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2024 Vol. 43, No. 10 Published: 2024-05-28 1 Vortex-induced vibration characteristics and mechanisms of portal steel bridge tower LEI Wei1,2，WANG Qi1,2，LIAO Haili1,2，LI Zhiguo1,2 The steel bridge tower is one kind of tall and slender structure which is highly sensitive to wind loads and prone to vortex-induced vibrations (VIVs). To investigate the VIV characteristics of a 217-meter-high steel bridge tower, 1:100 scale free-standing aeroelastic model wind tunnel tests were conducted. The experimental results show that in-phase VIVs occur in the low wind speed ranges, and out-of-phase VIVs occur in the high wind speed ranges at the wind directions range of 0° - 30°. The most unfavorable wind directions of in-phase and out-of-phase VIVs are 0° and 10°, respectively. In-phase along-wind displacement and out-of-phase torsion angle are 609.5 mm and 4.3°, respectively. Furthermore, the VIV triggering mechanisms were studied by computational fluid dynamics (CFD). The numerical simulation results show that the frequency of alternating vortex shedding near the two tower columns is close to the fundamental natural frequency, and the periodic pressure difference generated by this phenomenon leads to in-phase and out-of-phase VIVs. The findings and conclusions of this study provide some reference for the wind-resistant design of similar steel bridge towers. 2024 Vol. 43 (10): 1-8 [Abstract] ( 226 ) HTML (1 KB)  PDF (2272 KB)  ( 139 ) 9 Triple-shear subloading surface models for saturated clayey sand in the nanchang subway HU Xiaorong，LU Xiang，YUAN Hao Taking the triple-shear strength criterion as the failure criterion, the triple-shear failure stress ratio of saturated soil was derived. Considering the dilatancy of sand, the phase transformation stress ratio was modified by introducing dilatancy state parameters. A new yield function was obtained by replacing the fixed failure stress ratio in the modified Cambridge model with the phase transformation stress ratio. Combining the new yield function with the theory of subloading surface model, the triple-shear subloading surface model for saturated clayey sands was proposed. The underground sand and clay in a section of Nanchang Metro were taken as test soil samples. Clay with particle size of less than 0.075mm was added to the sand to make the clayey sands. The compactness of the sample was set to 70%, and the clay contents were set to 0%, 5% and 10%, and the model parameters were determined by relevant geotechnical tests. The results of constitutive model were compared with those of the conventional static triaxial tests and cyclic dynamic triaxial tests. The results of static triaxial test showed that the calculation results of the constitutive model are basically consistent with the experimental results, which indicates the validity of the constitutive model. Under the same conditions, with the increase of clay content, the shear strength of soil increases, the shear shrinkage stage becomes longer, and the dilatancy phenomenon becomes less obvious. The results of dynamic triaxial tests showed that the numerical calculation curves of the constitutive model are in good agreement with the experimental results. In the initial stage of loading, the plastic strain of soil develops rapidly. With the continuous alternations of loading and unloading and the increasing number of cycles, the hysteresis loops become more and more dense. 2024 Vol. 43 (10): 9-20 [Abstract] ( 97 ) HTML (1 KB)  PDF (2650 KB)  ( 114 ) 21 Aero-elastic experiment investigation on the aerodynamic damping of large-span single-layer cable-suspended photovoltaic modules XU Haiwei1，LI Junlong2，HE Xuhui3，DU Hang1，DING Kunyang1，LOU Wenjuan1 The large-span photovoltaic support structure is light and flexible, and is vulnerable to wind-induced aeroelastic effects. In order to study the aerodynamic damping characteristics of this structure, an aeroelastic model wind tunnel test was carried out to a typical large-span flexible photovoltaic support structure with module inclination of 0° and 10° under different wind speeds and pretensions. Based on the aeroelastic test results, empirical wavelet transform (EWT) and variational modal decomposition (VMD) combined with the improved random reduction method (RDT) were used to identify the aerodynamic damping ratio of photovoltaic structure under different wind speeds and directions, module inclinations, and cable pretensions. The study results show that the aerodynamic damping ratio is sensitive to the change of wind direction angle. When the module has an inclination of 10°, the aerodynamic damping of a large-span photovoltaic structure shows a negative value under the windward wind azimuth of 180°. Increase of pretension may lead to decrease of aerodynamic damping ratio of a horizontally installed module under a high wind speed. The aerodynamic damping ratio generally decreases with the increase of wind speed, it basically shows positive values under low wind speeds but may become negative under high wind speeds. Although the aerodynamic damping ratios identified by different methods were not the same, both of them show consistent variation pattern of aerodynamic damping. 2024 Vol. 43 (10): 21-29 [Abstract] ( 97 ) HTML (1 KB)  PDF (1671 KB)  ( 80 ) 30 Rocking properties and overturning risk of a freestanding package excited by longitudinal shock ZHU Dapeng1，CAO Xingxiao2，QI Zhenmin3 In cargo transportation, the large-scale freestanding package may overturn under longitudinal shock condition, this may lead to catastrophic consequences. Therefore, the analysis of overturning risks of freestanding package under longitudinal shock condition is critical to the package transportation safety. In this paper, the 3-parameter piece-wise function based on exponential expression is used to simulate single-lobe bell-shape shock acceleration produced by vehicle braking, the package is modeled by rigid rectangle block, the rocking motion equation of package is formulated. For small width-height ratio package, the rocking motion equation is linearized, the rocking response equation and overturning boundary condition are obtained analytically under β≠pT and β=pT conditions respectively, the analytical results indicate the freestanding package is more prone to overturn in free response phase. For non-slender package, the package rocking motion equation is rewritten in energy representation form, the approximation method for overturning boundary condition estimation is formulated. The numerical simulation results indicate the accuracy of this estimation method is acceptable. 2024 Vol. 43 (10): 30-36 [Abstract] ( 91 ) HTML (1 KB)  PDF (1057 KB)  ( 28 ) 37 Prediction of the fatigue life of acoustic black hole beams under random excitation WEI Caifeng1，DU Weiqi1，QIU Xiaobiao2 From an analytical perspective, a numerical model of acoustic black hole beams under random excitation was established for the cantilever beam structure of acoustic black holes (ABH) with truncated thickness, using random loads and four typical load spectra. Fatigue reliability analysis was conducted. The results indicate that the deviation of feature frequency and the accuracy of displacement PSD prediction are within the acceptable error range for engineering applications. The variation of vibration fatigue life in the ABH region varies with different load spectra, and the safest point is the tip position of the ABH beam. The minimum vibration life of a uniform beam is significantly higher than that of an ABH beam. In addition, it is not that the larger the truncation thickness h_0, the smaller the acoustic black hole radius r_ABH, and the safer the ABH beam. This is also related to the random vibration load spectrum, and different types of load spectra have different effects on the variation of beam vibration fatigue life. 2024 Vol. 43 (10): 37-43 [Abstract] ( 63 ) HTML (1 KB)  PDF (1493 KB)  ( 66 ) 44 Experimental study on the variable phase angle pulsation characteristics and vibration suppression of tandem gear pumps ZHAN Peng1，QIANG Yan1,2，WEI Liejiang1,2，FENG Zhengshun1，LUO Xiaomei3 Aiming at the problems of pressure pulsation and vibration impact in large flow tandem pumps, a vibration reduction and noise reduction approach with variable phase angle for tandem external gear pumps is proposed. The mathematical equations for the instantaneous flow rate and pulsation non-uniformity coefficient of tandem external gear pumps are derived. The instantaneous flow pulsation of tandem external gear pumps with different phase angles is theoretically analyzed, and the variation law of pulsation non-uniformity coefficient when changing phase angle is analyzed. The relationship between flow pulsation and pressure pulsation is derived. For tandem pumps with actual phase differences of 0 ° and 20 °, the double throttle valve is installed at the outlet of the tandem pump to obtain pressure pulsation under different operating conditions. The derived pressure pulsation is consistent with the experimental values. The pressure pulsation is composed of a series of i-th harmonics, with the same frequency as the flow pulsation, but different amplitudes and phases. And the experimental results showed that the pressure pulsation rate of the 20 ° phase angle tandem pump decreased by 34.05% compared to 0 °. The 20 ° phase angle tandem pump can reduce the vibration amplitude at most frequencies at 0 ° phase angle. Changing the phase angle of a tandem pump can reduce the vibration amplitude caused by fluid pulsation, and the variable phase angle does not have an impact on the outlet flow rate of the tandem pump. 2024 Vol. 43 (10): 44-51 [Abstract] ( 81 ) HTML (1 KB)  PDF (2148 KB)  ( 52 ) 52 Transition and coexistence characteristics of periodic motions of a single-degree-of-freedom vibro-impact system with dry friction LI Deyang1，LI Meng2，WU Shaopei2，LI Guofang2，DING Wangcai2，DING Jie2 The distribution, transition and coexistence characteristics of periodic motion in parameter and state plane of a single degree of freedom vibro-impact system with elastic constraints and dry friction are analyzed. Firstly, the connection conditions of each motion state (slip, stick and impact) of the system are given. A method of computing Floquet Matrix by disturbing response is presented. Secondly, the motion of the system is divided into six types according to the relationship between the phase trajectory and the stick surface. By the Floquet multiplier and the geometric conditions of sliping bifurcation, the stability and bifurcation types of adjacent periodic motions in the parameter plane during transition are judged. Based on cell mapping and shooting method, the distribution and transition of stable and unstable periodic motion coexisting in high frequency region are analyzed. It is found that the bifurcation coexistence phenomenon occurs at the intersection of the boundary lines of adjacen t multi-state coexistence regions, where different or the same type of bifurcation occurs in the system in different initial states. Since clearance and dry friction widely exist in practical mechanical systems, the study of the dynamical properties of such systems is great significance for the design of the subsequent system parameters and the control of various dynamical behaviors. 2024 Vol. 43 (10): 52-63 [Abstract] ( 59 ) HTML (1 KB)  PDF (5334 KB)  ( 29 ) 64 Mechanical property of a novel vibration isolation and dampingdevice for power equipments FENG Yulong1，WANG Tonglong1，WANG Decai2，WANYAN Jianfei3，WANG Chengjian3 Vibration isolators can effectively reduce the high frequency vibration generated due to the use of power equipment, however, the displacement response of the equipment vibration isolator is larger under low-frequency earthquakes. The disc spring and annular friction sleeve are used as a vertical vibration isolation unit and energy dissipation unit respectively, and a vibration gap is set in the vertical energy dissipation unit to achieve a two-stage mechanism of vibration isolation in normal work and damping in earthquakes, which forms a new type of vibration isolation and damping device for power equipment. Based on the theoretical analysis, the design process of the vibration isolation and damping device is given, and an example design is conducted. The static performance analysis of the device and the dynamic performance analysis of the power equipment entire system are carried out using ABAQUS software. The results show that the numerical simulations of the device and the system proposed match well with the theoretical calculation results; the designed example achieves a two-stage vibration isolation and damping mechanism, in which the device only isolates the equipment from vibration when the equipment is working normally, and the vertical energy dissipation unit is activated under earthquakes; the vertical energy dissipation unit reduces the equipment's vertical seismic displacement response by more than 50%, and a horizontal energy dissipation unit reduces the horizontal seismic shear force of the device by more than 80%, which reduce the risk of seismic overturning and damage of the device. 2024 Vol. 43 (10): 64-72 [Abstract] ( 76 ) HTML (1 KB)  PDF (2188 KB)  ( 31 ) 73 Numerical study on the vortex-induced vibration of a rectangular cross section cylinder with different side ratios ZHU Yuzhe，CHEN Fubin The change of the side ratio(D/B) for a rectangular cross cylinder will lead to the variation of the surrounding flow field, affecting the aerodynamic performance and vortex-induced vibration(VIV) response on the cylinder. Based on the Fluent platform, the effects of side ratio on vortex-induced vibration of a two-dimensional rectangular cross cylinder with Reynolds number 22000 were studied in combination with the overset grid technology and the fourth-order Runge-Kutta method. Firstly, a rectangular section with a side ratio of D/B=4.0 was selected, and the effectiveness of the simulation method and parameter settings was verified by comparing with the calculated results and relevant literature tests and simulations. Then, the effects of the side ratio on the response of VIV for the rectangular cross cylinder are compared and analyzed from the statistical values of aerodynamic force coefficients, the self-spectrum and the amplitude changes for the flow and transverse direction, and the phase transition. Finally, the influence of different reduced velocity on the wake vortex shedding was analyzed from the respect of transient flow field. The results show that, when the section area of the cross cylinder fixed, the response of VIV for the cylinder with a small side ratio is very weak, and the aerodynamic performance is significantly lower than that of the cylinder with a large side ratio. The aerodynamic performance and VIV response on the cylinder with a large side ratio are higher than that of the standard square cylinder. The amplitude ratio of the cylinder will also change abruptly at a lower reduced velocity, but will reach the peak amplitude at a higher reduced velocity. Compared with the cylindrical structure, the vortex shedding mode of the rectangular cylinder with fixed separation angle is not sensitive to the change of the reduced velocity, which is more obvious on the large side ratio rectangular cylinder than the square cylinder. 2024 Vol. 43 (10): 73-81 [Abstract] ( 66 ) HTML (1 KB)  PDF (2399 KB)  ( 58 ) 82 Enhanced dense connectivity network model applied to ECT image reconstruction MA Min，SUN Ni In order to solve the problem that traditional neural networks cannot integrate the bottom position features and the top semantic features of the capacitive feature tensor well in ECT image reconstruction, an enhanced dense connection network model is proposed. First, the initial dielectric constant distribution is obtained by training the Fully Connected Neural network, and the output characteristic map of the fully connected neural network is used as the input of the compensated U-net network. Secondly, a compensated U-net network is built, and a DenseNet-like dense jump connection mechanism is added between the encoder and decoder to retain a large amount of underlying location feature information and reduce the feature loss of multiple output nodes of the model. At the same time, the multi-scale dense cavity convolutional module is used to replace the ordinary convolution in the compensated U-net to enlarge the receptive field of the model and enrich the multi-scale information. Finally, an efficient channel attention mechanism module is used to realize the cross-channel interaction of the output features of sub-decoder nodes, which enhances the model's attention to important information and improves the nonlinear fitting ability of the model. The experimental results show that the reconstructed images based on this algorithm have higher resolution, clearer imaging edges, and more robustness than the Landweber iterative algorithm and the U-net algorithm. 2024 Vol. 43 (10): 82-88 [Abstract] ( 38 ) HTML (1 KB)  PDF (1781 KB)  ( 6 ) 89 Investigation on the tunable band-gap and vibration characteristics of phononic crystals based on FGMs XU Genghui1，XIAO Hanlin2，ZHANG Lin1，WANG Yutong1，ZHANG Tao1 To suppress low frequency vibrations in typical plate and shell structures of ships, this paper designs a cantilever beam phononic structure based on local resonance theory. The bandgap mechanism is revealed by numerical calculations to investigate the influence of dimensional parameter on the bandgap characteristics. In addition, natural frequency gradients approach is proposed based on the Functional Gradient Materials method, which can effectively widen the low frequency forbidden band range. Finally, vibration characteristics tests were designed and analysed for error reasons. The results show that: The longer the edge length of the cantilever beam, the narrower the band gap width. As the width and thickness of the cantilever beam increases, the band gap width widens. In the natural frequency gradient method, the band gap range is effectively widened when the overall rate of change is less than 8.1%. When the rate of change of adjacent natural frequencies is more than 12.27%, a multi-frequency band gap characteristic can be presented; increasing the number of cantilever beam installations can further widen the forbidden band range on the basis of the natural frequency gradient, and the research results can provide reference for the vibration isolation design of ship shell structures. 2024 Vol. 43 (10): 89-97 [Abstract] ( 64 ) HTML (1 KB)  PDF (3380 KB)  ( 84 ) 98 Numerical study on the flow-induced rotation coupled with vortex-induced vibration of a cylinder with Savonius impeller structure LIU Xinhan1，LOU Min1，WANG Yu1，LI Xiang2 A novel cylindrical energy conversion device with Savonius impeller structure is simulated, incorporating user-defined functions and the SST k-ω turbulence model to achieve fluid-structure coupling. Investigating the flow rotation and vibration response of the cylinder with Savonius impeller structure of different ellipticities. Revealing the mechanism of coupling between flow rotation and vortex-induced vibration. The results show that the impeller structure ellipticity is the key to influence the transverse flow displacement of the cylinder. For cylinders with the same ellipticity, the projected area is an important factor affecting the downstream displacement. At low reduction velocities, the cylinder rotates unsteadily, forming an asymmetric flow wake, showing a P+S wake pattern. At high reduction velocities, the cylinder rotates steadily in the clockwise direction. The rotational angular velocity fluctuates periodically. In the same rotation period, cylinders with smaller impeller structure ellipticities exhibit larger absolute values of the cylinder's instantaneous torque coefficient. 2024 Vol. 43 (10): 98-105 [Abstract] ( 42 ) HTML (1 KB)  PDF (1944 KB)  ( 36 ) 106 Unsupervised domain adaptation transfer learning for the fault diagnosis in rotating machinery ZHOU Xiangqi，FU Zhongguang，GAO Yucai Fault diagnosis is of great importance in the domain of rotating machinery, and the development of deep learning and transfer learning has provided new avenues in order to enhance the precision and resilience of fault diagnosis. In the context of fault diagnosis in rotating machinery, an unsupervised domain adaptation transfer learning method based on Domain-Adversarial Neural Network (DANN) and Multiple Kernel Maximum Mean Discrepancy (MK-MMD) is proposed. Firstly, vibration signal data from both the source working condition and the target working condition are gathered and converted into frequency domain signals utilizing the Fast Fourier Transform (FFT). Then, a ResNeXt-50 feature extractor is constructed, and DANN and MK-MMD methods are employed for feature mapping and domain adaptation, enabling transfer learning from the source working condition to the target working condition. The experimental findings validate that the proposed method enhances the accuracy of fault feature recognition. and exhibits better robustness in transfer experiments across different working conditions. 2024 Vol. 43 (10): 106-113 [Abstract] ( 67 ) HTML (1 KB)  PDF (1798 KB)  ( 30 ) 114 Seismic response of a S-wave incident elastic foundation free field under the effect of heat YANG Yiqi1，MA Qiang1,2 Based on the theory of wave propagation in thermoelastic media, this paper establishes a model of an elastic foundation free-field under plane S-wave incidence, uses the Helmholtz vector decomposition principle to analyze the wave field in the elastic foundation-free field under thermal effects, and obtains the analytical solution of seismic ground motion in elastic foundation free field under plane S-wave incidence under thermal effects. The influence law of thermal conductivity, medium temperature, thermal expansion coefficient, and other thermal physical parameters on the seismic ground motion of elastic foundation free field is analyzed through numerical calculations. The results show that there are significant differences between the horizontal and vertical displacement amplification coefficients obtained under the two theoretical models with and without thermal effects; the amplification coefficients of surface level and vertical displacement and the corresponding acceleration increase with the increase of thermal expansion coefficient and medium temperature; the effects of thermal conduction coefficient and heat flux phase delay on the amplification coefficients of surface displacement and acceleration are smaller; the amplification coefficients of surface displacement and acceleration increase gradually with the increase of incident wave frequency. 2024 Vol. 43 (10): 114-122 [Abstract] ( 54 ) HTML (1 KB)  PDF (1945 KB)  ( 28 ) 123 Dynamical complexity of a bistable energy harvesting system under Poisson white noise excitation XU Shuo1，HE Meijuan1，JIA Wantao2 The dynamic complexity of a bistable energy harvesting system under the combined effect of Poisson white noise and periodic signals is depicted by statistical complexity. Considering the complex statistical properties of Poisson white noise, firstly, the Bandt-Pompt algorithm was used to construct the residence time interval of the response of the bistatic energy harvesting system, based on which the statistical complexity and standard Shannon entropy of the system were obtained; secondly, the mean square voltage and effective output power of the system were calculated by numerical methods; finally, the effects of Poisson white noise, coupling coefficient, damping coefficient and periodic signal on the dynamics complexity and energy harvesting efficiency of the system were analyzed in detail. The results show that the non-monotonic evolution trend of the statistical complexity curve and the standard Shannon entropy curve indicates that the system generates stochastic resonance phenomenon, and the selection of appropriate system parameters can promote the stochastic resonance behavior, when the dynamical complexity of the system is maximized. In addition, the trends of mean square voltage and effective output power with parameters are consistent with the evolutionary behavior of the statistical complexity curves, and the stochastic resonance behavior occurs when the system has the highest energy harvesting efficiency. 2024 Vol. 43 (10): 123-131 [Abstract] ( 45 ) HTML (1 KB)  PDF (3349 KB)  ( 72 ) 132 Fault diagnosis of rolling bearings based on sfla optimized variational mode extraction ZHANG Huaibin1，CHEN Zhigang1,2，YANG Yuanpeng1，WANG Yanxue1 In order to solve problems that the selection of approximate center frequency and penalty factor in variational mode extraction (VME) depends too much on experts’ experience, a rolling bearing fault diagnosis method based on shuffled frog leaping algorithm (SFLA) and VME was proposed. Firstly, in order to solve problems of incomplete information when using a single index as an objective function to extract features, a new parameter optimization index-KIC was established with combining information entropy(IE), envelope spectral kurtosis and correlation coefficient. Then, the minimum value of KIC was used as the objective function of SFLA to adaptively select the approximate center frequency and penalty factor expected modes of VME. Finally, expected modes were analyzed with envelope demodulation for fault diagnosis. The analysis results of simulation signals and the related data sets of the bearing test-bed show that the proposed SFLA-VME method can accurately extract the desired mode and diagnosis of the bearing fault. 2024 Vol. 43 (10): 132-139 [Abstract] ( 57 ) HTML (1 KB)  PDF (4029 KB)  ( 63 ) 140 Hybrid control of the vortex-induced vibration of a pedestrian landscape bridge based on aerodynamic measures and pulley-type TMD CHEN Zhi1，FENG Zhouquan1，CHEN Jinlin1，SUN Xiugui2，HUA Xugang1 To address the issue of excessive static elongation of the spring in traditional Tuned Mass Dampers (TMD) used for controlling low-frequency vibrations in bridge structures, this paper introduces pulley-type TMD and their characteristics when it is used for structural vibration control, and points out that pulley-type TMD can effectively reduce the spring static elongation. Taking a pedestrian landscape bridge as an example, the effectiveness of aerodynamic measures and pulley-type TMD in controlling vortex-induced vibrations (VIV) of the bridge is investigated. Wind tunnel test results demonstrate that, with optimal aerodynamic measures, the VIV amplitude of the main girder is reduced by more than half, but it still does not meet the comfort requirements for pedestrians. Based on the Scanlan linear vortex excitation force model for the optimal design of pulley-type TMD, the vortex vibration control is further supplemented by pulley-type TMD based on aerodynamic measures. The results of the analysis show that aerodynamic measures combined with pulley-type TMD for VIV control can meet the pedestrian comfort requirements and ensure that the working stroke of the pulley-type TMD mass block does not exceed the limits. By simultaneously utilizing aerodynamic measures and pulley-type TMD, multiple requirements such as the VIV limit of the main girder, spring static elongation and working stroke of the pulley-type TMD can be met, effectively controlling the occurrence of VIV in the main girder. The proposed hybrid solution provides valuable insights for VIV control in similar engineering projects and offers guidance for engineering practice. 2024 Vol. 43 (10): 140-148 [Abstract] ( 38 ) HTML (1 KB)  PDF (2737 KB)  ( 50 ) 149 Analysis and test on influencing factors of the critical loosening load of bolts considering inertia force YIN Simai1，DENG Xiaowei1，ZHANG Daping2，WU Yiwen3，YU Zhengyue1 In order to accurately explore the loosening characteristics of bolt connection under transverse vibration conditions, this paper comprehensively considered the influence of local slip and torque slip, established a bolt connection model considering inertial force, analyzed the forces at different positions of the screw threads, and obtained a theoretical calculation method for calculating the critical loosening load of bolts, which is verified by the transverse vibration test. The results show that the theoretical calculation method has higher accuracy. The critical loosening load of bolts under different parameters such as preload, friction coefficient of thread surface, vibration number, pitch, vibration frequency and thread rise angle is quantitatively calculated, and the main influencing factors of bolt loosening are revealed. When the preload and friction coefficient of thread surface are increased and the vibration number, pitch, vibration frequency and thread rise Angle are reduced, the critical loosening load of bolts will increase, which is conducive to improving the anti-loosening ability of bolt connection against self-loosening. The research results have a guiding significance for the design of bolt-joint locking. 2024 Vol. 43 (10): 149-155 [Abstract] ( 35 ) HTML (1 KB)  PDF (1545 KB)  ( 8 ) 156 Free vibration of asymmetric porous functionally graded material sandwich plates on elastic foundations HUANG Zhicheng1，HAN Mengna1，WANG Xingguo1，CHU Fulei2 Based on the refine shear deformation theory, the free vibration of asymmetric porous functionally graded material(FGM) sandwich plates on elastic foundations is studied. A new free vibration model for asymmetric porous FGM sandwich plates on elastic foundations is proposed based on this theory, and the model only contains four unknown variables. The governing equation is established using the Hamilton’s principle and natural frequency of sandwich plate is obtained using the Navier method under four simple supports. The model is degraded into an asymmetric FGM sandwich plate on an inelastic foundation to verify the accuracy of the model. Finally, the influence of parameter changes on the free vibration behavior of asymmetric porous FGM sandwich plates on elastic foundations is discussed in detail. We have found that the natural frequency of asymmetric porous FGM sandwich plates increases with the increase of side-to-thickness ratio under different elastic coefficients, while its has different changes with the increase of volume fraction index under different elastic coefficients. 2024 Vol. 43 (10): 156-163 [Abstract] ( 42 ) HTML (1 KB)  PDF (1279 KB)  ( 15 ) 164 Multidimensional and multipoint elastic-plastic stochastic response analysis of curved beam bridges based on the absolute displacement method LI Ximei1,2，ZHAO Tinglong1,2，TAO Cheng3 The seismic response analysis of curved continuous beam bridges under the spatial effects of seismic motion often employs deterministic excitation inputs while neglecting the nonlinearity of the bridges. In this study, elastic-plastic response analysis was conducted on curved continuous beam bridges using multidimensional and multipoint non-stationary random excitations. A nonlinear finite element model was established, and the non-stationary seismic motion's EPSD (Energy Power Spectral Density) matrix was reduced and decoupled through dimensionality reduction. Nonlinear time history analysis of the bridges was carried out using the absolute displacement method. The study considered different apparent wave velocities, site conditions, coherence, and stationary/non-stationary seismic excitations to comprehensively analyze the random response, frequency-domain characteristics, and time-domain characteristics of curved continuous beam bridges. The results indicate that the spatial effects of seismic motion and the non-stationarity of the seismic motion have a significant impact on the random response of curved beam bridges. The spatial effects of seismic motion have a notable influence on the magnitude and frequency-domain distribution of the bridge's random response, while the non-stationarity affects both the magnitude and the temporal response trend of the random response. Therefore, it is essential to fully consider the spatial effects of seismic motion and the non-stationarity in the seismic analysis of curved continuous beam bridges to avoid inaccurately estimating the seismic performance of the bridges. The comprehensive analysis results provided in this study are of great significance for strengthening the seismic design and evaluation of curved continuous beam bridges, thereby improving their seismic performance and reliability. 2024 Vol. 43 (10): 164-173 [Abstract] ( 42 ) HTML (1 KB)  PDF (2672 KB)  ( 59 ) 174 Method for establishing the transfer function of acoustic structural units and its application ZHANG Benxi1,WANG Xiaoming1,MEI Yulin2 The transfer function model of acoustic structural unit is established through the time-domain simulation method of three-dimensional finite element analysis, and is accurately expressed as the function of structural parameters. The transfer function representation can simplify the design process of acoustic structure. First, two acoustic structural units are established, and their amplitude-frequency characteristics are simulated. And meanwhile, the simulated amplitude-frequency characteristics are verified by experimental measurements. Next, based on the amplitude-frequency characteristics, transfer functions of the two structural units are fit by adopting different zero-pole matching schemes. The results show that the fitting accuracy is the highest when matching 7 poles and no zero to fit the transfer function of the expansion chamber unit, and matching 2 poles and 2 zeros to fit the transfer function of the Helmholtz resonator unit. Then, the influence of the structural parameters of the acoustic unit on the amplitude-frequency characteristics is analyzed. Subsequently, based on the high accuracy form of the fitting function, the transfer function model of the acoustic structural unit is established by numerical simulation and fitting calculation. Finally, a composite acoustic structure composed of an expansion chamber and a Helmholtz resonator is constructed, and its transfer function is calculated based on the transfer function models of the units. The results of COMSOL and transfer function model are compared to verify the established unit transfer function models. 2024 Vol. 43 (10): 174-184 [Abstract] ( 39 ) HTML (1 KB)  PDF (2915 KB)  ( 9 ) 185 Experimental study on the effect of the preselection gear on the rattle dynamics analysis of a dual-clutch transmission ZHOU Yi1,2,HUANG Bin2,SHI Xiaohui3,GUO Dong3,MEI Ziyuan2,XU Huihui2 A transmission rattle bench that simulates the engine speed fluctuations was built. The housing vibration and the transient rotational signals of the gears of a dual-clutch transmission were measured to investigate the evolution of the rattle response and geartrain dynamics along with the varying input angular acceleration level and different preselection gears. According to the calculated results from a lumped parameter geartrain backlash-nonlinear dynamic model and the law of the gear meshing, a criterion for judging the gear motion state based on the characteristics of the angular acceleration amplitude of the gear’s characteristic frequency is proposed. The bench test results indicate that the preselection gear significantly varies the rattle response and gear pair dynamic behaviour in the DCT transmission. The DCT rattle response features a jump-up phenomenon once the input shaft angular acceleration level increases to a certain amplitude, a clear low-frequency dynamic coupling between the active and passive sub-gearboxes is clearly observed, and the rotational signal of the loaded gear shows significant multi-harmonic nonlinearity. The teeth separation and vibro-impact rattle of the loaded gear pair can be deduced based on the proposed criteria for the gear motion judgement. The dynamic coupling after the dynamic change in the geartrain considerably deteriorate the DCT rattle response. Finally, the dynamic coupling and rattle jump-up phenomenon are validated throughout the vehicle experiment. 2024 Vol. 43 (10): 185-196 [Abstract] ( 58 ) HTML (1 KB)  PDF (3966 KB)  ( 51 ) 197 Novel method for missing mechanical vibration signal reconstruction based on compressed sensing GUO Junfeng1,HU Jingyi1,WANG Zhiming1 In order to address the issue of missing vibration signal data in real-time monitoring of industrial machinery due to uncontrollable factors, a Compressed sensing missing signal reconstruction method based on the Adaptive Quadratic Proximity-Alternating Direction Method of Multipliers (AQ-ADMM) was proposed. The AQ-ADMM algorithm introduced a quadratic proximity term into the classic ADMM iterative process and adaptively selected penalty parameters. First, a signal reference database was established at the data center for creating an initial dictionary. Then, the missing signals were repaired using a reconstruction method based on the K-Singular Value Decomposition (K-SVD) dictionary learning algorithm and AQ-ADMM. Gaussian white noise was added to simulated signals and two real bearing signal datasets to serve as samples, the experimental results demonstrate that the proposed method exhibits significantly better performance indicators than other traditional methods when the signal compression ratio ranges from 50% to 70%. It achieves fast and accurate recovery of missing data signals while reconstructing the signals. 2024 Vol. 43 (10): 197-204 [Abstract] ( 39 ) HTML (1 KB)  PDF (1629 KB)  ( 72 ) 205 Free vibration analysis of embedded co-cured stitched damped composite beam LIU Zhaoyang,LIANG Sen,HU Zijian,SUN Ruijun Embedded Co-cured Stitched Damping Composite (ECSDC) has the advantages of high specific stiffness, high specific strength, high level bonding performance and three-way mechanical designability compared to conventional composite materials. In this paper, Hamilton's principle, combined with energy and complex stiffness methods, is applied to derive the kinetic differential equations of the ECSDC beam structure, and the theoretical solution of the model is obtained by transforming the partial differential equations into a linear system of chi-square equations and substituting the boundary conditions of the opposite side simple support. As an example, the typical structure of ECSDC beams was studied by conducting modal tests, using ANSYS finite element simulations and MATLAB numerical calculations, and the results obtained from the three were in good agreement, which verified the accuracy of the theoretical model and method. Based on this, the effect of design parameters on the inherent vibration characteristics of the ECSDC beam structure was investigated using the validated theoretical model. The results characterize that the embedded co-cured stitched damped composite beam structure has higher flexural stiffness than the continuous damped sandwiched composite beam structure, which provides a new idea at the theoretical level for the study of dynamic properties of damped composites. 2024 Vol. 43 (10): 205-214 [Abstract] ( 44 ) HTML (1 KB)  PDF (2343 KB)  ( 18 ) 215 Honeycomb structure protection device of an offshore wind turbine LIU Kunpeng,MIAO Weipao,WANG Yujin,LI Chun,YUE Xinzhi In order to facilitate the transportation, installation and maintenance of wind turbines, offshore wind farms are mostly in busy waterways, resulting in a significant increase in the probability of offshore wind turbines being collided by ships. In order to enhance the anti-collision ability of offshore wind turbine, reduce the damage degree of collision area and improve its anti-risk performance, this paper proposes a new type of protection device with honeycomb structure characteristics. The explicit dynamic analysis software LS-DYNA was used to simulate the collision process between the 5000t ship and the tripod of the 4MW offshore wind turbine, and the difference between the new honeycomb structure protection device and the traditional solid structure protection device was studied. The results show that the new protective device with honeycomb structure can effectively prolong the contact time and reduce the contact force. Compared with the traditional solid protection device, the internal energy conversion capacity of the new device is increased by more than 15%, and the honeycomb structure plays a role in improving the internal energy conversion capacity. The honeycomb structure protection device has a good energy absorption and buffering effect, which can effectively reduce the internal energy and kinetic energy transferred to the wind turbine structure, reduce the foundation damage, and improve the safety of the offshore wind turbine with tripod. 2024 Vol. 43 (10): 215-222 [Abstract] ( 57 ) HTML (1 KB)  PDF (1614 KB)  ( 69 ) 223 Vibration mechanics analysis of a perforating string under the influence of multiple factors YANG Wenwu1,LI Hao1,LIN Yong2,REN Siwu3,ZHANG Zhiliang1,4,XU Shaojun5,LI Fuqiang5 The impact load produced by the shaped charge perforating detonation acts on the downhole perforating string system, causing accidents such as tubing fracture and buckling. The effects of self-weight, perforating fluid damping, stratigraphic confining pressure, and explosive impact load were incorporated, and a dynamic model for the tubing-perforating gun system under perforation impact load was established. The differential equation for longitudinal vibration of the string in the perforation interval was derived. Finite element software was employed to conduct a dynamic response analysis of the perforated interval of the string. The simulated results were compared and validated against theoretical numerical solutions. The results reveal that stress waves propagate from the bottom of the string upward. Both the equivalent stress of the string and the axial displacement exhibit periodic changes and gradually attenuate. Analyzed the effects of different tubing lengths, outer diameters, wall thicknesses, and single explosive quantities of the perforating gun on the dynamic response of the string. Based on the numerical simulation results, the empirical formula for the peak stress of the string in the perforated interval was obtained by fitting with multiple nonlinear regression using MATLAB software. The formula was then compared with the field test data to verify the reliability of the formula. 2024 Vol. 43 (10): 223-229 [Abstract] ( 57 ) HTML (1 KB)  PDF (1834 KB)  ( 13 ) 230 Experimental study on the vertical coherence of the steady state downburst wind field FANG Zhiyuan1,HUANG Hanjie2,WANG Zhisong3 In order to study the vertical coherence of the horizontal wind speed of downburst, the steady downburst wind field was simulated using an impinging jet device, and the horizontal wind speed under different radial positions, vertical distances, terrain conditions and jet velocities was measured. The vertical correlation and coherence curve of the horizontal wind speed were emphatically analyzed, and the coherence function model of the steady downburst wind field was proposed. The results show that the correlation coefficient first increases and then decreases with the increase of the radial distance, and the maximum correlation coefficient appears near r=1.0Djet, and the ground roughness and jet wind speed have little influence on the correlation coefficient. The coherence function is closely related to the vertical spacing of the measuring points, the radial position and jet wind speed have little influence on the coherence function, and the increase of the surface roughness will reduce the coherence of the near-earth measuring point pair. Based on the test data, the vertical coherence function model of the steady-state downburst is established, which is in good agreement with the experimental wind field. 2024 Vol. 43 (10): 230-235 [Abstract] ( 41 ) HTML (1 KB)  PDF (2046 KB)  ( 20 ) 236 Prediction and analysis of non-circular grinding process stability based on dynamic grinding process simulation LIU Tao1,2,DENG Zhaohui3,YAO Qishui1,2,L Lishu4,YU Jianghong1,2 Grinding chatter is one of the most important factors for restricting the efficient and high-quality grinding of camshaft. Based on the analysis of the geometric and kinematic characteristics of camshaft grinding, the calculation method of dynamic grinding force in high-speed grinding of camshaft is deduced considering the time delay effect and the elastic concession mechanism of grinding wheel-workpiece comprehensively, and the multi-factor coupling camshaft grinding dynamics model and camshaft dynamic grinding simulation model are established. Based on the stability lobe diagram method and dynamic grinding process simulation method, the high-speed grinding stability of camshaft is predicted and analyzed. Experiments are carried out to verify the correctness of the proposed model and method. Finally, the influence of modal parameters on the stability of camshaft high-speed grinding process is analyzed by simulating the variable modal parameters of dynamic grinding process. The results show that increasing the stiffness and damping of the process system and reducing the modal mass of the process system can improve the grinding stability and obtain a greater stable grinding limit. 2024 Vol. 43 (10): 236-247 [Abstract] ( 38 ) HTML (1 KB)  PDF (2983 KB)  ( 9 ) 248 New magneto-inducible magnetorheological damper WANG Chenglong1,WU Lujie1,WEI Xueqian2,ZENG Qingliang1 A new magneto-inducible MR damper was proposed on the basis of the conventional MR damper to solve the problem that the performance of the traditional magnetorheological damper was limited under certain size of structure, and the coupling dynamics model of the magnetic field and the flow field was established. Taking the damping force and the dynamic adjustable coefficient as the optimization objective functions, the structure size of internal piston of the new MR damper was optimized based on the MOGA. On this basis, the multi-physical coupling model was established, and the simulation and impact tests were carried out. The simulation results showed that the length of effective damping channel of the new MR damper is 64 mm, which was 60% higher than that of the ordinary MR damper. The mechanical properties and dynamic adaptability of the new MR damper were superior. When 2.0 A current was applied and the piston speed was 0.09 m/s, the damping force of the new MR damper was 55.9 kN, which was 72.5% higher than that of the ordinary MR damper (32.4 kN). The peak pressure and energy absorption capacity of the new MR damper were obviously higher than those of the ordinary one when different amounts of current were applied. The impact test results showed that the peak pressure reached 11.64 MPa when 2.0 A current was applied and the impact velocity was 2.45 m /s, which was about 41% higher than that of the ordinary MR damper. The comparison between the peak pressure test results and the simulation results showed that the trend of the simulation results and the test results was consistent, and the relative error was within 0.1，which indicated the effectiveness of the simulation model. 2024 Vol. 43 (10): 248-259 [Abstract] ( 39 ) HTML (1 KB)  PDF (3094 KB)  ( 18 ) 260 Vibration energy transfer characteristics of a centrifugal compressor skid base based on the structural intensity method WANG Fengde1,MA Yunteng2,LUO Jiaqi3,LIU Bing1,XIAO Wensheng2 Offshore skid mounted centrifugal natural gas compressors are highly integrated and prone to vibration failures. In order to explore the transfer characteristics of vibration energy in compressor skid and reduce the cost of vibration control， the structural intensity method was applied to the research field of vibration control of skid-mounted reciprocating compressor. The acoustic intensity field analysis model of the skid base was established by using self-programming and finite element tools. Combined with data visualization technology， the acoustic intensity analysis and visualization method of the skid base was proposed. The method was applied to solve and visualize the structural acoustic intensity field of the skid base. The transfer characteristics of vibration energy in the skid base and the quantitative relationship between mechanical energy and structural acoustic intensity were studied， the main transfer path， vibration source and vibration manifold of vibration energy in the skid base under the extreme working conditions were revealed. Vibration control measures are proposed for sensitive area of precision equipment. The results show that maximum amplitude of structural sound intensity appears in the compressor installation area， the vibration energy is mainly converted into kinetic energy of the skid base，and the vibration energy is mainly transferred in a divergent manner along the width and height of the skid. The research results can support the vibration control of compressor skids in the engineering field and provide a basis for the study of vibration energy transfer characteristics of plate and beam composite structures in the theoretical aspect. 2024 Vol. 43 (10): 260-267 [Abstract] ( 34 ) HTML (1 KB)  PDF (2548 KB)  ( 5 ) 268 Analysis on the shear mechanical properties of a LYP225 low yield point steel web hourglass pin damper LIAN Ming1,2, DAI Baihao1, LI Wei1 In order to study the hysteresis and fatigue performance of LYP225 low yield point steel web hourglass pin damper (LYP-WHP) under shear loading, two LYP-WHP specimens were tested for hysteresis loading and fatigue loading respectively. Based on the experimental results, a Chaboche combined hardening model was used to establish 12 finite element models of LYP-WHP by ABAQUS, with the inner diameter, outer diameter and length of energy dissipation section of the damper as parameters, respectively, to study the influence law of the above parameters on the hysteresis performance of LYP-WHP under shear loading. The formula for calculating the elastic stiffness of LYP-WHP is derived, and a preliminary method for determining the yield force and yield displacement of LYP-WHP is given, and based on the results of experimental and numerical analysis, the proposed value of the stiffness discount factor of LYP-WHP after yielding is obtained. The research results show that LYP-WHP has good hysteresis and fatigue properties under shear displacement; Increasing the outer and inner diameters can significantly improve the load carrying capacity, stiffness and energy dissipation capacity of LYP-WHP, while increasing the length of the energy dissipation section will reduce the load carrying capacity, stiffness and energy dissipation capacity of LYP-WHP; Increasing the inner diameter and outer diameter makes the utilization of the material first increase and then decrease, and increasing the length of the energy-consuming section has little effect; the derived formula for calculating the elastic stiffness of LYP-WHP can calculate the elastic stiffness of LYP-WHP accurately; Based on the analysis results of this paper, it is suggested that the inner diameter to outer diameter ratio of LYP-WHP is taken as 0.375~0.625 and the stiffness reduction factor after yielding is taken as 0.11; the Bi-linearl skeleton curve is obtained. 2024 Vol. 43 (10): 268-278 [Abstract] ( 35 ) HTML (1 KB)  PDF (3456 KB)  ( 12 ) 279 Stochastic resonance of monostable system induced by strong noise and aperiodic pulse and its application SUN Bowen1, HUANG Shengping1, WANG Zhongqiu2, YANG Jianhua1, LI Shangyuan1, YANG Yan1 Stochastic resonance is the optimal response of nonlinear system to weak signals in noise background, which can enhance weak signals. Compared with traditional bistable systems, biased monostable systems exhibit good resonance characteristics under non-periodic pulse excitation. However, the parameters of the nonlinear system affect the optimal output of the system. For different aperiodic pulse excitation, the system is difficult to adjust adaptively. To solve these problems, this paper studies the biased monostable adaptive stochastic resonance under strong noise and aperiodic pulse excitation. First, adaptive stochastic resonance under different aperiodic pulse excitation is realized based on optimization algorithm. Then, taking the magnetic flux leakage detection signal of steel wire rope under strong noise background as the application object, after the output of adaptive stochastic resonance of the biased monostable system, the peak-to-peak value is used as the evaluation index of damage feature evolution to evaluate the difference between different weak damage features. At the same time, the bias monostable adaptive stochastic resonance method and the adaptive shift average method are used to compare and analyze the magnetic flux leakage signal of steel wire rope in the strong noise background. With the peak-to-peak gain and signal-to-noise ratio gain as indicators, the results show that the bias monostable adaptive stochastic resonance method is better than the adaptive shift average method. Finally, the influence of noise intensity on monostable adaptive Stochastic resonance is discussed, and it is found that biased monostable adaptive stochastic resonance has strong anti-noise ability. 2024 Vol. 43 (10): 279-284 [Abstract] ( 34 ) HTML (1 KB)  PDF (1650 KB)  ( 15 ) 285 Thermal transient vibration characteristics of a heavy duty gas turbine rod-fastened rotor GAO Jin， HUANG Tao， GONG Junjun， ZHAO Shizhi， AI Song During the load increase with constant speed of heavy gas turbine cold start stage, there is often relative slip caused by inconsistency radial deformation between the discs, the rod-fastened rotor will experience thermal transient vibration, which significantly changes with the increase of gas turbine rotor temperature. The mechanical model of relative slip between discs of the circumferential rod-fastened rotor with plane friction and spigot is established, which includes the mechanical model for plane friction, circumferential rod and spigot. The thermal transient vibration a certain type of heavy-duty gas turbine rod-fastened rotor that occurred during its cold start process was analyzed. Based on the relative slip law of the wheel discs, the thermal transient vibration of the heavy-duty gas turbine rod-fastened during cold start was successfully optimized by reducing the inconsistency radial deformation between the discs and appropriately increasing the spigot interference. 2024 Vol. 43 (10): 285-291 [Abstract] ( 41 ) HTML (1 KB)  PDF (1231 KB)  ( 43 ) 292 Bearing fault diagnosis method based on improved approximate conjugate gradient pursuit HUI Yicong, ZHANG Yanchao, CHEN Runlin, LI Zhe, LIU Jiaxin, CUI Yahui Ensuring the dependability, functionality, production effectiveness, and safety of mechanical systems necessitates assessing the condition and detecting faults in rolling bearings. However, this can be challenging due to the interference of background noise and other unstable factors. To address this issue, we propose using a weak selection approximate conjugate gradient pursuit method (WACGP) and an improved sine cosine algorithm (ISCA) for more effective extraction of bearing fault features. SCA includes an inertia weight and nonlinear parameter update approach to improve the efficiency and accuracy of sparse signal representation, while the ACGP has been modified to increase the speed and ability of identifying bearing fault characteristics. The validity of the method is confirmed by analyzing the bearing fault simulation signal and the actual vibration signal of the bearing's inner and outer ring. The proposed method outperforms the gradient pursuit algorithm based on sine cosine optimization in terms of efficiency and accuracy. 2024 Vol. 43 (10): 292-298 [Abstract] ( 46 ) HTML (1 KB)  PDF (2134 KB)  ( 69 ) 299 New approach to diagnose faults in aero-pipelines based on spatial-temporal model fused with self-attention mechanism YANG Tongguang1, YUAN Shengyou1, ZHOU Xianwen2, HAN Qingkai1, YU Xiaoguang3 The structure of the external hydraulic pipeline of aero-engine is complicated and the fault signal of the pipeline is accompanied by strong noise interference, which makes it difficult to extract the fault characteristics of the aviation pipeline. Meanwhile, the parameters and calculation amount of the current diagnostic model are relatively large, which is not suitable for efficient transplantation to mobile and embedded equipment. In the face of these challenges, this paper proposes a new method for fault diagnosis of aero-engine hydraulic pipelines based on lightweight air-time model fusion attention mechanism, and named the S-Bi-ATM-Net model. Then, the lightweight pipeline time feature extraction module is designed, and the coarse-grained features of the pipeline are continuously fused from the fine-grained features to achieve the fusion of coarse-fine-grained features. In addition, the self-attention mechanism is integrated into the space-time model for optimization, which makes the final decision more focused and further improves the diagnostic accuracy of the proposed model. Based on the same data set, comparing and analyzing the proposed method with the current mainstream methods, it is found that the proposed method can more accurately identify different fault states of air pipelines, which proves the superiority and stability of the method. 2024 Vol. 43 (10): 299-310 [Abstract] ( 46 ) HTML (1 KB)  PDF (3590 KB)  ( 28 ) 311 Numerical simulation on the airworthiness compliance of aircraft engines during bird strikes LI Junjie1, CHAI Xianghai2, JIN Xianlong1, YANG Peizhong1 Airworthiness certification of aircraft turbine engines with respect to bird ingestion is reliant on physical tests of a full scale engine. Due to the complexity of the engine structure, there are problems, such as computational efficiency and difficulty in determining critical ingestion parameters, in numerical simulation of the whole engine during bird strikes. which is not adopted by engineering wor…ks. In compliance with bird ingestion requirements, numerical analysis of an aeroengine subjected to bird strikes is an economical and efficient method. Based on the numerical simulation requirements of aircraft engine due to bird strikes, simplified modeling of aircraft engine and critical ingestion parameters were investigated. Firstly, considering relationships and interactions among engine components under operating conditions, the finite element model of a full-scale aeroengine was developed using the SPH method. Secondly, based on simulations of fan blades during a bird-strike event, critical ingestion parameters of a large single bird and medium flocking birds were determined. Finally, with regard to the full-scale FE model of a turbine engine subjected to bird strikes under the most critical condition, impact force, rotating unbalance, unbalancing load and blade damage induced by large single bird, medium flocking birds, medium single bird and large flocking bird, respectively, were captured. The numerical results show that the bird-strike damage generated by the large single bird poses the greatest threat to the safety of engine components, while blade damage induced by flocking birds covered a wider area. It is invaluable for engine manufacturers to incorporate a predictive modeling methodology of a turbine engine under bird strikes into structural safety design and bird ingestion certification. 2024 Vol. 43 (10): 311-318 [Abstract] ( 62 ) HTML (1 KB)  PDF (2525 KB)  ( 19 )

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