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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Smart Structures and Systems
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Volume 14, Issue 6 - Dec 2014
Volume 14, Issue 5 - Nov 2014
Volume 14, Issue 4 - Oct 2014
Volume 14, Issue 3 - Sep 2014
Volume 14, Issue 2 - Aug 2014
Volume 14, Issue 1 - Jul 2014
Volume 13, Issue 6 - Jun 2014
Volume 13, Issue 5 - May 2014
Volume 13, Issue 4 - Apr 2014
Volume 13, Issue 3 - Mar 2014
Volume 13, Issue 2 - Feb 2014
Volume 13, Issue 1 - Jan 2014
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Period doubling of the nonlinear dynamical system of an electrostatically actuated micro-cantilever
Chen, Y.M. ; Liu, J.K. ;
Smart Structures and Systems, volume 14, issue 5, 2014, Pages 743~763
DOI : 10.12989/sss.2014.14.5.743
The paper presents an investigation of the nonlinear dynamical system of an electrostatically actuated micro-cantilever by the incremental harmonic balance (IHB) method. An efficient approach is proposed to tackle the difficulty in expanding the nonlinear terms into truncated Fourier series. With the help of this approach, periodic and multi-periodic solutions are obtained by the IHB method. Numerical examples show that the IHB solutions, provided as many as harmonics are taken into account, are in excellent agreement with numerical results. In addition, an iterative algorithm is suggested to accurately determine period doubling bifurcation points. The route to chaos via period doublings starting from the period-1 or period-3 solution are analyzed according to the Floquet and the Feigenbaum theories.
Performance analyses of antagonistic shape memory alloy actuators based on recovered strain
Shi, Zhenyun ; Wang, Tianmiao ; Da, Liu ;
Smart Structures and Systems, volume 14, issue 5, 2014, Pages 765~784
DOI : 10.12989/sss.2014.14.5.765
In comparison with conventional shape memory actuated structures, antagonistic shape memory alloy (SMA) actuators permits a fully reversible two-way response and higher response frequency. However, excessive internal stress could adversely reduce the stroke of the actuators under repeated use. The two-way shape memory effect might further decrease the range of the recovered strain under actuation of an antagonistic SMA actuator unless additional components (e.g., spring and stopper) are added to regain the overall actuation capability. In this paper, the performance of all four possible types of SMA actuation schemes is investigated in detail with emphasis on five key properties: recovered strain, cyclic degradation, response frequency, self-sensing control accuracy, and controllable maximum output. The testing parameters are chosen based on the maximization of recovered strain. Three types of these actuators are antagonistic SMA actuators, which drive with two active SMA wires in two directions. The antagonistic SMA actuator with an additional pair of springs exhibits wider displacement range, more stable performance under reuse, and faster response, although accurate control cannot be maintained under force interference. With two additional stoppers to prevent the over stretch of the spring, the results showed that the proposed structure could achieve significant improvement on all five properties. It can be concluded that, the last type actuator scheme with additional spring and stopper provide much better applicability than the other three in most conditions. The results of the performance analysis of all four SMA actuators could provide a solid basis for the practical design of SMA actuators.
An evolutionary fuzzy modelling approach and comparison of different methods for shear strength prediction of high-strength concrete beams without stirrups
Mohammadhassani, Mohammad ; Nezamabadi-pour, Hossein ; Suhatril, Meldi ; shariati, Mahdi ;
Smart Structures and Systems, volume 14, issue 5, 2014, Pages 785~809
DOI : 10.12989/sss.2014.14.5.785
In this paper, an Adaptive nerou-based inference system (ANFIS) is being used for the prediction of shear strength of high strength concrete (HSC) beams without stirrups. The input parameters comprise of tensile reinforcement ratio, concrete compressive strength and shear span to depth ratio. Additionally, 122 experimental datasets were extracted from the literature review on the HSC beams with some comparable cross sectional dimensions and loading conditions. A comparative analysis has been carried out on the predicted shear strength of HSC beams without stirrups via the ANFIS method with those from the CEB-FIP Model Code (1990), AASHTO LRFD 1994 and CSA A23.3 - 94 codes of design. The shear strength prediction with ANFIS is discovered to be superior to CEB-FIP Model Code (1990), AASHTO LRFD 1994 and CSA A23.3 - 94. The predictions obtained from the ANFIS are harmonious with the test results not accounting for the shear span to depth ratio, tensile reinforcement ratio and concrete compressive strength; the data of the average, variance, correlation coefficient and coefficient of variation (CV) of the ratio between the shear strength predicted using the ANFIS method and the real shear strength are 0.995, 0.014, 0.969 and 11.97%, respectively. Taking a look at the CV index, the shear strength prediction shows better in nonlinear iterations such as the ANFIS for shear strength prediction of HSC beams without stirrups.
Simulation of PZT monitoring of reinforced concrete beams retrofitted with CFRP
Providakis, C.P. ; Triantafillou, T.C. ; Karabalis, D. ; Papanicolaou, A. ; Stefanaki, K. ; Tsantilis, A. ; Tzoura, E. ;
Smart Structures and Systems, volume 14, issue 5, 2014, Pages 811~830
DOI : 10.12989/sss.2014.14.5.811
A numerical study has been carried out to simulate an innovative monitoring procedure to detect and localize damage in reinforced concrete beams retrofitted with carbon fiber reinforced polymer (CFRP) unidirectional laminates. The main novelty of the present simulation is its ability to conduct the electromechanical admittance monitoring technique by considerably compressing the amount of data required for damage detection and localization. A FEM simulation of electromechanical admittance-based sensing technique was employed by applying lead zirconate titanate (PZT) transducers to acquire impedance spectrum signatures. Response surface methodology (RSM) is finally adopted as a tool for solving inverse problems to estimate the location and size of damaged areas from the relationship between damage and electromechanical admittance changes computed at PZT transducer surfaces. This statistical metamodel technique allows polynomial models to be produced without requiring complicated modeling or numerous data sets after the generation of damage, leading to considerably lower cost of creating diagnostic database. Finally, a numerical example is carried out regarding a steel-reinforced concrete (RC) beam model monotonically loaded up to its failure which is also retrofitted by a CFRP laminate to verify the validity of the present metamodeling monitoring technique. The load-carrying capacity of concrete is predicted in the present paper by utilizing an Ottosen-type failure surface in order to better take into account the passive confinement behavior of retrofitted concrete material under the application of FRP laminate.
Time-varying physical parameter identification of shear type structures based on discrete wavelet transform
Wang, Chao ; Ren, Wei-Xin ; Wang, Zuo-Cai ; Zhu, Hong-Ping ;
Smart Structures and Systems, volume 14, issue 5, 2014, Pages 831~845
DOI : 10.12989/sss.2014.14.5.831
This paper proposed a discrete wavelet transform based method for time-varying physical parameter identification of shear type structures. The time-varying physical parameters are dispersed and expanded at multi-scale as profile and detail signal using discrete wavelet basis. To reduce the number of unknown quantity, the wavelet coefficients that reflect the detail signal are ignored by setting as zero value. Consequently, the time-varying parameter can be approximately estimated only using the scale coefficients that reflect the profile signal, and the identification task is transformed to an equivalent time-invariant scale coefficient estimation. The time-invariant scale coefficients can be simply estimated using regular least-squares methods, and then the original time-varying physical parameters can be reconstructed by using the identified time-invariant scale coefficients. To reduce the influence of the ill-posed problem of equation resolving caused by noise, the Tikhonov regularization method instead of regular least-squares method is used in the paper to estimate the scale coefficients. A two-story shear type frame structure with time-varying stiffness and damping are simulated to validate the effectiveness and accuracy of the proposed method. It is demonstrated that the identified time-varying stiffness is with a good accuracy, while the identified damping is sensitive to noise.
A new methodology of the development of seismic fragility curves
Lee, Young-Joo ; Moon, Do-Soo ;
Smart Structures and Systems, volume 14, issue 5, 2014, Pages 847~867
DOI : 10.12989/sss.2014.14.5.847
There are continuous efforts to mitigate structural losses from earthquakes and manage risk through seismic risk assessment; seismic fragility curves are widely accepted as an essential tool of such efforts. Seismic fragility curves can be classified into four groups based on how they are derived: empirical, judgmental, analytical, and hybrid. Analytical fragility curves are the most widely used and can be further categorized into two subgroups, depending on whether an analytical function or simulation method is used. Although both methods have shown decent performances for many seismic fragility problems, they often oversimplify the given problems in reliability or structural analyses owing to their built-in assumptions. In this paper, a new method is proposed for the development of seismic fragility curves. Integration with sophisticated software packages for reliability analysis (FERUM) and structural analysis (ZEUS-NL) allows the new method to obtain more accurate seismic fragility curves for less computational cost. Because the proposed method performs reliability analysis using the first-order reliability method, it provides component probabilities as well as useful byproducts and allows further fragility analysis at the system level. The new method was applied to a numerical example of a 2D frame structure, and the results were compared with those by Monte Carlo simulation. The method was found to generate seismic fragility curves more accurately and efficiently. Also, the effect of system reliability analysis on the development of seismic fragility curves was investigated using the given numerical example and its necessity was discussed.
Magnetic circuit optimization in designing Magnetorheological damper
Yazid, Izyan I.M. ; Mazlan, Saiful A. ; Kikuchi, Takehito ; Zamzuri, Hairi ; Imaduddin, Fitrian ;
Smart Structures and Systems, volume 14, issue 5, 2014, Pages 869~881
DOI : 10.12989/sss.2014.14.5.869
This paper presents the materials analysis for combination of working modes of Magnetorheological (MR) damper. The materials were selected based on the optimum magnetic field strength at the effective areas in order to obtain a better design of MR damper. The design of electromagnetic circuit is one of the critical criteria in designing MR dampers besides the working mechanism and the types of MR damper. The increase in the magnetic field strength is an indication of the improvement in the damping performance of the MR damper. Eventually, the experimental test was performed under quasi-static loading to observe the performances of MR damper in shear mode, squeeze mode and mixed mode. The results showed that the increment of forces was obtained with the increased current due to higher magnetic flux density generated by electromagnetic coils. In general, it can be summarized that the combination of modes generates higher forces than single mode for the same experimental parameters throughout the study.
Testing and modelling of shape memory alloy plates for energy dissipators
Heresi, Pablo ; Herrera, Ricardo A. ; Moroni, Maria O. ;
Smart Structures and Systems, volume 14, issue 5, 2014, Pages 883~900
DOI : 10.12989/sss.2014.14.5.883
Shape memory alloys (SMA) can dissipate energy through hysteresis cycles without significant residual deformation. This paper describes the fabrication and testing of copper-based SMA hourglass-shaped plates for use in energy dissipation devices and the development of a numerical model to reproduce the experiments. The plates were tested under cyclic flexural deformations, showing stable hysteresis cycles without strength degradation. A detailed nonlinear numerical model was developed and validated with the experimental data, using as input the constitutive relationship for the material determined from cyclic tests of material coupons under tension loading. The model adequately reproduces the experimental results. The study is focused on the exploitation of SMA in the martensite phase.
Simulation study of magnetorheological testing cell design by incorporating all basic operating modes
Mughni, Mohd J. ; Mazlan, Saiful A. ; Zamzuri, Hairi ; Yazid, Izyan I.M. ; Rahman, Mohd A.A. ;
Smart Structures and Systems, volume 14, issue 5, 2014, Pages 901~916
DOI : 10.12989/sss.2014.14.5.901
Magnetorheological (MR) fluid is one of the field-responsive fluids that is of interest to many researchers due to its high yield stress value, which depends on the magnetic field strength. Similar to electrorheological (ER) fluid, the combination of working modes is one of the techniques to increase the performance of the fluids with limited focus on MR fluids. In this paper, a novel MR testing cell incorporated with valve, shear and squeeze operational modes is designed and constructed in order to investigate the behaviour of MR fluid in combined mode. The magnetic field distribution in the design concept was analyzed using finite element method in order to verify the effective areas of each mode have the acceptable range of flux density. The annular gap of valve and shear were fixed at 1 mm, while the squeeze gap between the parallel circular surfaces was varied up to 20 mm. Three different coil configurations, which were made up from 23 SWG copper wires were set up in the MR cell. The simulation results indicated that the magnetic field distributed in the squeeze gap was the highest among the other gaps with all coils were subjected to a constant applied current of 1 A. Moreover, the magnetic flux densities in all gaps were in a good range of magnitude based on the simulations that validated the proposed design concept. Hence, the 3D model of the MR testing cell was designed using Solidworks for manufacturing processes.
An integrated approach for structural health monitoring using an in-house built fiber optic system and non-parametric data analysis
Malekzadeh, Masoud ; Gul, Mustafa ; Kwon, Il-Bum ; Catbas, Necati ;
Smart Structures and Systems, volume 14, issue 5, 2014, Pages 917~942
DOI : 10.12989/sss.2014.14.5.917
Multivariate statistics based damage detection algorithms employed in conjunction with novel sensing technologies are attracting more attention for long term Structural Health Monitoring of civil infrastructure. In this study, two practical data driven methods are investigated utilizing strain data captured from a 4-span bridge model by Fiber Bragg Grating (FBG) sensors as part of a bridge health monitoring study. The most common and critical bridge damage scenarios were simulated on the representative bridge model equipped with FBG sensors. A high speed FBG interrogator system is developed by the authors to collect the strain responses under moving vehicle loads using FBG sensors. Two data driven methods, Moving Principal Component Analysis (MPCA) and Moving Cross Correlation Analysis (MCCA), are coded and implemented to handle and process the large amount of data. The efficiency of the SHM system with FBG sensors, MPCA and MCCA methods for detecting and localizing damage is explored with several experiments. Based on the findings presented in this paper, the MPCA and MCCA coupled with FBG sensors can be deemed to deliver promising results to detect both local and global damage implemented on the bridge structure.
Pose-graph optimized displacement estimation for structural displacement monitoring
Lee, Donghwa ; Jeon, Haemin ; Myung, Hyun ;
Smart Structures and Systems, volume 14, issue 5, 2014, Pages 943~960
DOI : 10.12989/sss.2014.14.5.943
A visually servoed paired structured light system (ViSP) was recently proposed as a novel estimation method of the 6-DOF (Degree-Of-Freedom) relative displacement in civil structures. In order to apply the ViSP to massive structures, multiple ViSP modules should be installed in a cascaded manner. In this configuration, the estimation errors are propagated through the ViSP modules. In order to resolve this problem, a displacement estimation error back-propagation (DEEP) method was proposed. However, the DEEP method has some disadvantages: the displacement range of each ViSP module must be constrained and displacement errors are corrected sequentially, and thus the entire estimation errors are not considered concurrently. To address this problem, a pose-graph optimized displacement estimation (PODE) method is proposed in this paper. The PODE method is based on a graph-based optimization technique that considers entire errors at the same time. Moreover, this method does not require any constraints on the movement of the ViSP modules. Simulations and experiments are conducted to validate the performance of the proposed method. The results show that the PODE method reduces the propagation errors in comparison with a previous work.
Theoretical analyses for a 2-2 cement-based piezoelectric curved composite with electrode layers
Zhang, Taotao ;
Smart Structures and Systems, volume 14, issue 5, 2014, Pages 961~980
DOI : 10.12989/sss.2014.14.5.961
Based on the general theory of elasticity, the static behavior of 2-2 cement-based piezoelectric curved composites is investigated. The actuator consists of 2 cement layers and 1 piezoelectric layer. Considering the electrode layer between the cement layer and the piezoelectric layer as the elastic layer, the exact solutions of the mechanical and electrical fields of the curved composites are obtained by utilizing the Airy stress function method. Furthermore, the theoretical results are compared with the FEM results and good agreements (with almost no error) are obtained, thus proving the validity of this study. Furthermore, the influence of certain parameters is discussed, which can help to get the desired displacements and stresses. Finally, it is seen that the analytical model established in this paper works well, which could benefit the design of this kind of cement-based smart devices.
Toward a paradigm for civil structural control
Casciati, S. ; Chassiakos, A.G. ; Masri, S.F. ;
Smart Structures and Systems, volume 14, issue 5, 2014, Pages 981~1004
DOI : 10.12989/sss.2014.14.5.981
Structural control is a very broad field combining the areas of automatic control and structural engineering, with applications ranging from aerospace and mechanical engineering to building and civil infrastructure systems. In this paper, the focus is placed on civil engineering applications only. The goal is to address the issues concurring to form the scientific paradigm. As a resut, possible future directions of research into this field are identified.