S. Limkatanyu, Worathep Sae-Long, J. Rungamornrat, C. Buachart, P. Sukontasukkul, S. Keawsawasvong, P. Chindaprasirt
This study presents a newly developed size-dependent beam-substrate medium model for bending, buckling, and free-vibration analyses of nanobeams resting on elastic substrate media. The Euler-Bernoulli beam theory describes the beam-section kinematics and the Winkler-foundation model represents interaction between the beam and its underlying substrate medium. The reformulated strain-gradient elasticity theory possessing three non-classical material constants is employed to address the beam-bulk material small-scale effect. The first and second constants is associated with the strain-gradient and couple-stress effects, respectively while the third constant is related to the velocity-gradient effect. The Gurtin-Murdoch surface elasticity theory is adopted to account for the surface-free energy. To obtain the system governing equation as well as corresponding boundary conditions, Hamilton’s principle is called for. Three numerical simulations are presented to characterize the influences of the material small-scale effect, the surface-energy effect, and the surrounding substrate medium on bending, buckling, and free vibration responses of nanobeam-substrate medium systems. The first simulation focuses on the bending response and shows the ability of the proposed model to eliminate the paradoxical characteristic inherent to nanobeam models proposed in the literature. The second and third simulations perform the sensitivity investigation of the system parameters on the buckling load and the natural frequency, respectively. All analytical results reveal that both material small-scale and surface-energy effects consistently stiffen the system response while the velocity-gradient effect weakens the system response. Furthermore, these sized-scale effects are more pronounced when the underlying substrate medium becomes softer.
{"title":"BENDING, BUCKLING AND FREE VIBRATION ANALYSES OF NANOBEAM-SUBSTRATE MEDIUM SYSTEMS","authors":"S. Limkatanyu, Worathep Sae-Long, J. Rungamornrat, C. Buachart, P. Sukontasukkul, S. Keawsawasvong, P. Chindaprasirt","doi":"10.22190/fume220506029l","DOIUrl":"https://doi.org/10.22190/fume220506029l","url":null,"abstract":"This study presents a newly developed size-dependent beam-substrate medium model for bending, buckling, and free-vibration analyses of nanobeams resting on elastic substrate media. The Euler-Bernoulli beam theory describes the beam-section kinematics and the Winkler-foundation model represents interaction between the beam and its underlying substrate medium. The reformulated strain-gradient elasticity theory possessing three non-classical material constants is employed to address the beam-bulk material small-scale effect. The first and second constants is associated with the strain-gradient and couple-stress effects, respectively while the third constant is related to the velocity-gradient effect. The Gurtin-Murdoch surface elasticity theory is adopted to account for the surface-free energy. To obtain the system governing equation as well as corresponding boundary conditions, Hamilton’s principle is called for. Three numerical simulations are presented to characterize the influences of the material small-scale effect, the surface-energy effect, and the surrounding substrate medium on bending, buckling, and free vibration responses of nanobeam-substrate medium systems. The first simulation focuses on the bending response and shows the ability of the proposed model to eliminate the paradoxical characteristic inherent to nanobeam models proposed in the literature. The second and third simulations perform the sensitivity investigation of the system parameters on the buckling load and the natural frequency, respectively. All analytical results reveal that both material small-scale and surface-energy effects consistently stiffen the system response while the velocity-gradient effect weakens the system response. Furthermore, these sized-scale effects are more pronounced when the underlying substrate medium becomes softer.","PeriodicalId":51338,"journal":{"name":"Facta Universitatis-Series Mechanical Engineering","volume":null,"pages":null},"PeriodicalIF":7.9,"publicationDate":"2022-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72690009","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Derick M. P. Kucharski, V. Pinto, L. Rocha, E. D. dos Santos, C. Fragassa, L. Isoldi
Several stiffened plates arrangements subjected to bending were configured applying the Constructal Design Method (CDM) and solved by Finite Element Method (FEM), aiming through the Exhaustive Search (ES) technique analyze the influence of transverse I-Shaped or T-Shaped stiffeners in mechanical behavior. Considering a non-stiffened plate as reference and maintaining the total steel volume constant, a portion of the reference plate was deducted from its thickness, and transformed into stiffeners through the ???? volume fraction parameter, which represents the ratio between the steel volume of the stiffeners and the steel volume of the reference plate. Assuming ???? = 0.3, 25 plates with just I-Shaped stiffeners in longitudinal and transverse directions and 25 plates with I-Shaped stiffeners in longitudinal direction and T-Shaped stiffeners in transverse direction were proposed. The results showed that the plates with transverse T-Shaped stiffeners are more effective, reducing the maximum von Mises stress and maximum deflection, respectively, in up to more than 60% and 50% when compared with the plates with just I-Shaped stiffeners.
{"title":"GEOMETRIC ANALYSIS BY CONSTRUCTAL DESIGN OF STIFFENED STEEL PLATES UNDER BENDING WITH TRANSVERSE I-SHAPED OR T-SHAPED STIFFENERS","authors":"Derick M. P. Kucharski, V. Pinto, L. Rocha, E. D. dos Santos, C. Fragassa, L. Isoldi","doi":"10.22190/fume211016070k","DOIUrl":"https://doi.org/10.22190/fume211016070k","url":null,"abstract":"Several stiffened plates arrangements subjected to bending were configured applying the Constructal Design Method (CDM) and solved by Finite Element Method (FEM), aiming through the Exhaustive Search (ES) technique analyze the influence of transverse I-Shaped or T-Shaped stiffeners in mechanical behavior. Considering a non-stiffened plate as reference and maintaining the total steel volume constant, a portion of the reference plate was deducted from its thickness, and transformed into stiffeners through the ???? volume fraction parameter, which represents the ratio between the steel volume of the stiffeners and the steel volume of the reference plate. Assuming ???? = 0.3, 25 plates with just I-Shaped stiffeners in longitudinal and transverse directions and 25 plates with I-Shaped stiffeners in longitudinal direction and T-Shaped stiffeners in transverse direction were proposed. The results showed that the plates with transverse T-Shaped stiffeners are more effective, reducing the maximum von Mises stress and maximum deflection, respectively, in up to more than 60% and 50% when compared with the plates with just I-Shaped stiffeners.","PeriodicalId":51338,"journal":{"name":"Facta Universitatis-Series Mechanical Engineering","volume":null,"pages":null},"PeriodicalIF":7.9,"publicationDate":"2022-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78337902","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The present study aims at improving corrosion resistance of magnesium nanocomposites through autocatalytic Ni-P coating. Electroless Ni-P coatings with different concentration of sodium hypophosphite are deposited on 2% WC incorporated magnesium nanocomposites (AZ31-2WC) and the coated samples are further heat-treated. Basic characterizations and compositional analyses are done by using scanning electron microscope (SEM), energy dispersive x-ray analysis (EDAX), and X-ray diffraction analysis (XRD). Microhardness values of the developed materials are also evaluated. The attempt is made to improve corrosion resistance of AZ31-2WC by modifying surface roughness. Corrosion characteristics of Ni-P coated AZ31-2WC nanocomposites are examined by performing potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS). Corrosion resistance improves with enhancement of surface quality. Corrosion resistance of AZ31-2WC nanocomposite also improves due to application of Ni-P coating. Finally, corrosion morphologies are scrutinized by SEM micrographs of corroded surface.
{"title":"IMPROVING CORROSION RESISTANCE OF MAGNESIUM NANOCOMPOSITES BY USING ELECTROLESS NICKEL COATINGS","authors":"Sudip Banerjee, Pujan Sarkar, P. Sahoo","doi":"10.22190/fume210714068b","DOIUrl":"https://doi.org/10.22190/fume210714068b","url":null,"abstract":"The present study aims at improving corrosion resistance of magnesium nanocomposites through autocatalytic Ni-P coating. Electroless Ni-P coatings with different concentration of sodium hypophosphite are deposited on 2% WC incorporated magnesium nanocomposites (AZ31-2WC) and the coated samples are further heat-treated. Basic characterizations and compositional analyses are done by using scanning electron microscope (SEM), energy dispersive x-ray analysis (EDAX), and X-ray diffraction analysis (XRD). Microhardness values of the developed materials are also evaluated. The attempt is made to improve corrosion resistance of AZ31-2WC by modifying surface roughness. Corrosion characteristics of Ni-P coated AZ31-2WC nanocomposites are examined by performing potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS). Corrosion resistance improves with enhancement of surface quality. Corrosion resistance of AZ31-2WC nanocomposite also improves due to application of Ni-P coating. Finally, corrosion morphologies are scrutinized by SEM micrographs of corroded surface.","PeriodicalId":51338,"journal":{"name":"Facta Universitatis-Series Mechanical Engineering","volume":null,"pages":null},"PeriodicalIF":7.9,"publicationDate":"2022-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74721660","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
B. Safaei, Emmanuel Chukwueloka Onyibo, Dogus Hurdoganoglu
The bending and critical buckling loads of a sandwich beam structure subjected to thermal load and axial compression were simulated and temperature distribution across sandwich layers was investigated by finite element analysis and validated analytically. The sandwich structure was consisted of two face sheets and a core, carbon fiber and carbon foam were used as face sheet and core respectively for more efficient stiffness results. The analysis was repeated with different materials to reduce thermal strain and heat flux of sandwich beams. Applying both ends fixed as temperature boundary conditions, temperature induced stresses were observed, steady-state thermal analysis was performed, and conduction through sandwich layers along with their deformation nature were investigated based on the material properties of the combination of face sheets and core. The best material combination was found for the reduction of heat flux and thermal strain, and addition of aerogel material significantly reduced thermal stresses without adding weight to the sandwich structure.
{"title":"THERMAL BUCKLING AND BENDING ANALYSES OF CARBON FOAM BEAMS SANDWICHED BY COMPOSITE FACES UNDER AXIAL COMPRESSION","authors":"B. Safaei, Emmanuel Chukwueloka Onyibo, Dogus Hurdoganoglu","doi":"10.22190/fume220404027s","DOIUrl":"https://doi.org/10.22190/fume220404027s","url":null,"abstract":"The bending and critical buckling loads of a sandwich beam structure subjected to thermal load and axial compression were simulated and temperature distribution across sandwich layers was investigated by finite element analysis and validated analytically. The sandwich structure was consisted of two face sheets and a core, carbon fiber and carbon foam were used as face sheet and core respectively for more efficient stiffness results. The analysis was repeated with different materials to reduce thermal strain and heat flux of sandwich beams. Applying both ends fixed as temperature boundary conditions, temperature induced stresses were observed, steady-state thermal analysis was performed, and conduction through sandwich layers along with their deformation nature were investigated based on the material properties of the combination of face sheets and core. The best material combination was found for the reduction of heat flux and thermal strain, and addition of aerogel material significantly reduced thermal stresses without adding weight to the sandwich structure.","PeriodicalId":51338,"journal":{"name":"Facta Universitatis-Series Mechanical Engineering","volume":null,"pages":null},"PeriodicalIF":7.9,"publicationDate":"2022-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89674766","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A building or a bridge might collapse after a heat shock. This paper shows that a porous hierarchy of a coating can effectively prevent a building or a bridge from such damage. A cocoon’s geometrical structure is studied and its resistance to the heat shock is revealed by a thermal oscillator. The theoretical model reveals an extremely low frequency of the thermal oscillator, which is very important for cocoons’ biomechanism, especially in the heat insulation function. At the same time, it shows that the cocoons have the best thickness to protect the pupa from the environment. In addition, surface temperature measurement of hierarchical mulberry leaves is performed. This work provides new insights into biomimetic design of the protective building and coatings.
{"title":"THERMAL OSCILLATION ARISING IN A HEAT SHOCK OF A POROUS HIERARCHY AND ITS APPLICATION","authors":"Fujuan Liu, Ting Zhang, Chun-Hui He, Dan Tian","doi":"10.22190/fume210317054l","DOIUrl":"https://doi.org/10.22190/fume210317054l","url":null,"abstract":"A building or a bridge might collapse after a heat shock. This paper shows that a porous hierarchy of a coating can effectively prevent a building or a bridge from such damage. A cocoon’s geometrical structure is studied and its resistance to the heat shock is revealed by a thermal oscillator. The theoretical model reveals an extremely low frequency of the thermal oscillator, which is very important for cocoons’ biomechanism, especially in the heat insulation function. At the same time, it shows that the cocoons have the best thickness to protect the pupa from the environment. In addition, surface temperature measurement of hierarchical mulberry leaves is performed. This work provides new insights into biomimetic design of the protective building and coatings.","PeriodicalId":51338,"journal":{"name":"Facta Universitatis-Series Mechanical Engineering","volume":null,"pages":null},"PeriodicalIF":7.9,"publicationDate":"2022-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86489551","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Mahmood, Zied Bahroun, M. Ghommem, H. Alshraideh
E-noses that combine machine learning and gas sensor arrays (GSAs) are widely used for the detection and identification of various gases. GSAs produce signals that provide vital information about the exposed gases for the machine learning algorithms, rendering them indispensable within the smart-gas sensing arena. In this work, we present a detailed assessment of several machine learning techniques employed for the detection of gases and estimation of their concentrations. The modeling and predictive analysis conducted in this paper are based on kNN, ANN, Decision Trees, Random Forests, SVM and other ensembling-based techniques. Predictive models are implemented and tested on three different MoX gas sensor-based experimental datasets as reported in the literature. The assessment includes a delineated analysis of the different models’ performance followed by a detailed comparison against results found in the literature. It highlights factors that play a pivotal role in machine learning for gas sensing and sheds light on the predictive capability of different machine learning approaches applied on experimental GSA datasets.
{"title":"ASSESSMENT AND PERFORMANCE ANALYSIS OF MACHINE LEARNING TECHNIQUES FOR GAS SENSING E-NOSE SYSTEMS","authors":"L. Mahmood, Zied Bahroun, M. Ghommem, H. Alshraideh","doi":"10.22190/fume220307022m","DOIUrl":"https://doi.org/10.22190/fume220307022m","url":null,"abstract":"E-noses that combine machine learning and gas sensor arrays (GSAs) are widely used for the detection and identification of various gases. GSAs produce signals that provide vital information about the exposed gases for the machine learning algorithms, rendering them indispensable within the smart-gas sensing arena. In this work, we present a detailed assessment of several machine learning techniques employed for the detection of gases and estimation of their concentrations. The modeling and predictive analysis conducted in this paper are based on kNN, ANN, Decision Trees, Random Forests, SVM and other ensembling-based techniques. Predictive models are implemented and tested on three different MoX gas sensor-based experimental datasets as reported in the literature. The assessment includes a delineated analysis of the different models’ performance followed by a detailed comparison against results found in the literature. It highlights factors that play a pivotal role in machine learning for gas sensing and sheds light on the predictive capability of different machine learning approaches applied on experimental GSA datasets.","PeriodicalId":51338,"journal":{"name":"Facta Universitatis-Series Mechanical Engineering","volume":null,"pages":null},"PeriodicalIF":7.9,"publicationDate":"2022-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83198600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The present numerical work deals with the optimization of the micro-channel heat sink using irreversibility analysis. The nanofluid of Al2O3-water with the different nanoparticles concentration and the temperature-dependent property is chosen as a coolant. The flow is considered as fully developed, steady, and laminar in the constant cross-section of circular channels. Navier-Stokes and energy equations are solved for a single-phase flow with total mass flow rate and heat flow rate as constant. The objective functions related to the frictional and heat transfer irreversibilities are framed to assess the performance of the micro-channel heat sink. The optimum channel diameter corresponding to the optimum number of channels is determined at the lowest total irreversibility for both constant property solution and variable property solution. Designed optimum diameter is observed maximum for 2.5% Al2O3-water nanofluid with μ(T) variation followed by 1% Al2O3-water nanofluid with μ(T) variation, 2.5% Al2O3-water nanofluid with constant property solution, and 1% Al2O3-water nanofluid with constant property solution.
{"title":"IRREVERSIBILITY ANALYSIS IN Al2O3-WATER NANOFLUID FLOW WITH VARIABLE PROPERTY","authors":"K. Kumar, P. R. Chauhan, Rajan Kumar, R. S. Bharj","doi":"10.22190/fume210308050k","DOIUrl":"https://doi.org/10.22190/fume210308050k","url":null,"abstract":"The present numerical work deals with the optimization of the micro-channel heat sink using irreversibility analysis. The nanofluid of Al2O3-water with the different nanoparticles concentration and the temperature-dependent property is chosen as a coolant. The flow is considered as fully developed, steady, and laminar in the constant cross-section of circular channels. Navier-Stokes and energy equations are solved for a single-phase flow with total mass flow rate and heat flow rate as constant. The objective functions related to the frictional and heat transfer irreversibilities are framed to assess the performance of the micro-channel heat sink. The optimum channel diameter corresponding to the optimum number of channels is determined at the lowest total irreversibility for both constant property solution and variable property solution. Designed optimum diameter is observed maximum for 2.5% Al2O3-water nanofluid with μ(T) variation followed by 1% Al2O3-water nanofluid with μ(T) variation, 2.5% Al2O3-water nanofluid with constant property solution, and 1% Al2O3-water nanofluid with constant property solution.","PeriodicalId":51338,"journal":{"name":"Facta Universitatis-Series Mechanical Engineering","volume":null,"pages":null},"PeriodicalIF":7.9,"publicationDate":"2022-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74446643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Enhancing the mechanical reliability of metal interconnects is important for achieving highly reliable flexible/wearable electronic devices. In this study, Ag nanowire and Cu thin-film hybrid interconnects were explored as a novel concept to enhance mechanical reliability under bending fatigue. Bending fatigue tests were conducted on the Cu thin films and Cu/Ag nanowire/polyimide (CAP) interconnects. The increase in resistance was larger for the Cu thin films than for the CAP. The single-component Cu electrodes showed multiple crack initiation and propagation due to bending strain, which degraded the electrical conductivity. In CAP, however, no long-range cracks were observed, even after 300,000 cycles of bending, although a wavy structure was observed, probably due to the delamination of the Ag nanowires under repeated bending. Our study confirms that flexible Ag nanowire and metal thin-film hybrids can enhance the mechanical reliability of metal thin-film interconnects under bending fatigue.
{"title":"BENDING FATIGUE BEHAVIOR OF AG NANOWIRE/CU THIN-FILM HYBRID INTERCONNECTS FOR WEARABLE ELECTRONICS","authors":"B. Hwang, Yurim Han, P. Matteini","doi":"10.22190/fume220730040h","DOIUrl":"https://doi.org/10.22190/fume220730040h","url":null,"abstract":"Enhancing the mechanical reliability of metal interconnects is important for achieving highly reliable flexible/wearable electronic devices. In this study, Ag nanowire and Cu thin-film hybrid interconnects were explored as a novel concept to enhance mechanical reliability under bending fatigue. Bending fatigue tests were conducted on the Cu thin films and Cu/Ag nanowire/polyimide (CAP) interconnects. The increase in resistance was larger for the Cu thin films than for the CAP. The single-component Cu electrodes showed multiple crack initiation and propagation due to bending strain, which degraded the electrical conductivity. In CAP, however, no long-range cracks were observed, even after 300,000 cycles of bending, although a wavy structure was observed, probably due to the delamination of the Ag nanowires under repeated bending. Our study confirms that flexible Ag nanowire and metal thin-film hybrids can enhance the mechanical reliability of metal thin-film interconnects under bending fatigue.","PeriodicalId":51338,"journal":{"name":"Facta Universitatis-Series Mechanical Engineering","volume":null,"pages":null},"PeriodicalIF":7.9,"publicationDate":"2022-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81381555","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The present investigation examines the range of effect of nonlocal parameters on dynamic behavior of a smart beam-like nanostructure modeled as sandwich functionally graded porous nanobeam with piezoelectric layers. Therefore, the study is concentrated on determining length of the structure for which nonlocal effects are observed for vibration of nanobeam under in-plane electro-mechanical forces. The nanobeam-based NEMS device model is obtained based on assumptions of the nonlocal strain gradient theory in conjunction with Reddy higher-order shear deformation theory. The investigation present differences in obtained results for nanostructure’s free vibration based on classical and nonlocal assumptions. To study range of application of nonlocal parameters for different length of simply supported nanobeam, defined eigenvalue problem is solved in view of variation of length to thickness ratio, distribution of material properties, as well as electro-mechanical loads. What is more, the study attempts to determine and calibrate values of size-dependent coefficients based on expected natural frequencies, material properties, and applied loads. The results are completed with extensive discussion on the dependence of nonlocal parameters on nanobeam’s dynamic response, thus may be an important step forward to extend understanding of ultra-small structure’s behavior.
{"title":"DETECTION OF NONLOCAL CALIBRATION PARAMETERS AND RANGE INTERACTION FOR DYNAMICS OF FGM POROUS NANOBEAMS UNDER ELECTRO-MECHANICAL LOADS","authors":"P. Jankowski","doi":"10.22190/fume210207007j","DOIUrl":"https://doi.org/10.22190/fume210207007j","url":null,"abstract":"The present investigation examines the range of effect of nonlocal parameters on dynamic behavior of a smart beam-like nanostructure modeled as sandwich functionally graded porous nanobeam with piezoelectric layers. Therefore, the study is concentrated on determining length of the structure for which nonlocal effects are observed for vibration of nanobeam under in-plane electro-mechanical forces. The nanobeam-based NEMS device model is obtained based on assumptions of the nonlocal strain gradient theory in conjunction with Reddy higher-order shear deformation theory. The investigation present differences in obtained results for nanostructure’s free vibration based on classical and nonlocal assumptions. To study range of application of nonlocal parameters for different length of simply supported nanobeam, defined eigenvalue problem is solved in view of variation of length to thickness ratio, distribution of material properties, as well as electro-mechanical loads. What is more, the study attempts to determine and calibrate values of size-dependent coefficients based on expected natural frequencies, material properties, and applied loads. The results are completed with extensive discussion on the dependence of nonlocal parameters on nanobeam’s dynamic response, thus may be an important step forward to extend understanding of ultra-small structure’s behavior.","PeriodicalId":51338,"journal":{"name":"Facta Universitatis-Series Mechanical Engineering","volume":null,"pages":null},"PeriodicalIF":7.9,"publicationDate":"2022-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88263107","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hamed Mobki, Morteza Homayoun Sedighi, A. Azizi, Mir Mohammad Eskandari
The presence of faults in a system leads to a lower value for efficiency, accuracy and speed, and, in some cases, even a complete breakdown. Thus, early fault detection is a major factor in efficiency and productivity of the procedure. In recent decades, many research studies have been conducted on troubleshooting and secondary fault detection. The current work presents an efficient and novel observer design capable of stabilizing the residue and dynamic error for the nonlinear Lipschitz systems with faults as well as a troubleshooting analysis and determining the formation of secondary faults in defective systems. The observer is designed based on linearizing dynamic error considering uncertainty, disturbance, and defects by employing non-linear gain factors instead of using state transformation. The dynamic error and residue stabilization of a non-linear faulty system have been discussed as well as the likelihood of secondary fault generation. The results indicate that the observer is able to determine fault-emergence, fault-disappearance and secondary fault formation well and quite fast.
{"title":"DESIGNING AN EFFICIENT OBSERVER FOR THE NON-LINEAR LIPSCHITZ SYSTEM TO TROUBLESHOOT AND DETECT SECONDARY FAULTS CONSIDERING LINEARIZING THE DYNAMIC ERROR","authors":"Hamed Mobki, Morteza Homayoun Sedighi, A. Azizi, Mir Mohammad Eskandari","doi":"10.22190/fume220528043m","DOIUrl":"https://doi.org/10.22190/fume220528043m","url":null,"abstract":"The presence of faults in a system leads to a lower value for efficiency, accuracy and speed, and, in some cases, even a complete breakdown. Thus, early fault detection is a major factor in efficiency and productivity of the procedure. In recent decades, many research studies have been conducted on troubleshooting and secondary fault detection. The current work presents an efficient and novel observer design capable of stabilizing the residue and dynamic error for the nonlinear Lipschitz systems with faults as well as a troubleshooting analysis and determining the formation of secondary faults in defective systems. The observer is designed based on linearizing dynamic error considering uncertainty, disturbance, and defects by employing non-linear gain factors instead of using state transformation. The dynamic error and residue stabilization of a non-linear faulty system have been discussed as well as the likelihood of secondary fault generation. The results indicate that the observer is able to determine fault-emergence, fault-disappearance and secondary fault formation well and quite fast.","PeriodicalId":51338,"journal":{"name":"Facta Universitatis-Series Mechanical Engineering","volume":null,"pages":null},"PeriodicalIF":7.9,"publicationDate":"2022-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76541586","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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