodic Minimal Structures (TPMS) With Tunable Mechanical Strength for Energy Absorption","authors":"Zipeng Guo, Ruizhe Yang, Jun Liu, J. Armstrong, Ruogang Zhao, Chi Zhou","doi":"10.1115/imece2022-95806","DOIUrl":"https://doi.org/10.1115/imece2022-95806","url":null,"abstract":"A fast additive manufacturing (AM) protocol to fabricate multi-network hydrogels is reported in this work. The gas-permeable PDMS film creates a polymerization-inhibition zone, facilitating the continuous stereolithography (SLA) 3D printing of hydrogels. The fabricated multi-bonding network integrates the rigid covalent bonding and the tough ionic bonding. The elastic modulus and strength could be effectively tuned by varying the ratio between the covalent and ionic bonding networks to fulfill various loading conditions. The printed triply periodic minimal structures (TPMS) hydrogels demonstrated high compressibility for up to 80% recoverable strain. Moreover, the dried TPMS hydrogels show novel energy absorption properties. We fabricated uniform and gradient hydrogels and compared their energy absorption capability. The anisotropy and quasi-isotropy behavior of TPMS structures were analyzed using simulation studies, providing insights into designing and controlling the TPMS structures for energy absorption. The results showed that the gradient TPMS hydrogels are preferable energy absorbers and have potential applications in impact resistance and absorption.","PeriodicalId":146276,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization and Applications; Advances in Aerospace Technology","volume":"33 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":"130971068","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 use of rotating beam-like structures is very common in engineering systems including power generation machines, automotive systems, aircraft structures, energy harvesting systems, and many more. The dynamic response analysis of these systems is of utmost importance for proper prediction of their performance and life. Among different outcomes of the dynamic response analysis, one of the major parameters is the frequency of the free vibration. Because of realistic loads and couplings between different degrees-of-freedom of motion, for majority of the cases, there is no analytical solution available. Hence, the governing equations need to be solved numerically. There are several numerical approaches available to solve for the coupled frequency of free vibration of rotating beams. In this paper, an overview of the different numerical methods is presented for coupled, free vibration analysis of slender, rotating beam-like structures. Three different degrees-of-freedom including out-of-plane bending, in-plane bending, and torsional deformations are considered for the most general case. At first, the eigen value problem of the coupled, mathematical model of free vibration of the beam is presented analytically. Following that, the use of different numerical methods is presented with relevant examples and corresponding beam parameters. Finally, the implementation of the finite difference method is presented to compare the corresponding results with that obtained by other methods.
{"title":"Numerical Analysis of the Vibration of Slender Beams","authors":"Pratik Sarker, U. Chakravarty","doi":"10.1115/imece2022-95186","DOIUrl":"https://doi.org/10.1115/imece2022-95186","url":null,"abstract":"\u0000 The use of rotating beam-like structures is very common in engineering systems including power generation machines, automotive systems, aircraft structures, energy harvesting systems, and many more. The dynamic response analysis of these systems is of utmost importance for proper prediction of their performance and life. Among different outcomes of the dynamic response analysis, one of the major parameters is the frequency of the free vibration. Because of realistic loads and couplings between different degrees-of-freedom of motion, for majority of the cases, there is no analytical solution available. Hence, the governing equations need to be solved numerically. There are several numerical approaches available to solve for the coupled frequency of free vibration of rotating beams. In this paper, an overview of the different numerical methods is presented for coupled, free vibration analysis of slender, rotating beam-like structures. Three different degrees-of-freedom including out-of-plane bending, in-plane bending, and torsional deformations are considered for the most general case. At first, the eigen value problem of the coupled, mathematical model of free vibration of the beam is presented analytically. Following that, the use of different numerical methods is presented with relevant examples and corresponding beam parameters. Finally, the implementation of the finite difference method is presented to compare the corresponding results with that obtained by other methods.","PeriodicalId":146276,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization and Applications; Advances in Aerospace Technology","volume":"24 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":"133665185","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}
Due to the rapid growth of the aviation industry, the concentrations of hazardous pollutants in the atmosphere are rising and the need for more environment-friendly solutions is higher than ever. This study aims to test and show the benefits of hybrid-electric propulsion systems in UAVs in two possible configurations, parallel and series. The hybrid propulsion system combines a 28-cc 2-stroke internal combustion engine with a 200-watt frameless generator. As a primary approach, the engine alone with a 16-inch diameter and 12-inch pitch propeller is characterized by its torque, power and specific fuel consumption throughout the engine’s operating range. In a second approach, the hybrid component is added and a comparison between both results taken is made. Preliminary results show that parallel configuration offers lower specific fuel consumption in comparison with the engine alone. Also, the higher load on the engine used as the primary powerplant seems to promote a more stable operation, with higher throttle control and lower vibrations. In a final remark, considerations regarding the two configurations are made. These considerations aim to establish the best points to operate each architecture and which one is best suited to be implemented on a UAV depending on the mission profile.
{"title":"Hybrid-Electric Propulsion Solutions for UAV Application","authors":"Diogo Marto, F. Brójo","doi":"10.1115/imece2022-95375","DOIUrl":"https://doi.org/10.1115/imece2022-95375","url":null,"abstract":"\u0000 Due to the rapid growth of the aviation industry, the concentrations of hazardous pollutants in the atmosphere are rising and the need for more environment-friendly solutions is higher than ever. This study aims to test and show the benefits of hybrid-electric propulsion systems in UAVs in two possible configurations, parallel and series. The hybrid propulsion system combines a 28-cc 2-stroke internal combustion engine with a 200-watt frameless generator. As a primary approach, the engine alone with a 16-inch diameter and 12-inch pitch propeller is characterized by its torque, power and specific fuel consumption throughout the engine’s operating range. In a second approach, the hybrid component is added and a comparison between both results taken is made. Preliminary results show that parallel configuration offers lower specific fuel consumption in comparison with the engine alone. Also, the higher load on the engine used as the primary powerplant seems to promote a more stable operation, with higher throttle control and lower vibrations. In a final remark, considerations regarding the two configurations are made. These considerations aim to establish the best points to operate each architecture and which one is best suited to be implemented on a UAV depending on the mission profile.","PeriodicalId":146276,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization and Applications; Advances in Aerospace Technology","volume":"27 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":"128809793","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 this article, the detrimental time-averaged thrust performance of a two-dimensional elliptic symmetrical flapping airfoil at very high flapping frequencies is addressed, and an attempt is made to enhance the thrust performance by implementing two separate flapping frequencies during the downstroke and upstroke of a flapping cycle thus making it asymmetric. Three different pivot locations, three effective angle of attack amplitudes, and a specific range of St are considered for our investigation, keeping the Reynolds number fixed as 5000. In general, the downstroke flapping frequency is always selected with a value higher than the critical Strouhal number, but the upstroke flapping frequency is kept fixed as the critical Strouhal number. It is worth highlighting that the observations are periodic and swapped suitably when the flapping stroke frequency selection is reversed in the flapping cycle. Asymmetric flapping stroke configurations yield more time-averaged thrust and non-zero lift than symmetric flapping stroke at thrust degrading flapping frequency range. Interestingly, the leading edge side pivot point produces positive lift when the implementation of a faster downstroke and slower upstroke configuration. At the same time, it’s the opposite for the center and trailing edge pivot points. To understand these enhanced aerodynamic performances at high flapping frequencies, we have further analyzed the transient thrust and lift force profiles and their associated flow structures for all the pivot locations.
{"title":"Mitigation of Thrust Deterioration at a High Flapping Frequency of a 2D Airfoil in Forwarding Flight Conditions Using Asymmetric Flapping Strokes","authors":"Jit Sinha, Sohan Roy, Sunil Manohar Dash","doi":"10.1115/imece2022-95121","DOIUrl":"https://doi.org/10.1115/imece2022-95121","url":null,"abstract":"\u0000 In this article, the detrimental time-averaged thrust performance of a two-dimensional elliptic symmetrical flapping airfoil at very high flapping frequencies is addressed, and an attempt is made to enhance the thrust performance by implementing two separate flapping frequencies during the downstroke and upstroke of a flapping cycle thus making it asymmetric. Three different pivot locations, three effective angle of attack amplitudes, and a specific range of St are considered for our investigation, keeping the Reynolds number fixed as 5000. In general, the downstroke flapping frequency is always selected with a value higher than the critical Strouhal number, but the upstroke flapping frequency is kept fixed as the critical Strouhal number. It is worth highlighting that the observations are periodic and swapped suitably when the flapping stroke frequency selection is reversed in the flapping cycle. Asymmetric flapping stroke configurations yield more time-averaged thrust and non-zero lift than symmetric flapping stroke at thrust degrading flapping frequency range. Interestingly, the leading edge side pivot point produces positive lift when the implementation of a faster downstroke and slower upstroke configuration. At the same time, it’s the opposite for the center and trailing edge pivot points. To understand these enhanced aerodynamic performances at high flapping frequencies, we have further analyzed the transient thrust and lift force profiles and their associated flow structures for all the pivot locations.","PeriodicalId":146276,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization and Applications; Advances in Aerospace Technology","volume":"44 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":"127853718","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. Cornejo, H. Baykara, Natividad Garcia, J. Garcés, Walter Correa, Cecibel Frere, Julio Torres
Alkaline hybrid type cement is an interesting multi-component system that incorporates a high content of mineral additions, low content of Portland clinker (CK) (< 40%), and alkaline activator. The development of these types of cement allows a significant reduction in the clinker factor, thus leading to an economic and mainly environmental benefit.This study explores the possible development of such cement. Hybrid cement samples were prepared by alkaline activation of the natural zeolite, mainly composed of mordenite, and utilizing a NaOH solution. After mixing with OPC and with an alkaline solution, zeolite-rich tuff formed cement pastes with an activator/binder ratio of 0.5 that were cured for 24 hours at room temperature and then for 7 days underwater. The optimal alternative was evaluated based on compressive strength, quantitative X-ray diffraction, and Fourier Transform Infrared spectroscopy. As a result, the best dosage was that of 60% zeolite ruch tuffs and 40% CEM Type I showing values of compressive strength of 10 and 14 MPa at 7 and 28 days, respectively.
碱性混合型水泥是一种有趣的多组分体系，它包含高含量的矿物添加剂、低含量的硅酸盐熟料(CK)(< 40%)和碱性活化剂。开发这些类型的水泥可以显著减少熟料因素，从而带来经济效益和主要环境效益。本研究探讨了这种水泥的可能发展。以丝光沸石为主的天然沸石为原料，利用NaOH溶液进行碱性活化，制备了杂化水泥样品。与OPC和碱性溶液混合后，富沸石凝灰岩形成活化剂/粘合剂比为0.5的水泥浆体，室温固化24小时，然后在水下固化7天。基于抗压强度、定量x射线衍射和傅里叶变换红外光谱对最佳替代方案进行了评估。结果表明，最佳投加量为60%沸石凝灰岩和40% CEM I型，7天和28天的抗压强度分别为10和14 MPa。
{"title":"Preparation of Hybrid Alkaline Cement Based on Natural Zeolite As Sustainable Building Material","authors":"M. Cornejo, H. Baykara, Natividad Garcia, J. Garcés, Walter Correa, Cecibel Frere, Julio Torres","doi":"10.1115/imece2022-94558","DOIUrl":"https://doi.org/10.1115/imece2022-94558","url":null,"abstract":"\u0000 Alkaline hybrid type cement is an interesting multi-component system that incorporates a high content of mineral additions, low content of Portland clinker (CK) (< 40%), and alkaline activator. The development of these types of cement allows a significant reduction in the clinker factor, thus leading to an economic and mainly environmental benefit.This study explores the possible development of such cement. Hybrid cement samples were prepared by alkaline activation of the natural zeolite, mainly composed of mordenite, and utilizing a NaOH solution. After mixing with OPC and with an alkaline solution, zeolite-rich tuff formed cement pastes with an activator/binder ratio of 0.5 that were cured for 24 hours at room temperature and then for 7 days underwater. The optimal alternative was evaluated based on compressive strength, quantitative X-ray diffraction, and Fourier Transform Infrared spectroscopy. As a result, the best dosage was that of 60% zeolite ruch tuffs and 40% CEM Type I showing values of compressive strength of 10 and 14 MPa at 7 and 28 days, respectively.","PeriodicalId":146276,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization and Applications; Advances in Aerospace Technology","volume":"19 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":"115384702","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：