Shahid Chamran University of AhvazJournal of Applied and Computational Mechanics2383-45363120170401Low Velocity Impact Response of Laminated Composite Truncated Sandwich Conical Shells with Various Boundary Conditions Using Complete Model and GDQ Method1151254710.22055/jacm.2017.12547ENA.AziziDepartment of Mechanical and Aerospace Engineering, Science and Research Branch, Islamic Azad University, Tehran, IranS. Mohammad RezaKhaliliCentre of Excellence for Research in Advanced Materials and Structures, Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Tehran, IranK.Malekzadeh FardMalek Ashtar University of Technology, Department of Mechanical Engineering,
4th Kilameter, Makhsous RD, Tehran, IranJournal Article20161114In this paper, the dynamic analysis of the composite sandwich truncated conical shells (STCS) with various boundary conditions subjected to the low velocity impact was studied analytically, based on the higher order sandwich panel theory. The impact was assumed to occur normally over the top face-sheet, and the contact force history was predicted using two solution models of the motion which were derived based on Hamilton’s principle by considering the displacement continuity conditions between the layers⸳ In order to obtain the contact force and the displacement histories, the differential quadrature method (DQM) was used. In this investigation, the effects of different parameters such as the number of layers of the face sheets, the boundary conditions, the semi vertex angle of the cone, and the impact velocity of the impactor on the impact response of the complete model were studied.Shahid Chamran University of AhvazJournal of Applied and Computational Mechanics2383-45363120170401Free Vibration of a Thick Sandwich Plate Using Higher Order Shear Deformation Theory and DQM for Different Boundary Conditions16241254810.22055/jacm.2017.12548ENM.NasihatgozarDepartment of Mechanical and Aerospace Engineering, Science and Research Branch, Islamic Azad University, Tehran, IranS. Mohammad RezaKhaliliCentre of Excellence for Research in Advanced Materials and Structures, Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Tehran, IranJournal Article20161124In this paper, the effect of different boundary conditions on the free vibration analysis response of a sandwich plate is presented using the higher order shear deformation theory. The face sheets are orthotropic laminated composites that follow the first order shear deformation theory (FSDT) based on the Rissners-Mindlin (RM) kinematics field. The motion equations are derived considering the continuity boundary conditions between the layers based on the energy method and Hamilton's principle. The frequency and mode shapes of the structure are obtained using the differential quadrature method (DQM). The effects of different parameters such as the face sheet-to-core stiffness ratio, the boundary conditions, and the core-to-face sheet thickness ratio on the frequency of the sandwich plate are shown. Moreover, the numerical results indicate that the frequency of the CCCC and CFFF sandwich plates predict the higher and lower frequency, respectively.Shahid Chamran University of AhvazJournal of Applied and Computational Mechanics2383-45363120170401Pole placement algorithm for control of civil structures subjected to earthquake excitation25361260310.22055/jacm.2017.12603ENNikosPnevmatikosTechnological Educational Institute of Athens
Department of Civil EngineeringJournal Article20161205In this paper the control algorithm for controlled civil structures subjected to earthquake excitation is thoroughly investigated. The objective of this work is the control of structures by means of the pole placement algorithm, in order to improve their response against earthquake actions. Successful application of the algorithm requires judicious placement of the closed-loop eigenvalues from the part of the designer. The pole placement algorithm was widely applied to control mechanical systems. In this paper, a modification in the mathematical background of the algorithm in order to be suitable for civil fixed structures is primarily presented. The proposed approach is demonstrated by numerical simulations for the control of both single and multi-degree of freedom systems subjected to seismic actions. Numerical results have shown that the control algorithm is efficient in reducing the response of building structures, with small amount of required control forces.Shahid Chamran University of AhvazJournal of Applied and Computational Mechanics2383-45363120170401Modeling of heat generations for different tool profiles in friction stir welding: study of tool geometry and contact conditions37591261910.22055/jacm.2017.12619ENAkindoye AWaheedFederal University of Agriculture, Abeokuka, Ogun, NigeriaLawrence OlumideJayesimiUniversity of LagosM. A.IsmailaFederal University of Agriculture, Abeokuka, Ogun, NigeriaU ODairoFederal University of Agriculture, Abeokuka, Ogun, NigeriaJournal Article20170106In this work, improved heat generation models are developed for straight and tapered shoulder geometries with different tool pin profiles in friction stir welding. The models are developed considering the welding process as a combination of the pure sliding and the pure sticking conditions. From the results, the amount of heat generation is directly proportional to the number of edges in the pin profiles in such a way that the heat generated in the profiles increases from the triangular pin profile to hexagonal pin profile. Also, increase in the tool rotational speed under constant weld speed increases the heat input while increase in the weld speed under constant tool rotational speed decreases the heat input and the rate of heat generation at the shoulder in a flat shoulder tool is more than that of conical/tapered shoulder tool. The predicted results show good agreements with the experimental results in literature.Shahid Chamran University of AhvazJournal of Applied and Computational Mechanics2383-45363120170401Thermo-mechanical nonlinear vibration analysis of fluid-conveying structures subjected to different boundary conditions using Galerkin-Newton-Harmonic balancing method60791262010.22055/jacm.2017.12620ENGbeminiyi MSobamowoUNIVERSITY OF LAGOS0000-0003-2402-1423Bayo YemisiOgunmolaUniversity of Lagos, Nigeria.Charles AttahOshekuCentre for Space Transport and Propulsion, National Space Research and Development Agency, Federal Ministry of Science and Technology, FCT, Abuja, Nigeria.Journal Article20170109The development of mathematical models for describing the dynamic behaviours of fluid conveying pipes, micro-pipes and nanotubes under the influence of some thermo-mechanical parameters results into nonlinear equations that are very difficult to solve analytically. In cases where the exact analytical solutions are presented either in implicit or explicit forms, high skills and rigorous mathematical analyses were employed. It is noted that such solutions do not provide general exact solutions. Inevitably, comparatively simple, flexible yet accurate and practicable solutions are required for the analyses of these structures. Therefore, in this study, approximate analytical solutions are provided to the nonlinear equations arising in flow-induced vibration of pipes, micro-pipes and nanotubes using Galerkin-Newton-Harmonic Method (GNHM). The developed approximate analytical solutions are shown to be valid for both small and large amplitude oscillations. The accuracies and explicitness of these solutions were examined in limiting cases to establish the suitability of the method.Shahid Chamran University of AhvazJournal of Applied and Computational Mechanics2383-45363120170410A DWT and SVM based method for rolling element bearing fault diagnosis and its comparison with Artificial Neural Networks80911273910.22055/jacm.2017.21576.1108ENSunilTyagiDefence Institute of Advanced TechnologyS. K.PanigrahiDefence Institute of Advanced Technology
Girinagar, Pune - 411025, IndiaJournal Article20170302<span>A classification technique using Support Vector Machine (SVM) classifier for detection of rolling element bearing fault is presented here. The SVM was fed from features that were extracted from of vibration signals obtained from experimental setup consisting of rotating driveline that was mounted on rolling element bearings which were run in normal and with artificially faults induced conditions. The time-domain vibration signals were divided into 40 segments and simple features such as peaks in time domain and spectrum along with statistical features such as standard deviation, skewness, kurtosis etc. were extracted. Effectiveness of SVM classifier was compared with the performance of Artificial Neural Network (ANN) classifier and it was found that the performance of SVM classifier is superior to that of ANN. The effect of pre-processing of the vibration signal by Discreet Wavelet Transform (DWT) prior to feature extraction is also studied and it is shown that pre-processing of vibration signal with DWT enhances the effectiveness of both ANN and SVM classifiers. It has been demonstrated from experiment results that performance of SVM classifier is better than ANN in detection of bearing condition and pre-processing the vibration signal with DWT improves the performance of SVM classifier.</span>