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Nonlinear Dynamics Analysis and Vibration Reduction of Two Sandwich Beams connected by a Joint with clearance

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SSRN 2024年

作者： Guo, Zhenkun Jiang, Shuai Shen, Yongjun Jiang, Guoqing Xiao, Boya Xu, Qi Li, Meng Beijing Engineering Research Center of Monitoring for Construction Safety Beijing University of Civil Engineering and Architecture Beijing100044 China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China School of Mechanical Engineering Zhejiang Sci-Tech University Hangzhou310018 China Key Laboratory of Microgravity Chinese Academy of Sciences Beijing100190 China School of Mechanics and Aerospace Engineering Southwest Jiaotong University Chengdu610031 China

The dynamics and vibration reduction characteristics of the hinged sandwich beams with clearance fixed at both ends is studied theoretically and experimentally. A transverse and torsional spring system with clearance is used to equivalent the joint model. The homogenization method is used to equivalent the core layer and Rayleigh-Ritz method is utilized to derive the mode function of the interconnected sandwich beam by using a sequence of orthogonal polynomials. The nonlinear motion equation of the two jointed sandwich beam structure with clearance is derived by the application of the Hamilton principle and then solved using an improved Newmark integration approach. In order to validate the accuracy of the natural frequency and vibration mode, the finite element model is established. This paper examines the impact of clearance on the amplitude-frequency response and vibration transmission of a two jointed sandwich beam structure, it is found the hinged sandwich beams show obvious nonlinear characteristics and intermittent vibration transmission phenomenon due to the clearance. Moreover, the vibration transmission analysis reveals that the existed clearance demonstrates significant vibration reduction effect, for which an experiment is conducted to validate the results. In general, this work proposes a novel approach for modeling sandwich structures with clearance with improved vibration reduction performance. © 2024, The Authors. All rights reserved.

关键词： Homogenization method

Mitigation of Shady-Sunny Slopes Effect on Subgrade by Photovoltaic Sheltered Boards in Permafrost Regions

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SSRN 2024年

作者： Tian, Run-Ze Li, Xiao-Kang Zhang, Yu Zhang, Lu-Xin Yue, Zu-Run Li, Xu Key Laboratory of Urban Underground Engineering of Ministry of Education Beijing Jiaotong University Beijing China School of Traffic and Transportation Lanzhou Jiaotong University Lanzhou730070 China China Railway Northwest Science Research Institute Co. Ltd China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang China

The temperature disparity between shady and sunny slopes leads to uneven subgrade deformation in permafrost regions. In response, this paper introduces a novel photovoltaic sheltered boards (PSB) subgrade and conducts a numerical investigation into its mitigation of shady-sunny slopes effect. The study commences with developing a two-dimensional heat transfer model, accounting for the coupled boundary of solar radiation and air convection. The numerical model was validated through monitored temperature data from the Beiluhe observation station. Subsequently, the study calculates the temperature distribution of the exposed subgrade to illustrate the effect of shady-sunny slopes and identify influencing ***, this study explores the feasibility of equalizing differential temperatures through insulated boards (IB), which refers to the traditional subgrade with laid IB and the novel PSB subgrade with suspended IB. Finally, the mitigation effects of temperature difference of two modes are compared, considering key parameters including solar radiation, subgrade alignment, wind speeds, and reflection rate. The study concludes that solar radiation significantly influences the shady-sunny slope effect, followed by subgrade direction, wind speed, and reflection rate. Both IB and PSB modes can reduce thaw depths and mitigate the shady-sunny slope effect by blocking solar radiation, with PSB demonstrating superior effects due to heat convection among an adjustable suspension height. Additionally, PSB results in a reduction of over 3 ℃ in the average annual temperature of the sunny slope and is recommended to be suspended at a height exceeding 5.3 cm in the research area. In summary, the PSB subgrade effectively mitigates shady-sunny slopes and is recommended with comprehensive consideration of mitigation performance and carbon emissions. © 2024, The Authors. All rights reserved.

关键词： Heat convection

compressive Sensing Reconstruction for Rolling Bearing Vibration Signal Based on Improved Iterative Soft Thresholding Algorithm

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SSRN 2022年

作者： Wang, Haiming Yang, Shaopu Liu, Yongqiang Li, Qiang School of Mechanical Electronic and Control Engineering Beijing Jiaotong University Beijing010044 China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China

A new method of acquisition and reconstruction based on compressive sensing theory is introduced in this paper. An improved ISTA (IISTA) is proposed. Firstly, an acceleration operator considering step size is proposed to estimate the gradient, which can accelerate convergence speed. Then for breaking the limitation of fixed internal gradient step size, a bidirectional search principle is introduced to backtrack its iteration step size. Finally, the constraints of the quadratic approximation model on the reconstruction objective function is proposed to adaptively determine optimal iteration step size. The effectiveness of the method is verified by the reconstruction of bearing vibration signals in different health states. The results show that the proposed method can achieve convergence faster, improve the sparsity of the regular term, and has a better reconstruction performance than the conventional ISTA under different sampling rates. © 2022, The Authors. All rights reserved.

关键词： compressed sensing

Reinforcing shell elements for fiber-reinforced composites undergoing large deformations and general motion

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composite structures 2025年 366卷

作者： Li, Yanhu Lu, Yongjie Song, Jibo Zhang, Linao State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University No. 17 North 2nd Ring East Road Shijiazhuang Hebei050043 China School of Mechanical Engineering Shijiazhuang Tiedao University No. 17 North 2nd Ring East Road Shijiazhuang Hebei050043 China Department of Mechanical and Electrical Engineering Shijiazhuang College of Applied Technology No. 226 Tianning Road Shijiazhuang Hebei050043 China

Fiber-reinforced composites offer excellent mechanical properties and lightweight advantages in multibody systems. However, their significant anisotropy and geometrical and material nonlinearities present challenges for accurate modeling and simulation. In this paper, two new types of reinforcing shell elements are developed within the Absolute Nodal coordinate Formulation framework. The first type assumes that each fiber behaves as an Euler beam with only tensile and bending stiffness, making it suitable for simulating reinforcing fibers with arbitrary orientations and nonuniform materials and cross-section areas. The second type employs elastic force formulation based on Kirchhoff–Love theory or continuum mechanics. It is suitable for simulating reinforcing fibers that appear in a layered form with unique orientation, material, and cross-section area. The fibers and matrix are described independently in these new reinforcing elements, coupled through consistent deformation compatibility conditions. This approach allows different material models and element formulations for the fibers and matrix to be used. Furthermore, multiple fibers (or layers) can be embedded within a single reinforcing shell element, providing more accurate representations of the actual physical structure. The effectiveness of the developed reinforcing elements is validated through several benchmark problems. Numerical results demonstrate that both types of reinforcing shell elements are locking-free and can automatically capture the reinforcing effects of the fibers and the coupled deformation modes. This investigation enriches the element library of the Absolute Nodal coordinate Formulation and provides an effective tool for the accurate simulation and optimal design of fiber-reinforced composites in multibody systems. © 2025

关键词： Shells (structures)

Indentation Responses of Piezoelectric Semiconductors

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SSRN 2023年

作者： Liu, Jinxi Gao, Shijing Zhang, Zeran Nie, Guoquan chen, Weiqiu State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China School of Mechanical Engineering Shijiazhuang Tiedao University Shijiazhuang050043 China Department of Engineering Mechanics Hebei Key Laboratory for Mechanics of Intelligent Materials and Structures Shijiazhuang Tiedao University Shijiazhuang050043 China Key Lab of CAD & CG Key Laboratory of Soft Machines and Smart Devices of Zhejiang Province Department of Engineering Mechanics Zhejiang University Hangzhou310027 China

In this paper, the indentation responses of a piezoelectric semiconductor (PSc) half-space by an insulating and rigid spherical indenter are investigated. It is assumed that the contact area between the indenter and the PSc is frictionless. Based on the Hankel integral transformation, the considered indentation problem is reduced to a pair of dual integral equations. Due to the complexity of the coupled governing differential equations, the explicit closed-form expressions for the PSc indentation responses cannot be derived like the piezoelectric counterparts. Therefore, the dual integral equations are converted into the Fredholm integral equation of the second kind, which is numerically solved to determine the concerned responses. These responses include the relationships of the indentation force, the electric potential and the change of carrier concentration with the indentation depth. The numerical results show that the semiconducting property has a significant influence on the indentation characteristics. In addition, the three-dimensional finite element simulations are carried out to validate the theoretical results computed by the singular integral equation method. It turns out that the two results are well consistent. The distributions of the stress and electric potential near the contact area are simulated by finite element method to reveal the effect of the steady carrier concentration. The obtained findings are useful for understanding the interaction between piezoelectricity and semiconducting property. © 2023, The Authors. All rights reserved.

关键词： Indentation

Influence of External Structure and Internal Stacking on Wind Load characteristics of Large Span Spherical Shell Structure

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SSRN 2023年

作者： Liu, Xiaobing chen, Anjie Yang, Qun Feng, Bin Tian, Xuedong State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China Innovation Center for Wind Engineering and Wind Energy Technology of Hebei Province Shijiazhuang050043 China School of Civil Engineering Shijiazhuang Tiedao University Shijiazhuang050043 China

In order to study the wind load characteristics of the large span spherical shell structure, a rigid model pressure test was conducted in a wind tunnel laboratory to study the effects of different external structures and internal stacking forms on wind loads of a spherical shell structure in an actual project. The variation laws of the shape factor and the integral force coefficient of the spherical shell structure under different test cases are compared and analyzed. The results show that the shape factor of the spherical shell structure is only affected near the interference when the transfer station and trestle are arranged. When the two spherical shell structures are arranged in series and the adjacent spherical shell structure is located upstream, the shape factor of the spherical shell structure is most affected, and there is a significant reduction effect at the bottom of the windward surface. compared with the external structure, the influence of different internal stacking forms on the shape factor of the spherical shell structure is relatively weak. The interference effect of the adjacent spherical shell structure makes the stress situation of the spherical shell structure better than that of the spherical shell structure without the adjacent spherical shell structure in most wind directions. The integral force coefficient of the spherical shell structure is the highest when the internal stacking is full, and the lowest when there is no internal stacking. Therefore, the integral force coefficient of the spherical shell structure when the internal stacking is full can be used as a reference for the design of the frame of the spherical shell structure. © 2023, The Authors. All rights reserved.

关键词： Shells (structures)

Experimental Study on Fluctuating Aerodynamic Force and Wind Pressure Distribution characteristics of Three circular cylinders Arranged Inline

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SSRN 2023年

作者： Liu, Xiaobing Jiang, Huimin Wang, Shibo Liu, Xiqiang Yang, Qun State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China Innovation Center for Wind Engineering and Wind Energy Technology of Hebei Province Shijiazhuang050043 China School of Civil Engineering Shijiazhuang Tiedao University Shijiazhuang050043 China

The fluctuating aerodynamic force and wind pressure distribution characteristics of three circular cylinders arranged inline at different incidence angles and spacing ratios were studied via rigid model pressure measurement wind tunnel tests. The results were compared with those of a single cylinder. The Reynolds number is 6.4×104. The range of incidence angle α and spacing ratio L/D (the ratio of the center distance between adjacent cylinders to the diameter of the cylinder) are 0°~90° and 1.2~4.0, respectively. The spacing ratio and incidence angle greatly influence the fluctuating aerodynamic force coefficients and wind pressure coefficients. According to the spacing ratio, the fluctuating aerodynamic characteristics can be roughly divided into three states: small spacing ratios (1.2≤L/D≤2.0), medium spacing ratios (2.0 © 2023, The Authors. All rights reserved.

关键词： circular cylinders

Load Distribution Uniformity of Assembled Emergency Steel Bridge Pier columns

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SSRN 2024年

作者： Liu, Zi-Yu chen, Shi-Tong Zhi, Mo-Mo cheng, Shuai-Qi Fan, Xin Collaborative Innovation Center for Performance and Security of Large-scale Infrastructure Shijiazhuang Tiedao University Shijiazhuang China Hebei Eng. Innovation Center for Traffic Emergency and Guarantee Shijiazhuang Tiedao University Shijiazhuang China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang China

Throughout the utilization of assembled emergency steel bridge piers, there is a significant discrepancy in the load carried between different columns, which can lead to premature failure of individual columns and potentially trigger the collapse of the entire structure. currently, there is no mature method for calculating and implementing load distribution. Based on an improved Fourier series and energy principle, this paper proposes a universal calculation method for the load distribution of columns in assembled emergency steel piers. A specific assembled emergency steel pier is selected as the research subject to conduct model tests and simulation experiments. Through mutual verification of theory, experiments, and simulations, this study analyzes the key factors affecting the load distribution of columns, examines the mechanisms and patterns of their impacts, and explores general principles for the even distribution of loads. The research shows: As the column height or diameter-to-thickness ratio increases, the proportion of load borne by the corner columns and transverse edge columns increases, while the central and longitudinal edge columns see a reduction in their load proportions. A pier-beam linear stiffness ratio based on an overall consideration is proposed. As the height of the columns or the diameter-to-thickness ratio increases, the pier-beam linear stiffness ratio tends to decrease. Using the coefficient of variation of column loads as the standard for evaluating the pier-beam linear stiffness ratio, the recommended threshold for the application of the pier-beam linear stiffness ratio in engineering should be between 3 and 3.86. © 2024, The Authors. All rights reserved.

关键词： Steel bridges

Analyzing convective Heat Transfer in combined Solar chimneys: A Theoretical and Numerical Study of key Influencing Parameters

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SSRN 2024年

作者： cui, Huimin Han, Mengjiao Zhang, Jitao Han, Zhiming Liu, Qingkuan State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China Innovation Center for Wind Engineering and Wind Energy Technology of Hebei Province Shijiazhuang050043 China Department of Mathematics and Physics Shijiazhuang Tiedao University Shijiazhuang050043 China School of Civil Engineering Shijiazhuang Tiedao University Shijiazhuang050043 China

combined solar chimneys represent a potent mechanism for harnessing solar energy to bolster natural ventilation in green building designs. This study focuses on the impact of structural parameters and external conditions on the ventilation and heat transfer performance of such systems. Through scaling analysis and numerical simulations, we investigate the flow dynamics and heat transfer mechanisms. We examine the mechanism and the influence of three critical control parameters: inlet size ratio (h/H), ratio of inclined to vertical section lengths (L/H), and Rayleigh number (Ra). Our findings indicate that ventilation and heat exchange performance exhibit an initial increase followed by a decline as the inlet size ratio expands from 0.10 to 0.40. Optimal ventilation efficiency is observed at a Rayleigh number of 1.98×1014 with an inlet size ratio of 0.15. conversely, a low ratio of inclined to vertical section lengths (L/H=0.20) correlates with suboptimal ventilation performance. Both ventilation intensity and efficiency are positively correlated with increases in Ra. This research quantitatively delineates these relationships, providing a theoretical foundation for the design of natural ventilation systems in sustainable buildings using combined solar chimneys. © 2024, The Authors. All rights reserved.

关键词： computational fluid dynamics