Pub Date : 2021-05-01DOI: 10.12989/SSS.2021.27.5.761
M. Kang, S. Im, Y. An
This paper presents crack opening phenomenon evaluation using digital image correlation (DIC) with a statistically optimized subset size. In conventional DIC analysis, the subset sizes varying from several pixels to more than hundred pixels have been often selected by experts' subjective judgement based on conventional subset size determination algorithms. Since these conventional subset size determination algorithms, however, calculate speckle pattern features at a certain location of a single target image, it is difficult to consider not only all speckle pattern features within region of interest (ROI) but also the random measurement noises during the digital image acquisition process. To overcome the technical limitation, a statistical optimization algorithm of the subset size, which calculates the optimal subset size by the 3-loop iteration of normalized cross correlation within the entire ROI, is newly proposed. In addition, the optimal subset-based DIC analysis is applied to crack opening phenomenon evaluation in a mock-up concrete specimen under step loading conditions. The validation test results show 3.6 μm maximum error compared with the ground truth which is obtained by direct measurement, while a conventional subset size determination algorithm-based DIC analysis produces the maximum error of 62.7 μm.
{"title":"Evaluation of crack opening phenomenon using subset-optimized digital image correlation","authors":"M. Kang, S. Im, Y. An","doi":"10.12989/SSS.2021.27.5.761","DOIUrl":"https://doi.org/10.12989/SSS.2021.27.5.761","url":null,"abstract":"This paper presents crack opening phenomenon evaluation using digital image correlation (DIC) with a statistically optimized subset size. In conventional DIC analysis, the subset sizes varying from several pixels to more than hundred pixels have been often selected by experts' subjective judgement based on conventional subset size determination algorithms. Since these conventional subset size determination algorithms, however, calculate speckle pattern features at a certain location of a single target image, it is difficult to consider not only all speckle pattern features within region of interest (ROI) but also the random measurement noises during the digital image acquisition process. To overcome the technical limitation, a statistical optimization algorithm of the subset size, which calculates the optimal subset size by the 3-loop iteration of normalized cross correlation within the entire ROI, is newly proposed. In addition, the optimal subset-based DIC analysis is applied to crack opening phenomenon evaluation in a mock-up concrete specimen under step loading conditions. The validation test results show 3.6 μm maximum error compared with the ground truth which is obtained by direct measurement, while a conventional subset size determination algorithm-based DIC analysis produces the maximum error of 62.7 μm.","PeriodicalId":51155,"journal":{"name":"Smart Structures and Systems","volume":"27 1","pages":"761"},"PeriodicalIF":3.5,"publicationDate":"2021-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41360978","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.2021.27.5.861
Sang Yeob Kim, Jong-Sub Lee, Won-Taek Hong
For the efficient management of geo-infrastructures in the field, engineering properties of the subgrade should be reliably and rapidly investigated. The objective of this study is to estimate and compare the strength and stiffness parameters of subgrades using portable in-situ devices. An automated dynamic cone penetrometer (ACP), dynamic cone penetrometer (DCP), and light falling weight deflectometer (LFWD) are adopted and applied at nine points of soft ground in South Korea. The Nvalue from the ACP (NACP), which efficiently assesses the relatively deep subgrade, is correlated with the dynamic cone penetration index (DCPI) and dynamic deflection modulus (Evd). Test results show that the DCPI and Evd can be estimated in terms of NACP. In particular, the relationship between Evd and NACP is improved when the strain influence factor of the target ground is considered. For the assessment of strength and stiffness parameters, the California bearing ratio (CBR), relative density (Dr), internal friction angle (φ), and elastic moduli determined by the plate loading test (PLT), soil stiffness gauge (SSG), falling weight deflectometer (FWD) are estimated using NACP. The ACP test with the relationships between engineering parameters and NACP may be an effectively method to assess the overall characteristics of the subgrade.
{"title":"Subgrade assessment using automated dynamic cone penetrometer to manage geo-infrastructures","authors":"Sang Yeob Kim, Jong-Sub Lee, Won-Taek Hong","doi":"10.12989/SSS.2021.27.5.861","DOIUrl":"https://doi.org/10.12989/SSS.2021.27.5.861","url":null,"abstract":"For the efficient management of geo-infrastructures in the field, engineering properties of the subgrade should be reliably and rapidly investigated. The objective of this study is to estimate and compare the strength and stiffness parameters of subgrades using portable in-situ devices. An automated dynamic cone penetrometer (ACP), dynamic cone penetrometer (DCP), and light falling weight deflectometer (LFWD) are adopted and applied at nine points of soft ground in South Korea. The Nvalue from the ACP (NACP), which efficiently assesses the relatively deep subgrade, is correlated with the dynamic cone penetration index (DCPI) and dynamic deflection modulus (Evd). Test results show that the DCPI and Evd can be estimated in terms of NACP. In particular, the relationship between Evd and NACP is improved when the strain influence factor of the target ground is considered. For the assessment of strength and stiffness parameters, the California bearing ratio (CBR), relative density (Dr), internal friction angle (φ), and elastic moduli determined by the plate loading test (PLT), soil stiffness gauge (SSG), falling weight deflectometer (FWD) are estimated using NACP. The ACP test with the relationships between engineering parameters and NACP may be an effectively method to assess the overall characteristics of the subgrade.","PeriodicalId":51155,"journal":{"name":"Smart Structures and Systems","volume":"24 7","pages":"861"},"PeriodicalIF":3.5,"publicationDate":"2021-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41299828","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.2021.27.5.803
Shengyun Peng, Ling-Feng Yan, Bin He, Ying Zhou
In the field of structural health monitoring (SHM), cameras record videos and tracking methods can be applied to calculate the structural displacement. Commercial and unmanned aerial vehicle (UAV) cameras are promising non-contact sensors owning to their high availability and easy installation. However, effective tracking methods need to be developed. In this study, we firstly propose an end-to-end vision measuring framework with a novel deep neural network (DNN) tracker, named Siamese Single Decoder Network (SiamSDN). The system requires no target installation and uses cellphone cameras. For SiamSDN, the position and scale of bounding box are formulated through statistical parameter estimation. Unlike generative trackers, SiamSDN does not require manually extracted features or pre-defined motion areas. The tracking object is solely identified in the first frame. A shaking table test of a five-storey structure is carried out to demonstrate the efficiency. Besides, a UAV is used to simulate the field test. To minimize the error caused by the vibrations of UAV, digital video stabilization (DVS) is proposed to eliminate the drifts. Videos taken by both the commercial and UAV cameras are analyzed to calculate the displacements. Comparing our DNN tracker with feature point matching approach, SiamSDN improves the displacement measuring accuracy by 66.16% and 57.54%, respectively, and the frequency characteristics are obtained precisely.
在结构健康监测(SHM)领域，可以采用摄像机记录视频和跟踪方法来计算结构位移。商用和无人机(UAV)相机是非接触式传感器，因为它们的高可用性和易于安装。然而，需要开发有效的跟踪方法。在这项研究中，我们首先提出了一个端到端视觉测量框架，该框架采用了一种新型的深度神经网络(DNN)跟踪器，称为SiamSDN (Siamese Single Decoder network)。该系统不需要目标安装，使用手机摄像头。对于SiamSDN，通过统计参数估计确定边界框的位置和尺度。与生成式跟踪器不同，SiamSDN不需要手动提取特征或预定义的运动区域。跟踪对象在第一帧中被单独识别。通过某五层结构的振动台试验验证了该方法的有效性。此外，还利用一架无人机进行了现场模拟试验。为了最大限度地减少无人机振动引起的误差，提出了数字视频稳定(DVS)来消除漂移。分析商用和无人机摄像机拍摄的视频以计算位移。与特征点匹配方法相比，SiamSDN的位移测量精度分别提高了66.16%和57.54%，并准确地获得了频率特征。
{"title":"A novel DNN tracking algorithm for structural system identification","authors":"Shengyun Peng, Ling-Feng Yan, Bin He, Ying Zhou","doi":"10.12989/SSS.2021.27.5.803","DOIUrl":"https://doi.org/10.12989/SSS.2021.27.5.803","url":null,"abstract":"In the field of structural health monitoring (SHM), cameras record videos and tracking methods can be applied to calculate the structural displacement. Commercial and unmanned aerial vehicle (UAV) cameras are promising non-contact sensors owning to their high availability and easy installation. However, effective tracking methods need to be developed. In this study, we firstly propose an end-to-end vision measuring framework with a novel deep neural network (DNN) tracker, named Siamese Single Decoder Network (SiamSDN). The system requires no target installation and uses cellphone cameras. For SiamSDN, the position and scale of bounding box are formulated through statistical parameter estimation. Unlike generative trackers, SiamSDN does not require manually extracted features or pre-defined motion areas. The tracking object is solely identified in the first frame. A shaking table test of a five-storey structure is carried out to demonstrate the efficiency. Besides, a UAV is used to simulate the field test. To minimize the error caused by the vibrations of UAV, digital video stabilization (DVS) is proposed to eliminate the drifts. Videos taken by both the commercial and UAV cameras are analyzed to calculate the displacements. Comparing our DNN tracker with feature point matching approach, SiamSDN improves the displacement measuring accuracy by 66.16% and 57.54%, respectively, and the frequency characteristics are obtained precisely.","PeriodicalId":51155,"journal":{"name":"Smart Structures and Systems","volume":"27 1","pages":"803"},"PeriodicalIF":3.5,"publicationDate":"2021-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43974498","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.2021.27.5.745
Yinghao Zhao, C. Bai, Chengyong Xu, L. K. Foong
Due to the benefits of the early prediction of concrete slump, introducing an efficient model for this purpose is of great importance. Considering this motivation, four strong metaheuristic algorithms, namely electromagnetic field optimization (EFO), water cycle algorithm (WCA), teaching-learning-based optimization (TLBO), and multi-tracker optimization algorithm (MTOA) are used to supervise a neural predictive system in analyzing the slump pattern. This supervision protects the network against computational issues like pre-mature convergence. The overall results (e.g., Pearson correlation indicator larger than 0.839 and 0.807 for the training and testing data, respectively) revealed the competency of the proposed models. However, investigating the rankings of the models pointed out the superiority of the WCA (MAEtrain = 3.3080 vs. 3.7821, 3.5782, and 3.6851; and MAEtest = 3.8443 vs. 4.0326, 4.1417, and 4.0871 obtained for the EFO, TLBO, and MTOA, respectively). Moreover, the high efficiency of the EFO in terms of model complexity and convergence rate, as well as the adequate accuracy of prediction, demonstrated the suitability of the corresponding ensemble. Therefore, the neural systems trained by these two algorithms (i.e., the WCA and EFO) are efficient slump evaluative models and can give an optimal design of the concrete mixture for any desirable slump.
考虑到混凝土坍落度的早期预测的好处，引入一种有效的模型对此具有重要意义。考虑到这一动机，利用电磁场优化(EFO)、水循环算法(WCA)、基于教学的优化(TLBO)和多跟踪器优化算法(MTOA)等四种强元启发式算法对滑塌模式分析的神经预测系统进行监督。这种监督保护网络免受早熟收敛等计算问题的影响。总体结果(例如，训练数据和测试数据的Pearson相关指标分别大于0.839和0.807)显示了所提出模型的胜任力。然而，通过对模型排名的调查，发现WCA的优势(MAEtrain = 3.3080 vs. 3.7821、3.5782和3.6851);MAEtest = 3.8443，而EFO、TLBO和MTOA分别为4.0326、4.1417和4.0871)。此外，EFO在模型复杂度和收敛速度方面的高效率，以及足够的预测精度，证明了相应集合的适用性。因此，由这两种算法训练的神经系统(即WCA和EFO)是有效的坍落度评价模型，可以给出任何理想坍落度的混凝土混合料的最优设计。
{"title":"Efficient metaheuristic-retrofitted techniques for concrete slump simulation","authors":"Yinghao Zhao, C. Bai, Chengyong Xu, L. K. Foong","doi":"10.12989/SSS.2021.27.5.745","DOIUrl":"https://doi.org/10.12989/SSS.2021.27.5.745","url":null,"abstract":"Due to the benefits of the early prediction of concrete slump, introducing an efficient model for this purpose is of great importance. Considering this motivation, four strong metaheuristic algorithms, namely electromagnetic field optimization (EFO), water cycle algorithm (WCA), teaching-learning-based optimization (TLBO), and multi-tracker optimization algorithm (MTOA) are used to supervise a neural predictive system in analyzing the slump pattern. This supervision protects the network against computational issues like pre-mature convergence. The overall results (e.g., Pearson correlation indicator larger than 0.839 and 0.807 for the training and testing data, respectively) revealed the competency of the proposed models. However, investigating the rankings of the models pointed out the superiority of the WCA (MAEtrain = 3.3080 vs. 3.7821, 3.5782, and 3.6851; and MAEtest = 3.8443 vs. 4.0326, 4.1417, and 4.0871 obtained for the EFO, TLBO, and MTOA, respectively). Moreover, the high efficiency of the EFO in terms of model complexity and convergence rate, as well as the adequate accuracy of prediction, demonstrated the suitability of the corresponding ensemble. Therefore, the neural systems trained by these two algorithms (i.e., the WCA and EFO) are efficient slump evaluative models and can give an optimal design of the concrete mixture for any desirable slump.","PeriodicalId":51155,"journal":{"name":"Smart Structures and Systems","volume":"27 1","pages":"745"},"PeriodicalIF":3.5,"publicationDate":"2021-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48474018","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.2021.27.5.769
Jiazeng Shan, Jie Liu, C. Loong, Weichao Wu
A plate-type eddy-current damper with high energy-dissipation capability is designed and analyzed. The damper is configured in a dimension of 270 mm × 500 mm × 80 mm by employing 16 pairs of rectangular magnets and a rectangular copper plate. The paired magnets are arranged as two rows of 4-by-4 arrays with polarities alternating along the moving direction, while the copper plate is embedded inside two rows of magnets. A finite-element model is developed to investigate eddy-current force. The damping coefficient of damper under a constant velocity of 0.2 m/s is 24.44 kN-s/m. The eddy-current force under harmonic motion can be fitted as a sum of a linear elastic force and a linear damping force. The stiffness coefficient is increased by 77 times and the damping coefficient is reduced relatively by 19%, for vibration frequency increased from 0.5 to 10.0 Hz. The sensitivity of stiffness and damping coefficients on the physical dimensions of magnet and copper plate are discussed. The phase lag is sensitive to copper-plate thickness but insensitive to clear gap between two rows of magnets. The damper is implemented on a based-isolated structure. It is shown that the damper could reduce the peak of base drift and absolute acceleration response spectra by 71.9% and 73.1%, respectively.
{"title":"Design and analysis of plate-type eddy-current damper with high energy-dissipation capability","authors":"Jiazeng Shan, Jie Liu, C. Loong, Weichao Wu","doi":"10.12989/SSS.2021.27.5.769","DOIUrl":"https://doi.org/10.12989/SSS.2021.27.5.769","url":null,"abstract":"A plate-type eddy-current damper with high energy-dissipation capability is designed and analyzed. The damper is configured in a dimension of 270 mm × 500 mm × 80 mm by employing 16 pairs of rectangular magnets and a rectangular copper plate. The paired magnets are arranged as two rows of 4-by-4 arrays with polarities alternating along the moving direction, while the copper plate is embedded inside two rows of magnets. A finite-element model is developed to investigate eddy-current force. The damping coefficient of damper under a constant velocity of 0.2 m/s is 24.44 kN-s/m. The eddy-current force under harmonic motion can be fitted as a sum of a linear elastic force and a linear damping force. The stiffness coefficient is increased by 77 times and the damping coefficient is reduced relatively by 19%, for vibration frequency increased from 0.5 to 10.0 Hz. The sensitivity of stiffness and damping coefficients on the physical dimensions of magnet and copper plate are discussed. The phase lag is sensitive to copper-plate thickness but insensitive to clear gap between two rows of magnets. The damper is implemented on a based-isolated structure. It is shown that the damper could reduce the peak of base drift and absolute acceleration response spectra by 71.9% and 73.1%, respectively.","PeriodicalId":51155,"journal":{"name":"Smart Structures and Systems","volume":"27 1","pages":"769"},"PeriodicalIF":3.5,"publicationDate":"2021-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49349046","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.2021.27.5.783
Junyeon Chung, H. Sohn
Bolt loosening is one of the most common types of damage for bolt-connected plates. Existing vision techniques detect bolt loosening based on the measurement of bolt rotation or the exposure of bolt threads. However, these techniques examine bolt tightness only in a qualitative manner, or require a reference measurement at the initially tightened state of the bolt for quantitative estimation. In this study, the exposed shank length of a bolt is quantitatively measured using an RGB-depth camera and a mask-region-based convolutional neural network but without requiring any measurement from the initial state of the bolt. The performance of the proposed technique is validated by conducting lab-scale experiments, in which the angle and distance of the camera are varied with respect to a target inspection area. The proposed technique successfully detects bolt loosening at exposed shank length over 3 mm with a resolution of 1 mm and 97% accuracy at different camera angles (40°–90°) and distances (up to 65 cm).
{"title":"Detection and quantification of bolt loosening using RGB-D camera and Mask R-CNN","authors":"Junyeon Chung, H. Sohn","doi":"10.12989/SSS.2021.27.5.783","DOIUrl":"https://doi.org/10.12989/SSS.2021.27.5.783","url":null,"abstract":"Bolt loosening is one of the most common types of damage for bolt-connected plates. Existing vision techniques detect bolt loosening based on the measurement of bolt rotation or the exposure of bolt threads. However, these techniques examine bolt tightness only in a qualitative manner, or require a reference measurement at the initially tightened state of the bolt for quantitative estimation. In this study, the exposed shank length of a bolt is quantitatively measured using an RGB-depth camera and a mask-region-based convolutional neural network but without requiring any measurement from the initial state of the bolt. The performance of the proposed technique is validated by conducting lab-scale experiments, in which the angle and distance of the camera are varied with respect to a target inspection area. The proposed technique successfully detects bolt loosening at exposed shank length over 3 mm with a resolution of 1 mm and 97% accuracy at different camera angles (40°–90°) and distances (up to 65 cm).","PeriodicalId":51155,"journal":{"name":"Smart Structures and Systems","volume":"27 1","pages":"783"},"PeriodicalIF":3.5,"publicationDate":"2021-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43649413","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 : 2021-04-01DOI: 10.12989/SSS.2021.27.4.571
Süleyman İpek, Esra Mete Gűneyisi
In this study, the structural response of concrete-filled single and double skin steel tubular (CFST and CFDST) composite tapered columns was investigated through the finite element method (FEM). In the development of the FEM model, the concentric axial loading condition and circular section were adopted. Experimental results available in the literature were used to verify the proposed FEM model. In addition, a parametric study was performed to visualize the effectiveness of tapered angle and material strengths on the ultimate capacity of CFST and CFDST tapered columns. To this aim, a total of 60 tapered column samples (including 30 CFST and 30 CFDST columns) were modeled by taking into consideration five tapered angles, two steel tube yield strengths, and three concrete cube compressive strengths. The verification of the FEM model revealed that the developed model has a reliable and trustable assessment capability. It was noticed that the tapered angle was the most crucial parameter, influencing significantly the ultimate axial strength and stiffness of both CFST and CFDST composite tapered columns. As well, it was overtly beheld from the study that CFST composite tapered column specimens had better ultimate axial strength values than CFDST composite tapered column specimens with the same sectional and material properties.
{"title":"Nonlinear analysis of concrete-filled single and double skin steel tubular tapered columns under axial loading","authors":"Süleyman İpek, Esra Mete Gűneyisi","doi":"10.12989/SSS.2021.27.4.571","DOIUrl":"https://doi.org/10.12989/SSS.2021.27.4.571","url":null,"abstract":"In this study, the structural response of concrete-filled single and double skin steel tubular (CFST and CFDST) composite tapered columns was investigated through the finite element method (FEM). In the development of the FEM model, the concentric axial loading condition and circular section were adopted. Experimental results available in the literature were used to verify the proposed FEM model. In addition, a parametric study was performed to visualize the effectiveness of tapered angle and material strengths on the ultimate capacity of CFST and CFDST tapered columns. To this aim, a total of 60 tapered column samples (including 30 CFST and 30 CFDST columns) were modeled by taking into consideration five tapered angles, two steel tube yield strengths, and three concrete cube compressive strengths. The verification of the FEM model revealed that the developed model has a reliable and trustable assessment capability. It was noticed that the tapered angle was the most crucial parameter, influencing significantly the ultimate axial strength and stiffness of both CFST and CFDST composite tapered columns. As well, it was overtly beheld from the study that CFST composite tapered column specimens had better ultimate axial strength values than CFDST composite tapered column specimens with the same sectional and material properties.","PeriodicalId":51155,"journal":{"name":"Smart Structures and Systems","volume":"27 1","pages":"571"},"PeriodicalIF":3.5,"publicationDate":"2021-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44493149","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 : 2021-04-01DOI: 10.12989/SSS.2021.27.4.719
Hichem Bellifa, M. Selim, ABDELBAKI CHIKH, A. Chikh, A. A. Bousahla, F. Bourada, A. Tounsi, K. H. Benrahou, M. Al-Zahrani, A. Tounsi
The interest of this work is the analysis of the effect of porosity on the nonlinear thermal stability response of power law functionally graded beam with various boundary conditions. The modelling was done according to the Euler-Bernoulli beam model where the distribution of material properties is imitated polynomial function. The thermal loads are assumed to be not only uniform but linear as well non-linear and the temperature rises through the thickness direction. The effects of the porosity parameter, slenderness ratio and power law index on the thermal buckling of P-FG beam are discussed.
{"title":"Influence of porosity on thermal buckling behavior of functionally graded beams","authors":"Hichem Bellifa, M. Selim, ABDELBAKI CHIKH, A. Chikh, A. A. Bousahla, F. Bourada, A. Tounsi, K. H. Benrahou, M. Al-Zahrani, A. Tounsi","doi":"10.12989/SSS.2021.27.4.719","DOIUrl":"https://doi.org/10.12989/SSS.2021.27.4.719","url":null,"abstract":"The interest of this work is the analysis of the effect of porosity on the nonlinear thermal stability response of power law functionally graded beam with various boundary conditions. The modelling was done according to the Euler-Bernoulli beam model where the distribution of material properties is imitated polynomial function. The thermal loads are assumed to be not only uniform but linear as well non-linear and the temperature rises through the thickness direction. The effects of the porosity parameter, slenderness ratio and power law index on the thermal buckling of P-FG beam are discussed.","PeriodicalId":51155,"journal":{"name":"Smart Structures and Systems","volume":"27 1","pages":"719"},"PeriodicalIF":3.5,"publicationDate":"2021-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46022606","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 : 2021-04-01DOI: 10.12989/SSS.2021.27.4.667
A. Eyvazian, Chunwei Zhang, M. Alkhedher, M. Demiral, Afrasyab Khan, T. Sebaey
This research is deal with thermal buckling and post-buckling of carbon nanotube/fiber/polymer composite beams. The beam is considered to be under uniform temperature rise. Firstly, the effective material properties of a two phase nanocomposite consisting of CNT and polymer are extracted. Then, the modified Chamis rule is utilized to obtain the equivalent thermo-mechanical properties of multiscale hybrid composite (MHC). Based on the first order shear deformation theory, Von-Karman type of geometrically nonlinear strain-deformation equations and also the virtual work rule, the equilibrium equations of a three phace composite beam are derived. Bifurcation buckling and also the thermal post-buckling is analysed using the generalized differential quadrature technique. In the thermal buckling phenomena, a linear eigenvalue problem is solved; however, due to the nonlinearity, the thermal postbuckling study is performed using an iterative displacement control strategy. After validation study, several novel results demonstrate the influences of length-to-thickness ratio, agglomeration of applied CNTs and fibers in the composite media and number and orientation of layers on the critical temperature and displacement loading path.
{"title":"Thermal postbuckling of shear deformable multiscale hybrid composite beams","authors":"A. Eyvazian, Chunwei Zhang, M. Alkhedher, M. Demiral, Afrasyab Khan, T. Sebaey","doi":"10.12989/SSS.2021.27.4.667","DOIUrl":"https://doi.org/10.12989/SSS.2021.27.4.667","url":null,"abstract":"This research is deal with thermal buckling and post-buckling of carbon nanotube/fiber/polymer composite beams. The beam is considered to be under uniform temperature rise. Firstly, the effective material properties of a two phase nanocomposite consisting of CNT and polymer are extracted. Then, the modified Chamis rule is utilized to obtain the equivalent thermo-mechanical properties of multiscale hybrid composite (MHC). Based on the first order shear deformation theory, Von-Karman type of geometrically nonlinear strain-deformation equations and also the virtual work rule, the equilibrium equations of a three phace composite beam are derived. Bifurcation buckling and also the thermal post-buckling is analysed using the generalized differential quadrature technique. In the thermal buckling phenomena, a linear eigenvalue problem is solved; however, due to the nonlinearity, the thermal postbuckling study is performed using an iterative displacement control strategy. After validation study, several novel results demonstrate the influences of length-to-thickness ratio, agglomeration of applied CNTs and fibers in the composite media and number and orientation of layers on the critical temperature and displacement loading path.","PeriodicalId":51155,"journal":{"name":"Smart Structures and Systems","volume":"27 1","pages":"667"},"PeriodicalIF":3.5,"publicationDate":"2021-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45379813","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 : 2021-04-01DOI: 10.12989/SSS.2021.27.4.705
Pei‐Ching Chen, Bryan J. Sugiarto, Kai-yi Chien
The linear-quadratic regulator (LQR) has been applied to structural vibration control for decades; however, selection of the weighting matrices of an LQR mostly depends on trial and error. In this study, a novel metaheuristic optimization method named as symbiotic organisms search (SOS) algorithm is applied to tuning LQR weighting matrices for active mass damper (AMD) control systems. A 10-story shear building with an active mass damper installed at the top is adopted as a benchmark for numerical simulation in order to realize the optimization performance considering three objective functions for mitigation of structural acceleration. Two common optimization methods including genetic algorithm (GA), and particle swarm optimization (PSO) are also applied to this benchmark for comparison purposes. Numerical simulation results indicate that SOS is superior to GA and PSO on searching the minimized solution of the three objective functions. Meanwhile, minimizing the square root of the sum of the squares of peak modal acceleration achieves the best control performance of structural acceleration among the three objective functions. In addition, force saturation is proposed and applied in the optimization process such that the control force level is close to the force capacity of AMD under specified earthquake intensity. Furthermore, the control performance of the optimized LQR is compared with that of the LQR designed by applying three common weighting selection methods when the 10-story building is subjected to various earthquake excitations. Simulation results demonstrate that the optimized LQR significantly outperforms the three LQRs on structural acceleration responses as expected and reduces story drift slightly better than the three LQRs. Finally, the performance-based optimized LQR is experimentally validated by conducting shake table testing in the laboratory. The experimental results and structural control performance are discussed and summarized thoroughly.
{"title":"Performance-based optimization of LQR for active mass damper using symbiotic organisms search","authors":"Pei‐Ching Chen, Bryan J. Sugiarto, Kai-yi Chien","doi":"10.12989/SSS.2021.27.4.705","DOIUrl":"https://doi.org/10.12989/SSS.2021.27.4.705","url":null,"abstract":"The linear-quadratic regulator (LQR) has been applied to structural vibration control for decades; however, selection of the weighting matrices of an LQR mostly depends on trial and error. In this study, a novel metaheuristic optimization method named as symbiotic organisms search (SOS) algorithm is applied to tuning LQR weighting matrices for active mass damper (AMD) control systems. A 10-story shear building with an active mass damper installed at the top is adopted as a benchmark for numerical simulation in order to realize the optimization performance considering three objective functions for mitigation of structural acceleration. Two common optimization methods including genetic algorithm (GA), and particle swarm optimization (PSO) are also applied to this benchmark for comparison purposes. Numerical simulation results indicate that SOS is superior to GA and PSO on searching the minimized solution of the three objective functions. Meanwhile, minimizing the square root of the sum of the squares of peak modal acceleration achieves the best control performance of structural acceleration among the three objective functions. In addition, force saturation is proposed and applied in the optimization process such that the control force level is close to the force capacity of AMD under specified earthquake intensity. Furthermore, the control performance of the optimized LQR is compared with that of the LQR designed by applying three common weighting selection methods when the 10-story building is subjected to various earthquake excitations. Simulation results demonstrate that the optimized LQR significantly outperforms the three LQRs on structural acceleration responses as expected and reduces story drift slightly better than the three LQRs. Finally, the performance-based optimized LQR is experimentally validated by conducting shake table testing in the laboratory. The experimental results and structural control performance are discussed and summarized thoroughly.","PeriodicalId":51155,"journal":{"name":"Smart Structures and Systems","volume":"27 1","pages":"705"},"PeriodicalIF":3.5,"publicationDate":"2021-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47071752","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}
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