Shock and Vibration https://www.hindawi.com The latest articles from Hindawi © 2017 , Hindawi Limited . All rights reserved. Pullout Test on Fully Grouted Bolt Sheathed by Different Length of Segmented Steel Tubes Mon, 20 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/sv/2017/4304190/ In order to evaluate the anchorage performance of rebar bolt sheathed by different length of segmented steel tubes, a total of eight groups of pullout tests were conducted in this study. The steel tubes, segmented by 5 cm, 7 cm, 9 cm, 10 cm, and 15 cm, utilized in current study were bonded together by a high performance two-component adhesive to form standard 30 cm long steel tube. Unlike axial stress distribution in bolt, the axial stress distribution in steel tube showed exponential decrease trend from tube-clamp end to bolt-clamp end; thus a series of interesting results were observed. For instance, the sequence for segments detachment had its specific order of priority; the failure form of bolting system, the load oscillation characteristics, and the final displacement were highly determined by the length of the last segment, namely, the one fixed by clamp of testing machine. Moreover, the load-displacement relationship for some particular samples was further investigated from the perspective of energy transformation, and the disequilibrium extension of interfacial decoupling was also discussed. This paper, from a relatively idealized perspective, presents a laboratorial solution to interpret the mechanical performance of the bolt installed in layered strata; so far at least it demonstrates that a bolt installed in comparatively thicker layer of strata can last more durable and stable. Xiaowei Feng, Nong Zhang, Guichen Li, and Gangye Guo Copyright © 2017 Xiaowei Feng et al. All rights reserved. A Spectrum Detection Approach for Bearing Fault Signal Based on Spectral Kurtosis Sun, 19 Feb 2017 09:59:20 +0000 http://www.hindawi.com/journals/sv/2017/6106103/ According to the similarity between Morlet wavelet and fault signal and the sensitive characteristics of spectral kurtosis for the impact signal, a new wavelet spectrum detection approach based on spectral kurtosis for bearing fault signal is proposed. This method decreased the band-pass filter range and reduced the wavelet window width significantly. As a consequence, the bearing fault signal was detected adaptively, and time-frequency characteristics of the fault signal can be extracted accurately. The validity of this method was verified by the identifications of simulated shock signal and test bearing fault signal. The method provides a new understanding of wavelet spectrum detection based on spectral kurtosis for rolling element bearing fault signal. Yunfeng Li, Liqin Wang, and Jian Guan Copyright © 2017 Yunfeng Li et al. All rights reserved. Influence of the Radial Clearance of a Squeeze Film Damper on the Vibratory Behavior of a Single Spool Gas Turbine Designed for Unmanned Aerial Vehicle Applications Sun, 19 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/sv/2017/4312943/ This study presents a numerical investigation using the finite element method on the vibratory behavior of a single spool gas turbine designed for unmanned aerial vehicle applications. The shaft of the rotor-bearing system is supported on a front bearing composed of a deep groove ball bearing with a vibration absorber element and a rear squeeze film damper bearing. Three radial clearances for the squeeze film damper were analyzed to determine the best geometric configuration for the rear bearing, considering the rotordynamic performance of the entire system. Whirl speeds and unbalanced system responses were carefully evaluated to determine the best radial clearance for the squeeze film damper. After defining the best radial clearance, a transient analysis was performed to simulate the transition of the system through resonance, and a spectral map is presented to illustrate the vibratory behavior of the system considering the influence of all related important frequencies. The rotordynamic behavior of the system is predicted, and vibration problems are avoided. Its mechanical drawings were released to manufacturing, and the first prototype is in the experimental test phase, thus indicating that the numerical results presented in this study are consistent. Geraldo Creci, José Orlando Balastrero, Sidney Domingues, Luis Vanderlei Torres, and João Carlos Menezes Copyright © 2017 Geraldo Creci et al. All rights reserved. Intelligent Fault Diagnosis Based on Vibration Signal Analysis Sun, 19 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/sv/2017/9186989/ Minvydas Ragulskis, Lu Chen, Ganging Song, and Ameen El Sinawi Copyright © 2017 Minvydas Ragulskis et al. All rights reserved. Vibration of Elastic Functionally Graded Thick Rings Thu, 16 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/sv/2017/1803710/ The free vibration behaviors of functionally graded rings were investigated theoretically. The material graded in the thickness direction according to the power law rule and the rings were assumed to be in plane stress and plane strain states. Based on the first-order shear deformation theory and the kinetic relation of von Kárman type, the frequency equation for free vibration of functionally graded ring was derived. The derived results were verified by those in literatures which reveals that the present theory can be appropriate to predict the free vibration characteristics for quite thick rings with the radius-to-thickness ratio from 60 down to 2.09. Comparison between the plane stress case and the plane strain case indicates a slight difference. Meanwhile, the effects of the structural dimensional parameters and the material inhomogeneous parameter are examined. It is interesting that the value of the logarithmic form of vibration frequency is inversely proportional to the logarithmic form of the radius-to-thickness ratio or the mean radius. Guang-Hui Xu, Huai-Wei Huang, and Yong-Qiang Zhang Copyright © 2017 Guang-Hui Xu et al. All rights reserved. Effects of Crack on Vibration Characteristics of Mistuned Rotated Blades Wed, 15 Feb 2017 12:26:39 +0000 http://www.hindawi.com/journals/sv/2017/1785759/ Rotated blades are key mechanical components in turbine and high cycle fatigues often induce blade cracks. Meanwhile, mistuning is inevitable in rotated blades, which often makes it much difficult to detect cracks. In order to solve this problem, it is important and necessary to study effects of crack on vibration characteristics of mistuned rotated blades (MRBs). Firstly, a lumped-parameter model is established based on coupled multiple blades, where mistuned stiffness with normal distribution is introduced. Next, a breathing crack model is adopted and eigenvalue analysis is used in coupled lumped-parameter model. Then, numerical analysis is done and effects of depths and positions of a crack on natural frequency, vibration amplitude, and vibration localization parameters are studied. The results show that a crack causes natural frequency decease and vibration amplitude increase of cracked blade. Bifurcations will occur due to a breathing crack. Furthermore, based on natural frequencies and vibration amplitudes, variational factors are defined to detect a crack in MRBs, which are validated by numerical simulations. Thus, the proposed method provides theoretical guidance for crack detection in MRBs. Hailong Xu, Zhongsheng Chen, Yongmin Yang, Limin Tao, and Xuefeng Chen Copyright © 2017 Hailong Xu et al. All rights reserved. Screw Remaining Life Prediction Based on Quantum Genetic Algorithm and Support Vector Machine Wed, 15 Feb 2017 10:40:10 +0000 http://www.hindawi.com/journals/sv/2017/9581379/ To predict the remaining life of ball screw, a screw remaining life prediction method based on quantum genetic algorithm (QGA) and support vector machine (SVM) is proposed. A screw accelerated test bench is introduced. Accelerometers are installed to monitor the performance degradation of ball screw. Combined with wavelet packet decomposition and isometric mapping (Isomap), the sensitive feature vectors are obtained and stored in database. Meanwhile, the sensitive feature vectors are randomly chosen from the database and constitute training samples and testing samples. Then the optimal kernel function parameter and penalty factor of SVM are searched with the method of QGA. Finally, the training samples are used to train optimized SVM while testing samples are adopted to test the prediction accuracy of the trained SVM so the screw remaining life prediction model can be got. The experiment results show that the screw remaining life prediction model could effectively predict screw remaining life. Xiaochen Zhang and Dongxiang Jiang Copyright © 2017 Xiaochen Zhang and Dongxiang Jiang. All rights reserved. Research into 2D Dynamics and Control of Small Oscillations of a Cross-Beam during Transportation by Two Overhead Cranes Wed, 15 Feb 2017 07:10:39 +0000 http://www.hindawi.com/journals/sv/2017/9605657/ A new mathematical model of a 3DOF 2D mechanical system “transported cross-beam, two moving bridge cranes” has been proposed. Small system oscillations have been derived through the introduction of Lagrange equations. The numerical estimation of 3DOF system motion has been carried out with equation-based Modelica language. The present article uses the Lagrange method and numerical and optimization methods, realized with JModelica.org and Optimica freeware. The absolute swaying of the cross-beam with respect to the displacement of the two moving bridge cranes was estimated. The phase portraits of the 3DOF system for linear and angular coordinates were presented. An open loop optimal control problem was posed for the motion of the bridge cranes. A “bang-bang” control strategy was implemented for the derivation of an optimal control solution, which enables the travel of two bridge cranes at a prescribed distance for minimum time and minimum swaying of a heavy cross-beam. The derived results of the numerical simulation can be easily practically realized by crane operators with good agreement with simple engineering estimations. The proposed control strategy enables synchronous motion of two bridge cranes with a cross-beam that practically solves the posed problem of unwanted excessive oscillations of a heavy cross-beam during transportation. Alexander V. Perig, Alexander N. Stadnik, Alexander A. Kostikov, and Sergey V. Podlesny Copyright © 2017 Alexander V. Perig et al. All rights reserved. Magnetoelastic Principal Parametric Resonance of a Rotating Electroconductive Circular Plate Tue, 14 Feb 2017 13:17:57 +0000 http://www.hindawi.com/journals/sv/2017/5196847/ Nonlinear principal parametric resonance and stability are investigated for rotating circular plate subjected to parametric excitation resulting from the time-varying speed in the magnetic field. According to the conductive rotating thin circular plate in magnetic field, the magnetoelastic parametric vibration equations of a conductive rotating thin circular plate are deduced by the use of Hamilton principle with the expressions of kinetic energy and strain energy. The axisymmetric parameter vibration differential equation of the variable-velocity rotating circular plate is obtained through the application of Galerkin integral method. Then, the method of multiple scales is applied to derive the nonlinear principal parametric resonance amplitude-frequency equation. The stability and the critical condition of stability of the plate are discussed. The influences of detuning parameter, rotation rate, and magnetic induction intensity are investigated on the principal parametric resonance behavior. The result shows that stable and unstable solutions exist when detuning parameter is negative, and the resonance amplitude can be weakened by changing the magnetic induction intensity. Zhe Li, Yu-da Hu, and Jing Li Copyright © 2017 Zhe Li et al. All rights reserved. Normal Reflection Characteristics of One-Dimensional Unsteady Flow Shock Waves on Rigid Walls from Pulse Discharge in Water Tue, 14 Feb 2017 08:00:40 +0000 http://www.hindawi.com/journals/sv/2017/6958085/ Strong shock waves can be generated by pulse discharge in water, and the characteristics due to the shock wave normal reflection from rigid walls have important significance to many fields, such as industrial production and defense construction. This paper investigates the effects of hydrostatic pressures and perturbation of wave source (i.e., charging voltage) on normal reflection of one-dimensional unsteady flow shock waves. Basic properties of the incidence and reflection waves were analyzed theoretically and experimentally to identify the reflection mechanisms and hence the influencing factors and characteristics. The results indicated that increased perturbation (i.e., charging voltage) leads to increased peak pressure and velocity of the reflected shock wave, whereas increased hydrostatic pressure obviously inhibited superposition of the reflection waves close to the rigid wall. The perturbation of wave source influence on the reflected wave was much lower than that on the incident wave, while the hydrostatic pressure obviously affected both incident and reflection waves. The reflection wave from the rigid wall in water exhibited the characteristics of a weak shock wave, and with increased hydrostatic pressure, these weak shock wave characteristics became more obvious. Dong Yan, Jinchang Zhao, and Shaoqing Niu Copyright © 2017 Dong Yan et al. All rights reserved. Chaotic Behaviour Investigation of a Front Opposed-Hemispherical Spiral-Grooved Air Bearing System Tue, 14 Feb 2017 07:17:24 +0000 http://www.hindawi.com/journals/sv/2017/8985040/ In recent years, spiral-grooved air bearing systems have attracted much attention and are especially useful in precision instruments and machines with spindles that rotate at high speed. Load support can be multidirectional and this type of bearing can also be very rigid. Studies show that some of the design problems encountered are dynamic and include critical speed, nonlinearity, gas film pressure, unbalanced rotors, and even poor design, all of which can result in the generation of chaotic aperiodic motion and instability under certain conditions. Such irregular motion on a large scale can cause severe damage to a machine or instrument. Therefore, understanding the conditions under which aperiodic behaviour and vibration arise is crucial for prevention. In this study, numerical analysis, including the Finite Difference and Differential Transformation Methods, is used to study these effects in detail in a front opposed-hemispherical spiral-grooved air bearing system. It was found that different rotor masses and bearing number could cause undesirable behaviour including periodic, subperiodic, quasi-periodic, and chaotic motion. The results obtained in this study can be used as a basis for future bearing system design and the prevention of instability. Cheng-Chi Wang Copyright © 2017 Cheng-Chi Wang. All rights reserved. Failure Characteristics of Joint Bolts in Shield Tunnels Subjected to Impact Loads from a Derailed Train Mon, 13 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/sv/2017/2829783/ Impact loads generated by derailed trains can be extremely high, especially in the case of heavy trains running at high speeds, which usually cause significant safety issues to the rail infrastructures. In shield tunnels, such impact loads may not only cause the damage and deformation of concrete segments, but also lead to the failure of segmental joint bolts. This paper presents a numerical study on the failure behavior of segmental joint bolts in the shield tunnel under impact loading resulting from train derailments. A three-dimensional (3D) numerical model of a shield tunnel based on the finite element (FE) modelling strategy was established, in which the structural behavior of the segmental joint surfaces and the mechanical behavior of the segmental joint bolts were determined. The numerical results show that the occurrence of bolt failure starts at the joints near the impacted segment and develops along the travel direction of train. An extensive parametric study was subsequently performed and the influences of the bolt failure on the dynamic response of the segment were investigated. In particular, the proposed FE model and the analytical results will be used for optimizing the design method of the shield tunnel in preventing the failure of the joint bolts due to the impact load from a derailed HST. Qixiang Yan, Zhixin Deng, Yanyang Zhang, and Wenbo Yang Copyright © 2017 Qixiang Yan et al. All rights reserved. Experimental Evaluation for the Microvibration Performance of a Segmented PC Method Based High Technology Industrial Facility Using 1/2 Scale Test Models Sun, 12 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/sv/2017/2452598/ The precast concrete (PC) method used in the construction process of high technology industrial facilities is limited when applied to those with greater span lengths, due to the transport length restriction (maximum length of 15~16 m in Korea) set by traffic laws. In order to resolve this, this study introduces a structural system with a segmented PC system, and a 1/2 scale model with a width of 9000 mm (hereafter Segmented Model) is manufactured to evaluate vibration performance. Since a real vibrational environment cannot be reproduced for vibration testing using a scale model, a comparative analysis of their relative performances is conducted in this study. For this purpose, a 1/2 scale model with a width of 7200 mm (hereafter Nonsegmented Model) of a high technology industrial facility is additionally prepared using the conventional PC method. By applying the same experiment method for both scale models and comparing the results, the relative vibration performance of the Segmented Model is observed. Through impact testing, the natural frequencies of the two scale models are compared. Also, in order to analyze the estimated response induced by the equipment, the vibration responses due to the exciter are compared. The experimental results show that the Segmented Model exhibits similar or superior performances when compared to the Nonsegmented Model. Sijun Kim and Se Woon Choi Copyright © 2017 Sijun Kim and Se Woon Choi. All rights reserved. Fuzzy Semiactive Vibration Control of Structures Using Magnetorheological Elastomer Thu, 09 Feb 2017 13:40:10 +0000 http://www.hindawi.com/journals/sv/2017/3651057/ In this research, a novel variable stiffness vibration isolator that uses magnetorheological elastomers (MREs) accompanied with a fuzzy semiactive vibration control was developed. Firstly, the viscoelastic characteristics of MREs in shear mode were clarified systematically in order to achieve a mathematical basis for the controller development. Secondly, the fuzzy semiactive vibration control with a strategy based on the Lyapunov theory and dynamic characteristic of MREs was proposed for minimizing the movement of the isolator. In the conventional semiactive algorithm, the command applied current of MRE-based isolator is set at either minimum or maximum value which causes high acceleration and jerk peaks periodically, thus leading to the degeneration of the overall system quality. However, the fuzzy semiactive algorithm presented here is able to produce the sufficient applied current and thus viscoelastic force is desirably produced. The effectiveness of the developed isolator was evaluated numerically by MATLAB simulation and experimentally in comparison with the performances of a passive system and a system with on-off type semiactive controller. The results showed that the developed controller was successful in overcoming the disadvantages of conventional on-off semiactive control. Xuan Bao Nguyen, Toshihiko Komatsuzaki, Yoshio Iwata, and Haruhiko Asanuma Copyright © 2017 Xuan Bao Nguyen et al. All rights reserved. A Time-Frequency Research for Ultrasonic Guided Wave Generated from the Debonding Based on a Novel Time-Frequency Analysis Technique Thu, 09 Feb 2017 13:03:18 +0000 http://www.hindawi.com/journals/sv/2017/5686984/ Carbon fibre composites have a promising application in the future of the vehicle, because of their high strength and light weight. Debonding is a major defect of the carbon fibre composite. The time-frequency analysis is fundamental to identify the defect on ultrasonic nondestructive evaluation and testing. In order to obtain the instantaneous frequency and the peak time of modes of the ultrasonic guided wave, an algorithm based on the Smoothed Pseudo Wigner-Ville distribution and the peak-track algorithm is presented. In the algorithm, a masking step is proposed, which can guarantee that the peak-track algorithm can automatically exact the instantaneous frequency and the instantaneous amplitude of different modes on the Smoothed Pseudo Wigner-Ville distribution. An experiment for detecting the debonding for a type of carbon fibre composite is done. The presented algorithm is employed on the experimental signals. The processed result of experimental signals reveals that the defect can stimulate new modes, and there is a quantitative relationship between the defect size and the frequency of the new mode. The presented technique provides a valuable way to detect the presentence, calculate the size, and locate the position of the debonding defect. Junhua Wu, Zheshu Ma, and Yonghui Zhang Copyright © 2017 Junhua Wu et al. All rights reserved. Arc-Surfaced Frictional Damper for Vibration Control in Container Crane Thu, 09 Feb 2017 11:36:20 +0000 http://www.hindawi.com/journals/sv/2017/3675470/ In this paper, a new arc-surfaced frictional damper (AFD) is proposed and its hysteretic behavior is experimentally studied. Then the device is applied to container crane based on a seesaw mechanism. The major advantage of the seesaw damping system is that the long tension cables can be utilized as bracing between the seesaw member and the portal legs to avoid compression and buckling of the cables. A simplified trilinear force-displacement model on the basis of experimental results is adopted to represent the hysteretic behavior of AFD. After that, seismic responses of container crane with and without dampers to four earthquakes are studied using nonlinear dynamic time-history analysis. Besides this system, a diagonal-brace-AFD system is studied for comparison. A method based on the displacement and energy dissipation ratio is proposed to find the optimum slip force for seesaw damping system. Performance of AFD control system is assessed though various parameters including displacement and maximum portal frame drift angle. Results prove a feasible application of AFD control system to absorb large amounts of seismic energy and significantly reduce the structural responses. Gongxian Wang, Yang-Yang Wang, Jianming Yuan, Yi Yang, and Dong Wang Copyright © 2017 Gongxian Wang et al. All rights reserved. Development of a Point Pyroshock Source Simulator Mon, 06 Feb 2017 07:45:28 +0000 http://www.hindawi.com/journals/sv/2017/6834601/ We developed a point pyroshock source simulator (PPSS) for the study on the source isolation approach (SIA) in this study. In spite of the potentiality of the SIA for avionics protection against pyroshock, it has rarely been investigated due to lack of pyroshock source simulators. To overcome such a situation, we proposed the PPSS using a mechanically excited tuned resonator simulating a release device itself. The PPSS was designed using explicit finite element analysis and Seigel’s gas gun model. To verify the proposed PPSS, the prototype was fabricated and tested. From the results, we have shown that the prototype of the PPSS simulates a near-field pyroshock and is able to evaluate the SIA. Ju-won Jeong, Jae hyuk Lim, Kyung-won Kim, and Jung-ju Lee Copyright © 2017 Ju-won Jeong et al. All rights reserved. The Dispersion Rule of Fragments about the Asymmetric Shell Mon, 06 Feb 2017 06:36:34 +0000 http://www.hindawi.com/journals/sv/2017/9810978/ In order to obtain the dispersion rule of fragments about the asymmetric shell subjected to internal blast loading, two different cross section structures, concave-shaped and convex-shaped, were carried out by experimental and numerical methods. The simulation results well coincided with the experimental results, and the spatial distribution and fragment velocity were obtained. The optimal curvatures for the different concave structures changed from 4r to 6r (r represents the charge radius), as the central angle of concave structure changed from 90° to 120°. However, the optimal curvature changed weakly when the central angle of concave structure was larger than 120°. In addition, a formula which can rapidly predict the projection angle range was fitted for the convex structure. The conclusions can provide a reference for concave-shaped and convex-shaped structures to achieve a higher effectiveness of fragments. Liangliang Ding, Zhenduo Li, Minzu Liang, Xiangyu Li, and Fangyun Lu Copyright © 2017 Liangliang Ding et al. All rights reserved. Experimental and Theoretical Analysis for a Fluid-Loaded, Simply Supported Plate Covered by a Damping and Decoupling Composite Acoustic Coating Mon, 06 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/sv/2017/7460457/ This work presents a vibroacoustic response model for a fluid-loaded, simply supported rectangular plate covered by a composite acoustic coating consisting of damping and decoupling layers. The model treated the damping layer and base plate as a unified whole under pure bending moments and the decoupling layer as a three-dimensional, isotropic, linear elastic solid. The validity of the model was verified by both numerical analysis and experiments and was shown to accurately extend previous studies that were limited to a plate covered by a single damping or decoupling layer with an evaluation confined solely to numerical analysis. The trends of the numerical and experimental results are generally consistent, with some differences due to the influences of water pressure and the frequency dependence of the material parameters, which are not taken into account by the numerical analysis. Both experimental and numerical results consistently show that the radiated noise reduction effect of the composite coating is superior to that of single-type coatings, which is attributed to the fact that the composite coating combines the merits of both the high vibration suppression performance of the damping layer and the superior vibration isolation performance of the decoupling layer. Baihua Yuan, Meng Chen, Yu Liu, Shexu Zhao, and Heng Jiang Copyright © 2017 Baihua Yuan et al. All rights reserved. Passive Shock Isolation Utilising Dry Friction Thu, 02 Feb 2017 09:56:04 +0000 http://www.hindawi.com/journals/sv/2017/7313809/ A novel shock isolation strategy for base excited system is presented by introducing a two-degree-of-freedom model with passive friction, where the friction is applied to an attached mass instead of directly to the primary isolated mass. The model is evaluated against the benchmark case of single-degree-of-freedom system with friction applied directly to the primary isolated mass. The performances of the models are compared in terms of the maximum displacement response and the acceleration during the application of the shock input for the case when the shock input duration is approximately equal to the natural period of the system (amplification region). From the results, the two-degree-of-freedom model can produce both maximum displacement reduction and smoother acceleration at the point of motion transition. An experimental rig was built to validate the theoretical results against the experimental results; it is found that the experimental results closely match the theoretical predictions. Mohd Ikmal Ismail and Neil Stuart Ferguson Copyright © 2017 Mohd Ikmal Ismail and Neil Stuart Ferguson. All rights reserved. Pounding Dynamic Responses of Sliding Base-Isolated Rectangular Liquid-Storage Structure considering Soil-Structure Interactions Tue, 31 Jan 2017 11:40:25 +0000 http://www.hindawi.com/journals/sv/2017/8594051/ The soil-structure interaction (SSI) is simulated by an artificial boundary, the pounding that occurs between the sliding base-isolated rectangular liquid-storage structure (LSS) and the surrounding moat wall is considered, the instantaneous pounding is simulated using the Hertz-damp model, and a simplified mechanical model with two particles and four degrees of freedom is established. Dynamic equation is obtained using Hamilton principle; effects of SSI, initial gap, and friction coefficient on the pounding responses under the action of near-field pulse-like Chi-Chi earthquake and far-field Imperial Valley-06 earthquake are studied. The results show that SSI will amplify liquid sloshing height but that structural acceleration and impact force will be reduced because of SSI. The responses caused by Chi-Chi earthquake are far greater than those of Imperial Valley-06 earthquake. Initial gap has a small effect on liquid sloshing height; structural acceleration and impact force first increase as the initial gap increases and then begin to decrease; in the design of moat wall of sliding isolation LSS, a certain gap exists that will more adversely affect the pounding responses of structure. Liquid sloshing height is less affected by coefficient of friction, but structural acceleration and impact force decrease as friction coefficient increases in general. Xuansheng Cheng, Wei Jing, Jia Chen, and Xiaoyan Zhang Copyright © 2017 Xuansheng Cheng et al. All rights reserved. An Analytical Solution for Predicting the Vibration-Fatigue-Life in Bimodal Random Processes Tue, 31 Jan 2017 09:11:02 +0000 http://www.hindawi.com/journals/sv/2017/1010726/ Predicting the vibration-fatigue-life of engineering structures subjected to random loading is a critical issue for. Frequency methods are generally adopted to deal with this problem. This paper focuses on bimodal spectra methods, including Jiao-Moan method, Fu-Cebon method, and Modified Fu-Cebon method. It has been proven that these three methods can give acceptable fatigue damage results. However, these three bimodal methods do not have analytical solutions. Jiao-Moan method uses an approximate solution, Fu-Cebon method, and Modified Fu-Cebon method needed to be calculated by numerical integration which is obviously not convenient in engineering application. Thus, an analytical solution for predicting the vibration-fatigue-life in bimodal spectra is developed. The accuracy of the analytical solution is compared with numerical integration. The results show that a very good agreement between an analytical solution and numerical integration can be obtained. Finally, case study in offshore structures is conducted and a bandwidth correction factor is computed through using the proposed analytical solution. Chaoshuai Han, Yongliang Ma, Xianqiang Qu, and Mindong Yang Copyright © 2017 Chaoshuai Han et al. All rights reserved. Dynamic Reliability Evaluation of Road Vehicle Subjected to Turbulent Crosswinds Based on Monte Carlo Simulation Sun, 29 Jan 2017 06:11:13 +0000 http://www.hindawi.com/journals/sv/2017/2365812/ As a vehicle moves on roads, a complex vibration system of the running vehicle is formed under the collective excitations of random crosswinds and road surface roughness, together with the artificial handing by the drivers. Several numerical models in deterministic way to assess the safety of running road vehicles under crosswinds were proposed. Actually, the natural wind is a random process in time domain due to turbulence, and the surface roughness of a road is also a random process but in spatial domain. The nature of a running vehicle therefore is an extension of dynamic reliability excited by random processes. This study tries to explore the dynamic reliability of a road vehicle subjected to turbulent crosswinds. Based on a nonlinear vibration system, the dynamic responses of a road vehicle are simulated to obtain the dynamic reliability. Monte Carlo Simulation with Latin Hypercube Sampling is then applied on the possible random variables including the vehicle weight, road friction coefficient, and driver parameter to look at their effects. Finally, a distribution model of the dynamic reliability and a corresponding index for the wind-induced vehicle accident considering these random processes and variables is proposed and employed to evaluate the safety of the running vehicle. Bin Wang, Yongle Li, Helu Yu, and Haili Liao Copyright © 2017 Bin Wang et al. All rights reserved. Impact of In Situ Stress Distribution Characteristics on Jointed Surrounding Rock Mass Stability of an Underground Cavern near a Hillslope Surface Sun, 29 Jan 2017 00:00:00 +0000 http://www.hindawi.com/journals/sv/2017/2490431/ In this paper, a series of numerical simulations are performed to analyze the in situ stress distribution characteristics of the rock mass near different slope angles hillslope surfaces, which are subjected to the vertical gravity stress and different horizontal lateral stresses and the influence which the in situ stress distribution characteristics of 45° hillslope to the integral stability of surrounding rock mass when an underground cavern is excavated considering three different horizontal distances from the underground cavern to the slope surface. It can be concluded from the numerical results that different slope angles and horizontal lateral stresses have a strong impact on the in situ stress distribution and the integral surrounding rock mass stability of the underground cavern when the horizontal distance from the underground cavern to the slope surface is approximately 100 m to 200 m. The relevant results would provide some important constructive suggestions to the engineering site selection and optimization of large-scale underground caverns in hydropower stations. Bangxiang Li, Yong Li, Weishen Zhu, Chao Li, and Zhenxing Dong Copyright © 2017 Bangxiang Li et al. All rights reserved. Adaptive Active Noise Suppression Using Multiple Model Switching Strategy Sun, 29 Jan 2017 00:00:00 +0000 http://www.hindawi.com/journals/sv/2017/7289076/ Active noise suppression for applications where the system response varies with time is a difficult problem. The computation burden for the existing control algorithms with online identification is heavy and easy to cause control system instability. A new active noise control algorithm is proposed in this paper by employing multiple model switching strategy for secondary path varying. The computation is significantly reduced. Firstly, a noise control system modeling method is proposed for duct-like applications. Then a multiple model adaptive control algorithm is proposed with a new multiple model switching strategy based on filter-u least mean square (FULMS) algorithm. Finally, the proposed algorithm was implemented on Texas Instruments digital signal processor (DSP) TMS320F28335 and real time experiments were done to test the proposed algorithm and FULMS algorithm with online identification. Experimental verification tests show that the proposed algorithm is effective with good noise suppression performance. Quanzhen Huang, Suxia Chen, Mingming Huang, and Zhuangzhi Guo Copyright © 2017 Quanzhen Huang et al. All rights reserved. Dynamic Response of Parallel Hoisting System under Drive Deviation between Ropes with Time-Varying Length Sun, 29 Jan 2017 00:00:00 +0000 http://www.hindawi.com/journals/sv/2017/6837697/ The dynamic responses of parallel hoisting system with time-varying length and rigid guidance under drive deviation are investigated considering tension and torsion characteristics of the ropes. The variable-domain three-node elements of rope are employed and the corresponding differential algebraic equations (DAEs) are derived using Lagrange’s equations of the first kind. The slack situation of the rope is considered, and the dynamic equations which are systems of DAEs are transformed to ordinary differential equations (ODEs). The dynamic responses of tension, torsion, and acceleration are analyzed considering radius’ error of the drums, which indicates that the drive deviation between ropes can cause large influence on the tension difference and even cause one of the ropes to slack. However, the torsion of the corresponding rope is active. And unreasonable discordance between ropes should be controlled for the design and manufacture of drum on super deep parallel hoisting system. Guohua Cao, Xiang Cai, Naige Wang, Weihong Peng, and Jishun Li Copyright © 2017 Guohua Cao et al. All rights reserved. Wavelet Denoising of Vehicle Platform Vibration Signal Based on Threshold Neural Network Thu, 26 Jan 2017 08:50:49 +0000 http://www.hindawi.com/journals/sv/2017/7962828/ Vehicle Platform Vibration Signal (VPVS) denoising is essential to achieve high measurement accuracy of precise optical measuring instrument (POMI). A method to denoise the VPVS is proposed based on the wavelet coefficients thresholding and threshold neural network (TNN). According to the characteristics of VPVS, a novel thresholding function is constructed, and then its optimized threshold is selected through unsupervised learning of TNN. The original VPVS mixed in trend and random noise is constructed as VPVS model. A VPVS denoising flow is proposed based on the power spectral and energy distribution of the VPVS model. The simulation shows that the proposed denoising method achieves better results, compared to the previous denoising methods using the indexes of SNR and RMSE. The experiment demonstrates that it is efficient for denoising VPVS polluted by the trend and random noise. Mingzhu Li, Zhiqian Wang, Jun Luo, Yusheng Liu, and Sheng Cai Copyright © 2017 Mingzhu Li et al. All rights reserved. A New Method Based on Laplace Transform and Its Application to Stability of Pipe Conveying Fluid Tue, 24 Jan 2017 00:00:00 +0000 http://www.hindawi.com/journals/sv/2017/1472601/ A new differential transformation method is developed in this paper and is applied for free vibration problem of pipes conveying fluid. The natural frequencies, critical flow velocities, and vibration mode functions of such pipes with several typical boundary conditions are obtained and compared with the results predicted by Galerkin method and finite element method (FEM) and with other results archived. The results show that the present method is of high precision and can serve as an analytical method for the vibration of pipes conveying fluid. H. B. Wen, Y. R. Yang, P. Li, Y. D. Li, and Y. Huang Copyright © 2017 H. B. Wen et al. All rights reserved. Characteristics of Rainfall in Wind Field of a Downburst and Its Effects on Motion of High-Voltage Transmission Line Mon, 23 Jan 2017 00:00:00 +0000 http://www.hindawi.com/journals/sv/2017/7350369/ Despite most weather-related failures of high-voltage transmission lines (HVTLs) being attributed to the downbursts accompanied by heavy rainfall, research works mainly focused on the behaviors of the high-voltage transmission tower-line structures under dry downburst winds. This paper thus presents a preliminary study to discuss the characteristics of rainfall in the downbursts and their effects on responses of HVTLs. Based on Vicroy model, the velocities of raindrops and their loads and pressure ratios of downburst wind-driven rain and only downburst wind on the surface of HVTLs per unit length are obtained. A downburst wind-rain induced vibration model is established to calculate the effects of the rainfall intensity and wind velocities on the motions of HVTLs. To verify the feasibility and accuracy of the model, the model is applied to evaluate responses of HVTLs with measured aerodynamic coefficients. The responses of HVTLs from the evaluated (the model) and the field observation results are compared. The results indicated that the model is feasible and can capture main features of the rainfall acting on HVTLs in the downbursts. Furthermore, the effects of rainfall cannot be neglected, and more attention should be paid to the wet downbursts and their effects on aerodynamic property of HVTLs. Chao Zhou, Li Li, and Yibing Liu Copyright © 2017 Chao Zhou et al. All rights reserved. Experimental and Analytical Study on the Penetration of Corundum-Rubble Concrete Subjected to Projectile Impact Sun, 22 Jan 2017 00:00:00 +0000 http://www.hindawi.com/journals/sv/2017/1396567/ A new type of composite concrete which can be called corundum-rubble concrete (CRC) was presented to improve the resistance of protective structure to the projectile impact. Comparative experiments were conducted between CRC and reinforced concrete, and a modified Taylor model was proposed to predict the penetration depth of CRC targets. Experimental results show that CRC is much higher than reinforced concrete in both strength and hardness and shows excellent resistance to the 0.125 m-diameter projectile impact. Theoretical analyses demonstrated that the modified Taylor model’s predicted results were in good agreement with the measured values. Y. L. Xue, D. G. Tang, W. X. Chen, Z. Z. Li, D. P. Li, and M. L. Yao Copyright © 2017 Y. L. Xue et al. All rights reserved.