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2013 Vol. 32, No. 5 Published: 2013-03-15        论文 1 An Ultrasonic Linear Motor Based on both the H-shaped Vibrator’s Longitudinal mode and Bending mode HE Hong-lin;WU Dong-mei;LIU Wen-guang DOI: To develop theoretical instructions for design of high performance linear motor, a piezoelectric linear motor based on an H-shaped vibrator is presented, which employed the vibrator’s 2nd bending vibration mode and 1st longitudinal to drive the motor. Firstly, the motor’s working principle is proposed, and the generating of elliptical motions generated on the driving ends of the vibrator’s two longitudinal bars is described. Then, a FEM model is built for the vibrator so as to calculate the working modes and execute harmonic the response analysis and sensitivity analysis for the vibrator. Furthermore, the optimal size of the vibrator is given and the motor assembly structure is designed. Finally, modal test is done for the vibrator which validates that the vibrator is of the assumed work modes and shows that longitudinal vibration amplitude and the bending vibration amplitude of the vibrator’s driving end could reach 1.4μm and 1.2μm respectively. It is concluded that the vibrator could generate larger thrust and speed. 2013 Vol. 32 (5): 1-5 [Abstract] ( 566 ) HTML (0 KB)  PDF (1723 KB)  ( 813 ) 6 The assessment of reinforced concrete beam carrying capacity based on acoustic emission LI Xu;HUO Lin-sheng;LI Hong-nan DOI: Based on the energy balance during the process of concrete fracture and the relationship between the acoustic emission and fracture mechanics, the correspondence of acoustic emission and the flexural rigidity of reinforced concrete beam at the stage of crack development was derived. The bending destructive experiments of reinforced concrete beam subjected to dynamic and static load were conducted to verify the proposed equation. The results show that, it is feasible to establish the relation between the acoustic emission parameters and the surplus carrying capacity based on the theory of energy balance. At the stage of crack development, the flexural rigidity of reinforced concrete beam is exactly calculated by acoustic emission parameters acquired from the acoustic emission transducers. 2013 Vol. 32 (5): 6-9 [Abstract] ( 526 ) HTML (0 KB)  PDF (1346 KB)  ( 297 ) 10 Analysis on the Loads from Ice Shedding Conductors in Heavy Icing Areas YANG Feng-li;YANG Jing-bo DOI: A FEA model of seven continuous span conductors and insulators for UHV transmission line in heavy icing area was established for the ice-shedding analysis. Some parameters were considered in the ice-shedding simulating analysis, which include the damping ratio, the ice-shedding modes and the ice thickness. The dynamic responses of jumping heights, unbalanced tension and vertical load at the end of the insulator were obtained. Effects of different parameters on the dynamic responses were studied. The values of unbalanced tensions and vertical loads were determined for the UHV suspension tower in heavy icing area. For the case of ice shedding in one span conductor and the damping ratio is 5%, the percent of unbalanced tension to the maximum working tension is lower than the values regulated in the design regulations. The dynamic magnification factors of the vertical load are from 1.28 to 1.40. For the suspension tower in 20mm and 30mm icing area, the percent of the up-pull load to the maximum working tension is proposed to 10 percentages. For the suspension tower in 40mm and 50mm icing area, the percent of the up-pull load to the maximum working tension is proposed to 5 percentages. 2013 Vol. 32 (5): 10-15 [Abstract] ( 564 ) HTML (0 KB)  PDF (1146 KB)  ( 339 ) 16 Compressive behavior and deformation mechanism of aluminum foam under different temperature WANG Peng-fei;XU Song-lin;HU Shi-sheng DOI: Using the Hopkinson bar and MTS devices to study the dynamic and quasi-static compression behavior in different temperature conditions. The compressive stress strain curve of the Aluminum foam was found to be strongly temperature dependent. It is obvious that the curve under high temperatures was close to that under low temperatures and exhibited a consistent relationship of time-temperature equivalent. At low temperatures the matrix material reveals more brittle characteristic and causes the cell structures to collapse abruptly, and results in a notable “stress drop” and remarkable vibration. But when raising the ambient temperature, the material tends to exhibit ductile property, and deformation of cell structure is mainly through plasticity buckling instead of abrupt collapse. 2013 Vol. 32 (5): 16-19 [Abstract] ( 537 ) HTML (0 KB)  PDF (1353 KB)  ( 510 ) 20 Experimental study on bridge damage identification based on wavelet packet energy curvature difference method YU Zhu;XIA He;GOICOLEA J M;ZHAN Jia-wang DOI: Among those damage identification methods, the Wavelet Packet Energy Curvature Difference (WPECD) Method is an effective one. However, most of the existing methods rely on numerical simulation and are unverified via experiment, and very few of them have been applied to practice. In this paper, the validity of WPECD in structural damage identification is verified by a numerical example. A damage simulation experiment is taken on a real replaced girder at the Ziya River New Bridge in Cangzhou. Two damage cases are applied and the acceleration responses at the measuring points are obtained, based on which the damages are identified with the WPECD Method, and the influence of wavelet function and decomposition level is studied. The results show that the WPECD Method can identify structure damage efficiently and can be put into practice. 2013 Vol. 32 (5): 20-25 [Abstract] ( 537 ) HTML (0 KB)  PDF (1893 KB)  ( 393 ) 26 A control strategy of earthquake simulation test based on elastic payload TIAN Pan;CHEN Zhang-Wei DOI: The specimen is assumed to be rigid payload in traditional earthquake simulation test control. To overcome the poor control precision of this control, an earthquake simulation control strategy is proposed. This control strategy configures servo-control parameters reasonably by analyzing physical modal of elastic payload，so the transfer function of shaking table unify approximately under a variety of load. On this basis, the system identification method of vibration control is optimized. The shaking table system can obtain high simulation precision for seismic wave without pre-test step. The experimental results which are got in Zhejiang University shaking table indicate that control strategy can obtain the first frame correlation coefficient of reference signal and control signal in time domain above 85% without pre-test step in the case of parameter optimization; after several frames of earthquake simulation test, the correlation coefficient of reference signal and control signal in time domain can reach 90% through identifying the transfer function continuously. 2013 Vol. 32 (5): 26-30 [Abstract] ( 539 ) HTML (0 KB)  PDF (2414 KB)  ( 648 ) 31 Vibration performance analysis and experimental research on a new type planetary transmission with small tooth number difference WANG Jia-xu;HUANG Chao;XIAO Ke;LI Min;LI Jun-yang DOI: Aimed at a planetary transmission with small tooth number difference, improved structural design was executed firstly. Secondly, by means of the dynamic contact finite element method, the internal dynamic excitations of teeth mesh were obtained, including mesh stiffness excitation, transmission error excitation and mesh impact excitation. Thirdly, according to the established model for dynamic finite element modal analysis, the natural frequencies and mode shapes of the planetary transmission were calculated, and its structural dynamic response and structural noise were researched with the comprehensive consideration of internal and external excitations. Finally, the noise and vibration testing was carried out utilizing the vibration test equipment. The results confirm that the predicted values are consistent with the experimental results. 2013 Vol. 32 (5): 31-37 [Abstract] ( 607 ) HTML (0 KB)  PDF (1948 KB)  ( 1055 ) 38 Gearbox fault diagnosis based on local target space alignment and multi-kernel support vector machine CHEN Fa-fa;TANG Bao-ping;SONG Tao DOI: Aimed at the overlapping of the gearbox fault features and these features are difficult to distinguish, a fault diagnosis model based on local target space alignment and multi-kernel support vector machine for gearbox is proposed. In the vibration feature space constructed by time domain statistics and intrinsic mode energy value, the nonlinear multi-dimensionality reduction based on local target space alignment to get the initial low-dimensional manifold feature value is firstly executed, then the low-dimensional feature vector which have the fault characteristics are regarded as the input feature vector of the multi-kernel support vector machine for gearbox fault classification. Local target space alignment overcome the shortcoming of the traditional reduction method, multi-kernel support vector machine realized the high-precision, automated intelligent diagnosis for gearbox. The gearbox fault diagnosis experiment shows the effectiveness of this novel model. 2013 Vol. 32 (5): 38-42 [Abstract] ( 603 ) HTML (0 KB)  PDF (1589 KB)  ( 310 ) 43 Time-frequency characteristics extraction of vehicle-track coupling system based on Hilbert-Huang transform CHEN Shuang-xi;LIN Jian-hui;CHEN Jian-zheng DOI: In order to learn the influence of various excitations on dynamic time-frequency characteristics of vehicle-track coupling system, the Hilbert-Huang Transform (HHT) based on improved Empirical Mode Decomposition (EMD) is introduced to the vibration signal analysis. Vibration signal of coupling system is firstly decomposed into intrinsic mode functions (IMFs) by improved EMD method, and then Hilbert Time-frequency-amplitude spectrum and marginal spectrum are obtained from Hilbert-Huang Transform. The simulation indicates that Hilbert-Huang Transform has higher resolution and accuracy than Fourier Transform in frequency domain and can effectively seize modulated vibration signal of coupling system caused by wheel defect and track harmonic irregularity. Nonlinear change of vertical car body acceleration varies with the wavelength and amplitude of track irregularity. The modulated component of vibration acceleration decreases with the increase of irregularity amplitude (amplitude from 2mm to 10mm, wavelength of 10m) and has nonlinear change with the increase of irregularity wavelength (wavelength from 10m to 50m, amplitude of 10mm). 2013 Vol. 32 (5): 43-47 [Abstract] ( 567 ) HTML (0 KB)  PDF (1986 KB)  ( 493 ) 48 Near-field acoustic holography based fault diagnosis and its system development LU Wen-bo JIANG Wei-kang DOI: Vibration signal based fault diagnosis has the limitation of contacting measurement, and traditional acoustic-based diagnosis (ABD) can only partly reflect acoustic information. These disadvantages can be overcome by introducing near-field acoustic holography (NAH) to fault diagnosis. Mechanical fault diagnosis system with non-contacting measurement is developed based on LabVIEW platform. Acoustic images are obtained by reconstructing sound pressure field near sound source surface with NAH technology. Gray level co-occurrence matrix features reflecting spatial distribution of sound field are extracted from acoustic images. Combining with support vector machines, intelligent fault diagnosis is implemented. The system has some key functions, such as fault diagnosis, sound source visualization, data analysis. The gearbox faults are diagnosed using the proposed system with diagnostic accuracy 97.3%, which is better than the result from traditional ABD. The reliability and practicality is demonstrated on the practical application. 2013 Vol. 32 (5): 48-51 [Abstract] ( 555 ) HTML (0 KB)  PDF (1584 KB)  ( 534 ) 52 Power iteration subspace tracing for identification of piezoelectric smart structures LIU Qing-hua;OUYANG Shan; DOI: For the subspace identification of piezoelectric smart structure model, the power iteration subspace tracing algorithm is presented based on the fact that the column space of the extended observability matrix is the same with the signal subspace of autocorrelation matrix of the observation vector, which converges globally and exponentially to the principal subspace. In order to avoid the error propagation of the principal subspace derivation at each iteration, the multistage power iteration decomposition is proposed. The simulation results compared with the projection approximation subspace tracking method show that there are smaller angle between the estimation and the true extended observability matrix, lower root mean square error of output, and higher tracking precision. Finally, the application to the actual model is given to demonstrate the efficiency of the proposed algorithm. 2013 Vol. 32 (5): 52-57 [Abstract] ( 507 ) HTML (0 KB)  PDF (1915 KB)  ( 212 ) 58 An indirect measurement of rotational dynamic flexibility and its applications in experimental component mode synthesis method DONG Xing-jian;MENG Guang DOI: To overcome the obstacles of measuring rotational dynamic flexibility and exerting moment excitation on the substructure which lie in experimental component mode synthesis method, a numerical differentiation formula is utilized to estimate the rotational displacement, the moment excitation is represented by a parallel force system, and then a newly indirect measuring technique for the rotational dynamic flexibility is developed. By measuring a set of force induced translational dynamic flexibilities at a limited number of points using hammer excitation method or frequency sweeping method, it is possible to express approximately the moment induced rotational dynamic flexibilities in terms of those measured quantities. The merits of this indirect measuring technique are that no attached T block is needed, moment excitation is also not needed, and even the parallel force excitations are not needed. The indirect measurement of rotational dynamic flexibility is then brought into the fixed frequency residual dynamic flexibility based experimental component mode synthesis method to satisfy the rotational compatibility at the interface of the substructures. Finally, numerical examples have demonstrated the validity and efficiency of the proposed method. 2013 Vol. 32 (5): 58-61 [Abstract] ( 537 ) HTML (0 KB)  PDF (861 KB)  ( 215 ) 62 Degradation analysis of the spindle of machine tool based on maximum entropy and discrimination information ONG Xin-feng;LI Hao-lin;YU Hui-jie DOI: spindle system is a common component of the machine tool. The state of the spindle system have serious implication on workpiece to be machined, So the detection of the spindle system is necessary. In this paper, the method of maximum entropy and discrimination information were applied for the degradation analysis of the X2 direction of the M1432 griding machine from April to October. First , we use the maximum entropy prinple to obtain accurate maximum entropy probability density distribution of the vibration, then, use the discrimination information to analyze the changes of maximum entropy probability density distribution that can judge the state of the spindle system of the machine tool. The results show that the X2 direction of the workpiece spindle of the M1432B grinding machine have tiny degradation. 2013 Vol. 32 (5): 62-64 [Abstract] ( 527 ) HTML (0 KB)  PDF (1518 KB)  ( 260 ) 65 Bridge deflection real-time monitoring based on inclined angle measurement LI Yong;YAN Wei-ming;CHEN Yan-jiang DOI: Deflection monitoring is an important aspect of health monitoring system, and inclined angle measurement can real-time (RT) and precisely obtain the structural deflection. The relation between inclined angle and deflection is deduced based on cantilever and simply supported beam. Then the deflection is integrated and fitted though inclined angle by MATLAB and this method is compared with the direct deflection measurement during a test of a steel beam under loads. Finally, a health monitoring engineering project is introduced to show inclinometers implication on the deflection monitoring. The analysis shows that the relationship between incliner angle and deflection is reasonable, while the boundary conditions should be considered with regard to different structures. The deflection integrated though incliner angle is nearly identical with the deflection measurement. If the inclinometers are used on the health monitoring system, then the RT deflection and deflection at an arbitrary time point of the structures can be obtained. 2013 Vol. 32 (5): 65-69 [Abstract] ( 504 ) HTML (0 KB)  PDF (2230 KB)  ( 378 ) 70 Simulation research of time domain model of road roughness with time-space correlation WANG Ya;CHEN Si-zhong;ZHENG Kai-feng DOI: It is of significance to establish the time domain model of road for the theoretical research of modern vehicle. Harmony superposition method is applied to establish the road roughness of a single wheel. Two kinds of method are proposed to calculate the coherence of bilateral tract excitation, combined with the correlation of front and rear wheel, road roughness model of 4-wheel vehicle is built. Simulation results show that the two modeling method is correct in theory of coherence and can be applied to simulate stochastic road with a specific spectrum. Compared with other methods, proposed methods improve the efficiency of modeling. 2013 Vol. 32 (5): 70-74 [Abstract] ( 514 ) HTML (0 KB)  PDF (1386 KB)  ( 1158 ) 75 Fragility analysis of long span continuous rigid frame bridge under multi-support excitations LI Ji-tao;YANG Qing-shan;LIU Yang-bing DOI: Due to wave passage effect, incoherence effect, local effect and other factors in seismic ground motion, the internal force and deformation of long span continuous rigid framed bridges will be error-estimated when seismic responses analysis is performed under identical support ground motion excitations. A Monte Carlo simulation method is used to establish the random sample (large-span continuous rigid frame bridge and ground motion), by means of considering the uncertainties of the structural material and ground motion, both for identical support ground motion excitations and multiple support ground motion excitations. The ductility ratio of piers is defined as the damage state of the bridge. And the seismic fragility analysis is carried out for two different excitation method and the fragility curves of the bridge are given base on the damage state definition. The peak acceleration relationship of different excitation methods is obtained under the same level damage. 2013 Vol. 32 (5): 75-80 [Abstract] ( 591 ) HTML (0 KB)  PDF (1623 KB)  ( 308 ) 81 A study on the effects of case on the underwater explosion for aluminized explosive XIANG Da-lin;RONG Ji-li;LI Jan;YANG Rong-jie DOI: Underwater explosion experiments were carried out on the cylindrical aluminized explosives. The charges surrounded by 6mm thick steel casing、AL casing and PVC casing, and two bare charges were also fired. The shock wave pressure-time curves were measured at the distance of 3m、5m and 7m, and the peak pressure、impulse、energy of shock wave and bubble energy were also work out. Numerical simulations using AUTODYN-2D supported experimental results. According to the dimensional analysis and numerical simulation, the variation of shock wave profile、peak pressure and bubble period with the relative charge mass was studied. The results show that the peak pressure and energy of the shock wave would be all enhanced when the relative charge mass is small, but decrease when the relative charge mass too large. The bubble period was lower for the casing charge than that of the bare charge. The optimal relative charge mass was 1.45 for the steel casing charge. The finite element model and calculation results can provide a reference for the design of underwater weapons. 2013 Vol. 32 (5): 81-85 [Abstract] ( 593 ) HTML (0 KB)  PDF (1779 KB)  ( 407 ) 86 Study on preparation and properties of high damping and wide-temperature-range CIIR composites DING Guo-fang;CAO Jun;SHI Yao-gang;LUO Shi-kai DOI: The high damping and wide-temperature-range CIIR crosslinking composites were prepared successfully with the basic materials CIIR materials through the technology of anti-plasticization interactions. And their damping properties、mechanical properties and microstructure were investigated. The results showed that the CIIR/CP-70/PF composites have only one tanδ peak, which displays the excellent compatibility between the CP-70 and the CIIR matrix. More importantly , the tanδ peaks of the composites shift to the higher temperature with the use of CP-70 in the composites, and the tanδ value of the composites obviously synchronously increases to about 1.38, and the temperature range were improved to above 90℃.At the same time, the mechanical properties of the composites results in considerable tensile strength. The high damping and mechanical properties endow the composites with a potential and promising application future in engineering. SEM and DSC results prove that the majority of AO-2246 dissolve in the CIIR matrix and results illustrate that CP-70 in the matrix exists in anamorphous forms. The results prove that strong anti-plasticization interactions are formed between CP-70 and CIIR matrix. 2013 Vol. 32 (5): 86-89 [Abstract] ( 538 ) HTML (0 KB)  PDF (940 KB)  ( 473 ) 90 Experimental research of AFRP confined concrete under repeated impact LIANG Lei;GU Qiang-kang;YUAN Lu DOI: To study the dynamic mechanical properties of Aramid Fiber-Reinforced Plastic (AFRP) confined concrete under the impact of repeated dynamic load, using Ф100mm Split Hopkinson pressure bar (SHPB), the dynamic mechanical properties of three kind strength of concrete (C30, C40 and C50) with 1~3 layers AFRP confined was tested in a similar strain rate condition. Through an ultrasonic non-destructive test, damage law of concrete specimens was studied after every impact. The results show that the dynamic peak stress of 1~3 layers AFRP confined concrete is insensitive to the impact cycles, it fluctuating less than 8% shows that AFRP confined concrete is steady; the dynamic peak strain and the damage to inner concrete are increasing with the increased impact frequency, and the damage factor is linear to the impact cycles; AFRP confined concrete remains the shape as a whole test piece when the damage on inner concrete reaches the utmost limit value of common concrete under the same situation. Further more, the AFRP confined concrete test piece remains the ability to withstand next impact. 2013 Vol. 32 (5): 90-95 [Abstract] ( 628 ) HTML (0 KB)  PDF (1857 KB)  ( 216 ) 96 Numerical calculation analysis on dynamics parameter of explosive welding in sharp wedge zone XIE Fei-hong;WU Qi-hong;LI Wen-yuan;WAN Shi-ming;YANG You-lian DOI: Used to high-precision differential format of movement interface for deriving two-dimensional Navier-stokes equation， to directly simulate pressure and velocity flow field in based-upset board installation sharp wedge of collision point at different explosives detonation velocity， mainly analyze pressure distributions characteristic and duration action lasted form of explosive Composite plate explosion in sharp wedge zone， it will be found different degrees of anti-shock produced phenomenon under detonation pressure in substrate surface， also can simulate to find air medium flow distribution in fan-shaped jet state laminar flow bending shape between upset and based plate， this study can be certain reference for explosive welding melt layer formed analysis. A finite element model and its boundary conditions of quayside gantry crane are established in this paper. The first ten natural frequencies， the corresponding mode shapes and time-history of displacement response are given based on the analysis of the modes and dynamic response of this gantry crane system. The calculation and analysis above may be helpful for preventing the gantry crane from working on resonant area and for keeping the oversize dynamic deformation under restraint， which can be applied to design quayside gantry crane systems. 2013 Vol. 32 (5): 96-98 [Abstract] ( 603 ) HTML (0 KB)  PDF (1375 KB)  ( 224 ) 99 Transverse vibration control of belt drive systems by variable structure control YU Xiao-gang;JIA Xiu-li DOI: The prototypical model of belt drive systems contains a driving pulley，a driven pulley，an actuator and belts。The transverse vibrations of belts are coupled with the vibrations of the driving pulley，driven pulley and actuator。And so，the transverse vibration displacements of belts have effects on the driving pulley，driven pulley and actuator。The transverse vibration displacements of the belts under the harmonic excitation are formulated in this paper。And the variable structure control theory and exponentially reaching law are employed to design the controlling force which controls the tensioner arm orientation。And the transverse vibration displacements of the belts can effectively restrain under the controlling force。A numerical simulation is made via Matlab to verify the efficiency of the control under the initial conditions and harmonic excitation。And the results of numerical simulation demonstrate that under the harmonic excitation，the transverse vibration displacements of the belts are reduced。 2013 Vol. 32 (5): 99-103 [Abstract] ( 579 ) HTML (0 KB)  PDF (1165 KB)  ( 232 ) 104 A novel multidirectional-sensitive MEMS inertial switch by non-silicon surface micromachining ZHU Bin;YANG Zhuo-qing;CHEN Wen-guo;DING Gui-fu;ZHAO Xiao-lin DOI: Based on non-silicon surface micromachining technology, a new novel three-dimension micro inertial switch with multidirectional-sensitive has been designed and fabricated. Using typical mass spring damper system, the switch mainly consists of mobile electrode (mass) with beam spring, flexible fixed planar and vertical electrodes. By finite element analysis (FEA) simulation, modal analysis of the device has been using to determine the natural frequency of the device; dynamic simulation of the device to verify the working principle. After fabrication, micro-switches are tested by using drop weight. The results show that the threshold accelerations distribute between 50g and 60g, which basically fulfils the expected 60g; and the response time to 1ms half-sine waved shock is above 40 s. 2013 Vol. 32 (5): 104-107 [Abstract] ( 562 ) HTML (0 KB)  PDF (1837 KB)  ( 278 ) 108 Analysis and application of non-linear vibration signal of inclined cables based on particle filter YE Qing-wei;YUAN De-bin;WANG Xiao-dong;ZHOU Yu DOI: To the non-linear vibration signal of inclined cables,the paper use PF theory to process and applicate. primarily, nonlinear dynamic model of the cable-stayed beam coupling system is dispersed in temporal dimension by using the finite difference method, so as to get discrete nonlinear vibration equation of any cable element. The next place, based on least square-fit, fit discrete nonlinear system to get state equations needed by PF theory. Finally, PF theory is used to process collected non-linear vibration signal on the state equations, to get excellent nonlinear denoising signal and its stable tracking and predictive function. By abundant simulation experiment and trial of the practice inclined cables’s nonlinear vibration signal, it turn out that if the frequency of sampling is big enough, PF theory can effectively remove noise from the nonlinear vibration signal, and provide reliable and stable signal tracking and predictive method. 2013 Vol. 32 (5): 108-112 [Abstract] ( 520 ) HTML (0 KB)  PDF (1221 KB)  ( 370 ) 113 The mechanical behavior and effects of reinforced concrete members under different loadings WANG De-bin;LI Hong-nan DOI: Based on Beam with Hinges Element in OpenSees, the linear elastic shear restoring force model that defined on section is adopted. The zero length section element with bond-slip material is introduced to simulate the bond-slip at the end of element. Meanwhile, the geometric non-linearity caused by the P-D effect is taken into consideration. The Mohle-Kunnath constitutive model which is able to accurately simulate the low-cycle fatigue damage and cracking phenomenon of steel is used to analysis the mechanical property of component under different loading history. This paper studies the mechanical properties of component under monotonic loading, asymmetric cyclic loading and symmetric cyclic loading. Under different cycle numbers, the mechanical properties of component with symmetric and asymmetric loading and the changing characteristics of steel strain with displacement loading history are further analysed. The results indicate that under cyclic loading conditions stiffness degradation and strength degradation phenomena of the reinforced concrete frame columns are obvious. The damage of the component gradually exacerbates with the decrease of shear span ratio and the increase of shaft pressure ratio, while the damage is more obvious with the increase of the cycle numbers. The strain of reinforced materials change significantly with the increase of cycle numbers, the stiffness degradation and strength degradation become more obvious with the increase of axial compression ratio and the decrease of shear span ratio, the strain of steel also increase to some extent. 2013 Vol. 32 (5): 113-118 [Abstract] ( 509 ) HTML (0 KB)  PDF (3752 KB)  ( 263 ) 119 Numerical analysis of fluid excitation to a thermowell CHEN Qing-guang;JIA Xiang-xing DOI: Thermowells were often fractured due to the impact of fluid flow with high temperature and high velocity. The large eddy simulation technique was utilized to simulate the unsteady internal pipe flow field around a specified thermowell. The force and the vibration of the thermowell induced by the unsteady flow were analysed. An improved measure, which set up an interference equipment in the front of the thermowell, was presented to suppress the vibration and reduce the force of the thermowell. The effect of the improved measure was also verified. This study would be useful to the structural optimization design for thermowells. 2013 Vol. 32 (5): 119-121 [Abstract] ( 531 ) HTML (0 KB)  PDF (1297 KB)  ( 210 ) 122 The single-channel vibration signal separation by combining the empirical mode decomposition with time-frequency analysis LI Qiang;FU Cong;JIANG Hong;PENG Xian-min DOI: The separation method of single-channel vibration signal was explored to accomplish the extraction of mechanical vibration source signals. The ensemble empirical mode decomposition technology was utilized to construct the pseudo multi-channel measurement signals. The principal component analysis method was used to determine the number of vibration source signals by the distribution of eigenvalues. Then, the blind source separation algorithm based on time-frequency analysis was implemented to acquire the vibration source signals. Experiments showed that the single-channel vibration signal could be effectively separated. The proposed method is feasible and practical. 2013 Vol. 32 (5): 122-126 [Abstract] ( 617 ) HTML (0 KB)  PDF (1514 KB)  ( 356 ) 127 Research fault severity asessment for bearing based on vibration image GUAN Zhen-zhen;ZHENG Hai-qi;YE Ming-hui DOI: Aiming at problems that the research of fault classification on bearing is more but the research of fault degree identification is litter, the information of vibration image is abundance but it has not been used fully, the method of fault degree identification of bearing using vibration image is proposed. The original vibration signals are de-noised with EMD- morphology filter, then is converted to bispectrum contour image, after it calculated using gray-level co-occurrence matrix and principal component analysis, the fault degree character parameters are acquired. At last the fault degree is diagnosed by support vector machine. The results of experiments show that this method can diagnose the fault degree of bearing effectively, and it provides a new diagnosis approach for the fault degree of rotating machinery. 2013 Vol. 32 (5): 127-131 [Abstract] ( 530 ) HTML (0 KB)  PDF (2342 KB)  ( 631 ) 132 Numerical investigation on aerodynamic coefficients of iced quad bundle conductor CAI Meng-qi;YAN Bo;Lü Xin;ZHOU Lin-shu DOI: Numerical model for fluid flow around a typical iced quad bundle conductor is set up, and the aerodynamic coefficients varying with wind attack angle of the conductor are numerically investigated by means of FLUENT software. The Den Hartog and Nigol coefficients determined by numerical simulation are agreed with those obtained by the wind tunnel test. Moreover, galloping of iced quad bundle conductor lines based on aerodynamic coefficients obtained by numerical simulation method and wind tunnel test are simulated by ABAQUS software. The galloping characteristics of the transmission lines based on the aerodynamic coefficients by numerical method and test are agree, which demonstrates that the availability applying the numerical simulation method to obtain the aerodynamic coefficients of iced conductors for analysis of galloping of transmission lines. 2013 Vol. 32 (5): 132-137 [Abstract] ( 575 ) HTML (0 KB)  PDF (3179 KB)  ( 597 ) 138 Model updating for hybrid testing with unscented Kalman filter WANG Tao;WU Bin DOI: In a hybrid simulation, the whole system is divided into physical parts and numerical parts. For hybrid simulation of large-scale structures subjected to strong earthquake, it is usually difficult to keep the numerical substructure within linear range. So the concerns are raised how the modeling of the numerical part is reliable. A model updating for hybrid testing method with the unscented Kalman filter (UKF) is presented in order to improve the accuracy of model for numerical substructures. The new testing method assumes that the numerical substructures have the similar hysteretic behavior with the physical substructures, but the parameters of the hysteretic model are updated after they are identified with the unscented Kalman filter approach based on the data from experimental parts. The performance of UKF is investigated by numerical simulation for a single freedom nonlinear system. The effectiveness of the proposed test method is verified by an actual testing. The results show the method has good accuracy compared to conventional hybrid testing. 2013 Vol. 32 (5): 138-143 [Abstract] ( 621 ) HTML (0 KB)  PDF (1928 KB)  ( 465 ) 144 Roller bearing fault diagnosis based on locality preserving projection YAO pei;WANG Zhong-sheng;JIANGH Hong-kai;LIU Zhen-bao;BU Shu-hui DOI: We present a novel method for roller bearing fault diagnosis based on Locality Preserving Projection (LPP) and adaptive boosting algorithm (Adaboost). Firstly, we obtained several parameters from vibration signals and set up the original dataset, including time domain parameters, frequency domain parameters, and time-frequency domain parameters. Successively, we extract dimension reduced features from the original dataset using LPP. And finally, we use the adaptive boosting algorithm for training and classification. In this paper, we analyze on normal condition, inner race defect, outer race defect, and ball defect of roller bearing. To verify its advantage, we make some comparative trails, and simulation result shows its effectiveness and superiority. 2013 Vol. 32 (5): 144-148 [Abstract] ( 604 ) HTML (0 KB)  PDF (2284 KB)  ( 256 ) 149 Fault Diagnosis Method for Rotating Machinery Base on Manifold Learning and K-Nearest Neighbor Classifier SONG Tao;TANG Bao-ping;LI Feng DOI: With the problems of needing manual intervention 、low accuracy and difficult to obtain fault samples for rotating machinery fault diagnosis, a fault diagnosis method is proposed based on manifold learning and K-Nearest Neighbor Classifier(KNNC).Multi-domain information entropy for vibration signal is extracted to reflect the working status fully and construct high-dimensional characteristic sets. Then the second feature extraction property of nonlinear manifold learning algorithm Orthogonal Neighborhood Preserving Embedding(ONPE) is used for dimensionality reduction and make the characters get better clustering property. Finally, improved KNNC is used for Pattern classification and it is more suitable for small sample classification. The diagnostic case for bearing proved the effectiveness of the model. 2013 Vol. 32 (5): 149-153 [Abstract] ( 589 ) HTML (0 KB)  PDF (955 KB)  ( 998 ) 154 On the stability and axial vibration of compressive bars based on nonlocal elasticity theory LI Cheng;HUANG Wei-guo;ZHU Zhong-kui DOI: The stability and axial vibration of a compressive bar are investigated through the nonlocal elasticity approach. The explicit solutions for critical pressure and inherent frequency are obtained according to three typical kinds of boundary conditions. It is shown that an increase in dimensionless small scale parameter causes the critical pressure and inherent frequency to decrease. A numerical example is presented and it indicates the nonlocal critical pressure decreases with increasing the length of compressive bars, and critical pressure approaches to a constant when the length is closed to macro size. Nonlocal critical pressure and inherent frequency are lower than the results from classical continuum mechanics, namely, the classical mechanics overestimates the critical pressure and inherent frequency of a structure at small scale. With an increase in length of the compressive bars, nonlocal results are in good agreement with classical results. 2013 Vol. 32 (5): 154-156 [Abstract] ( 566 ) HTML (0 KB)  PDF (983 KB)  ( 258 ) 157 Prediction of fluctuating wind pressure on low building’s roof WANG Ying-ge;LI Zheng-nong;WU Hong-hua;ZHANG Ling-hui DOI: The taps are usually finite in structure’s surface wind pressure research by measurement method, as restricts the wind field’s sufficient appearance. Interpolation is a regular choice, but it’s hard to directly interpolate time series. Basing on POD technique and referring ‘grid’ thought in geographical statistics, this paper processed spatial latent vectors. The Kriging interpolation method was introduced to frame Matlab program interfacing Surfer software whose powerful spatial interpolation capacity got used to spatially interpolate the structure’s surface latent vectors of each phase. Data from measured wind pressure time series of a low-rise building in typhoon are used to verify the feasibility of this method. Research shows that Kriging method can offset deficiency of triangular linear interpolation which can not extrapolate the point out of the scope; moreover Kriging method is better than the inverse distance method on prediction effect when wind pressure varies sharply. This method is relatively universal, could be widely applied in wind tunnel tests & field measuring. 2013 Vol. 32 (5): 157-162 [Abstract] ( 474 ) HTML (0 KB)  PDF (2049 KB)  ( 210 ) 163 Research on impact fracture of rock based on fractal theory LIU Shi;XU Jin-yu;BAI Er-lei;GAO Zhi-gang DOI: The impact experiment is made on the sericite-quartz schist and sandstone samples with SHPB apparatus of 100mm in diameter, and the fragment-size distribution of fragmental rocks is obtained through sieving and statistics of rock samples. Fractal dimensions of sericite-quartz schist and sandstone are calculated by using fractal geometric methods and the relationship between the dynamic compressive strength and the fractal dimensions of two rocks are analyzed. The experimental results indicate that the values of fractal dimensions of sericite-quartz schist range from 1.9 to 2.4 and the values of fractal dimensions of sandstone range from 2.5 to 3.0. The fractal dimensions of two rocks increase linearly with increasing in impact speed. However, the dynamic compressive strength of sericite-quartz schist has no obvious correlation with the fractal dimensions and the dynamic compressive strength of sandstone increases with increasing in fractal dimensions. Thus using the fractal dimensions to describe the dynamic compressive strength of two rocks may provide a new approach to investigate the inherence law between fractal characteristics and impact mechanical properties of rock materials. 2013 Vol. 32 (5): 163-166 [Abstract] ( 565 ) HTML (0 KB)  PDF (1170 KB)  ( 320 ) 167 Active Loudness Control of Enclosed Cabin Noise by Using New Algorithm JIANG Shun-ming;;CHEN Nan DOI: The control objective of active noise control (ANC) system is modified from minimizing sound pressure to minimizing loudness. The improved loudness-filtered least square mean (LFLMS) algorithm is derived based on delay-compensated structure and inverse-model structure. A double channel ANC system is installed in a passenger car cabin. Three algorithms are used to attenuate the engine noise in the cabin. The experimental results indicate that the improved LFLMS algorithm converge faster than LFLMS algorithm, and the loudness control can achieve better subjective effects than the sound pressure control in terms of loudness reduction. 2013 Vol. 32 (5): 167-170 [Abstract] ( 538 ) HTML (0 KB)  PDF (1596 KB)  ( 274 ) 171 A Large Deformation Finite Element Analysis of Rubber Isolator ZHOU Zhen-kai;XU Bing;HU Wen-jun;WEI Li-ming;Niu Wei DOI: The finite element analyses of deformation of rubber isolator in tensile, compression and shear and torsion were performed using hyperelastic constitutive model. The finite element modeling techniques for incompressible deformation of rubber was discussed in this study as well. The analysis also focused on the deformation models of rubber structures at various loading conditions and material test data that the FEA need. Compared with experimental results, the best type of material test data for filling the constitutive model of rubber isolator under three different conditions was obtained, which provided a good reference for the numerical simulation of rubber structure. 2013 Vol. 32 (5): 171-175 [Abstract] ( 627 ) HTML (0 KB)  PDF (1368 KB)  ( 796 )

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