COVID-19 is a multi-spectral crisis that has added an acute layer over a panoply of complex emergencies across the world. In the process, it has not only exposed actually-existing emergencies, but also exacerbated them as the global gaze has turned inward. As a crisis, COVID-19 straddles and challenges the boundaries between humanitarianism, development and global health - the frames and categories through which emergencies are so often understood and intervened upon. Reflection on these fundamental categories is, we argue, an important geographical endeavour. Drawing on Geoffrey Bowker's analytical lens of the 'infrastructural inversion', we explore how humanitarianism has been upended by Covid-19 along two axes that are of core concern to geographers: (1) the spatial; and (2) the temporal. We first contextualise current debates on the humanitarian endeavour and its future within recent geographical research. We then set out the complex structure by which COVID-19 has been both imagined and intervened upon as a humanitarian emergency. In so doing, we then pave the way for a deeper empirical analysis of the spatial and temporal inversions that have been brought forth by COVID-19. The paper concludes by examining the conceptual value of the 'inversion' in developing geographical research agendas better attuned to the increasing porosity of humanitarianism, development and global health.
{"title":"Humanitarian inversions: COVID-19 as crisis.","authors":"Clare Herrick, Ann Kelly, Jeanne Soulard","doi":"10.1111/tran.12544","DOIUrl":"10.1111/tran.12544","url":null,"abstract":"<p><p>COVID-19 is a multi-spectral crisis that has added an acute layer over a panoply of complex emergencies across the world. In the process, it has not only exposed actually-existing emergencies, but also exacerbated them as the global gaze has turned inward. As a crisis, COVID-19 straddles and challenges the boundaries between humanitarianism, development and global health - the frames and categories through which emergencies are so often understood and intervened upon. Reflection on these fundamental categories is, we argue, an important geographical endeavour. Drawing on Geoffrey Bowker's analytical lens of the 'infrastructural inversion', we explore how humanitarianism has been upended by Covid-19 along two axes that are of core concern to geographers: (1) the spatial; and (2) the temporal. We first contextualise current debates on the humanitarian endeavour and its future within recent geographical research. We then set out the complex structure by which COVID-19 has been both imagined and intervened upon as a humanitarian emergency. In so doing, we then pave the way for a deeper empirical analysis of the spatial and temporal inversions that have been brought forth by COVID-19. The paper concludes by examining the conceptual value of the 'inversion' in developing geographical research agendas better attuned to the increasing porosity of humanitarianism, development and global health.</p>","PeriodicalId":38552,"journal":{"name":"Engineering Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9115393/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72888467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-04DOI: 10.24423/ENGTRANS.1326.20211004
Jin Xu, Xiucai Ding, Zhu Zhang, Lang Chen
The wind turbine gearbox is a critical equipment transforming the speed of the rotor hub to the generator, the condition of which is the reflection of operational efficiency and reliability of wind turbines. As the initial stage of the wind turbine gearbox, the fault feature extraction of the planetary gear set is challenging since it is prone to be affected by complicated structure, vibration from other high-speed stages and background noise. In this paper, a double Q factor wavelet-based sparse decomposition is applied to the fault feature extraction of the wind turbine planetary gearbox. Considering the sparsest wavelet coefficients, the vibration signal is iteratively decomposed into high Q and low Q components. The fault feature is generally hidden in the low Q component. With further demodulation, the fault information of planetary gears can be easily detected.
{"title":"Application of Double Q Wavelet-based Sparse Decomposition to Fault Feature Extraction of Wind Turbine Planetary Gearbox","authors":"Jin Xu, Xiucai Ding, Zhu Zhang, Lang Chen","doi":"10.24423/ENGTRANS.1326.20211004","DOIUrl":"https://doi.org/10.24423/ENGTRANS.1326.20211004","url":null,"abstract":"The wind turbine gearbox is a critical equipment transforming the speed of the rotor hub to the generator, the condition of which is the reflection of operational efficiency and reliability of wind turbines. As the initial stage of the wind turbine gearbox, the fault feature extraction of the planetary gear set is challenging since it is prone to be affected by complicated structure, vibration from other high-speed stages and background noise. In this paper, a double Q factor wavelet-based sparse decomposition is applied to the fault feature extraction of the wind turbine planetary gearbox. Considering the sparsest wavelet coefficients, the vibration signal is iteratively decomposed into high Q and low Q components. The fault feature is generally hidden in the low Q component. With further demodulation, the fault information of planetary gears can be easily detected.","PeriodicalId":38552,"journal":{"name":"Engineering Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48691336","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}
Pub Date : 2021-09-08DOI: 10.24423/ENGTRANS.1320.20210908
K. Frydrych
The paper presents the simulations of texture evolution of the AZ31B Mg alloy subjected to equal channel angular pressing (ECAP) and rotary swaging (RS) processes. It is shown that using the crystal plasticity (CP) parameters obtained by curve fitting conducted on simple mechanical tests with the aid of the evolutionary algorithm, it is possible to correctly predict the texture evolution in both processes. The influence of the initial texture as well as the CP parameters is discussed.
{"title":"Texture Evolution of Magnesium Alloy AZ31B Subjected to Severe Plastic Deformation","authors":"K. Frydrych","doi":"10.24423/ENGTRANS.1320.20210908","DOIUrl":"https://doi.org/10.24423/ENGTRANS.1320.20210908","url":null,"abstract":"The paper presents the simulations of texture evolution of the AZ31B Mg alloy subjected to equal channel angular pressing (ECAP) and rotary swaging (RS) processes. It is shown that using the crystal plasticity (CP) parameters obtained by curve fitting conducted on simple mechanical tests with the aid of the evolutionary algorithm, it is possible to correctly predict the texture evolution in both processes. The influence of the initial texture as well as the CP parameters is discussed.","PeriodicalId":38552,"journal":{"name":"Engineering Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47761140","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}
Pub Date : 2021-08-26DOI: 10.24423/ENGTRANS.1329.20210826
Abdel-Nasser Sharkawy
In this paper, the mathematical analysis of the robot effective mass is presented. The calculation of this effective mass and its ellipsoid are included. The relationship between the robot effective mass and the external force (collision) affecting the robot end-effector is investigated. The effective mass is analyzed using different robot configurations and different end-effector positions. This analysis is conducted using 2-DOF and 3-DOF planar robots and executed using MATLAB. The results from this analysis prove that the robot effective mass depends on the its configurations and end-effector position. Effective mass can thus be considered as one of the criteria in optimizing robot kinematics and configuration.
{"title":"An Investigation on the Effective Mass of the Robot: Dependence on the End-Effector Position","authors":"Abdel-Nasser Sharkawy","doi":"10.24423/ENGTRANS.1329.20210826","DOIUrl":"https://doi.org/10.24423/ENGTRANS.1329.20210826","url":null,"abstract":"In this paper, the mathematical analysis of the robot effective mass is presented. The calculation of this effective mass and its ellipsoid are included. The relationship between the robot effective mass and the external force (collision) affecting the robot end-effector is investigated. The effective mass is analyzed using different robot configurations and different end-effector positions. This analysis is conducted using 2-DOF and 3-DOF planar robots and executed using MATLAB. The results from this analysis prove that the robot effective mass depends on the its configurations and end-effector position. Effective mass can thus be considered as one of the criteria in optimizing robot kinematics and configuration.","PeriodicalId":38552,"journal":{"name":"Engineering Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42375499","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}
Pub Date : 2021-08-26DOI: 10.24423/ENGTRANS.1367.20210826
Arkadeb Mukhopadhyay, S. Sahoo
Structures, constructions and bridges in coastal areas are greatly affected by the corrosive attack of chlorides. This reduces their lifetime and leads to losses due to their maintenance. This study aims to improve the lifetime and corrosion-proof behavior of steel rebars in the saline environment (3.5% NaCl) by applying electroless Ni-Cu-P coatings with high corrosion resistance. Ni-Cu-P coating was deposited on Fe-600 steel rebars. The coating was deposited by varying bath condition parameters, such as concentration of nickel sulphate, sodium hypophosphite and copper sulphate. This led to a variation in Ni, P and Cu content, and finally, the optimal bath combination was obtained using the Taguchi-based grey relational analysis. For concentrations of 25, 10 and 0.3 g/l nickel sulphate, sodium hypophosphite and copper sulphate, enhanced corrosion resistance of the coated rebars could be achieved with 350 mV E corr and 0.4 μA/cm 2 I corr . At the same time, the bare rebars had E corr of -653 mV and I corr of 11.7 μA/cm 2 .
沿海地区的结构、建筑和桥梁受到氯化物腐蚀性侵蚀的影响很大。这会缩短它们的使用寿命，并导致由于维护而造成的损失。本研究旨在通过化学镀高耐蚀性的Ni-Cu-P涂层来提高钢筋在含盐环境（3.5%NaCl）中的使用寿命和耐腐蚀性能。在Fe-600钢筋表面沉积了Ni-Cu-P镀层。通过改变浴条件参数，如硫酸镍、次磷酸钠和硫酸铜的浓度来沉积涂层。这导致了Ni、P和Cu含量的变化，最后，使用基于田口的灰色关联分析获得了最佳浴组合。在25、10和0.3克/升硫酸镍、次磷酸钠和硫酸铜浓度下，350 mV E corr和0.4μA/cm2 I corr可提高涂层钢筋的耐腐蚀性。同时，裸露钢筋的E corr为-653mV，I corr为11.7μA/cm2。
{"title":"Optimized Electroless Ni-Cu-P Coatings for Corrosion Protection of Steel Rebars from Pitting Attack of Chlorides","authors":"Arkadeb Mukhopadhyay, S. Sahoo","doi":"10.24423/ENGTRANS.1367.20210826","DOIUrl":"https://doi.org/10.24423/ENGTRANS.1367.20210826","url":null,"abstract":"Structures, constructions and bridges in coastal areas are greatly affected by the corrosive attack of chlorides. This reduces their lifetime and leads to losses due to their maintenance. This study aims to improve the lifetime and corrosion-proof behavior of steel rebars in the saline environment (3.5% NaCl) by applying electroless Ni-Cu-P coatings with high corrosion resistance. Ni-Cu-P coating was deposited on Fe-600 steel rebars. The coating was deposited by varying bath condition parameters, such as concentration of nickel sulphate, sodium hypophosphite and copper sulphate. This led to a variation in Ni, P and Cu content, and finally, the optimal bath combination was obtained using the Taguchi-based grey relational analysis. For concentrations of 25, 10 and 0.3 g/l nickel sulphate, sodium hypophosphite and copper sulphate, enhanced corrosion resistance of the coated rebars could be achieved with 350 mV E corr and 0.4 μA/cm 2 I corr . At the same time, the bare rebars had E corr of -653 mV and I corr of 11.7 μA/cm 2 .","PeriodicalId":38552,"journal":{"name":"Engineering Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48654530","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}
Pub Date : 2021-08-26DOI: 10.24423/ENGTRANS.1239.20210826
M. Bilal, Saban Inam, S. Kanwal, M. Nazeer
An analytical study of a two-dimensional boundary layer flow of an upper-convected Maxwell fluid is examined. In addition, an aligned magnetic field over the inclined shrinking/stretching stratified sheet in a non-Darcian porous medium is considered. The heat transfer effects are employed through nonlinear convection and variable thermal conductivity. The associated higher-order nonlinear equations are transformed to ordinary first-order differential equations by using similarity transformation. The resulting ordinary first-order differential equations are then solved numerically by the shooting method. This paper aims to investigate the special effects of parameters on velocity and temperature profiles. The results are also discussed, graphically and numerically for the skin friction and Nusselt number.
{"title":"Aspects of the Aligned Magnetic Field Past a Stratified Inclined Sheet with Nonlinear Convection and Variable Thermal Conductivity","authors":"M. Bilal, Saban Inam, S. Kanwal, M. Nazeer","doi":"10.24423/ENGTRANS.1239.20210826","DOIUrl":"https://doi.org/10.24423/ENGTRANS.1239.20210826","url":null,"abstract":"An analytical study of a two-dimensional boundary layer flow of an upper-convected Maxwell fluid is examined. In addition, an aligned magnetic field over the inclined shrinking/stretching stratified sheet in a non-Darcian porous medium is considered. The heat transfer effects are employed through nonlinear convection and variable thermal conductivity. The associated higher-order nonlinear equations are transformed to ordinary first-order differential equations by using similarity transformation. The resulting ordinary first-order differential equations are then solved numerically by the shooting method. This paper aims to investigate the special effects of parameters on velocity and temperature profiles. The results are also discussed, graphically and numerically for the skin friction and Nusselt number.","PeriodicalId":38552,"journal":{"name":"Engineering Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48272402","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}
Pub Date : 2021-08-02DOI: 10.24423/ENGTRANS.1266.20210802
E. Dawood, Marwa Saadi Mhmood
The large quantity of waste or by-product materials (such as waste glass and steel slag) released to landfills is considered to be a real problem. The use of these materials as cement replacements makes it possible to solve this problem and reduce the quantity of carbon dioxide emitted from the cement manufacturing process. This paper presents the effect of waste glass powder (GP) and steel slag powder (SSP) on the properties of blended cement mortar. The flow, compressive strength, direct tensile strength and dry density of cement mortar containing GP and SSP as cement replacements with and without superplasticizer (SP) are studied and compared with the control mix. The results show that the glass and steel slag powders, once they are simultaneously added as a ternary blended cement mortar, reduce the water binder ratio required to achieve flowability. Additionally, the compressive strength results of such blended mortar showed that the increased GP content exhibits better performance than that of slag powder for the same level of waste materials replacements.
{"title":"Properties of Binary Blended Cement Mortars Containing Glass Powder and Steel Slag Powder","authors":"E. Dawood, Marwa Saadi Mhmood","doi":"10.24423/ENGTRANS.1266.20210802","DOIUrl":"https://doi.org/10.24423/ENGTRANS.1266.20210802","url":null,"abstract":"The large quantity of waste or by-product materials (such as waste glass and steel slag) released to landfills is considered to be a real problem. The use of these materials as cement replacements makes it possible to solve this problem and reduce the quantity of carbon dioxide emitted from the cement manufacturing process. This paper presents the effect of waste glass powder (GP) and steel slag powder (SSP) on the properties of blended cement mortar. The flow, compressive strength, direct tensile strength and dry density of cement mortar containing GP and SSP as cement replacements with and without superplasticizer (SP) are studied and compared with the control mix. The results show that the glass and steel slag powders, once they are simultaneously added as a ternary blended cement mortar, reduce the water binder ratio required to achieve flowability. Additionally, the compressive strength results of such blended mortar showed that the increased GP content exhibits better performance than that of slag powder for the same level of waste materials replacements.","PeriodicalId":38552,"journal":{"name":"Engineering Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47128312","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}
Pub Date : 2021-07-09DOI: 10.24423/ENGTRANS.1290.20210709
H. Fakhreddine, A. Adri, M. Chajdi, S. Rifai, R. Benamar
The present paper concerns the study of geometrically non-linear forced vibrations of beams resting on two different types of springs: rotational and translational. Assuming that the motion is harmonic, the displacement is extended as a series of spatial functions determined by solving the linear problem. Hamilton’s principle and spectral analysis are used to reduce the problem to a non-linear algebraic system solved using a previously developed approximate method. The effects of the nature of the added springs and their location on the non-linear behaviour of the beam are examined. A multimode approach is used in the forced case to obtain results over a wide range of vibration amplitudes. This leads to examining the non-linear forced dynamic response for different positions of each spring and different levels of excitations. Following a parametric study, the non-linear forced mode shapes and their associated bending moments are presented for different levels of excitations and for different vibration amplitudes to give an estimation of the stress distribution over the beam length.
{"title":"Large Amplitude Forced Vibrations of Restrained Beams Resting on Elastic Point Supports","authors":"H. Fakhreddine, A. Adri, M. Chajdi, S. Rifai, R. Benamar","doi":"10.24423/ENGTRANS.1290.20210709","DOIUrl":"https://doi.org/10.24423/ENGTRANS.1290.20210709","url":null,"abstract":"The present paper concerns the study of geometrically non-linear forced vibrations of beams resting on two different types of springs: rotational and translational. Assuming that the motion is harmonic, the displacement is extended as a series of spatial functions determined by solving the linear problem. Hamilton’s principle and spectral analysis are used to reduce the problem to a non-linear algebraic system solved using a previously developed approximate method. The effects of the nature of the added springs and their location on the non-linear behaviour of the beam are examined. A multimode approach is used in the forced case to obtain results over a wide range of vibration amplitudes. This leads to examining the non-linear forced dynamic response for different positions of each spring and different levels of excitations. Following a parametric study, the non-linear forced mode shapes and their associated bending moments are presented for different levels of excitations and for different vibration amplitudes to give an estimation of the stress distribution over the beam length.","PeriodicalId":38552,"journal":{"name":"Engineering Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48557397","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}
Pub Date : 2021-06-09DOI: 10.24423/ENGTRANS.1294.20210607
I. Ecsedi, A. Baksa
In this paper, two inequality relations are proven for the torsional rigidity of orthotropic elastic solid cross sections. By using the derived inequality relations, lower and upper bounds can be obtained for the torsional rigidity. All results of the paper follow from the Saint-Venant theory of uniform torsion. The presented bounding formulae are based on the mean value theorem of integral calculus.
{"title":"Estimation of the Torsional Rigidity of Orthotropic Solid Cross Section","authors":"I. Ecsedi, A. Baksa","doi":"10.24423/ENGTRANS.1294.20210607","DOIUrl":"https://doi.org/10.24423/ENGTRANS.1294.20210607","url":null,"abstract":"In this paper, two inequality relations are proven for the torsional rigidity of orthotropic elastic solid cross sections. By using the derived inequality relations, lower and upper bounds can be obtained for the torsional rigidity. All results of the paper follow from the Saint-Venant theory of uniform torsion. The presented bounding formulae are based on the mean value theorem of integral calculus.","PeriodicalId":38552,"journal":{"name":"Engineering Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48934637","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}
Pub Date : 2021-06-09DOI: 10.24423/ENGTRANS.1233.20210607
G. Sobamowo, James A. Akanmu, O. Adeleye, S. Akingbade, A. Yinusa
The present work focuses on nonlinear dynamics models of multi-walled carbon nanotubes with initial curvature resting on Winkler-Pasternak elastic foundations in a nonlinear thermomagnetic environment using nonlocal elasticity theory. The derived systems of nonlinear vibration models are solved with the aid of the Galerkin decomposition and the homotopy perturbation method. Effects of temperature, magnetic field, multi-layer, and other thermomechanical parameters on the dynamic responses of the slightly curved multi-walled carbon nanotubes are investigated and discussed. As the temperature increases, the frequency ratio decreases as the linear natural frequency of the system increases. The results reveal that the frequency ratios decrease as the number of nanotube walls, temperature, spring constants, magnetic field strength, and the ratio of the radius of curvature to the length of the slightly curved nanotubes increase. These trends are the same for all the boundary conditions considered. However, clamped-simple and clamped-clamped supported multi-walled nanotube have the highest and lowest frequency ratio, respectively. Also, from the parametric studies to control nonlinear vibration of the carbon nanotubes, it is shown that quadruple-walled carbon nanotubes can be taken as pure linear vibration even at any value of linear Winkler and Pasternak constants. Therefore, this can be used for the restraining of the chaos vibration in the objective structure. These research findings will assist the designers and manufacturers in developing multi-walled carbon nanotubes for various structural, electrical, mechanical, and biological applications, especially in the areas of designing nanoelectronics, nanodevices, nanomechanical systems, nanobiological devices, and nanocomposites, and particularly when they are subjected to thermal loads, magnetic fields and elastic foundations.
{"title":"Nonlinear Vibration of Multi-Walled Carbon Nanotubes with Initial Curvature Resting on Elastic Foundations in a Nonlinear Thermo-Magnetic Environment","authors":"G. Sobamowo, James A. Akanmu, O. Adeleye, S. Akingbade, A. Yinusa","doi":"10.24423/ENGTRANS.1233.20210607","DOIUrl":"https://doi.org/10.24423/ENGTRANS.1233.20210607","url":null,"abstract":"The present work focuses on nonlinear dynamics models of multi-walled carbon nanotubes with initial curvature resting on Winkler-Pasternak elastic foundations in a nonlinear thermomagnetic environment using nonlocal elasticity theory. The derived systems of nonlinear vibration models are solved with the aid of the Galerkin decomposition and the homotopy perturbation method. Effects of temperature, magnetic field, multi-layer, and other thermomechanical parameters on the dynamic responses of the slightly curved multi-walled carbon nanotubes are investigated and discussed. As the temperature increases, the frequency ratio decreases as the linear natural frequency of the system increases. The results reveal that the frequency ratios decrease as the number of nanotube walls, temperature, spring constants, magnetic field strength, and the ratio of the radius of curvature to the length of the slightly curved nanotubes increase. These trends are the same for all the boundary conditions considered. However, clamped-simple and clamped-clamped supported multi-walled nanotube have the highest and lowest frequency ratio, respectively. Also, from the parametric studies to control nonlinear vibration of the carbon nanotubes, it is shown that quadruple-walled carbon nanotubes can be taken as pure linear vibration even at any value of linear Winkler and Pasternak constants. Therefore, this can be used for the restraining of the chaos vibration in the objective structure. These research findings will assist the designers and manufacturers in developing multi-walled carbon nanotubes for various structural, electrical, mechanical, and biological applications, especially in the areas of designing nanoelectronics, nanodevices, nanomechanical systems, nanobiological devices, and nanocomposites, and particularly when they are subjected to thermal loads, magnetic fields and elastic foundations.","PeriodicalId":38552,"journal":{"name":"Engineering Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44064971","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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