Pub Date : 2021-06-01DOI: 10.12989/SSS.2021.27.6.891
H. Cui, Rufu Hu, Nan Chen
An integrated control system with smart structure is proposed for active structural acoustic control (ASAC). It is mainly used to integrate the advantages of centralized and decentralized ASAC. Each smart structure contains a relatively independent controller, which forms a distributed control. The coordination and cooperation between smart structures is mainly realized by sending control factors (secondary generalized modal force) from the upper coordination unit (coordination structure) to each smart structure. The control factor can reflect the weight of each smart structure on vibration noise control, and play a key role in noise control. The control factors are extracted from the blend function in the bottom control units (smart structures) and stored in the coordination structure. This design method ensures the consistency of the internal functions of each smart structure and lays a foundation for decentralized control. In addition, whether the control factor is allocated to the smart structure depends on the real-time changes of the sound field. Through the intelligent allocation of the control factors, the global (centralized) control is realized and the coupling problem between smart structures is solved. Since the control system does not have a centralized controller, it appears as a decentralized control in form; at the same time, the centralized control in algorithm is achieved by extracting and redistributing the control factors. Therefore, the control system integrates the advantages of decentralized and centralized control.
{"title":"Active structural acoustic control using an integrated control system with smart structures","authors":"H. Cui, Rufu Hu, Nan Chen","doi":"10.12989/SSS.2021.27.6.891","DOIUrl":"https://doi.org/10.12989/SSS.2021.27.6.891","url":null,"abstract":"An integrated control system with smart structure is proposed for active structural acoustic control (ASAC). It is mainly used to integrate the advantages of centralized and decentralized ASAC. Each smart structure contains a relatively independent controller, which forms a distributed control. The coordination and cooperation between smart structures is mainly realized by sending control factors (secondary generalized modal force) from the upper coordination unit (coordination structure) to each smart structure. The control factor can reflect the weight of each smart structure on vibration noise control, and play a key role in noise control. The control factors are extracted from the blend function in the bottom control units (smart structures) and stored in the coordination structure. This design method ensures the consistency of the internal functions of each smart structure and lays a foundation for decentralized control. In addition, whether the control factor is allocated to the smart structure depends on the real-time changes of the sound field. Through the intelligent allocation of the control factors, the global (centralized) control is realized and the coupling problem between smart structures is solved. Since the control system does not have a centralized controller, it appears as a decentralized control in form; at the same time, the centralized control in algorithm is achieved by extracting and redistributing the control factors. Therefore, the control system integrates the advantages of decentralized and centralized control.","PeriodicalId":51155,"journal":{"name":"Smart Structures and Systems","volume":"27 1","pages":"891"},"PeriodicalIF":3.5,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47192946","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-06-01DOI: 10.12989/SSS.2021.27.6.969
Xue Songtao, Yi Zhuoran, Liyu Xie, G. Wan
To avoid the issues of incomplete strain transfer ratio and insufficient bonding strength of a monolithic stressed antenna, this paper presents an unstressed deformation sensor based on two-layer patch antenna for structural health monitoring. The proposed sensor is composed of a monolithic patch antenna and a stacked patch generating two fundamental resonant frequencies within a 3-to-7 GHz band. The resonant frequencies' shifts caused by the offset of the stacked patch were selected as the sensing parameters. An equivalent circuit was used to analyze the sensing method, which shows the relative displacement to be linear to the shift of resonant frequencies. This phenomenon was then checked by numerical simulation using the Ansoft High Frequency Structure Simulator 15 (HFSS15) and experiments in laboratory using both wired and wireless setups. Furthermore, the accuracy of measurement is verified to be increased by combining two resonant frequencies.
{"title":"Double-frequency passive deformation sensor based on two-layer patch antenna","authors":"Xue Songtao, Yi Zhuoran, Liyu Xie, G. Wan","doi":"10.12989/SSS.2021.27.6.969","DOIUrl":"https://doi.org/10.12989/SSS.2021.27.6.969","url":null,"abstract":"To avoid the issues of incomplete strain transfer ratio and insufficient bonding strength of a monolithic stressed antenna, this paper presents an unstressed deformation sensor based on two-layer patch antenna for structural health monitoring. The proposed sensor is composed of a monolithic patch antenna and a stacked patch generating two fundamental resonant frequencies within a 3-to-7 GHz band. The resonant frequencies' shifts caused by the offset of the stacked patch were selected as the sensing parameters. An equivalent circuit was used to analyze the sensing method, which shows the relative displacement to be linear to the shift of resonant frequencies. This phenomenon was then checked by numerical simulation using the Ansoft High Frequency Structure Simulator 15 (HFSS15) and experiments in laboratory using both wired and wireless setups. Furthermore, the accuracy of measurement is verified to be increased by combining two resonant frequencies.","PeriodicalId":51155,"journal":{"name":"Smart Structures and Systems","volume":"27 1","pages":"969"},"PeriodicalIF":3.5,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45745764","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-06-01DOI: 10.12989/SSS.2021.27.6.1031
Y. Qi, Cheng Yuan, Qingzhao Kong, Bing Xiong, Peizhen Li
Implementing unmanned aerial vehicles (UAVs) on concrete surface-crack inspection leads to a promising visual crack detection approach. One of the challenges for automated field visual cracking inspection is image degradation caused by the rain or fog and motion blur during data acquisition. The present study combines two deep neural networks to address the image degradation problem. By using the Variance of Laplacian algorithm for quantifying image clarity, the proposed deep neural networks can remarkably enhance the sharpness of the degraded images. After vision enhancement process, Mask Region Convolutional Neutral Network (Mask R-CNN) was developed to perform automated crack identification and segmentation. Results show a 8~13% enhancement in prediction accuracy compared to the degraded images, indicating that the proposed deep learning-based vision enhancement method can effectivey identify and segment concrete surface cracks from photos captured by UAVs.
{"title":"A deep learning-based vision enhancement method for UAV assisted visual inspection of concrete cracks","authors":"Y. Qi, Cheng Yuan, Qingzhao Kong, Bing Xiong, Peizhen Li","doi":"10.12989/SSS.2021.27.6.1031","DOIUrl":"https://doi.org/10.12989/SSS.2021.27.6.1031","url":null,"abstract":"Implementing unmanned aerial vehicles (UAVs) on concrete surface-crack inspection leads to a promising visual crack detection approach. One of the challenges for automated field visual cracking inspection is image degradation caused by the rain or fog and motion blur during data acquisition. The present study combines two deep neural networks to address the image degradation problem. By using the Variance of Laplacian algorithm for quantifying image clarity, the proposed deep neural networks can remarkably enhance the sharpness of the degraded images. After vision enhancement process, Mask Region Convolutional Neutral Network (Mask R-CNN) was developed to perform automated crack identification and segmentation. Results show a 8~13% enhancement in prediction accuracy compared to the degraded images, indicating that the proposed deep learning-based vision enhancement method can effectivey identify and segment concrete surface cracks from photos captured by UAVs.","PeriodicalId":51155,"journal":{"name":"Smart Structures and Systems","volume":"27 1","pages":"1031"},"PeriodicalIF":3.5,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42613927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-06-01DOI: 10.12989/SSS.2021.27.6.903
B. Oh, B. Glisic, H. Park
This study presents a damage detection method based on modal responses for building structures using convolutional neural networks (CNNs). The modal responses used in the method are obtained from the dynamic responses, which are measured in a building structure under ambient excitations; these are then transformed to a modal participation ratio (MPR) value for a measuring point and mode. As modal responses vary after damages in the structures, the MPR for a specific location and mode also changes. Thus, in this study, MPR variations, which can be obtained by comparing the MPRs of damaged and healthy structures, are utilized for damage detection without the need for identification of modal parameters. Since MPRs are derived for the number of measuring points (N) in the structure as well as the same number of modes (N), the MPRs and MPR variations can be arranged as an N × N matrix. This low-dimensional MPR variations set is used as the input map of the presented CNN architecture and information about damage locations and severities of the target structure is set as the output of the CNN. The presented CNN is trained for establishing the relationship between MPR variations and damage information and utilized to estimate the damage. The presented damage detection method is applied to numerical examples for two multiple degrees of freedoms and a three-dimensional ASCE benchmark numerical model. Training datasets created from damage scenarios assuming changes in the stiffness are used to train the CNN and the performance of this CNN is verified. Finally, this study examines how variations in the operator size and number of layers in the CNN architecture affect the damage detection performance of CNNs.
{"title":"Convolutional neural network-based damage detection method for building structures","authors":"B. Oh, B. Glisic, H. Park","doi":"10.12989/SSS.2021.27.6.903","DOIUrl":"https://doi.org/10.12989/SSS.2021.27.6.903","url":null,"abstract":"This study presents a damage detection method based on modal responses for building structures using convolutional neural networks (CNNs). The modal responses used in the method are obtained from the dynamic responses, which are measured in a building structure under ambient excitations; these are then transformed to a modal participation ratio (MPR) value for a measuring point and mode. As modal responses vary after damages in the structures, the MPR for a specific location and mode also changes. Thus, in this study, MPR variations, which can be obtained by comparing the MPRs of damaged and healthy structures, are utilized for damage detection without the need for identification of modal parameters. Since MPRs are derived for the number of measuring points (N) in the structure as well as the same number of modes (N), the MPRs and MPR variations can be arranged as an N × N matrix. This low-dimensional MPR variations set is used as the input map of the presented CNN architecture and information about damage locations and severities of the target structure is set as the output of the CNN. The presented CNN is trained for establishing the relationship between MPR variations and damage information and utilized to estimate the damage. The presented damage detection method is applied to numerical examples for two multiple degrees of freedoms and a three-dimensional ASCE benchmark numerical model. Training datasets created from damage scenarios assuming changes in the stiffness are used to train the CNN and the performance of this CNN is verified. Finally, this study examines how variations in the operator size and number of layers in the CNN architecture affect the damage detection performance of CNNs.","PeriodicalId":51155,"journal":{"name":"Smart Structures and Systems","volume":"27 1","pages":"903-916"},"PeriodicalIF":3.5,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47927165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-06-01DOI: 10.12989/SSS.2021.27.6.951
A. Aldrees, Abubakr Taha Bakheit Bakheit, H. Assilzadeh
The NRCS-CN model is one of the commonly used models for the estimation of discharge peak in a watershed in Saudi Arabia using the DEM outputs and daily rainfall data. The current study aims to classify the sub-basins using rainfall volume, rain off volume and estimate the discharge peak using NRCS-CN method. The drainage map of the studied sub-basin areas was extracted from SRTM Dem 30 m outputs. To estimate the surface runoff and its discharge peak, the drainage area was divided into four tributary basins for Wadi Al-Aqiq using the WMS software outputs from SRTM Dem 30 m. The extracted subbasins were Wadis Rim, Al Yitimah, Al Ishsh and Sha'ib Ruwawah. The results indicate the importance of the integrated use of the digital processing outputs of the DEM in extracting the morphometric variables necessary in calculating the concentrationtime, unit peak discharge and the land resources map in determining the runoff curve. In addition, the weighted curve numbers were ranged between 88.4, 89.9, and 92.1 in Wadi Al Ishsh, wadi Rim, and wadi Al Aqiq watersheds, respectively. It was evident that the attained results can be calibrated by the actual recorded discharge and related to several watersheds.
NRCS-CN模型是使用DEM输出和日降雨量数据估计沙特阿拉伯流域流量峰值的常用模型之一。目前的研究旨在使用降雨量、降雨量对子流域进行分类，并使用NRCS-CN方法估计流量峰值。研究的子流域区域的排水图是从SRTM Dem 30m的输出中提取的。为了估算地表径流及其流量峰值，使用SRTM Dem 30m的WMS软件输出，将流域划分为Wadi Al Aqiq的四个支流流域。提取的子流域为Wadis Rim、Al Yitimah、Al Issh和Sha’ib Ruwawah。结果表明，综合利用DEM的数字处理输出，提取计算汇流时间、单位洪峰流量所需的形态计量变量，以及确定径流曲线所需的土地资源图，具有重要意义。此外，Wadi Al-Ishh、Wadi Rim和Wadi Al-Aqiq流域的加权曲线数分别在88.4、89.9和92.1之间。很明显，所获得的结果可以通过实际记录的流量进行校准，并与几个流域有关。
{"title":"Intelligent estimation of the discharge peak in Al Aqiq drainage basin: A case study in Al Madinah Munwwarah region","authors":"A. Aldrees, Abubakr Taha Bakheit Bakheit, H. Assilzadeh","doi":"10.12989/SSS.2021.27.6.951","DOIUrl":"https://doi.org/10.12989/SSS.2021.27.6.951","url":null,"abstract":"The NRCS-CN model is one of the commonly used models for the estimation of discharge peak in a watershed in Saudi Arabia using the DEM outputs and daily rainfall data. The current study aims to classify the sub-basins using rainfall volume, rain off volume and estimate the discharge peak using NRCS-CN method. The drainage map of the studied sub-basin areas was extracted from SRTM Dem 30 m outputs. To estimate the surface runoff and its discharge peak, the drainage area was divided into four tributary basins for Wadi Al-Aqiq using the WMS software outputs from SRTM Dem 30 m. The extracted subbasins were Wadis Rim, Al Yitimah, Al Ishsh and Sha'ib Ruwawah. The results indicate the importance of the integrated use of the digital processing outputs of the DEM in extracting the morphometric variables necessary in calculating the concentrationtime, unit peak discharge and the land resources map in determining the runoff curve. In addition, the weighted curve numbers were ranged between 88.4, 89.9, and 92.1 in Wadi Al Ishsh, wadi Rim, and wadi Al Aqiq watersheds, respectively. It was evident that the attained results can be calibrated by the actual recorded discharge and related to several watersheds.","PeriodicalId":51155,"journal":{"name":"Smart Structures and Systems","volume":"27 1","pages":"951"},"PeriodicalIF":3.5,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49576069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-01DOI: 10.12989/SSS.2021.27.5.847
Abdelghani Belarouci, A. Fekrar
In this work, a new theory quasi-3D shear deformation is presented to analyze the bending of thick FGM (functionally graded materials) plates resting on Pasternak elastic foundations, whose number of variables is limited to five. The mathematical model used presents a new range of displacement based on indeterminate integral variables where the stretching of thickness is taken into account according to the power laws P-FGM, E-FGM and S-FGM. The compositions and volume fractions of the constituents in the FGM are supposed to change through the thickness. The principle of virtual work, as well as the Naiver method, is used in this study to solve the governing equations of motion to study these types of plates. The equilibrium equations according to the FG plate resting on Pasternak foundations are presented. The results obtained are compared to those determined by the other authors. It was observed from the comparative studies that quasi-3D theories that take into account thickness stretching effects can predict bending behavior more accurately than other theories.
{"title":"A new quasi-3D theory for the study of the bending of thick FGM's plates on elastic foundation","authors":"Abdelghani Belarouci, A. Fekrar","doi":"10.12989/SSS.2021.27.5.847","DOIUrl":"https://doi.org/10.12989/SSS.2021.27.5.847","url":null,"abstract":"In this work, a new theory quasi-3D shear deformation is presented to analyze the bending of thick FGM (functionally graded materials) plates resting on Pasternak elastic foundations, whose number of variables is limited to five. The mathematical model used presents a new range of displacement based on indeterminate integral variables where the stretching of thickness is taken into account according to the power laws P-FGM, E-FGM and S-FGM. The compositions and volume fractions of the constituents in the FGM are supposed to change through the thickness. The principle of virtual work, as well as the Naiver method, is used in this study to solve the governing equations of motion to study these types of plates. The equilibrium equations according to the FG plate resting on Pasternak foundations are presented. The results obtained are compared to those determined by the other authors. It was observed from the comparative studies that quasi-3D theories that take into account thickness stretching effects can predict bending behavior more accurately than other theories.","PeriodicalId":51155,"journal":{"name":"Smart Structures and Systems","volume":"27 1","pages":"847"},"PeriodicalIF":3.5,"publicationDate":"2021-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43258539","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-01DOI: 10.12989/SSS.2021.27.5.729
M. Khadimallah, M. Hussain, M. Naeem, A. Qazaq, Abdulaziz Alqahtani, A. Tounsi
Here the Rayleigh - Ritz method has been applied to derive the shell vibration frequency equation. This equation has been formed as an eigenvalue problem form. MATLAB software package has been utilized for extracting shell frequency spectra. Nature of materials used for construction of cylindrical shells also has visible impact on shell vibration characteristics. For isotropic materials, the physical properties are same everywhere, the laminated and functionally graded materials vary from point to point. Here the shell material has been taken as functionally graded material. Moreover, the impact of ring supports around the shell circumferential has been examined for the various positions along the shell axial length. These shells are stiffened by rings in the tangential direction. These ring supports are located at various positions along the axial direction round the shell circumferential direction. These variations have been plotted against the locations of ring supports for three values of exponents of volume fraction law. For three conditions, frequency variations show different behavior with these values of exponent law. The influence of the positions of ring supports for simply supported end conditions is very visible. The frequency first increases and gain maximum value in the midway of the shell length and then lowers down. The comparisons of frequencies have been made for efficiency and robustness for the present numerical procedure.
{"title":"Vibration analysis of FG cylindrical shell: Evaluation of Ritz-polynomial mixed with ring terms","authors":"M. Khadimallah, M. Hussain, M. Naeem, A. Qazaq, Abdulaziz Alqahtani, A. Tounsi","doi":"10.12989/SSS.2021.27.5.729","DOIUrl":"https://doi.org/10.12989/SSS.2021.27.5.729","url":null,"abstract":"Here the Rayleigh - Ritz method has been applied to derive the shell vibration frequency equation. This equation has been formed as an eigenvalue problem form. MATLAB software package has been utilized for extracting shell frequency spectra. Nature of materials used for construction of cylindrical shells also has visible impact on shell vibration characteristics. For isotropic materials, the physical properties are same everywhere, the laminated and functionally graded materials vary from point to point. Here the shell material has been taken as functionally graded material. Moreover, the impact of ring supports around the shell circumferential has been examined for the various positions along the shell axial length. These shells are stiffened by rings in the tangential direction. These ring supports are located at various positions along the axial direction round the shell circumferential direction. These variations have been plotted against the locations of ring supports for three values of exponents of volume fraction law. For three conditions, frequency variations show different behavior with these values of exponent law. The influence of the positions of ring supports for simply supported end conditions is very visible. The frequency first increases and gain maximum value in the midway of the shell length and then lowers down. The comparisons of frequencies have been made for efficiency and robustness for the present numerical procedure.","PeriodicalId":51155,"journal":{"name":"Smart Structures and Systems","volume":"27 1","pages":"729"},"PeriodicalIF":3.5,"publicationDate":"2021-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44866787","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-01DOI: 10.12989/SSS.2021.27.5.837
M. Farajollahi, Mehrad Goharzay, Daryoosh Borzuei, S. F. Moosavian
Corrugated and flat circular diaphragm-based piezoresistive pressure sensors are designed and proposed for different applications. Regarding to different criteria including maximum stress, sensitivity and natural frequency, different diaphragms with semicircular, sinusoidal and trapezoidal corrugation are modeled, simulated and investigated in finite element software. The finite element model is validated by experimental results from the literature and also with theoretical formula to ensure the accuracy of the finite element modeling process. Wavelength and location of the corrugation are optimized to achieve best performing sensor. For the application with large acceptable induced stress, circular flat diaphragm is proposed. To enhance the sensitivity of the sensor as a crucial parameter, semicircular corrugation for circular diaphragm with 360 μmm wavelength and 240 μmm distance from the center is designed and proposed. This configuration shows obvious improvement of the sensitivity with more than 18% enhancement. To extend the working range of the sensor regarding to input frequency, trapezoidal corrugation with 360 μm wavelength and 240 μmm distance from the center is proposed to reach more than 29% enlargement in first natural frequency. Eventually, this paper tries to provide an overview to design the optimal pressure sensor according to desired specifications.
{"title":"Stress, sensitivity and frequency analysis of the corrugated diaphragm for different corrugation structures","authors":"M. Farajollahi, Mehrad Goharzay, Daryoosh Borzuei, S. F. Moosavian","doi":"10.12989/SSS.2021.27.5.837","DOIUrl":"https://doi.org/10.12989/SSS.2021.27.5.837","url":null,"abstract":"Corrugated and flat circular diaphragm-based piezoresistive pressure sensors are designed and proposed for different applications. Regarding to different criteria including maximum stress, sensitivity and natural frequency, different diaphragms with semicircular, sinusoidal and trapezoidal corrugation are modeled, simulated and investigated in finite element software. The finite element model is validated by experimental results from the literature and also with theoretical formula to ensure the accuracy of the finite element modeling process. Wavelength and location of the corrugation are optimized to achieve best performing sensor. For the application with large acceptable induced stress, circular flat diaphragm is proposed. To enhance the sensitivity of the sensor as a crucial parameter, semicircular corrugation for circular diaphragm with 360 μmm wavelength and 240 μmm distance from the center is designed and proposed. This configuration shows obvious improvement of the sensitivity with more than 18% enhancement. To extend the working range of the sensor regarding to input frequency, trapezoidal corrugation with 360 μm wavelength and 240 μmm distance from the center is proposed to reach more than 29% enlargement in first natural frequency. Eventually, this paper tries to provide an overview to design the optimal pressure sensor according to desired specifications.","PeriodicalId":51155,"journal":{"name":"Smart Structures and Systems","volume":"27 1","pages":"837"},"PeriodicalIF":3.5,"publicationDate":"2021-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47518965","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-01DOI: 10.12989/SSS.2021.27.5.819
P. M. B. Mendoza, D. Ambrosini, B. Luccioni
The objective of this study was to determine friction ratios that maximize energy dissipation on a seismic damper. The aforementioned friction damper basically consists of mass blocks that are able to slide on a flat surface. To carry out this analysis, a numerical-experimental approach was used. Firstly, the theoretical background and equations of motion for a SDOF system consisting of a mass supported on a flat surface with friction are introduced. Special emphasis is made on the fundamentals of stick-slip motion as well as energy considerations. Secondly, experimental studies carried out on a shaking table with harmonic and seismic records are described. These tests consisted of lead blocks contained on a U-shaped channel type aluminum section with its open end facing upwards. This configuration allowed blocks to slide solely in the direction of the base motion. Five different types of contact interfaces were considered to determine potential friction coefficients for the damper's design. Additionally, computational models based on rigid-body dynamics are presented. Numerical results were satisfactory particularly when comparing model's dissipated energy with empirical results. An analysis was carried out by calculating dissipated energy for the experimentally-calibrated models with varying friction ratios. For this purpose, eight near-fault seismic records were selected. Intervals with friction coefficients that maximize energy dissipation are proposed for each record. Finally, relationships between the computed friction ratios and register's peak ground acceleration (PGA) and root mean square acceleration (RMS) are discussed.
{"title":"Energy dissipation by friction for sliding blocks subjected to near-fault seismic base motion","authors":"P. M. B. Mendoza, D. Ambrosini, B. Luccioni","doi":"10.12989/SSS.2021.27.5.819","DOIUrl":"https://doi.org/10.12989/SSS.2021.27.5.819","url":null,"abstract":"The objective of this study was to determine friction ratios that maximize energy dissipation on a seismic damper. The aforementioned friction damper basically consists of mass blocks that are able to slide on a flat surface. To carry out this analysis, a numerical-experimental approach was used. Firstly, the theoretical background and equations of motion for a SDOF system consisting of a mass supported on a flat surface with friction are introduced. Special emphasis is made on the fundamentals of stick-slip motion as well as energy considerations. Secondly, experimental studies carried out on a shaking table with harmonic and seismic records are described. These tests consisted of lead blocks contained on a U-shaped channel type aluminum section with its open end facing upwards. This configuration allowed blocks to slide solely in the direction of the base motion. Five different types of contact interfaces were considered to determine potential friction coefficients for the damper's design. Additionally, computational models based on rigid-body dynamics are presented. Numerical results were satisfactory particularly when comparing model's dissipated energy with empirical results. An analysis was carried out by calculating dissipated energy for the experimentally-calibrated models with varying friction ratios. For this purpose, eight near-fault seismic records were selected. Intervals with friction coefficients that maximize energy dissipation are proposed for each record. Finally, relationships between the computed friction ratios and register's peak ground acceleration (PGA) and root mean square acceleration (RMS) are discussed.","PeriodicalId":51155,"journal":{"name":"Smart Structures and Systems","volume":"27 1","pages":"819"},"PeriodicalIF":3.5,"publicationDate":"2021-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45070335","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-01DOI: 10.12989/SSS.2021.27.5.871
Yongqiang He, Rayed Alyousef, A. Alaskar, Hisham Alabduljabbar, A. M. Mohamed, N. Maureira-Carsalade, Á. Roco-Videla, A. Issakhov, H. Assilzadeh
This study examined the relations between permeability of the concrete due to addition of new cracks. The different concrete types analyzed were standard concrete, reinforced steel fiber concrete, and reinforced concrete polypropylene fiber. In consideration of the improved polypropylene content of polypropylene fiber reinforced concrete, the crack diameter was decreased by 72-93% for up to 0.25% fiber and cracks were eliminated with 0.3% fiber inclusion. In terms of steel fiberreinforced concrete, the results showed that steel reinforcing macro fibers decrease the permeability of cracked concrete at wider crack widths. While the permeability of unreinforced concrete was the highest, 0.5% steel content resulted in lower permeability while a higher steel content concrete with 1% steel had the lowest permeability. Crack stitching phenomenon and the effect of multiple cracks may be attributed to the decrease in the permeability. With respect to normal concrete, the findings showed the crack opening displacement at the highest tension is less than 20 microns. At this loading stage, after unloading, around 80% of the displacement is restored and the residual crack opening is notably small, indicating the low impact of cracking on concrete permeability (CP) and showing that CP was increased with crack width. As a result, adding polypropylene aggregate to concrete could significantly reduce the width of crack, while adding steel fiber to concrete reduces the permeability of cracked concrete compared to normal concrete which may result in a minor crack on CP.
{"title":"Influence of crack on the permeability of plastic concrete","authors":"Yongqiang He, Rayed Alyousef, A. Alaskar, Hisham Alabduljabbar, A. M. Mohamed, N. Maureira-Carsalade, Á. Roco-Videla, A. Issakhov, H. Assilzadeh","doi":"10.12989/SSS.2021.27.5.871","DOIUrl":"https://doi.org/10.12989/SSS.2021.27.5.871","url":null,"abstract":"This study examined the relations between permeability of the concrete due to addition of new cracks. The different concrete types analyzed were standard concrete, reinforced steel fiber concrete, and reinforced concrete polypropylene fiber. In consideration of the improved polypropylene content of polypropylene fiber reinforced concrete, the crack diameter was decreased by 72-93% for up to 0.25% fiber and cracks were eliminated with 0.3% fiber inclusion. In terms of steel fiberreinforced concrete, the results showed that steel reinforcing macro fibers decrease the permeability of cracked concrete at wider crack widths. While the permeability of unreinforced concrete was the highest, 0.5% steel content resulted in lower permeability while a higher steel content concrete with 1% steel had the lowest permeability. Crack stitching phenomenon and the effect of multiple cracks may be attributed to the decrease in the permeability. With respect to normal concrete, the findings showed the crack opening displacement at the highest tension is less than 20 microns. At this loading stage, after unloading, around 80% of the displacement is restored and the residual crack opening is notably small, indicating the low impact of cracking on concrete permeability (CP) and showing that CP was increased with crack width. As a result, adding polypropylene aggregate to concrete could significantly reduce the width of crack, while adding steel fiber to concrete reduces the permeability of cracked concrete compared to normal concrete which may result in a minor crack on CP.","PeriodicalId":51155,"journal":{"name":"Smart Structures and Systems","volume":"27 1","pages":"871-890"},"PeriodicalIF":3.5,"publicationDate":"2021-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43262918","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","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：