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  • Zhao-qing CHEN, Peng-fei SONG, Ke-ye YAN, Yue WU, Ning SU, Cong ZENG
    Journal of Vibration Engineering. 2024, 37(1): 31-39.

    Aero-elastic model wind tunnel test is carried out for a 1/3 rise-span ratio capsule-shaped pneumatic membrane structure,the characteristics of the wind-induced aero-elastic response of the structure are studied and the wind-induced dynamic vibration coefficients for practical design reference are given. The research confirms that the averaged deformation of the structure shows a trend of windward depression,top uplift and outward bulge in the transverse direction. This deformation trend is increasingly obvious with the decrement of internal pressure and the increment of wind speed. The averaged deformation and vibration amplitude decrease when the wind direction ranges from 0° up to 45°,then to 90°,and the extreme value of structural mean total displacements tends to appear at the center points of windward surface and top surface. Under 0° and 45° wind directions,the sort of vibration amplitudes of different components is vertical component,along-wind component and cross-wind component in descending order. Moreover,the structural vibration is dominated by the first-order mode. Under 90° wind direction,the amplitude of the crosswind direction is greater than two other directions,and the wind-induced vibration is dominated by the superposition of the first and second order modes. The internal pressure of the structure decreases in different extents under all cases. The response-based wind-induced dynamic vibration coefficients considering the fluid-structure interaction effect are given.

  • Lin HUANG, Jia-hui DONG, Qi WANG, Hai-li LIAO, Zhi-guo LI
    Journal of Vibration Engineering. 2024, 37(1): 40-51.

    The II-shaped composite girder is widely used in the construction of long-span cable-stayed bridges,but the weak vortex-induced vibration (VIV) performance of this type of section seriously limits its application prospects. A II-shaped composite girder double-tower cable-stayed bridge with a main span of 530 m is used as the engineering background,and the VIV performance and aerodynamic optimization measures of the II-shaped composite girder are studied by using wind tunnel tests. The tests show that the VIV of the original II-shaped section occurs at each wind attack angle,and the VIV amplitude of the girder can be reduced by setting guide vanes and the lower central stabilizer. The change in the inclination angle of guide vanes has a significant impact on the combined aerodynamic measure of VIV suppression performance. The combination measure VIV suppression performance with the guide vane of 30° inclination angle is the best,and the VIV can be significantly suppressed or even eliminated when the damping ratio required by the specification is 1.0%. The VIV suppression mechanism of the combined aerodynamic measure and the influence mechanism of the guide vane inclination angle change on the VIV suppression performance of the measure are studied by using computational fluid dynamics (CFD) numerical simulation. The calculation results show that the windward side guide vane in the 30° inclination guide vane combination measure can significantly improve the gas flow around the upstream section,and the cooperation with the lower central stabilizer can weaken the Karman vortex of the II-shaped section wake toy suppress the girder VIV. Changing the inclination angle of the guide vane not only affects the generation of vortices near the guide vane itself,but also affects the improvement of the lower central stabilizer on the vortex shedding state under the section,thereby significantly affecting the VIV suppression performance of the combined aerodynamic measure.

  • Jian-xiao MAO, Gui GUI, Hao WANG, Chao-yong YANG
    Journal of Vibration Engineering. 2024, 37(1): 52-59.

    To enrich the measured database of the modal parameters of the long-span cable-stayed bridge,based on the data collected by the structural health monitoring system of the Sutong Bridge,the modal parameters of the bridge during 2010 are obtained using the established automated modal identification and tracking method. On that basis,the variability of the modal parameters of the bridge with the changing temperature and wind speed is analyzed. Results show that the frequency of the bridge is controlled by both temperature and wind speed. The frequency decreases with the increased temperature and increases with the increased wind speed. The variability of the damping ratio of the main girder of the bridge is significantly greater than that of the frequency. The damping ratio of the first-order lateral bending modes of the main girder fluctuates between 0.5% and 15% at low wind speed interval. It gradually decreases and stabilizes at about 2% when the wind speed is greater than 9 m/s. The damping ratio of the first four vertical bending modes of the bridge is mainly affected by the aerodynamic damping. It increases slightly with the increase of wind speed at the low wind speed intervals. The obtained results can provide a reference for assessing the in-service performance and issuing operational management of the bridge.

  • Yan-wei HAN, Ming-liang SHEN, Meng-yuan GAO, Zi-jian ZHANG
    Journal of Vibration Engineering. 2024, 37(1): 60-70.

    In order to solve the problem of complex nonlinear vibration response in the traveling vehicle system,a nonlinear dynamical model for a coupled human-vehicle-road system with three-degree-of-freedom is established. The coupled vibration equations of human-vehicle-road with three-degree-of-freedom are derived by the Lagrange equation,and the sine and cosine functions of this system arise from the geometric nonlinearity of torsional deformation. The nonlinear restoring force surfaces,potential energy surfaces and analytical expressions of natural frequency are obtained for the free vibration of the human-vehicle-road system. For the forced vibration,the influence of vehicle system parameters of vehicle mass,moment of inertia,passenger mass,seat stiffness,suspension stiffness,damping,centroid position,road wavelength and wave amplitude on the response curves of amplitude velocity is analyzed by using the numerical simulation method. The experimental platform of the coupled human-vehicle-road vibration system is built and the reliability of theoretical analysis and numerical results is verified by the experiments. The results show that this nonlinear dynamical coupled system with three degree-of-freedom can accurately describe the human-vehicle-road response characteristics,and reasonable selection of the system parameters can effectively reduce the vibration response amplitude and improve the human riding comfort.

  • Peng-cheng LI, Hai-cheng ZHANG, Hua-qing JIN, Ren-gui BI, Dao-lin XU, Lei-lei LIU, Xin-yu WANG, Yu-chao CHEN
    Journal of Vibration Engineering. 2024, 37(1): 71-82.

    The constant erosion of ocean waves seriously affects the safe operation and service performance of ocean engineering equipment,and ocean wave energy is a green renewable energy with many advantages. How to reduce the wave load and utilize the ocean wave energy through the hybrid wave attenuation and energy harvesting structure is one of basic scientific problems in the field of ocean engineering. The traditional wave attenuation and energy harvesting structure,especially the floating structures in the deep sea,has the technical bottleneck of wave attenuation and energy harvesting at a low frequency range. In this paper,based on the idea of reducing the equivalent dynamic stiffness of the system,a nonlinear hybrid wave attenuation and energy harvesting structure is proposed,and the characteristics are studied. A new type of negative stiffness mechanism is designed and applied to hybrid wave attenuation and energy harvesting structure. In order to solve the fluid-structure interaction problem of nonlinear hybrid wave attenuation and energy harvesting structure,a semi-analytical nonlinear frequency domain method of hybrid eigenfunction expansion matching method and multi-harmonic balance method is proposed. The influence of the key parameters of the mechanism on the wave attenuation and energy harvesting performance is studied,and the “phase control” mechanism of the negative stiffness mechanism to improve the low frequency wave attenuation and energy harvesting performance is revealed.

  • Gang-hui XU, Chang-sheng ZHU
    Journal of Vibration Engineering. 2024, 37(1): 83-94.

    Considering the simply-supported cylindrical shells,the modal participation in dynamic responses is studied by considering the influence of sine and cosine modes,and a method for determining the order of modal truncation according to the distribution characteristics of modal participation factors is proposed. The dynamic responses of cylindrical shells under the impact excitation and rotating traveling wave excitation are obtained by the superposition of the sine and cosine modes,and the reliability of the determination method is verified by the convergence of responses. The results of theoretical calculations and finite element simulations show that the influence of sine and cosine modes must be considered simultaneously in calculation of the dynamic responses for cylindrical shells,which is different from the case of modal characteristics analysis. When cylindrical shells are subjected to impact excitation,the participation degree of each order sine and cosine modes is related to the location of the excitation point and observation point. When cylindrical shells are subjected to rotating traveling wave excitation,the participation degree of each order sine and cosine modes is closely related to the order and frequency of the excitation.

  • Shi-yu WANG, Dong WANG
    Journal of Vibration Engineering. 2024, 37(1): 95-103.

    The robust dynamic topology optimization of a continuum planar structure is studied to reduce its natural frequency variation when the structural material parameter uncertainties are considered. The uncertainties of the material properties are represented with the uncertain-but-bounded interval variables based on the non-probabilistic convex model. The dynamic topology optimization model for maximizing the first natural frequency is constituted by mitigating its variation,such that the robust optimization problem can be simply solved into a single-level framework. By the derivative analysis of the material parameters,a quadratic Taylor series expansion of the first natural frequency is obtained,and the design sensitivity of the natural frequency is accordingly evaluated in an explicit form under the uncertain material properties. By means of the material density-based strategy,the robust dynamic topology optimization is implemented with the material volume constraint,and the results are compared with those of the deterministic topology optimization. Optimal results show that the first-order natural frequency obtained with the proposed method has a higher robustness against the material property uncertainties,which fully demonstrates the importance of considering the uncertainties of the material parameters in the structural design stage.

  • Fei ZHANG, Yuan ZHENG, Yi-feng ZHAO, Kang-sheng WANG
    Journal of Vibration Engineering. 2024, 37(1): 104-112.

    The construction of a new power system requires to improve the response time of pumped storage units. In this paper,taking a specific pumped-storage unit as an example,systematical research is performed on the main differences of sequence control process and the variation law of unit stability parameters under normal and fast pumping to generating mode. Based on that,the inverse-time vibration evaluation method is introduced to evaluate the impact of transition modes on the unit vibration peak-to-peak values. By analyzing the pressure fluctuation in the vaneless zone with the frequency spectrum analysis method,the phenomenon of hydraulic resonance in the vaneless region at low speed is found in generating rotation,and the correlation between resonance amplitude,frequency and speed is revealed. The research indicates that the mode transition from pumping to generate the fast transition is better than the normal transition. Compared with the braking method of electrical brake plus mechanical brake in normal transition,the hydraulic braking mode under fast transition can significantly shorten the transition time from 438 s to 220 s. From the perspective of vibration damage to the unit,13 of the 14 vibration and runout monitoring points prove that fast transition is conducive to prolong the expected life of the unit. Meanwhile,the fast transition is favorable to pass the hydraulic resonance occurring in vaneless zone at low speed. The hydraulic resonance time is reduced from 15 s in normal transition to 5 s in the fast transition,and the resonance speed range is compressed by more than 60%.

  • Rong-liang YANG, Sen WANG, Xing WU, Xiao-qin LIU, Tao LIU
    Journal of Vibration Engineering. 2024, 37(1): 113-125.

    Aiming at the problem that the current traditional vibration sensor is limited by the installation and the number of measuring points when measuring the displacement of the rotating body,this paper uses a high-speed industrial camera as the acquisition medium,and collects the rotor vibration video on the rotor vibration test bench. The visual vibration measurement method tracks the full-field vibration displacement of multiple rotor targets. The feature pyramid network structure is introduced into the residual neural network,and the improved feature extraction backbone network is established by combining the attention mechanism. The identity re-identification method is used to strengthen the correlation of target displacement between adjacent frames,and to track the full-field vibration displacement signals of the rotator. Qualitative and quantitative comparisons of different network models on the rotor vibration displacement measurement dataset show that the network model proposed in this paper can obtain a tighter fit when the bounding box is regressed. The collected eddy current displacement signal is used as the standard value to compare the two rotor displacement signals,and the experimental results show that the waveform and spectral noise fitted by the multi-target tracking algorithm in this paper is the smallest and can match the eddy current signal. The experiments also prove the generalization performance of the algorithm in this paper,which reflects the engineering application value of visual measurement in the field of vibration displacement tracking of rotating bodies.

  • Jie YANG, Yi-fei REN, Wen-fu HE, Hao XU
    Journal of Vibration Engineering. 2024, 37(1): 126-136.

    The determination of the rocking state for an isolation structure is a fundamental issue to estimate the safety of the isolated layer under a seismic excitation. In this study,by using the tensile deformations at the vertical direction of the rubber support in the isolated layer,the rocking states of the isolation structure are divided into ones with unuplifting,uplifting,and rocking. A classification method is then proposed for estimating the rocking state of the high-rise structure with isolated layer. Inspired by the influences of the aspect ratio (AR),vertical yield-weight ratio (αv),horizontal yield-weight ratio (αh),vertical cycle (Tv),horizontal cycle (Th),system damping ratio(η) to the swing response of isolation structures under seismic excitation,boundary spectrum of isolation structures is achieved. It shows that swing response decreases with the increase of αv,Th and η (the effect of Th is most significant),which is beneficial to the control of the sway response as well; swing response increases with the increase of AR and Tv (the effect of Tv is most significant),which is not conducive to the control of swing response,and the most advantageous measure to control the swing response is increasing Th,decreasing Tv.