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Mechanical Analysis of Interface in Coating Structure under Conical Concave Indenter with FEM

Journal of Applied Mathematics and Physics 2022年第5期10卷 1509-1524页

作者： Shi-Qing Huang Pan-Jun Tang Wen-Hua Zhang MOE Key Lab of Disaster Forecast and Control in Engineering Jinan University Guangzhou China School of Mechanics and Construction Engineering Jinan University Guangzhou China

The evaluation of mechanical properties of coating structures has always been a very important topic in the fields of mechanics, materials, and machinery. The traditional evaluation methods are easy to produce deviation, because the ratio of coating thickness to substrate thickness is too small. Therefore, accurate analysis and calculation is particularly important. Indentation technology is an important means of coating structure analysis and measurement, the basis of standardized application and analysis of coating structure, and a classical method for accurate analysis and calculation of coating structure. The finite element method is a very good means to analyze and study this kind of problems because of its applicability. Based on the finite element method, this paper analyzes and studies the interface connection form, substrate, and local delamination effects of the indentation behavior of the coating structure under the conical concave indenter. In this paper, the finite element method, which is more convenient for analysis and calculation, is used to analyze the influence of interface connection form, substrate, and local delamination on the coating structure. The results of force displacement, interface normal stress, and interface shear stress are analyzed in detail, and the effects of the three effects on the coating structure are proved. The significance of this study is reflected in: based on the analysis of the three effects of interface connection form, substrate, and local delamination, the mechanical properties of the coating structure are more in-depth, which provides some reference for mechanical engineers to design and test the coating structure.

关键词： Coating Structure Finite Element Method Contact Mechanics Interfacial

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A Novel Improved Dragonfly Algorithm-Based Structural Damage Identification Approach Using Flexibility Assurance Criterion and Trace Lasso

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INTERNATIONAL JOURNAL OF STRUCTURAL STABILITY AND DYNAMICS 2024年第13期24卷 2450144-2450144页

作者： Chen, Zepeng Zhao, Di Liu, Qitian Zhang, Zhiyu Yu, Ling Foshan Univ Sch Transportat & Civil Engn & Architecture Foshan Peoples R China Jinan Univ Guangzhou MOE Key Lab Disaster Forecast & Control Engn Sch Mech & Construct Engn Jinan Peoples R China

Aiming to enhance the accuracy, stability, and noise robustness of swarm intelligence-based algorithms for structural damage identification (SDI), a novel improved dragonfly algorithm (IDA) is proposed. The IDA integrates the dragonfly algorithm (DA) with three key strategies including enhanced Levy flight, optimal solution bidirectional search, and greedy preservation. These strategies are introduced to enhance the exploration capability of the original DA and improve the IDA's capacity to obtain global optima. An objective function is defined using frequency change ratio and flexibility assurance criterion (FAC). Additionally, trace sparse regularization is also incorporated into the objective function since most of the damages in structures tend to be sparsely distributed, so that a sparse result is ensured to improve SDI accuracy. To evaluate the performance of the proposed algorithm, a comparison of the original DA and IDA is conducted using four benchmark functions. The results demonstrate that the proposed algorithm achieves improved convergent rate and accuracy. Furthermore, numerical simulations are performed on a 10-element simply-supported beam and a 31-element planar truss to validate the effectiveness and efficiency of the proposed algorithm in SDI. Significantly, the utilization of IDA instead of DA leads to a substantial reduction in the average calculated relative error for the truly damaged element within the considered damage cases of the simply-supported beam, decreasing from 13.05% to 6.15%. Moreover, an experimental simply-supported beam structure with several assumed damage cases is fabricated in the laboratory. The experimental results further confirm the robustness and capability of the proposed method in real-world SDI applications.

关键词： Structural damage identification (SDI) improved dragonfly algorithm (IDA) flexibility assurance criterion (FAC) trace sparse regularization model updating

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A Mathematical Analysis Method for Bending Problem of Clamped Shallow Spherical Shell on Elastic Foundation

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INTERNATIONAL JOURNAL OF COMPUTATIONAL METHODS 2022年第7期19卷

作者： Li, Shanqing Yang, Chunsheng Xia, Fengfei Yuan, Hong Jinan Univ Sch Mech & Construct MOE Key Lab Disaster Forecast & Control Engn Guangzhou Peoples R China

A mathematical analysis method is employed to solve the bending problem of slip clamped shallow spherical shell on elastic foundation. Using the slip clamped boundary conditions, the differential equations of the problem are simplified to a biharmonic equation. Using the R-function, the fundamental solution and the boundary equation of the biharmonic equation, a function is established. This function satisfies the homogeneous boundary condition of the biharmonic equation. The biharmonic equation of the slip clamped shallow spherical shell bending problem on elastic foundation is transformed to Fredholm integral equation of the second kind by using Green's formula. The vector expression of the integral equation kernel is derived. Choosing a suitable form of the normalized boundary equation, the singularity of the integral equation kernel is overcome. To obtain the numerical results, the discretization of the integral equation of the bending problem is conducted. The treatment of singular term in the discretization equation is to use the integration by parts. Numerical results of rectangular, trapezoidal, pentagonal, L-shaped and concave shape shallow spherical shells show high accuracy of the proposed method. The numerical results show fine agreement, with the ANSYS finite element method (FEM) solution, which shows the proposed method is an effective mathematical analysis method.

关键词： Clamped shallow spherical shell elastic foundation bending problem biharmonic equation Green function R-function

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Study on Parameter Measurement of Thin Films with Substrate Effect Based on Contact Mechanics

SSRN

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SSRN 2023年

作者： Zhang, Wen-Hua MOE Key Lab of Disaster Forecast and Control in Engineering Jinan University Guangzhou510632 China School of Mechanics and Construction Engineering Jinan University Guangzhou510632 China

The development of contact theories for film are valuable for high-precision machining and measurement. Herein, based on the constitutive equations and potential theory method, accurate contact mechanics theories of films under common indenter loading are established, where the film structures are "film with two free boundaries" and "film/rigid substrate". The displacement and stress at arbitrary position can be obtained with the exact solutions, which are represented by elementary functions. It is convenient for engineers applicating the theories when addressing contact problem of films. The influence of substrate effects and film parameters on contact radius and indentation depth was analyzed. It is found that Poisson’s ratio has little influence on indentation curves, which is mainly affected by the elastic modulus. An effective method for measurement of film material parameters is presented. With numerical software platforms, the analytic algorithm could be transformed into numerical codes and be integrated in special software. © 2023, The Authors. All rights reserved.

关键词： Constitutive equations

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The Effects of RF Power and Cavity Structure on the Plasma Discharge Characteristics of RPS

The Effects of RF Power and Cavity Structure on the Plasma D...

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2023 International Conference on Electronics and Devices, Computational Science, ICEDCS 2023

作者： Lin, Hai Su, Wei Chen, Ming Liu, Renhuai Jinan University School of Mechanics and Construction Engineering Guangzhou510632 China China Electronic Product Reliability and Environmental Testing Research Institute Sci. and Technol. on Reliability Phys. and Application Technology of Electronic Component Laboratory Guangzhou510610 China Moe Key Lab of Disaster Forecast and Control in Engineering Guangzhou510632 China

ISBN: (纸本)9798350343038

In this paper, a two-dimensional model of plasma diffusion in remote plasma source discharge chamber is established by COMSOL plasma module. The electron density and electron temperature distributions inside the discharge cavity were obtained by adjusting the thickness of alumina coating and the magnitude of RF power parameters. Based on the results, the authors discuss the effects of different alumina coating thickness and RF power on the electron density and electron temperature inside the discharge cavity, which provide theoretical guidance for the subsequent optimization of the internal structure of the discharge cavity and the discharge parameters. © 2023 IEEE.

关键词： Carrier concentration

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Evolution law of pulsating seepage and thermal deformation by injecting high-temperature steam into coal for thermal coalbed methane recovery

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Deep Underground Science and engineering 2025年第1期4卷 119-131页

作者： Zhiqiang Li Junliang Li Jinsheng Chen Ali Karrech Ningchao Zhang Ju Chang Kaiqi Jin Yangyang Yu Hongbin Wang Aijie Wang MOE Engineering Center of Mine Disaster Prevention and Rescue Henan Polytechnic UniversityJiaozuoChina Collaborative Innovation Center of Coal Work Safety and Clean High Efficiency Utilization Henan Polytechnic UniversityJiaozuoChina School of Safety Science and Engineering Henan Polytechnic UniversityJiaozuoChina Henan Provincial Key Lab of Gas Geology and Control-Cultivation Base of Provincial and Ministry Joint State Key Henan Polytechnic UniversityJiaozuoChina School of Engineering The University of Western AustraliaPerthAustralia

Chinese coal reservoirs are characterized by low pressure and low permeability,which need to be enhanced so as to increase ***,conventional methods for permeability enhancement can only increase the permeability in fractures,but not the ultra-low permeability in coal *** to enhance such impermeable structures lead to rapid attenuation of gas production,especially in the late stage of gas *** stimulation by injecting high-temperature steam is a promising method to increase gas *** critical scientific challenges that still hinder its widespread application are related to the evolution law of permeability of high-temperature steam in coal and the thermal deformation of *** this study,an experimental approach is developed to explore the high-temperature steam seepage coupled with the thermal deformation in coal under triaxial *** tests were conducted using cylindrical coal specimens of?50 mm×100 *** permeability and thermal strain in coal were investigated when high-temperature steam was injected at151.11,183.20,213.65,and 239.76°*** experimental results reveal for the first time that as the amount of injected fluid increases,the steam permeability shows periodic pulsation *** paper introduces and explains the main traits of this discovery that may shed more light on the seepage *** the injected steam temperature increases,the amplitude of pulsating permeability decreases,whereas the frequency increases;meanwhile,the period becomes shorter,the pulsation peak appears earlier,and the stabilization time becomes *** average peak permeability shows a“U-shaped”trend,decreasing first and then increasing as the steam temperature ***,with the extension of steam injection time,the axial,radial,and volumetric strains of coal show a stage-wise expansion characteristic at different temperatures of steam injection,except for the radial strains at 151.11°C.A two-phase flo

关键词： coalbed methane permeability pulsation steam thermal deformation two-phase flow

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Acceleration spectrum analysis of hyperbolic tangent package under random excitation

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PACKAGING TECHNOLOGY AND SCIENCE 2021年第9期34卷 579-587页

作者： Yang, Song-Ping Wang, Zhi-Wei Jinan Univ Packaging Engn Inst Zhuhai 519070 Peoples R China Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou Peoples R China

Many packaging cushion materials follow the hyperbolic tangent type of constitutive relation, so a hyperbolic tangent stiffness non-linearity was derived to describe the stiffness property of the package. Transport package was modelled as the single degree of freedom (SDOF) of hyperbolic tangent spring-mass-damping (SMD) system. The displacement and velocity responses of the system were obtained by Fokker-Planck-Kolmogorov (FPK) equation. Based on the kinematic equation and integral transforming, the approximate analytic solution of the acceleration response power spectral density (PSD) of the hyperbolic tangent package was established for the first time, and the influences of system non-linearities on the acceleration response PSD were investigated. Validation experiment with a complete packaged computer was carried out to verify the proposed approach. Non-linearity of the stiffness influenced the acceleration response PSD through the effect of parameter gamma and statistical moment m(i0). The frequency corresponding to acceleration response peak was determined by the damping correlation coefficient alpha and parameter gamma, which was determined by system characteristic parameter beta, frequency parameter omega(0) and statistical moment m(io). The proposed approach can be used to predict the acceleration response PSD of transport package, and the analysis has important value for packaging optimization design.

关键词： acceleration hyperbolic tangent package PSD random excitation

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Nonlinear vibration of SMA hybrid composite beams actuated by embedded pre-stretched SMA wires with tension-bending coupling effect

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JOURNAL OF SOUND AND VIBRATION 2024年 568卷

作者： Jin, Fusong Zhao, Chen Xu, Peng Xue, Jianghong Lin, Jixin Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China Hubei Engn Univ Sch Mech Engn Xiaogan 432000 Peoples R China

Theoretical and numerical analyses for nonlinear vibrations of the shape memory alloy hybrid composite(SMAHC) beam actuated by the pre-stretched shape memory alloy(SMA) fibers with tension-bending coupling effect are presented in this paper. Under the sudden action of thermal temperature, a recovery force and moment are caused in the SMAHC beam due to the phase transition in the SMA fibers, exciting the nonlinear vibration of the SMAHC beam. The onedimensional Brison constitutive model was adopted to express the influence of the phase transition temperature, initial volume fraction of martensite, and pre-strain on the phase transition in the shape memory alloy. On this basis, the constitutive law of the SMAHC beam is built by considering the tension-bending coupling effect and the phase transition in the SMAHC beam. The equation of motion for nonlinear vibration of the SMAHC beam with geometric nonlinearity and material nonlinearity is derived from the Hamilton principle and is discretized into matrix form using the Galerkin method. According to the algorithm of the NewMark-& beta;method, numerical solutions are computed by developing Matlab program and are compared with the results from ABAQUS analysis. It shows that the frequencies and amplitudes of the theoretical calculations are very consistent with those obtained from ABAQUS analysis. In addition, both the theoretical study and ABAQUS simulation indicates that the high frequency for longitudinal vibration is not observed in the spectrum diagram of transverse vibration, while the low frequencies for transverse vibration are captured in the longitudinal vibration. With the established Matlab program, parametric study is carried out to investigate the effect of the temperature and the location of the SMA fibers on the vibration responses of the SMAHC beam. The results from this study indicate that the transverse vibration of SMAHC beams is characterized as one of low frequency, while the longitudinal vibration ha

关键词： SMAHC Von-Karman nonlinear relationships Recovery force Coupling vibration

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Moving Force Identification Based on Group Lasso and Compressed Sensing

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INTERNATIONAL JOURNAL OF STRUCTURAL STABILITY AND DYNAMICS 2022年第15期22卷 2250170-2250170页

作者： Zhang, Luqi Liang, Yi Yu, Ling Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou Peoples R China

Moving force identification (MFI) is one of the challenging tasks in bridge structural health monitoring (SHM). Especially when the vehicles get on and off the bridge, or cross bridge expansion joints and speed humps, the impact of vehicle loads on bridge structures is commonly focused and the accuracy of MFI results still needs further enhancements. To address this issue, a new MFI framework is proposed by using both group sparsity theory and compressed sensing (CS) in this study. Specifically, with the help of the relationship between moving vehicle loads and bridge responses induced by the traffic, a redundant dictionary based on CS is used to establish the motion equation of the vehicle-bridge system in conjunction with classical theory of MFI. A group structure on the sparse coefficient vector of each moving force tends to be divided into different groups (no overlapping), where sparse coefficient vectors and measurement matrices are divided in different groupings and eventually reconstructed for unknown vectors of moving forces. Additionally, the effect of different ratios of number of groups to sparsity (g/k) on the MFI results is considered. Finally, numerical simulations and experimental verifications are carried out to assess the performance and capability of the proposed framework. The illustrated results show that the group lasso could precisely reconstruct the moving forces more accurately after proper grouping. The proposed new MFI framework outperforms the traditional L-2 regularization or CS methods with a higher identification accuracy and a good robustness to measurement noises, which can be effectively used for the MFI problem in practice.

关键词： Moving force identification group lasso compressed sensing block sparse model vehicle-bridge interaction

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Accurately and automatically simulating hysteresis loops of shape memory alloys

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CONTINUUM MECHANICS AND THERMODYNAMICS 2022年第3期34卷 739-761页

作者： Wang, Si-Yu Zhan, Lin Bruhns, Otto T. Xiao, Heng Jinan Univ Coll Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn West Huangpu Ave 601 Guangzhou 510632 Peoples R China Zhejian Univ Coll Aerosp & Aeronaut Engn Hangzhou 310058 Peoples R China Ruhr Univ Bochum Inst Mech D-44780 Bochum Germany

Toward directly simulating pseudo-elastic effects of shape memory alloys, new elastoplastic equations of von Mises type are proposed by correlating the yield surface radius with the yield surface center, thus establishing a new elastoplasticity model characterized by three coupled quantities for isotropic and anisotropic hardening. Within the framework of conventional macroscopic elastoplasticity, it is demonstrated that the new model can exactly reproduce pseudo-elastic hysteresis effects of shape memory alloys, with no need to characterize any microstructural features of solid-solid phase transitions. To this end, explicit expressions for the three hardening quantities introduced are presented in terms of two single-variable functions. Then, exact closed-form solutions are obtained for the uniaxial stress-strain responses in a loading and a subsequent unloading process, and such responses are shown to give rise to a hysteresis loop shaped just by the foregoing two single-variable functions. As such, hysteresis loops of arbitrary shapes can be simulated in a straightforward and accurate manner simply prescribing two single-variable functions shaping such loops. For the first time, cumbersome and time-consuming procedures both for conducting statistical averaging schemes and for identifying numerous unknown parameters may be bypassed with broad applicability.

关键词： Shape memory alloys Pseudo-elasticity Finite strain Elastoplastic equations Combined hardening

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