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A transfer function method to Predict Transportation-Induced Building Vibration on Saturated Soil

BUILDINGS 2025年第7期15卷 1097-1097页

作者： Yao, Jinbao Wu, Nianping Chen, Yueyue Beijing Jiaotong Univ Sch Civil Engn Beijing 100044 Peoples R China

Building vibration induced by running trains or other loads is related to soil vibration, building coupling loss, and the building floor's amplification factor. In order to predict the vibration response of the proposed building caused by various loads, the propagation law of Rayleigh wave in saturated foundation soil and the refraction and transmission coefficients of Rayleigh wave between saturated soil and building structure are analyzed by using the theoretical analysis method, and the building coupling loss coefficient is obtained. The dynamic equation of the building's structural vibration is established, and the analytical expression of the floor amplification factor is derived. A frame structure building is selected as the specific research object. Based on the Kirchhoff thin plate theory, the three-dimensional frame structure characteristic matrix of the building is obtained, and the vertical displacement values of each floor of the building under the action of the Ricker pulse load are calculated. The results are compared with the results in the literature, which verifies the effectiveness and accuracy of the transfer function method proposed in this study and fills the gap of insufficient research on the analysis of displacement transfer loss in soil structure interaction (SSI) in the literature.

关键词： transfer function method Rayleigh wave saturated foundation soil building vibration

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Improved transfer function method for flexible simulation of hydraulic-mechanical-electrical transient processes of hydro-power plants

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RENEWABLE ENERGY 2022年 196卷 390-404页

作者： Huang, Yifan Yang, Weijia Liao, Yiwen Zhao, Zhigao Ma, Weichao Yang, Jiebin Yang, Jiandong Wuhan Univ State Key Lab Water Resources & Hydropower Engn Sc Wuhan Peoples R China

The hydraulic-mechanical-electrical coupling dynamics of hydropower plants during transient processes is a key issue in engineering practice. Numerical simulation of transient process could provide support for practical operation of hydropower plants and avoid dangerous working conditions, indirectly increasing the unit operation time and improving economic benefits. Numerous previous studies used the transfer function method (TFM) for modelling and simulation of hydropower plants, but many previous models are oversimplified and cannot simulate some complicated transient processes. To solve this problem, a nonlinear and flexible model of hydropower plant is developed on Simulink in this work. TFM is adopted to model the waterway system with complicated hydraulic components, and an improved scheme of TFM is recommended. Quantitative comparison of time-domain and frequencydomain simulations demonstrates the accuracy of the improved TFM in simulating the water hammer in the waterway system. Besides, the improved TFM is applied to combine with complicated electrical modules on Simulink, simulating hydraulic-mechanical-electrical coupling dynamics under hydraulic disturbance and three-phase fault. In conclusion, the method developed in this paper has advantages of accuracy, flexibility, and expansibility, enabling deeper understanding and refined simulation for transient processes of hydropower plants. The hydraulic-mechanical-electrical coupling model can be used to simulate a variety of working conditions in engineering practice and support future research on the dynamic characteristics of hydropower plants.

关键词： Hydropower plant Transient process transfer function method Time & frequency domain simulation Simulink

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Free vibration analysis of closed and open horizontal cylindrical shells utilizing coupled transfer function method and differential transform method

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MECHANICS OF ADVANCED MATERIALS AND STRUCTURES 2024年

作者： Ameli-Basiri, Mahdi Tavakkolizadeh, Mohammadreza Aftabi-Sani, Ahmad Ferdowsi Univ Mashhad Fac Engn Dept Civil Engn Mashhad Iran

This article aims to analyze the free vibration of closed and open horizontal circular cylindrical shells based on the concept of state-space transformation in conjunction with the differential transform method (DTM). The governing equations of the cylinders were developed based upon Sanders' thin shell theory. Then, the set of coupled governing differential equations transformed into nine first-order differential equations. Afterwards, the well-established semi-analytical scheme so-called DTM was employed to solve the differential equations. The numerical investigation of the present method was also comprehensively carried out by analyzing some closed and open cylindrical shells with different boundary and compatibility conditions. To ensure the correctness of the results, the outcomes were compared with experimental and other numerical results, especially with the well-known finite element method. Furthermore, some plots of two-dimensional and three-dimensional mode shapes for the first and second axial modes are depicted.

关键词： Free vibration differential transform method transfer function method cylindrical shells modal analysis

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Thermal vibration analysis of functionally graded graphene platelets-reinforced porous beams using the transfer function method

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ENGINEERING STRUCTURES 2023年第1期284卷

作者： Chen, Chen Li, Daokui Zhou, Xuan Zhou, Lilin Natl Univ Def Technol Coll Aerosp Sci & Engn Changsha 410073 Hunan Peoples R China Hunan Key Lab Intelligent Planning & Simulat Aeros Changsha 410073 Hunan Peoples R China Civil Aviat Flight Univ China Aviat Engn Inst 46 Nanchang St Guang Han 618307 Sichuan Peoples R China

functionally graded graphene platelets-reinforced (FG-GPL) porous materials are advanced, designable, lightweight, and high-strength composite materials promising in launch vehicles, space shuttles, and hypersonic vehicles as integrated heat-protection and load-bearing structures. Thermal vibration analysis ensures service safety in environments with dynamic thermal loads. A free vibration analysis model of an FG-GPL porous beam was proposed based on the micromechanical model and Timoshenko beam theory (TBT) under a nonlinear temperature profile. First, three types of functionally graded porosity distributions and graphene-platelet dispersion patterns were assumed along the thickness direction of the beam. Material properties, including elastic modulus, Poisson's ratio, and density, were calculated using the Gaussian random field scheme and Halpin-Tsai model. Second, a nonlinear temperature profile was established considering the influence of porosity and graphene platelets by solving a one-dimensional-heat-conduction equation. Third, the governing equations of thermal vibration of the beam were obtained using the TBT and Hamilton's principle. The frequencies of different porosity distributions and graphene-platelet dispersion pattern combinations were calculated by solving the governing equations using the transfer function method. Finally, the results were validated, and the parameter effects of the temperature profiles, weight fraction of graphene platelets, porosity coefficient, and thermal gradient on the fundamental frequencies were analyzed. Compared to a linear temperature profile, the frequency under a nonlinear temperature profile is hardly changed for the combined symmetrically distributed porosity and GPL beams, while it is different for the asymmetric combinations.

关键词： functionally graded graphene platelets reinforced porous beam Timoshenko Free vibration Nonlinear temperature profile transfer function method

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Applicability of the transfer function method and periodic response factors method in coincident design weather data generation

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ENERGY AND BUILDINGS 2021年 250卷 111254-111254页

作者： Fang, Zhengcheng Chen, Youming Hunan Univ Coll Civil Engn Changsha 410082 Hunan Peoples R China Hunan Univ Key Lab Bldg Safety & Energy Efficiency Minist Educ Changsha 410082 Hunan Peoples R China

The coincidence of design weather data means the simultaneous occurrence of design weather elements. Correlative studies have indicated that the generation of coincident design weather data (CDWD) is affected by the building parameter characteristics and indoor cooling load. The transfer function method and periodic response factor method are commonly used to calculate the indoor cooling load. In previous studies on CDWD generation, the transfer function method was primarily used to calculate the cooling load, as it reflects the actual thermal process more accurately. However, the periodic response factor method may have more significant advantages, as it matches better with practical engineering application method. There no researcher has proposed the CDWD generation method based on the periodic response factor method, or has evaluated the applicability of the transfer function method and periodic response factor method in the study on CDWD generation. In this study, taking the accuracy of cooling load calculated by the generated CDWD as evaluation index, the applicability of transfer function method and periodic response factor method in the generation of CDWD was evaluated. The results show that for the practical engineering application, the correct rate of CDWD generated based on the periodic response factor method is significantly higher than that based on the transfer function method. Moreover, there is no significant difference between the design cooling load calculated based on the transfer function method and that based on the periodic response factor method. The conclusion indicates that the periodic response factor method is more applicable for the generation of (and engineering applications regarding) CDWD. (c) 2021 Elsevier B.V. All rights reserved.

关键词： transfer function method Periodic response factors method Radiant time series method Coincident design weather data Design cooling load Applicability evaluation

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transfer function method for the Nonlinear Flutter of a High-aspect-ratio Wing

Transfer Function Method for the Nonlinear Flutter of a High...

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2018 2nd International Conference on Artificial Intelligence: Technologies and Applications（ICAITA2018）

作者： Zhongyuan Zhang Jingbo Duan Ping Lu Department of UAV Engineering Army Engineering University Mechanics Engineering Department Shijiazhuang Tiedao University

The semi-analytical and semi-numerical transfer function method is applied to the nonlinear flutter of a high-aspect-ratio aircraft wing. Firstly, the flutter differential equation of a three-dimensional wing is established by combining the bend-twist vibration equations of the wing and the ONERA nonlinear aerodynamics model for wings. Then, using the transfer function method, the control equations are formulated in a state-space form by defining a state vector. Both the flutter velocity and flutter frequency are obtained by solving a complex eigenvalue problem. Finally, the differences of the flutter behavior of the linear and nonlinear aerodynamic models under the influence of parameters such as mass of unit length, semi-aspect ratio, the stiffness ratio of twist and bend are discussed.

关键词： high-aspect-ratio wing nonlinear aerodynamic force flutter transfer function method

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Aeroelastic Stability Analysis of Aircraft Wings with High Aspect Ratios by transfer function method

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INTERNATIONAL JOURNAL OF STRUCTURAL STABILITY AND DYNAMICS 2018年第12期18卷

作者： Duan, Jing Bo Zhang, Zhong Yuan Shijiazhuang Tiedao Univ Dept Engn Mech East 2nd Ring Rd Shijiazhuang 050043 Hebei Peoples R China Army Engn Univ Dept UAV Engn Heiping Rd Shijiazhuang 050003 Hebei Peoples R China

A new method is developed for the aeroelastic stability analysis of a high-aspect-ratio wing based on the transfer function. First, the flutter governing equations for three types of wing elements including clear wing element, wing element with a control surface and that with an external store are, respectively, established by combining the corresponding bend-twist vibration model with the Theodrosen's unsteady aerodynamic model. Then, in order to use the transfer function method, the element governing equations are processed by the Fourier transform and are formulated in a state-space form using state vector. Based on the finite element procedure, the global governing equations of the whole wing are obtained. Both the flutter velocity and flutter frequency are derived by solving a complex eigenvalue problem with the graphical approach. Additionally, the torsional divergence of the high-aspect-ratio wing is obtained by solving a real eigenvalue problem, which is a degenerated form of the wing flutter governing equations. Finally, illustrative examples are prepared to demonstrate the validity of the present method, which is insensitive to mesh density and does not require structural modal analysis for aeroelastic stability.

关键词： Aeroelastic stability flutter torsional divergence high aspect ratio aircraft wing transfer function method

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High-stability temperature control and frequency-domain analysis of sandwich-like insulation design based on phase change materials for satellite thermal management

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Science China(Technological Sciences) 2024年第8期67卷 2387-2404页

作者： WANG ZiHan HE ChenBo HU Yang TANG GuiHua Key Laboratory of Thermo-Fluid Science and Engineering Ministry of EducationSchool of Energy and Power EngineeringXi’an Jiaotong UniversityXi’an 710049China

High-stability thermal management is critical for the measurements of high sensitivity for temperature, but also challenging because any small thermal disturbances could lead to unacceptable temperature fluctuations. The present work delivers a design for passive temperature control, customized for a component in the satellites for gravitational wave detection. A novel sandwichlike structure is proposed with the configurations of proper materials, consisting of a layer of insulation material and two layers of nanocomposite phase change materials, bringing an integration of heat insulation and absorption/storage. Its performance is examined using an improved thermal network model and the revised transfer function method(TFM). The basic results of the two methods are validated by present COMSOL simulations and available numerical and experimental data in the literature. An effective reduction of temperature fluctuation is achieved to the scale of 0.1 K, even under two thermal disturbances from different directions: a radiative heat flux of 20 W m~(-2)(inside) and a temperature fluctuation of about 20 K(outside). Moreover,the TFM is employed to analyze the effects of the frequency of thermal disturbance: excellent damping performance is obtained for over 3.2 mHz and the underlying mechanism is discussed. Overall, the present design is expected to be combined with active temperature control to explore more possible ways for temperature control with higher stability.

关键词： temperature control sandwich insulation structure phase change material thermal network model transfer function method

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Study on vibration characteristics of anisotropic vehicle rubber bushings by conformal contact force analysis

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VEHICLE SYSTEM DYNAMICS 2024年

作者： Jeon, Jonghoon Kwon, Semin Kwon, Seungmin Park, Junhong Hanyang Univ Dept Mech Engn Seoul South Korea Purdue Univ Weldon Sch Biomed Engn W Lafayette IN USA Hyundai Motor Co Hwaseong Si South Korea

For ride comfort and handling performance design of vehicles, anisotropic rubber bushings are used as the connection between lower arms and body frames. The nonlinear vibration performance with the deformation amplitude is advantageous to minimise vibration transmission at low magnitude responses and to reduce deformation at large excitations. During transient deformation, the area under the force-deformation curve serves as an indicator for evaluating vibration reduction and isolation performance. The elastomer geometric variables such as the relative radius between the inner and outer contact surfaces are effective design parameters for controlling bushing dynamic behaviour. This study presents a dynamic model to understand the nonlinear stiffness by the contact theory after addressing the actions between elastomer surfaces. The proposed model was confirmed by the measured dynamics stiffness and damping performance. Their influence on the vehicle ride comfort was investigated.

关键词： Anisotropic rubber bushing nonlinear stiffness conformal contact model transfer function method

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Design of an improved impedance tube to measure sound absorption coefficients of flexible textile materials

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ENGINEERING RESEARCH EXPRESS 2024年第1期6卷 015413-015413页

作者： Li, Yunlong Dai, Yang Yao, Guangchun Luo, Wan Zhi, Chao Xing, Yu Xian Polytech Univ Sch Mech & Elect Engn Xian 710048 Peoples R China Northwestern Polytech Univ Sch Marine Sci & Technol Xian Peoples R China

Textile materials have demonstrated significant potential in sound noise reduction due to their porous, lightweight, and easily processed nature. However, the current experimental setup for measuring the sound absorption of small-sized samples is expensive. Additionally, there is a lack of suitable equipment for measuring the sound absorption of flexible textiles as it is challenging to mount flexible samples into an impedance tube. This paper presents the design, fabrication, and testing of impedance tubes specifically designed for measuring the sound absorption coefficients of textile materials. The impedance tubes were designed based on the transfer function and two-microphone methods, with diameters of 100 mm and 30 mm. These tubes covered frequency ranges from 200-1600 Hz and 500-6400 Hz, respectively. Furthermore, improved sample holders were developed to mount flexible textile materials without altering the acoustic impedance characteristics of the front surface of the test sample. Validation experiments were conducted on melamine foams, and the results were compared with those obtained from the commercial B&K 4206 setup. The results obtained from the designed setup showed good agreement with those from the B&K 4206 system. The maximum error observed was 8% at 2800 Hz for the 30 mm diameter tube and 8.3% at 1600 Hz for the 100 mm diameter tube. Finally, the designed system was used to measure the sound absorption coefficients of textile materials with varying densities. The results obtained were consistent with the material properties, demonstrating the effectiveness of the designed setup.

关键词： textile materials sound absorption impedance tube setup transfer function method

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