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A method of coating analysis based on cylindrical indenter loading on coated structure

ACTA MECHANICA 2023年第5期234卷 2223-2267页

作者： Huang, Shi-Qing Tang, Pan-Jun Hou, Peng-Fei Zhang, Wen-Hua Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China Jinan Univ Sch Mech & Construct Engn Guangzhou 510632 Peoples R China Chinese Acad Sci GBA Branch Aerosp Informat Res Inst Guangzhou 510700 Peoples R China Hunan Univ State Key Lab Adv Design & Mfg Vehicle Body Changsha 410082 Peoples R China Hunan Univ Dept Engn Mech Changsha 410082 Peoples R China

The most common coated structure contact problems include spherical, conical and cylindrical contact. The evaluation of mechanical performance for coating structures has always been a very important issue in the field of mechanics and materials;due to the too small proportion between the thickness of the coating and the substrate, the deviation of traditional evaluation methods becomes unacceptable. Indentation technology is the basis for analysis, measurement, and the standardized application of coating structures. The research object of this paper is cylindrical contact, which is one part of building the theoretical framework of contact mechanics of coating structures. In the paper, an accurate and efficient general theory of the frictional cylindrical contact problem for the coated structure is presented. The general solutions are expressed in the form of harmonic functions. 3D exact solutions of a transversely isotropic elasticity coated structure under frictional cylindrical punch contact are derived, based on the general solution and the boundary conditions. The theory is proposed in two cases, including the frictionless contact and the frictional contact. By contrast with existing theories (obtained in this paper by degradation), the numerical calculations show the good convergence, high accuracy, efficiency, and stability. The difference of stress singularity analysis between Finite Element Method (FEM) and the presented theory is explained, which shows the theory's validity and applicability. This analytical theory plays an important role in boundary stress singularity analysis. The finite element comparison shows that the analytical theory plays an important role in boundary stress singularity analysis and further, proves the validity and applicability of this theory. In the numerical analysis, the influence of coating thickness on interface stress is shown, the distribution forms of stress and displacement are given, and the influence of material paramete

关键词： Finite element method Coating

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Strengthening layer with nano-twins in titanium alloy induced by laser surface re-melting: Mechanism of high strength and ductility

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MATERIALS CHARACTERIZATION 2023年第1期196卷

作者： Li, Kunmao Liu, Xiaochun Liu, Yujing Wu, Xiang Zhang, Wencai Yang, Junjie Li, Wei Zhou, Shengfeng Jinan Univ Inst Adv Wear & Corros Resistance & Funct Mat MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China Changsha Univ Sci & Technol Coll Mat Sci & Engn Inst Met Sect 2 960 Wanjiali RD S Changsha 410004 Hunan Peoples R China Jinan Univ Affiliated Hosp 1 Dept Orthoped Guangzhou 510632 Peoples R China Chongqing Univ State Key Lab Mech Transmiss Chongqing 400044 Peoples R China

To increase the strength of titanium (Ti) alloys, severe plastic deformation techniques are usually adopted to refine their grain structure, but these methods have long processing cycle, high cost, and easily result in the oxidized of Ti alloys. This work proposes a strategy of laser surface re-melting (LSR) as-cast TC4-1Cu alloy, which can refine its grain into-63 nm at relatively lower costs and short manufacturing cycle. By forming a thin strengthening layer with a thickness of-60 mu m, the yield strength and tensile strength of the as-cast TC4-1Cu alloy are increased by 28% and 35%, respectively. More importantly, the {10-11} nano-twinned system is activated due to the tensile stress, thereby accommodating plastic strain. These improvements in properties are attributed to the surface strengthening layer with nano-twins and the homogenized elemental distribution, which can provide important implications for studying how to address the strength-ductility trade-off in as-cast Ti alloys.

关键词： Titanium alloy Laser surface re-melting (LSR) Nanostructured surface layer Nano-twins Mechanical properties

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Flow behavior of laval nozzle sets in steam turbine governing stage at low loads

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THERMAL SCIENCE AND engineering PROGRESS 2023年 46卷

作者： Gan, Yiming Huang, Chang Wang, Weiliang Jinan Univ Energy & Elect Res Ctr Zhuhai 519070 Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China

To achieve carbon neutrality, thermal power units (TPU) will be deeply involved in peak regulation, which is crucial for the development of renewable energy generation. However, the efficiency of TPU is significantly reduced at low loads. The main reason for this is that the convergent nozzles in conventional TPU are difficult to efficiently expand steam with large pressure differentials (i.e., pressure ratios below a critical value), and thus the unit is designed to operate in sliding-pressure mode, resulting in a low Rankine cycle efficiency. To reveal the mechanism of energy loss in the governing stage under peak shaving conditions, the flowing behavior of governing stage nozzle sets of a 330 MW steam turbine is investigated by CFD simulation in this study. The results indicated that the shock waves generated by the supercritical streamflow and the angle deviation at the exit of nozzle sets are the main factors leading to energy efficiency degradation. Based on this, two supersonic Laval nozzles were designed and analyzed in the 10 %similar to 40 % load range. Compared with conventional nozzles, the designed supersonic nozzles I and II showed average efficiency improvements of 4.9 % and 5.8 %, respectively, and maximum efficiencies of 6.6 % and 9.5 %, respectively. The research in this paper can provide theoretical support for the design and development of nozzle sets under deep peaking conditions, which can help achieve carbon neutrality.

关键词： Supersonic Laval nozzles Flow behavior Governing stage Carbon neutrality CFD simulation

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Exact large strain analysis for the Poynting effect of freely twisted thin-walled tubes made of highly elastic soft materials

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THIN-WALLED STRUCTURES 2023年第1期184卷

作者： Han, Meng-Liang Wang, Hui-Yu Wang, Si-Yu Xiao, Heng Jinan Univ Sch Mech & Construct Engn Guangzhou 510632 Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China

Toward handling nonlinear coupling effects at large elastic deformations, a decoupled form of the multi-axial elastic potential for highly elastic soft materials is first constructed based on Hencky's logarithmic strain, and this new potential is then used to obtain analytic results for the uniaxial extension and compression of a bar, the equi-biaxial extension of a plate, the plane-strain extension of a strip and, in particular, the large torsion of a thin-walled tube with free ends. Novelties are included in the following three respects: (a) Experimental data for responses of the uniaxial extension, equi-biaxial extension (uniaxial compression) and plane-strain extension (simple shear) may be accurately matched up to large strain with strain-stiffening effects;(b) exact responses for the Poynting effect of freely twisted thin-walled tubes may be derived for changes in the axial length and the wall thickness as well as the averaged radius;and (c) the coupling nonlinear complexities involved in all such responses may be worked out in a decoupled sense.

关键词： Soft materials Highly elastic Thin-walled tube Large free torsion Decoupled approach

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Study on parameter measurement of elastic thin films with substrate effect based on contact mechanics

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INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES 2023年第1期271卷

作者： Zhang, Wen-Hua Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China Jinan Univ Sch Mech & Construct Engn Guangzhou 510632 Peoples R China

The development of contact theories for films is valuable for high-precision machining and measurement. Accordingly, accurate contact mechanics theories for films under common indenter loading are established based on the constitutive equations and potential theory method, Here, the film structures are "film with two free boundaries" and "film/rigid substrate." The displacement and stress at arbitrary positions can be obtained using exact solutions represented by elementary functions. The application of the foregoing theories to resolve the contact problem encountered in films is convenient for engineers. The influences of substrate and film parameters on contact radius and indentation depth were analyzed. Indentation curves are slightly influenced by Poisson's ratio, but primarily affected by the elastic modulus. An effective method for measuring of film material parameters is presented. Using numerical software platforms, the method's analytic algorithm can be transformed into numerical codes and be integrated into special software.

关键词： Film Spherical contact Conical contact Cylindrical contact Mirror image method Substrate effect Measurement

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Debonding Analysis of Adhesively Bonded Pipe Joints Subjected to Combined Thermal and Mechanical Loadings

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INTERNATIONAL JOURNAL OF COMPUTATIONAL METHODS 2022年第6期19卷

作者： Yuan, Hong Han, Jun Zhang, Huanliang Zeng, Lan Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China

In order to better understand the interfacial debonding behavior of pipe joints during the whole loading process, an analytical solution for the full-range behavior of adhesively bonded pipe joints under combined thermal and mechanical tensile loadings is presented in this paper. The solution was developed based on a simplified rigid-softening bond-slip model, and two cases with different softening region development were discussed. The analytical results were presented in a finite element model, and the effect of temperature on load-displacement curves and ultimate loads was shown based on the model. Through the nonlinear fracture mechanics, the analytical expressions of the interfacial shear stress and the load-displacement relationship can be obtained. The stress transfer mechanism, the interface crack propagation and the ductility behavior of the joints can be explained. This analytical result can help improve the potential application of fabricated structural components, precision instruments, oil and gas pipelines.

关键词： Pipe joints interfacial debonding thermal and mechanical coupling bond-slip model finite element model

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Nonlinear eccentric bending and buckling of laminated cantilever beams actuated by embedded pre-stretched SMA wires

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COMPOSITE STRUCTURES 2022年 284卷

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

This paper presents a theoretical approach to analyze the eccentric bending and buckling of laminated cantilever beams actuated by embedded pre-stretched SMA wires. Two mechanisms are involved: phase transition of the SMA wires and the nonlinear bending of the laminated beam. On the basis of material model for shape memory alloy during the phase transition in thermal field proposed by Brison, constitutive relations of the SMA hybrid laminated beams are established to interpret the relationship among the recovery stress, the internal stress, the thermal temperature and the thermal expansion. Governing equations in terms of the slope function and the horizontal displacement are derived according to von-Kaman geometrically nonlinear relationships. The nonlinear bending deformation of the SMA hybrid laminated beams is analyzed by considering the deflection due to eccentric bending moment as an initial imperfection and is solved using perturbation approach. A compatible condition is proposed to ensure consistent deformation between the SMA wires and the laminated beams. By developing Matlab program, parametric studies are carried out to investigate the effect of the pre-strain, the volume fraction and the location of the SMA wires on the deflection, the critical temperature, the recovery stress and the internal stress of the SMA hybrid laminated beams. The efficiency and accuracy of the analytical solutions were expounded by comparing with the results from finite element analysis. It is found that buckling may or may not occur in the SMA hybrid laminated beam relying on the value of the pre-strain of the SMA wires.

关键词： SMAHC von-Kaman nonlinear relationships Recovery stress Buckling Critical temperature

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Free vibration of non-shallow, laminated cylinders submerged in a fluid with general boundary conditions

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APPLIED OCEAN RESEARCH 2022年 125卷

作者： Yao, Sishi Zhang, Yaqian Xue, Jianghong Jin, Fusong He, Zanhang Jinan Univ Sch Mech & Construction Engn Key Lab Disaster Forecast & Control Engn MOE Guangzhou 510632 Peoples R China

This paper presents a theoretical approach to analyze the free vibration of laminated cylinders with general boundary conditions submerged in a fluid. Based on the assumption that the fluid is inviscid, irrotational and incompressible, the equation of motion of the fluid is established. Fluid-structure interaction between the cylinder and the fluid is conducted by satisfying the continuity conditions of the force and of the vibration velocity at the interfaces of the cylinder and the fluid. The curvature-deflection relations are modified to include the effect of the initial curvatures in the circumferential direction of the non-shallow shell. According to the mechanics of composite materials, governing equations for the cylinder undergoing out-of-plane vibration are derived and are solved using Rayleigh-Ritz method. Likely functions of the displacements for cylinders with general boundary conditions are proposed. Furthermore, finite element simulations are fulfilled using ABAQUS. A good agreement between the analytical solutions and finite element results illustrates the efficiency and accuracy of the proposed approach. With the established models, the influence of the slenderness ratio, radius thickness ratio, the material properties and the fluid-structure interaction on the vibration performance of the laminated cylinder submerged in the fluid is evaluated.

关键词： Laminated composites Fluid-structure interaction Non-shallow cylindrical shells Free vibration Rayleigh-Ritz method

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Analyzing the Form-Finding of a Large-Span Transversely Stiffened Suspended Cable System: A Method Considering Construction Processes

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World Journal of engineering and Technology 2024年第2期12卷 229-244页

作者： Junyu Chen Yanfei Wang Ke Chen Shiqing Huang Xiaowen Xu MOE Key Lab of Disaster Forecast and Control in Engineering School of Mechanics and Construction Engineering Jinan University Guangzhou China China Construction Second Engineering Bureau Second Company Shenzhen China Department of Civil Engineering Dazhou Technician College Dazhou China Key Laboratory of Product Packaging and Logistics Packaging Engineering Institute College of Packaging Engineering Jinan University Zhuhai China

The precise control of the shape of transversely stiffened suspended cable systems is crucial. However, existing form-finding methods primarily rely on iterative calculations that treat loads as fixed known conditions. These methods are inefficient and fail to accurately control shape results. In this study, we propose a form-finding method that analyzes the load response of models under different sag and stress levels, taking into account the construction process. To analyze the system, a structural finite element model was established in ANSYS, and geometric nonlinear analysis was conducted using the Newton-Raphson method. The form-finding analysis results demonstrate that the proposed method achieves precise control of shape, with a maximum shape error ranging from 0.33% to 0.98%. Furthermore, the relationships between loads and tension forces are influenced by the deformed shape of the structures, exhibiting significant geometric nonlinear characteristics. Meanwhile, the load response analysis reveals that the stress level of the self-equilibrium state in the transversely stiffened suspended cable system is primarily governed by strength criteria, while shape is predominantly controlled by stiffness criteria. Importantly, by simulating the initial tensioning process as an initial condition, this method solves for a counterweight that satisfies the requirements and achieves a self-equilibrium state with the desired shape. The shape of the self-equilibrium state is precisely controlled by simulating the construction process. Overall, this work presents a new method for analyzing the form-finding process of large-span transversely stiffened suspended cable system, considering the construction process which was often overlooked in previous studies.

关键词： Cable Structure Long-Span Structure Form-Finding Analysis Finite Element Simulation Transverse Cable Stiffening System

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Failure Analyses of Cylindrical Lithium-Ion Batteries Under Dynamic Loading Based on Detailed Computational Model

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ACTA MECHANICA SOLIDA SINICA 2025年 1-13页

作者： Xi, Huifeng Zhao, Guicheng Wang, Shuo Li, Junkui He, Linghui Yang, Bao Jinan Univ Sch Mech & Construct Engn 601 West Huangpu Ave Guangzhou 510632 Peoples R China Jinan Univ Lab Disaster Forecast & Control Engn MOE West Huangpu Ave 601 Guangzhou 510632 Peoples R China Doctor Workstat Xuwen Cty Guangdong Hydropower Ene 207 Natl Highway Xuwen 524100 Peoples R China Univ Sci & Technol China CAS Key Lab Mech Behav & Design Mat Hefei 230026 Peoples R China South China Univ Technol Sch Civil Engn & Transportat Guangzhou 510640 Peoples R China

Electric vehicles, powered by electricity stored in a battery pack, are developing rapidly due to the rapid development of energy storage and the related motor systems being environmentally friendly. However, thermal runaway is the key scientific problem in battery safety research, which can cause fire and even lead to battery explosion under impact loading. In this work, a detailed computational model simulating the mechanical deformation and predicting the short-circuit onset of the 18,650 cylindrical battery is established. The detailed computational model, including the anode, cathode, separator, winding, and battery casing, is then developed under the indentation condition. The failure criteria are subsequently established based on the force-displacement curve and the separator failure. Two methods for improving the anti-short circuit ability are proposed. Results show the three causes of the short circuit and the failure sequence of components and reveal the reason why the fire is more serious under dynamic loading than under quasi-static loading.

关键词： 18,650 lithium-ion battery Detailed computational model Deformation Fracture mode Failure criteria

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