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2011 Vol. 30, No. 7
Published: 2011-07-25
 
       论文
1 Sensitivity Analysis of Vehicle Acceleration during Impact to Barrier
YAN Shu-ming
DOI:
Impact parameter errors existed in the test organization. In order to understand sensitivity of vehicle acceleration versus to impact parameters, finite element simulation model of a vehicle impact to a combined barrier was set up and sensitivity analysis was done after finite element model proved to be correct by impact test. The results indicate that the simulation method is reliable since the results of simulation match to that of crash test, the sensitivity coefficients of body acceleration versus to vehicle quality, to impact angle and to impact velocity are -0.58, 1.63 and 4.18, the impact speed is the most sensitive factors to vehicle acceleration. The research results have guidance significance to set out error range of barrier impact test.
2011 Vol. 30 (7): 1-4 [Abstract] ( 1363 ) HTML (0 KB)  PDF (1334 KB)  ( 1012 )
5 MONITORING DYNAMIC CHARACTERISTICS OF A HIGHRISE STRUCTURE BASED ON DIGITAL CAMERA TECHNOLOGY
CHEH Wei-huan; LU Zhong-rong; CHEN Shu-hui; Ni Yi-qing; LIAO Wei-yang
DOI:
In the field of structural health monitoring, the image processing technology based on digital camera is arousing widespread concern as a new technique of structure vibration monitoring. Taking the GZ New TV Tower as the research background, the author makes use of the industrial digital camera as well as the GPS and accelerometer to monitor the dynamic characteristics of the tower. The analysis of the data shows that the dynamic displacement time history obtained from the digital camera system matches well with the one obtained from GPS. The former can exactly obtained the lower natural frequency; meanwhile, the first natural frequency obtained from the digital camera system matches well with the results of the GPS, the accelerometer and the Finite Element Analysis. The research result of this paper shows that the application of digital camera technology in dynamic characteristics monitoring of highrise structure is an effective new technique in structural health monitoring.
2011 Vol. 30 (7): 5-9 [Abstract] ( 952 ) HTML (0 KB)  PDF (1533 KB)  ( 394 )
10 Dynamic Trait of Evolution Process on Cutting Vibration Acceleration Time Series
Kong Fan-sen;Liu Peng;Wang Xiao-ming
DOI:
The vibration acceleration time history from the cutter holder was separated into three parts that were chatter free, transition and chatter processes. The reconstructed attractor and probability density distribution of vibration acceleration time series were studied in order to observe the view of a system’s behavior in geometric form. And the Lyapunov exponent and Kolmogrov entropy were given for helping on judgment of cutting state. Meanwhile, the relation curves of the Lyapunov exponent and entropy versus machining parameters were plotted and discussed. The research shows that Lyapunov exponent and Kolmogrov entropy are toned up when the amplitude of vibration acceleration time history goes up from chatter free, transition and chatter. In addition, the relation curves of the Lyapunov exponent and entropy versus machining parameters go with the same and look like stability lobes. We can select the optimal machining parameters for decreasing the uncertainty of cutting vibration based on corresponding to the experimental data.
2011 Vol. 30 (7): 10-15,4 [Abstract] ( 872 ) HTML (0 KB)  PDF (2501 KB)  ( 433 )
16 Testing Researchs of Influence of Shock Environment in the Different Charges UNDEX of Surface Warships
Chen Hui;LI Yu-jie;Pan Jian-qiang;Yang Yun-chuan;Zhang Lun-ping;Liu Jian-hu
DOI:
The shock produced by a non-contact underwater explosion usually produces shock damage of on-board equipments to relatively large extent. Consequently, the survivability and battle capacity of the ship are affected. Therefor, the research of the shock environment imposed on the shipboard equipments based on structural dynamic responses of the ship arouses the attention from navy of many countries. Among these works, the research of the connection of the load in UNDEX and shock environment is important for shock isolating designs of equipments and toning up the subaqueous weapons’ power. Via UNDEX shock tests of the holistic model of a warship and the comparison of variational rules of the load in UNDEX and shock environment of the model, the connection of the parameters of shock environment and the load in UNDEX is educed. The results have referenced value.
2011 Vol. 30 (7): 16-20 [Abstract] ( 885 ) HTML (0 KB)  PDF (1664 KB)  ( 590 )
21 Research of area-averaged pressure on saddle roofs
Dong xin;Ye Ji-hong
DOI:
In order to complete the wind resistant design of enclosure structure and cladding elements, concept of area-averaged pressure is proposed, and its characteristics are systematically studied by wind tunnel test. Firstly, starting from conical vortex, the approaching flow conditions which cause the generation of conical vortex are identified. Based on suction and correlation coefficient of vortex cores, the most unfavorable attack angle for saddle roof is confirmed to be along the connection of high points. Secondly, the area-averaged pressures are calculated by averaging all pressure taps within the area at each instant of time. The relationships between peak loads over various tributary zones and increasing tributary area are presented and fitted, which are verified by the cumulative probability curve of single point pressure. Non-Gaussian feature of area-averaged pressure time series is analyzed and compared with that of point pressure according to skewness and kurtosis. Results indicate that area-averaged pressure, whose uniform fluctuations concentrate on low-frequency range, is more normally distributed than individual pressure.
2011 Vol. 30 (7): 21-30,6 [Abstract] ( 1713 ) HTML (0 KB)  PDF (3458 KB)  ( 679 )
31 Creative Design and Dynamics Analysis of the New Reciprocating Grinding Head of Polishing Machine
SHAO Jun-peng;XU Bin
DOI:
In order to investigate the Large Machining equipment for the tile. A new reciprocating grinding head of polishing machine is invented. Advantage of swing-style grinding head of polishing machine is inherited form the structure and principle, remedy a defect. Desire of the Large Machining equipment for the tile is attained. Combined with a given example of the new reciprocating grinding block holder system of grinding head. It established model of system mechanical and systems dynamics. It is concluded that motion trajectory of grinding block holder system is linear motion in Y direction. According to the analysis, it attained that structural stability of new grinding head of polishing machine is guarantee with grinding block mass less than other mass(except grinding block).
2011 Vol. 30 (7): 31-34,7 [Abstract] ( 1695 ) HTML (0 KB)  PDF (1421 KB)  ( 433 )
35 Rearch on aeroelastic stability of the transonic axial compressor fan blade
Zhao rui-yong;Yang hui; Wang yan-rong
DOI:
The aeroelastic stability of the NASA 67 transonic fan blade is predicted by using the energy method at the near stall condition. The CSD/CFD data transfer is based on the improved 3D linear interpolation method. The FLUENT dynamic mesh technology is used in the simulation of unsteady flow around the oscillating blade. The unsteady aerodynamics of NASA 67 blade with excitation of the first three modes is studied. It is found that the phase angle between unsteady aerodynamic forces and vibration displacements decides the unsteady aerodynamic force do positive or negative work. The analysis of unsteady surface pressures yields that the mode shape and the shock are the most important factors on the aeroelastic stability of the rotor blade.
2011 Vol. 30 (7): 35-39,8 [Abstract] ( 1609 ) HTML (0 KB)  PDF (2126 KB)  ( 1113 )
40 Line spectra reduction of vibration isolation system based on tracking chaotification method
ZHANG Zhen-hai; ZHU Shi-jian;LOU Jin-jun`
DOI:
Line spectra in the radiated noise of marine vessels are the most visible signs, which can be detected, tracked and identified by enemy’s passive sonar. The chaotifying technique for line spectra reduction can reduce the line spectra for improving the acoustic stealth of marine vessels，based on the fact that response spectrum of a nonlinear system under harmonic excitation is a continuous one when chaos occurs. In order to overcome two difficulties, i.e. how to maintain the chaotic motion and how to obtain chaos under small amplitude in the VIS, which arise from the practical implements of the chaotifying technique for line spectra reduction, the tacking control method was proposed. It make the VIS track a knowed chaotic system, in this way, the line spectra in the radiated noise can be reduced effectively. In the mean time the problom of founding the knowed chaos sytem was solved. The experimental results confirmed the effectiveness of this method.
2011 Vol. 30 (7): 40-44 [Abstract] ( 938 ) HTML (0 KB)  PDF (1551 KB)  ( 678 )
45 Analysis on wind-induced dynamic response of transmission line systems
XIE Hua-ping; HE Min-juan
DOI:
Power spectra expressions of along-wind and cross-wind fluctuating wind load acting on transmission tower were deduced based on the fundamental linear mode generalized force spectra obtained through a wind tunnel test.Time histories of along-wind and cross-wind fluctuating wind load were simulated based on these spectra. Dynamic characteristics of single tower and the coupling system were analyzed. The results show that The out-plane vibration modes of tower in the system are most likely to occur coupling with cables, even the frequency is far below the same order natural frequency of single tower. Time histories of displacement, acceleration and internal force et al were obtained based on nonlinear dynamic time-history analyses of the transmission towers-line system and single tower. The wind-induced response spectra and diffences between the case applying across-wind loads and the case not applying were analyzed.
2011 Vol. 30 (7): 45-51 [Abstract] ( 863 ) HTML (0 KB)  PDF (2076 KB)  ( 463 )
52 Study on Anti-Galloping of Iced Quad-bundled Conductors in Stochastic Wind Field
Yan Bo;Hu Jin;Zhou Song;Zhang Hong-yan
DOI:
A new anti-galloping device suitable for quad-bundled conductor is proposed, and its efficiency of the anti-galloping is numerically studied. The aerodynamic coefficients of the quad-bundled conductor covered with typical ice with attack angle determined by wind tunnel test are given out to provide the parameters for numerical simulation. Spatial stochastic wind fields, based which the aerodynamic loads on iced conductors are determined, are numerically simulated. The dynamic processes of a typical transmission line without and with anti-galloping device are numerically simulated. It is shown that the amplitude of the conductor in the typical line section is greatly decreased after the installation of the anti-galloping devices.
2011 Vol. 30 (7): 52-58 [Abstract] ( 994 ) HTML (0 KB)  PDF (2928 KB)  ( 483 )
59 Investigation on Static and Dynamic Stability for Simply Supported Flexible Beam with Axial Flow
WANG Jian-wei; XU Hui;MA Ning
DOI:
The liquid-solid coupling dynamic equation was established for a simply supported flexible beam with an axial flow on certain assumptions, and the dimensionless state-space equation with finite degrees-of-freedom was derived by introducing dimensionless variables, assuming modes and truncating higher order modes. On the basis of the static bifurcation theory, the Jacobi matrix of the perturbation equation for the system was analyzed, and the static bifurcation critical flow velocity was obtained theoretically. Numerical calculations show that if the flow velocity exceeds the critical velocity, the system is destabilized, and the flexible beam bends upward or downward at random under the external minimal disturbance. Utilizing the dynamic Hopf bifurcation theory and relative algebraic criterion for roots of real-coefficient polynomials, it is proved that the flutter destabilization can’t take place in this system.
2011 Vol. 30 (7): 59-62 [Abstract] ( 1861 ) HTML (0 KB)  PDF (1163 KB)  ( 353 )
63 Study on Relative Displacement Response Spectrum of Long-period Structures
CAO Jia-liang;SHI Wei-xing;LIU Wen-guang;JIANG Xiang-min
DOI:
Relative displacement response spectrum is not only essential in seismic design of long-period structures but also in displacement-based seismic design and in structural control design. However, spectrum specified by seismic codes is almost some normalized absolute acceleration spectrum. Problems existing in long-period range of relative displacement spectrum in codes were pointed out. By selecting 80 high-pass filtered digital horizontal strong motion records (PGA (Peak Ground Acceleration)≥0.10 g) with low cut off frequency (0.025 Hz ~0.125 Hz), relative displacement spectrum was constructed with period range (0~10.0 s) and damping ratio range (0.10~0.40). Furthermore, spectral influence factors and control parameters were calculated and illustrated. Taken account into influence on relative displacement spectrum of hypocenter parameters, ground motion amplitude, site conditions, spectral control parameters and damping ratio adjustment factors, elastic design displacement spectrum and relevant practical calculation formula for long-period structures were proposed. Moreover, value of PGD (peak ground displacement) was given based on statistical analysis. The results reveal that predominant period is one of significant parameters controlling value and shape of the relative displacement spectrum, and the relative displacement spectrum established in this paper is capable of yielding relatively good satisfaction with real displacement spectrum.
2011 Vol. 30 (7): 63-70 [Abstract] ( 1309 ) HTML (0 KB)  PDF (2881 KB)  ( 1227 )
71 RSM-based FEM model updating for carbon fiber honeycomb sandwich panel
Qin Yu-ling;Kong Xian-ren;Luo Wen-bo
DOI:
The honeycomb sandwich panel with high strength and light weight is a special composite material which is widely used in satellite and other spacecrafts. There are no honeycomb material paremeters in the FEM software such as MSC/NASTRAN and ANSYS, and the simplified equivalent structure parameters of the honeycomb sandwich panel are used to calculate, which results in the differences between the test data and the FEM data. The RSM-based model updating method avoids calling FEM process in every iteration process, which improves the calculation efficiency. The equivalent parameters of the honeycomb sandwich panel are calculated based on the honeycomb sandwich theory, the FEM of the multi-layer carbon fiber sandwich panel is established using SHELL91 in ANSYS, and the test data under all factors and effects are obtained based on uniform design method, the quadratic polynominal response surface model is established and the PSO with mutation factor is used to update the equivalent paremeters of the honeycomb sandwich panel, the updated paremeters are substituted into the FEM and the FEM quality is effectively improved.
2011 Vol. 30 (7): 71-76,8 [Abstract] ( 837 ) HTML (0 KB)  PDF (1577 KB)  ( 458 )
77 Contacting mechanism of nonlinear friction pair ofmetallic rubber and analysis for simulation results
Li Yu-yan;Huang Xie-qing;Song Kai
DOI:
From the mechanism of dry-friction damping of metallic rubber, a new mechanical model of nonlinear friction structure element of metallic rubber was put forward. The structural element was made up of axial and radial elastic elements. The two elements not only denoted friction characteristics among wires, but also elastic properties of spiral turns. Based on the mechanical model constructed, using the series connection structure made of many friction pairs, friction contacts between turns were studied. Through simulation for the system made of the structural elements, hysteresis loops were deeply analyzed and studied under different loading for metallic rubber elements. Under static loading, the effects of friction coefficient and friction angle on energy dissipation of metallic rubber were studied, and under dynamic loading the effects of force amplitude, frequency and initial phase on energy dissipation were also studied, which largely reduced the works in the respects of static and dynamic experiments.
2011 Vol. 30 (7): 77-81 [Abstract] ( 1644 ) HTML (0 KB)  PDF (1801 KB)  ( 913 )
82 A New Method based on HHT to analyze the dynamic characteristics of hydraulic cylinder
Wang Xin-qing;Liang Sheng; Xia Tian; He Hong-yang; Chen Liu-hai
DOI:
A new method based on HHT to analyze the dynamic characteristics of hydraulic cylinder was proposed. The oil pressure fluctuation signal under the periodic excitation was decomposed into IMFs by using EMD. Then classified IMFs by the Hilbert marginal spectrum of each IMF and the frequency of the free vibration and forced vibration. Reconstructing the signal after the classification, the free vibration component which reflected the dynamic characteristics of the hydraulic cylinder was extracted. The result showed that the proposed method had good performance to analyze the dynamic characteristics of hydraulic cylinder, and the free vibration component was useful for analyzing the dynamic characteristics of the hydraulic cylinder.
2011 Vol. 30 (7): 82-86 [Abstract] ( 1518 ) HTML (0 KB)  PDF (1772 KB)  ( 735 )
87 Multiple Scattering of Plane SH wave by an Arbitrary Configuration of Elastic Piles as Barrier
XIA Tang-dai;SUN Miao-miao;CHEN Chen;
DOI:
A new method that is different from the past ones to calculate the multiple scattering of SH wave by an arbitrary configuration of elastic piles as barrier for vibration isolation has been established. The multiple scattering problem is solved by applying the equations of equilibrium under the assumption of each order of scattering satisfying the elastic boundary conditions. The first order of scattering is generated from the excitation of each elastic pile by incident plane SH wave, and the second order results from the excitation of each pile by the first order of scattering induced by remaining piles, so does the rest to an infinite. Thus, the analytic solution contains sum of all the scattering orders after the undetermined scattering coefficients have been obtained. The contours of normalized displacement amplitude, which represent the ratio of total wave field displacement amplitude to incident wave field, are imposed. The parametric analysis such as scattering orders, shear modulus ratio, the separation between piles, pile numbers and the transmissibility index are investigated in the one-row piles barrier to evaluate the screening effectiveness. These numerical results count future discontinuous barrier design for useful conclusions.
2011 Vol. 30 (7): 87-90,9 [Abstract] ( 822 ) HTML (0 KB)  PDF (1485 KB)  ( 819 )
91 Shearing Force Analysis of Split-Level Region in Split-Level Structure with Uniform Mass Distribution under earthquake
WANG Zhi-jun;HAN Feng-xia
DOI:
In the split-level structure, the split-level height and form are the main factors influencing the loading capability of split-level region. In this paper, the regular split-level and symmetric trans-dimensional structure with uniform mass distribution were analyzed. Under frequent and rare earthquake excitations, the changing rule of shear force of the split-level region with different split-level height was studied through elastic-plastic time-history analysis. The shear force equation for the split-regen was further simplified. Considering the nonlinear influence, the magnifier of shear force for the split-level region was proposed.
2011 Vol. 30 (7): 91-95 [Abstract] ( 838 ) HTML (0 KB)  PDF (971 KB)  ( 427 )
96 Theory and Simulation Analysis for Penetration Overload on A Small Size Charge
XU Wen-zheng; WANG Jing-yu; LI Ji-lin; HUANG Hao
DOI:
The impact characteristic of a small size charge was carried by projectile penetrating into concrete target was studied. In theory analysis model, small size charge was set in a non-inertia coordinate system.The absolute acceleration of charge was the vector sum of convected acceleration and relative acceleration. Based on stress wave theory, a relative acceleration calculation model of small size charge was presented in which the consistency condition in front of stress wave was utilized. The formula of penetration acceleration of the charge was derived. The relationship of charge relative acceleration and projectile mass points that contact with charge was carried out. The numerical simulation of a small size charge set in a projectile into concrete target was performed. The good agreement of analytical and numerical results was in general obtained. Theoretic reference and analytical methods were provided for deceleration characteristic evaluation of small size charges.
2011 Vol. 30 (7): 96-100 [Abstract] ( 1422 ) HTML (0 KB)  PDF (1615 KB)  ( 490 )
101 Finite Element Analysis for Dynamic Meshing of Hypoid Gear
Tang Jin-yuan;Peng Fang-jin
DOI:
The method to build finite element model for dynamic meshing analysis of hypoid gears was discussed. A reasonable finite element model was introduced. Based on the theory of nonlinear dynamics and finite element explicit algorithm, the characteristics of the hypoid gear in dynamic meshing was studied. Obtained the laws of gear motion, the contact area, the contact stress and the tooth root bending stress in the dynamic meshing of hypoid gear. Take the example of the two typical work factors like speed and load. The influences of speed and load on the dynamic meshing characteristics were discussed. The contrast research shows that the rotational speed has an obvious influence up on the characteristics of the hypoid gear in dynamic meshing, and that the influence of load is related to the rotational speed. As the rotational speed increases, the influence of the same load change on the dynamic meshing characteristics becomes gradually weakened.
2011 Vol. 30 (7): 101-106 [Abstract] ( 1810 ) HTML (0 KB)  PDF (3610 KB)  ( 545 )
107 Research on Disturbance of Flexible Antenna Sheet on Satellite Antenna
YOU Bin-di;ZHAO Zhi-gang; WEI Cheng; ZHAO Yang
DOI:
To study disturbance of satellite antenna with flexible antenna surface, the fixed-interface component-mode synthesis method and Lagrange’s equations is used to achieve a lower order dynamic model by modal truncation. Under the large motions, the rigid-flexible coupling dynamics model of flexible satellite antenna is deduced through compatibility relations at the interface between axis end and antenna surface, and compensate for the neglect of elastic deformation. So the model should increase the computing efficiency without losing much accuracy. Then, satellite antenna dynamics is analyzed considering the antenna surface as rigid and flexible body separately. The result shows that the flexible antenna surface has little effect on satellite base attitude and antenna pointing at initial stage, but the shock may excite to aggravation its own elastic vibration with the joint continuing torques. Further, it can make the system vibrated and deviations of satellite base attitude and antenna pointing become larger. At the result, the satellite antenna pointing accuracy is seriously affected. The above conclusion has important theoretical value and practical significance engineering for the satellite antenna pointing accuracy of the analysis and control.
2011 Vol. 30 (7): 107-111, [Abstract] ( 1641 ) HTML (0 KB)  PDF (2125 KB)  ( 409 )
112 Design of a new type of piezoelectric actuator for middle ear implant
LIU Hou-guang;TA Na;RAO Zhu-shi
DOI:
A piezoelectric stack actuator for incus driving type middle ear implant was proposed and designed. To aid the design process, a coupling mechanics model of the human middle ear and the piezoelectric stack actuator was constructed. This model was build based on a complete set of computerized tomography section images of a healthy volunteer’s left ear by reverse engineering technology. The result shows that the stapes footplate displacement stimulated by the designed piezoelectric stack actuator’s excitation at 10.5 V rms was equivalent to that from acoustic stimulation at 90 dB SPL, which is adequate stimulation to the ossicular chain. The corresponding power consumption is 0.03 mW per volt of excitation at 1 kHz, which is low enough for the actuator to be used in a middle ear implant.
2011 Vol. 30 (7): 112-115, [Abstract] ( 1444 ) HTML (0 KB)  PDF (1302 KB)  ( 534 )
116 Study on the time function for borehole explosive loading and specific energybased on the different coupling medium
Zhong Ming-shou; Long Yuan;Li Xing-hua;Ma Hai-yang;Xie Quan-min
DOI:
To improve the explosive crushing effect and control the explosive vibration from the coupling medium, the calculation model of explosive loading and specific energy were established under the different coupling medium of explosion source. The time function and curve of explosive loading and specific energy were calculated by programming in rock medium. The results show that: the initial borehole explosive loading is maximum, but the attenuation is also the fastest when coupling charge; Although the value is smaller in water decoupling charge, the attenuation is slowest; the specific energy of water decoupling charge is maximum, the value of coupling charge is following; while all the value of air and soil-decoupling charge is minimum. So it’s good for improving the blasting crushing effect and bad for controlling blasting vibration, when the coupling medium is water.
2011 Vol. 30 (7): 116-119 [Abstract] ( 1638 ) HTML (0 KB)  PDF (1163 KB)  ( 378 )
120 Study on time-domain seismic response for gravity dam to obliquely incident seismic waves
Yuan Ju-wei;Du Cheng-bin;Liu Zhi-ming
DOI:
In this paper, the time-domain calculating method for dynamic interaction between gravity dam and foundation object to obliquely incident seismic waves is developed based on hypothesis of homogeneous foundation, in which both oblique plane SV wave and oblique plane P wave are input simultaneously at artificial boundary and produce similar seismic response to the design seismic component at surface of half space. According to theory of wave propagating in solid, both incidence angles and amplitudes of the oblique waves have deterministic relation. Taking the interaction between gravity dam and foundation as an example, the time-domain seismic response is calculated and analyzed. The preliminary results show that obliquely incident seismic waves have greater influence to area nearing interface of dam foundation than other area, where the dynamic response under obliquely incident seismic waves is more than that under vertical incident seismic waves. The method takes both design seismic component and radiation damping of foundation into account, and produces nonuniform motion at interface of structure and foundation, so it can well be used to study dynamic response of structure under nonuniform input.
2011 Vol. 30 (7): 120-126 [Abstract] ( 1274 ) HTML (0 KB)  PDF (1941 KB)  ( 404 )
127 Optimization design for headstock of machine tool based on orthogonal experimental method and grey relational analysis
LIU Shi-hao;YE Wen-hua;CHEN Wei-fang;Tang Dun-bing;XIAO Li-li
DOI:
In order to enhance the machine tool headstock’s comprehensive performance of static, dynamic, thermal, it must have good structure. The finite element model of a machine tool headstock was established in CAE software ANSYS, then its thermal-mechanical coupling analysis and modal analysis were conducted. The multi-objective orthogonal optimization design for headstock was carried on through taking the headstock’s mass, the maximum coupling stress, the maximum coupling deformation, the fist-step natural frequency as objective functions, the length, the width and the height of headstock’s main body as design variables. The best solution of optimization design was obtained by using grey relational analysis method, which made headstock’s mass only increasing 2.585%, the maximum thermal-mechanical coupling stress reducing 9.817%, the maximum thermal-mechanical coupling deformation reducing 16.393%, and the first-step natural frequency enhancing 8.634%. Studies have shown that the orthogonal experimental method and grey relational analysis have high engineering practicability.
2011 Vol. 30 (7): 127-132 [Abstract] ( 881 ) HTML (0 KB)  PDF (1295 KB)  ( 508 )
133 Experimental and numerical simulation on impact damage protecting of Tunnel surrounding rock
Dai Ren-ping;Guo Xue-bin;Gong Quan-mei;Zhou Shun-hua;Pu chuan-jin
DOI:
Based on the traditional charge stucture of smooth blasting, a new stucture that packed PVC-U material beside blasthole is proposed for protecting tunnel surrounding rock.The working theory of the material in reducing the impact damage toward tunnel surrounding rock is also investigated. For verificating the effect of PVC-U material in decreasing surrounding rock’s damage, the Ф57mm one-stage light-gas gun is used to carried out experiments with the LS-DYNA analysised software dissecting tests’ data. Test’s result indicates that with this protective layer could diminish the stress peak and damage of rock sample’blasting surface. And with same condition of impact velocity,the thicker of the PVC-U material layer, the lower of the blasting surface stress peak value. By using 4mm protective layer,the injury tolerance of rock test specimen reduced 21.1%.Moreover ,the validity of theoretical analysis and test result are also checked by numerical simulation method.And the conclution is that PVC-U material layer in the blast hole can reduce the blasting damage of tunnel surrounding rock.
2011 Vol. 30 (7): 133-137 [Abstract] ( 1859 ) HTML (0 KB)  PDF (1610 KB)  ( 583 )
138 Research on Natural Frequency Characteristics and Dynamic Stress of the Blade in Axial-Flow Compressor
LI De-xin; CHEN Jiang-hui
DOI:
By establishing a 3D finite element model of blade, the natural frequency characteristics of an Axial-Flow Compressor Blade is studied. The effect of spin softening and stress stiffening are analyzed from the theoretical. A case study on the first grade blade of Axial-Flow Compressor shows that the resonance frequency are changed caused by the effect of the spin softening and stress stiffening. The dynamic stress of blade is computed by the full method of transient analysis. The foundation of the frequency modulation and improving vibration Characteristics of the blade is provided by the analysis results.
2011 Vol. 30 (7): 138-142 [Abstract] ( 886 ) HTML (0 KB)  PDF (1811 KB)  ( 654 )
143 An investigation into wheel/rail impact noise generation due to high speed train passing over rail weld joints
YANG Xin-wen;;ZHAI Wan-ming;HE Zhen-xing
DOI:
In order to reduce greatly wheel/rail impact noise generation due to a wheel passing over the rail joints, seamless rails are widely used in high speed railway. But, because of low quality of rail weld and performance difference between welding materials and rail material, wheel/rail noise will be generated more severely when a wheel passing over these rail weld joints than the other places. To explore the influence of rail weld joints on the wheel-rail impact noise, based on vehicle-track coupled dynamics, random vibration theory and acoustics radiation theory, a model is developed to calculate the wheel/rail impact noises when a train passes over the rail weld joints. The result shows that the energy of wheel/rail impact noise generation due to rail weld boss concentrate in the frequency range of 1250～3000Hz, whereas the wheel/rail impact noise due to low rail weld joints concentrate in the frequency range of 400～1250Hz. With wavelength of rail weld shortwave irregularity increases, the maximum of wheel-rail noise level has been reduced. With wave depth of rail weld shortwave irregularity increases, the maximum of wheel-rail noise level has been increased.
2011 Vol. 30 (7): 143-147, [Abstract] ( 1561 ) HTML (0 KB)  PDF (1755 KB)  ( 862 )
148 Wind-induced response analysis for an “extensional” large roof
Yu Xian-feng; Quan Yong; Zhou Xuan-yi;Zhu Zhong-yi;Gu Ming
DOI:
Based on the data of the wind pressure measurement in wind tunnel test for its rigid model, wind-induced responses of the Shenzhen Terminal T3, which are structurally similar to an “extensional” large roof, were calculated with the CQC method, and then the characteristic of effective static load distributions are also discussed. The results show that the aerodynamic interferences among different parts of an extensional large roof are very fierce and complex, which may increase the wind loads on the whole structure, so the displacement not only on the cantilever edge of the roof but also in the middle parts of the roof are needed to be paid attention when the structure is designed. The static part of the total wind-induced responses are dominant, however the resonant responses are usually bigger than the background responses in the part of dynamic responses. All the conclusions can provide some useful references for the design of an “extensional” large roof structurally similar to Terminal T3 of Shenzhen airport.
2011 Vol. 30 (7): 148-152, [Abstract] ( 968 ) HTML (0 KB)  PDF (2550 KB)  ( 361 )
153 Stochastic Model and Algorithm of Floating Raft with Elastic Limiters
Wen Jian-ming;Feng Qi
DOI:
In this paper, for the floating raft with elastic limiters, using the unilateral kinetics equations, the deterministic model is established through adding the contact force. Supposing the external force of system is effected by the white noise. It is necessary to establish the random dynamical model for the system. Considering the universality of the noise, based on the random vibration theories a stochastic non-smooth model of the floating raft with elastic limiters is built up and the discrete computing formats are derived. There are many limiters in the floating raft system. So, it is difficult to determine the contact configurations of limiters. The artificial neural network can be used to dingtinguish the contact state of elastic limiters. The random responses of the floating raft have been analyzed by example. It is obtained that the effect of vibration by noise and the relations between the displacement variance and the gap of limiters.
2011 Vol. 30 (7): 153-156 [Abstract] ( 1132 ) HTML (0 KB)  PDF (1149 KB)  ( 343 )
157 A multi-mesh modeling method for nonlinear dynamic analysis of super-large-scale tunnel structure using FEM
Weng Yi-liu;Xianlong Jin;Yun Gu; Yang Zhi-hao
DOI:
This paper proposes a multi-mesh modeling method for nonlinear dynamic analysis of super-large-scale tunnel structure using FEM, compensating the incompetence of the traditional modeling techniques. Adopting parallel computing algorithm and making effective control of the time step, the simulation for the large-scale multi-mesh model can be done on super computers. The modeling and simulation of the Qing Cao Sha Raw Water Tunnel Project is a good example of how this modeling method can be utilized practically and effectively. The result of simulation shows a combination of overall and part detailed response of the tunnel lining, thus proving the feasibility of this modeling method.
2011 Vol. 30 (7): 157-163 [Abstract] ( 1633 ) HTML (0 KB)  PDF (2125 KB)  ( 491 )
164 Nonlinear dynamics behavior of Fractional-order Ver Del Pol-Duffing system
LI Yuan-ping;;ZHANG Wei
DOI:
A fractional differential Ver Del Pol-Duffing system，in which fractional derivative model introduced to simulate system’s damping characteristics，is proposed. The numerical computation scheme of fractional derivative is deducted. The dynamic characteristics influenced by the characteristic parameters under different external load are investigated. The results show that: this nonlinear system has the same self-excited vibration characteristics as the classic Ver Del Pol system, the q-order derivative has a large impact upon the system dynamics,namely in the period of the output oscillation. On the other hand, and as expected, the higher the value of damping coefficient and the nonlinear displacement coefficient the more nonlinear the system becomes. Under harmonic load, as the increase of amplitude or decrease of damping coefficient, the system should undergo quasi periodic motions to period-three vibration until to single period vibration. Under seismic load, the q-order derivative has a large impact upon the output energy.
2011 Vol. 30 (7): 164-168 [Abstract] ( 1546 ) HTML (0 KB)  PDF (2808 KB)  ( 475 )
169 Dynamic analysis of multi wire saw machine tool
FENG Yan-bo; SUN Tao
DOI:
Multi wire saw is a new force in semiconductor wafer processing industry, and becomes the most advanced processing method in silicon slicing with unique advantages. The dynamic performance of machine structure directly relates to the quality of material processing. To ensure the stability of machine tool operation, dynamic performance of machine tool entity was studied and research rationality of mechanical structures. Establish the three-dimensional machine body structure model. Apply finite element method to solve modal based on ANSYS software, natural frequency and mode shapes were calculated. Analyze vibration characteristics of mechanical systems by using dynamics analysis software ADAMS. Frequency responses of key components were obtained in machine tool. Make theoretical judgment on correctness of the mechanism design, and pointed out the direction for further improvement. The results benefit of improving the design of multi wire saw and improving the slicing quality.
2011 Vol. 30 (7): 169-172 [Abstract] ( 1836 ) HTML (0 KB)  PDF (1867 KB)  ( 462 )
173 Analysis on seismic responses of large crossing transmission tower-line system
Deng Hong-zhou;SI Rui-juan;DENG Ling-jun
DOI:
Under the background of the project of 500kV Rongjiang large crossing transmission lines in Shantou, Guangdong province, According to spatial finite element modal of the system, the frequent seismic responses were discussed by using mode-decomposition method and time-history analysis method respectively. Dynamic characteristics were summarized and comparisons of the results of the two methods were conducted. Moreover, contrastive analysis was carried out on earthquake internal forces and design critical forces of the key members. It is found that frequencies values of single tower is larger than that of the tower in the system while they are close to each other, responses of the system are smaller than that of single tower, the lines is benefit for the tower when considering earthquake action and seismic effects are not critical factor for the design. However, tensile members in crossarm and K bracing under the second slope are weak sections, the ratio of whose seismic forces and critical forces approximately is 90%. So, it is very necessary to consider earthquake actions for tensile members in crossarm and bracing members on tower body in large crossing transmission tower’ designs.
2011 Vol. 30 (7): 173-177 [Abstract] ( 1776 ) HTML (0 KB)  PDF (1443 KB)  ( 569 )
178 Developments of Multibody System Dynamics
RONG Bao;RUI Xiao-ting;Wang Guo-ping;YANG Fu-feng
DOI:
Multibody system dynamics is an important branch in the field of the modern mechanics. It provides a
strong tool for dynamic performance estimation and optimizing design of many mechanical systems in a lot of important
engineering fields, such as, weapon, aeronautics, astronautics, vehicle, robot, precision machinery, and so on. The study
on dynamic modeling, design and control of complex multibody systems is the urgent demand of modern engineering
problems. The studies on the dynamic modeling methods, computational strategies, control design, software
exploitations, and experiments of multibody systems in recently years are reviewed. The future directions of this field are
indicated.
2011 Vol. 30 (7): 178-187 [Abstract] ( 1694 ) HTML (0 KB)  PDF (856 KB)  ( 2532 )
188 Derivation the Frequency Equation of Sandwich Transducer With Complex Transformer
QIN Lei; WANG li-kun; TANG hui-yan;SUN Bai-sheng
DOI:
A kind of middle-frequency transducer with great direction is proposed and designed. It is a sandwich transducer with complex transformer. Base on the electro-mechanical equivalent circuit theory, the model of sandwich transducer has been build, and the frequency equation is deduced. Considering the influence of the latten electrodes on the density and the equivalent sound velocity, a modification of this equation is given out using the equivalent parameter theory. Transducers are prepared to validate this modification, the error between the calculation and the experimental results reduces from 2.09% (before modification) to 0.64% (after modification).
2011 Vol. 30 (7): 188-191 [Abstract] ( 1181 ) HTML (0 KB)  PDF (1190 KB)  ( 424 )
192 Study of Real-time Interactive Dynamics Simulation for Lunar Rover based on Terramechanics
WANG Zhe; GAO Feng; CHEN Zhiwei; SUN Peng
DOI:
Traction capability experiments of driving wheel were performed by using the wheel-terrain interaction test-bed. From the test data, the paper deduced an improved bulldozing resistance formula which was based on slip ratio of wheel. Meanwhile, according to the formula and terramechanics theories of soft soil, the lunar rover dynamic simulation was built and performed in the Visual C++9.0 platform by using Vortex API. By comparing simulation results and experiments results of the single driving wheel, it was show that the formula and the dynamic simulation are reliable. In this platform model of the whole lunar rover was also set up and the real-time interactive control are realizable through keyboard and mouse.
2011 Vol. 30 (7): 192-196, [Abstract] ( 1115 ) HTML (0 KB)  PDF (2007 KB)  ( 401 )
197 The threshold for wavelet de-noising based on multiple hypothesis test
Du Wen-liao; Liu Cheng-liang;Li Yan-ming
DOI:
Threshold de-noising method based on the wavelet transform is an effective approach to reduce the white noise in the digit signal. Considering the different characters of signal and white noise in the wavelet domain, a novel algorithm to determine the wavelet threshold is proposed with the multiple hypothesis test. Since the wavelet de-noising transform process can be regarded as a multiple hypothesis process and both the step-up and step-down procedure can control the FDR, the new method FDR step-up-down procedure combining the above-mentioned procedures determines the wavelet threshold. An attractive advantage of this method is it can obtain the desired result by adjusting the FDR level flexibly. The simulated numerical results show that this method works as effective as hearsure method and gives better SNR gains and MSE performance than both the traditional BH FDR and sqtwolog method. The selection of the significance level is also discussed, and point out that the relationship between the significant level and the improvement of the signal to noise ratio is nonlinear, then the tactic of selecting the proper significant level is proposed.
2011 Vol. 30 (7): 197-200 [Abstract] ( 1700 ) HTML (0 KB)  PDF (1462 KB)  ( 403 )
201 The Detection of Multi-hole Damages in Structures Based on Genetic Algorithms and Topology Optimization
Li xiao-ping;Zheng shi-jie
DOI:
In view of the respective advantages of the genetic and topology optimization in structural damages identification , a new method of multiple damages identification in two-dimensional structure is established by combining genetic algorithm, finite element method and topology optimization. The objective function and constraint equations of topology optimization are linked with the fitness function of GA; the design variables of topology optimization and parameters of genetic algorithm were unified; and while the constraint equations of topology optimization were set as a condition to control the whole genetic computing loop. Instead of using continuous variables topology optimization, binary-coded genetic algorithm is used in multi-damage identification of two-dimensional structure with the hole damages to avoid the possible negative impaction which is brought by the threshold parameter determination in using continuous variables topology optimization. The results of two models simulation examples show that this method is feasible in two-dimensional structure damages detection, the good agreements with the actual situation can also obtained which is difficult to get by using continuous variable topology optimization method.
2011 Vol. 30 (7): 201-204 [Abstract] ( 825 ) HTML (0 KB)  PDF (1095 KB)  ( 852 )
205 EXPERIMENTAL RESEARCH OF DYNAMIC MECHANICAL BEHAVIORS OF EPS CONCRETE
HU Jun;WU Xu-tao;HU Shi-sheng
DOI:
A split Hopkinson pressure bar(SHPB) was employed to study the dynamic characterteristics of EPS concrete for different size and containing of EPS beads . The results show that the characterteristics of EPS concrete is sensitive to strain rate under the loading conditions in this study.The stress-strain relationship of EPS concrete exhibited three different regions: linear-elasticity deformation due to bending of the cell walls；the plateau stress as result of plastic buckling of the cell walls and plastic collapse of the cells；and this behavior was gradually vanished as strain rates increased. The plasic characterteristics of small EPS bead sizes concrete for the same EPS volume fraction is more evident,in this study,the physical origin is identified for this phenomenon. the particle size effect becomes negligible for very high EPS volume fraction concretes. the post “peak-stress’’ behavior of EPS concretes is very evident with the increasing of strain-rate in that the EPS particle viscoelatic behavior.
2011 Vol. 30 (7): 205-209 [Abstract] ( 1221 ) HTML (0 KB)  PDF (1768 KB)  ( 797 )
210 Influence of Pipe Parameters on Fluid-structure Coupling Vibration of Fluid-conveying Pipe
YANG Chao;FAN Shi-juan
DOI:

Numerical calculation on fluid-structure coupling vibration responses of a reservoir-pipe-valve (RPV) system was carried out by the method of characteristics (MOC), the influences of pipe structure-damping, pipe Poisson’s Ratio and pipe wall thickness on vibration responses of the RPV system were studied. The numerical results show that the axial vibration energy of pipe wall is weakened with the increase of pipe wall damping, when pipe wall damping is greater a certain value, the vibration energy of the system mostly concentrates on fluid which enhances fluid pressure energy; pressure energy of fluid is enhanced meanwhile the axial vibration energy of pipe wall is weakened with the increase of pipe wall Poisson’s Ratio or pipe wall thickness.
2011 Vol. 30 (7): 210-213 [Abstract] ( 794 ) HTML (0 KB)  PDF (1354 KB)  ( 759 )
214 Applied Research on the Oblique Impact Theory of Detonation Waves at the Explosive-Metal Interface in Design of Shaped Charge
ZHANG Yang-yi; LONG Yuan; HE Yang-yang; JI Chong; XIE Quan-min
DOI:
The oblique impact theory of detonation waves at the explosive-metal was applied in design of shaped charge. Relationship between the pressure peak P in the interface of copper and incident angle φ0 was got by using LS-DYNA. The numerical simulation results coincided well with the theoretical calculation results and experimental datum. An engineering method to calculate the proper liner height of tapered and spherical shaped liner was established under the condition of one-point detonation, which was applied in the design of a grouped liner warhead. The calculation and analysis method above supple a design to define liner height, which can enrich the design method of shaped charge warhead.
2011 Vol. 30 (7): 214-217, [Abstract] ( 1130 ) HTML (0 KB)  PDF (1153 KB)  ( 772 )
218 Strain and Energy Ratio Based Damage Model of Steel Structures
XU Longhe;YANG Dongling;LI Zhongxian
DOI:
Damage model is an important tool to evaluate quantitatively residual strength of a structure after seismic excitations. From the point of view material, a damage model based on equivalent plastic strain and energy ratio is proposed in this paper, which considers structural behavior under triaxial stress, and it can be used to do the nonlinear analysis of 3-D structures under earthquakes. A nine-story benchmark model structure is built and the damage model is used to evaluate the collapse process of steel frame quantitatively, the results indicate that this damage model can evaluate the process of damage of vertical members and structure effectively.
2011 Vol. 30 (7): 218-222 [Abstract] ( 885 ) HTML (0 KB)  PDF (1749 KB)  ( 914 )
223 Research on Integration of GPS and Accelerometerfor High Building Vibration Monitoring
DAI Wujiao;WU Xi-xiu; LUO Fei-xue
DOI:
GPS-RTK offers direct three-dimensional coordinates measurements for structural health monitoring, but the measurements accuracy and reliability can not meet high building vibration monitoring requirements for multipath influence, cycle slip, low sampling rate and other factors. On the other hand, accelerometer offers precise, high sampling rate acceleration observations in structural vibration monitoring. Aiming at making full use of the two kinds of sensors, a Kalman filtering method with the integration of GPS and accelerometer is researched, which is of multi-rate filtering and robust features. The experimental results show that: this method can effectively improve the accuracy, reliability and sampling rate of high building vibration monitoring.
2011 Vol. 30 (7): 223-226, [Abstract] ( 1602 ) HTML (0 KB)  PDF (1536 KB)  ( 741 )
227 Influence of cast-in-place floor slab on damage style of frame structures under earthquake action
Yan Hong-xia; Yang Qing-shan
DOI:
Many reinforced concrete frame structures were severely damaged or even collapsed during the May 12, 2008 great Wenchuan earthquake. Based on survey data collected in Dujiangyan, it was found that column end, instead of beam end, appeared plastic hinges in many frame structures. This did not accord with “strong column-weak beam” seismic design criterion. It is believed one of the main reasons is insufficient understanding about the cast-in-site floor slab effect on frame structures. Applying finite software ABAQUS, 3D elastic-plastic time history simulation of a “strong beam -weak column” RC frame structure in Dujiangyan is analyzed to probe the influence of cast-in-slab on frame seismic performance from structural view. Results show that RC frame designed following current codes usually can not achieve “strong column-weak beam” yield mechanism. The numerical results suggest the rebar in the width of six times of the plate thickness may be taken into account in calculating the bearing capacity of negative moment at the beam end; the model of frame with floor slab should be applied in analyzing the deflection under rare big earthquakes.
2011 Vol. 30 (7): 227-232 [Abstract] ( 1723 ) HTML (0 KB)  PDF (2621 KB)  ( 711 )
233 Based on Transfer Loss Robust Design of Vehicle Intake System
YUE Gui-ping;ZHANG Yi-min
DOI:
The acoustic robust design of intake system is precondition to ensure vehicle inner acoustics index robustness. Firstly, based on acoustic theory, acoustic uncoupling of acoustic parts of intake system was completed; secondly, with groundwork of acoustic robust optimization of single acoustic part of intake system, based on transfer loss unitary parameters of whole intake system was educed; finally, associated with importance index of acoustic parts of intake system, based on transfer loss acoustic robust optimization of whole intake system was carried through. Through acoustic robust design of intake system, the information of integrative robust design of acoustic parts of intake system was rapidly and accurately obtained. Thus, based on transfer loss acoustic robust design can provide quantificational basis for the structure design of vehicle’s engine intake system, which is of great practical engineering significance.
2011 Vol. 30 (7): 233-236 [Abstract] ( 796 ) HTML (0 KB)  PDF (921 KB)  ( 366 )
237 Analysis on Aero Engine Rotor-case Vibration Signal Based on EMD and HHT
XU Ke-jun;QIN Hai-qin;JIANG Long-ping
DOI:
Based on the introduction of EMD and HHT theory, they were applied to the field of aero engine rotor-case vibration signal analysis. Then, the vibration signals from an aero engine when it is in bench tests were analyzed. The results reveal that the method can more clearly reappear to the process of rubbing between rotor and stator with change of rotate speed and sampling period. It can obtain the rubbing information between time and frequency domain overcoming the shortcoming of Fourier translation which can only display the information in frequency domain. It also shows that marginal spectrum can display the distribution of system’s frequency and amplitude more objectively.
2011 Vol. 30 (7): 237-240 [Abstract] ( 1848 ) HTML (0 KB)  PDF (1849 KB)  ( 829 )
241 Research on model identification method forelectrodynamic vibration shaker and its application
GUO Ji-feng; REN Wan-bin; KANG Yun-zhi; ZHAI Guo-fu
DOI:
Electrodynamic vibration shaker is the key equipment in vibration and shock environmental experiment, and model identification and estimation for the shaker are the necessary procedure for developing the research on vibration control technology and simulation technology. Basing the dynamic and electrical coupling model of electrodynamic vibration shaker, the system identification and parameter estimation method which taken the shock signal as motivation is proposed. The regulated shock waveform was achieved by using calculated model parameters accurately. The results showed the validity and feasibility of the model identification method by comparisons simulation results with experimental results.
2011 Vol. 30 (7): 241-244 [Abstract] ( 1660 ) HTML (0 KB)  PDF (1863 KB)  ( 1062 )
245 NATURAL FREQUENCY SIMULATION OF AXIALLY MOVING TIMOSHENKO BEAMS WITH HYBRID BOUNDARY
Hu Chao-rong; Ding Hu; Chen Li-qun;
DOI:
The differential quadrature method is developed to solve natural frequency of axially moving asymmetric hybrid supports Timoshenko beams, which have randomly-variable spring index at both sides. The weighting coefficient matrices to implement are modified for solving the hybrid boundary. The axially moving speed, the stiffness of the beam and the constraint stiffness are numerically investigated for the influence of the first two orders of the natural frequency, and the results are compared with the conclusion of semi-analytical and semi-numerical. The results show that the numerical results with the semi-analytical and semi-numerical results are basically consistent.
2011 Vol. 30 (7): 245-249 [Abstract] ( 1190 ) HTML (0 KB)  PDF (1279 KB)  ( 354 )
250 Modal Analysis and Experimental Research for Heavy Load Deflection Angle Milling Head
CAI Li-gang;MA Shi-ming;ZHAO Yong-sheng;LIU Zhi-feng;GUO Tie-neng
DOI:
The heavy load deflection angle milling head is an important functional component of 5-axis linkage CNC machine tool, which is used for processing large and complex free-form surface. The characteristics of this kind of milling head are implementing multiple degrees of freedom motion with revolution and deflection angle simultaneously, owning compact structure, heavy load and high stiffness. Mastering the relationship between modal characteristics of milling head and its influence factors is a pre-requisite solving problem for the development and research of heavy load deflection angle milling head independently. Therefore, an integrated research method which combines experiment validation and theoretical analysis with many constraint styles is introduced. In theoretical analysis aspect, modal analysis and comparison of milling head with appending and practical working state two constraint styles are carried through, which validate the correctness of theoretical analysis of the two constraint styles. In experimental research aspect, modal experimental research is carried through with free support for box, and initial fixing for the whole milling head. Experimental and theoretical analysis results are compared and analyzed. Therefore, exact modal characteristics of milling head and unsubstantial segments and its influence factors are gotten, which provide theoretical and experimental support for structure optimization and improving of heavy load deflection angle milling head.
2011 Vol. 30 (7): 250-255 [Abstract] ( 1975 ) HTML (0 KB)  PDF (1893 KB)  ( 601 )
256 Cable Force Detection Based on Variable Sensitivity Analysis
Chen Yan-jiang; Cheng Jian-qi; Yan Wei-ming; He Hao-xiang; Li Yong
DOI:
Taking into account the new construction technique and complex anchorage, The proposed method takes the tension force, flexural rigidity and length as unknown parameters, analyzes the sensitivity of parameters to natural frequencies. The algorithm based on sensitivity-updating is able to simultaneously identify the tension force, flexural rigidity and length. Next, the method is applied to four different hanger rods system, and it is approved that the proposed method not only has high accuracy, but also be applicable to the rods with high bending stiffness. At last, a testing on a CFST tied arch bridge proved the method is field applicable.
2011 Vol. 30 (7): 256-260 [Abstract] ( 1720 ) HTML (0 KB)  PDF (1527 KB)  ( 652 )
261 Bouc_Wen Model Parameter Identification for a MR damper based on Genetic Algorithm
LIU Yong-qiang; YANG Shao-pu; LIAO Ying-ying; Zhang Geng-ning
DOI:
How to identify parameters of Bouc_Wen model without any prior knowledge except for experimental data is a vital problem to be solved. A Bouc_Wen dynamic model of magnetorheological(MR) dampers is considered and its parameters are obtained by using genetic algorithm(GA) based on the mechanical characteristic experiment of a MR damper. Identification precision of GA is improved gradually by shrinking linear range of these parameters. Functional relationship between some parameters and applied current is determined using curve fitting through analyzing their characteristic curves. The specific function expressions are got by using GA . At last, the identification results and curve fitting results are verified with experiment data in different amplitude and frequency. The results shown that identification results of Bouc_Wen model which identification precision is improved by shrinking parameters range are close to global optimum values, and the model identified can meet need.
2011 Vol. 30 (7): 261-265 [Abstract] ( 1347 ) HTML (0 KB)  PDF (1833 KB)  ( 1425 )
266 EXPERIMENTAL MODAL ANALYSIS OF A HEAVY DUTY MARINE GEARBOX
XU Xiang-yang;ZHU Cai-chao;Zhang Xiao-rong;WANG Wen-lin;CHEN Hu-yi
DOI:
Due to the special working conditions of the heavy duty marine gearbox, its performance requirements are far higher than the other gearbox. Structure and transmission principle of a heavy duty marine gearbox were analyzed. According to the basic principles and methods of experimental modal analysis, frequency response function was optimized by least square method，modal parameter of heavy duty marine gearbox was identified using single-mode identification method, and the top 20 rank natural frequency and damping ratio were obtained. Results showed that the rotational frequency and meshing frequency of marine gearbox system were away from natural frequency of gearbox. Resonance of the system would not occurred. However, considering complicated speed variation of the gearbox in the actual work, intense resonance of the system would occur when the speed reached the critical speed. Test results can provide an analysis basis for further study of dynamic characteristics.
2011 Vol. 30 (7): 266-270 [Abstract] ( 1741 ) HTML (0 KB)  PDF (1916 KB)  ( 658 )
271 Optimization and Research on High Overload Ability of MEMS High-g Accelerometer
Shi Yun-bo;Li Ping;Zhu Zheng-qiang;Liu Jun;Wang Rui-rong
DOI:
The structure is easy to destroy if the designed MEMS high-g acceleration sensor has less-overload ability, when it is applied to the harsh impact environment. The paper analyzes the sensor structure on the impact of anti-overload capacity and the statistic of structural damage of the sensor in high impact testing, a new method is put forward, which can optimize the overload-resistant ability of the high-g acceleration sensor. The method is to add the chamfer in the root of beam which is the most fractured part，in order to disperse the stress of these areas. When the impact load takes effect on the sensor structure, it can increase the high-overload-resistant ability of the acceleration sensor.The method can be tested feasibitily from theoretical simulation. Then the sensors are tested by Hopkinson bar test method. The test result indicates that the high-overload-resistant capacity of the accelerometer can be increased from 180,000g to 240,000g, which shows the optimization method is obvious, and apparently enhances the high-overload-resistant ability of such kind of acceleration sensor. The designed acceleration sensor comes up to a more ideal high-overload ability.
2011 Vol. 30 (7): 271-274 [Abstract] ( 2057 ) HTML (0 KB)  PDF (1501 KB)  ( 1505 )
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