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Interfacial Torsional Behavior of Pipe Joints with Hardening and Softening Bond-Slip Law

INTERNATIONAL JOURNAL OF COMPUTATIONAL METHODS 2024年第10期21卷

作者： Yuan, Hong Han, Jun Lu, Huaqiang Mo, Ziyong Zeng, Lan Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China Guangzhou Inst Sci & Technol Sch Architectural Engn Guangzhou 510540 Peoples R China

For the purpose of a better understanding of the mechanical behavior of pipe joints' interface which is critical for the integral performance of a pipe system, and excessive torsional loading that is typical for their interfacial failure, the interfacial behavior of adhesive bonded pipe joints under torsion loads is theoretically studied throughout the full-ranged failure process based on a local bond-slip law with hardening and exponential softening. Firstly, closed-form solutions for the interfacial shear stress distribution and load-displacement response are derived to describe the four basic loading stages. Secondly, a simplified law is used by changing the exponential softening law into a tri-linear one to make the comparison. According to the analytical solutions of two laws, the influences of the bond length on load-displacement curve including the ultimate loads and relative slips are discussed, with the similarities and differences between the two laws being studied. Thirdly, by introducing a dimensionless damage parameter, the results of the finite element method (FEM) using ABAQUS modeling are compared with analytical results. Based on these coincident results, the parametric studies of bond lengths and ratios of torsion stiffness on specific cases were conducted to explain the stress transfer mechanism and interface crack propagation. Both their ultimate bearing capacity and ductility improve in an increase of bond lengths, while the ductility reduces as the ratio of torsion stiffness increases. The outcomes of this paper are helpful to improve the safety and applicability of bonded pipe joints in engineering design and application.

关键词： Pipe joint bond-slip load torsion load interfacial behavior

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Prestress Force and General Excitation Identification for Plate-like Concrete Bridges

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BUILDINGS 2024年第7期14卷 2032页

作者： Wang, Wensen Xiang, Ziru Wang, Yi Shao, Xuejun Lu, Jieyu Nantong Univ Sch Transportat & Civil Engn Nantong 226019 Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China Nantong Municipal Facil Management Dept Nantong 226006 Peoples R China

Prestress force dominates the carrying capacity of concrete girders, and is vital for bridge health monitoring. Many vibrational-based methods have been proposed to determine prestress using bridge responses induced by known excitations, which means that they can barely use the normal traffic of in-service bridges as excitation to achieve long-term monitoring. Moreover, most studies are based on beam theory, which may not be precise for plate-like bridges. Hence, this paper establishes a motion equation for a prestressed slab via Kirchhoff's plate theory and proposes a two-step procedure to assess the prestress and general excitation simultaneously through only bridge responses. The excitation is determined in the first step via the Load Shape function method and used as input for the prestress identification via state-space formulation in the second step. A numerical study on a prestressed plate subjected to a moving load is conducted. Considering different levels of measurement noise and load speed, the proposed method can determine the prestress and moving load with 7.33% and 10.18% error, respectively. A laboratory test on a prestressed box girder subjected to a fixed cyclic load is performed, the prestress and cyclic load are both determined to have good stability, and the errors are under 11.32%.

关键词： prestress force identification moving force identification state-space formulation

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Quantitative Simulation Study of Metal Additive Manufacturing by Kinetic Monte Carlo

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Journal of Applied Mathematics and Physics 2022年第5期10卷 1587-1601页

作者： Kepeng Ouyang Youdi Kuang School of Mechanics and Construction Engineering MOE Key Laboratory of Disaster Forecast and Control in Engineering Jinan Uni-versity Guangzhou China School of Civil Engineering and Architecture Wuyi University Jiangmen China

Metal additive manufacturing (AM) is a disruptive manufacturing technology that takes into account the needs of complex structural forming and high-performance component forming. At present, the understanding of metal additive manufacturing simulation methods is not thorough enough, which restricts the development of metal additive manufacturing. Present work discusses the evolution of KMC method simulation results for simulating metal additive manufacturing at different length ratios and different scanning speeds. The results reveal that as the scanning speed increases, the main grains in the simulation results are transformed from coarse columnar grains to crescent-shaped grains, which are in good agreement with the existing experimental results. Besides, as the ratio of unit physical length to unit simulation length increases, the ratio of unit physical time to unit simulation time gradually decreases.

关键词： Additive Manufacturing Kinetic Monte Carlo Simulation Grain Morphology

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Recursive principal component analysis based damage localization of bridge using two sensors 10

Recursive principal component analysis based damage localiza...

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10th International Conference on Structural Health Monitoring of Intelligent Infrastructure, SHMII 2021

作者： Nie, Zhenhua Xie, Yongkang Ma, Hongwei College of Science & Engineering Jinan University Guangdong Guangzhou China The Key Laboratory of Disaster Forecast and Control in Engineering Guangdong Guangzhou China Dongguan University of Technology Dongguan China

Vibration response based damage detection methods have attracted much attention due to that they are model free methods. However, in the most of structural health monitoring systems, excessive number of sensors installed on the bridge bring high costs and huge data. In this paper, a novel damage detection method based on recursive principal component analysis (RPCA) is proposed. The displacement responses are collected and decomposed recursively to obtain the orthogonal projection deviation at each moment while the moving vehicle is passing through the bridge. When the moving vehicle passes the damage location, a significant change of projection deviation will occur due to the discontinuity of the responses, which can be used to indicate the damage location. Numerical simulations performed on a simply supported beam bridge subjected to a moving load demonstrate the effectiveness of the proposed approach. It is noticed that only two sensors without limitation of placement location are needed in this data-driven method while no reference data is required, which leads the presented approach to be a good candidate for baseline free structural health monitoring with very limited measurement information. © 2021 International Conference on Structural Health Monitoring of Intelligent Infrastructure: Transferring Research into Practice, SHMII. All rights reserved.

关键词： Damage detection

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Fracture characteristics and in-situ damage mechanism of PIP-C/SiC composites to various temperatures and loading velocities

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engineering FRACTURE MECHANICS 2023年第1期286卷

作者： Zhao, Guicheng Jiang, Zhonghe Qu, Zhaoliang Xi, Huifeng Ai, Shigang Beijing Inst Technol Inst Adv Struct Technol Beijing 100081 Peoples R China Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China

C/SiC composites prepared by polymer infiltration and pyrolysis (PIP) are among the most promising materials for application in ultrahigh-temperature conditions. However, the mechan-ical properties and damage mechanisms of PIP-C/SiC composites at different loading velocities and temperatures have not been systematically studied. In this study, in-plane compression, bending, and in-plane shear experiments were systematically performed at different loading ve-locities and temperatures in an inert atmosphere. The ultimate strengths of the PIP-C/SiC com-posite were determined under different conditions, and the failure modes were revealed. In addition, in-situ X-ray microtomography tension experiments were conducted to study the failure mechanism of the PIP-C/SiC composite. The results showed that the ultimate strengths were considerably affected by the temperature and loading velocity, and the failure modes were dependent on experimental types. The fracture location of the PIP-C/SiC composite is affected by the defect. And the direction of crack propagation is toward the existing cracks and voids.

关键词： C SiC composites High temperature Mechanical properties In -situ tension Failure mechanism

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Vehicle weight identification based on equivalent loads reconstructed from responses of beam-like bridge

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JOURNAL OF SOUND AND VIBRATION 2022年 534卷

作者： Pan, Chudong Zhang, Liwen Ye, Xijun Sun, Zhuo Guangzhou Univ Sch Civil Engn Guangzhou Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou Peoples R China

Moving force identification (MFI) is an effective way for closely monitoring vehicle weight in a dynamic state. Time-varying position of vehicle is usually needed. This applying condition may limit the applicability because the measurement of time-varying position has certain difficulty. To tackle this problem, this study proposes an equivalent load-based method for identifying the gross weight of a vehicle moving on a beam-like bridge. The proposed method is developed based on an innovative concept of equivalent load and the application of force reconstruction. Herein, the equivalent loads are expressed as some concentrated loads whose acting positions are time invariant. Modal forces induced by the equivalent loads are equal to the ones caused by the vehicle-induced moving forces. Under the crucial assumption of equivalent loads, the first key step is to reconstruct the equivalent loads by using a force identification method that is imple-mented via matrix regularization. Since the equivalent loads have been estimated, the second step aims to introduce a practical strategy for identifying the vehicle weight from the sum of the identified equivalent loads rather than the sum of moving forces. Because of this, a highlight is that time-varying position of vehicle is not needed. To verify the effectiveness and feasibility of the proposed method, beam structures with single span are carried out for numerical simulations and experimental validations. Illustrated results show that the proposed method can be applied for identifying the gross weight of a vehicle moving on a beam-like bridge with high accuracy and strong robustness. Some related issues are discussed as well.

关键词： Vehicle weight identification Force reconstruction Equivalent load Matrix regularization Inverse problem

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Full Characterization of the Work-Hardening Behavior of Metals:An Accurate and Explicit Approach

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Acta Mechanica Solida Sinica 2020年第4期33卷 479-486页

作者： Zan Zhou Siyu Wang Lin Zhan Huifeng Xi Heng Xiao School of Mechanics and Construction Engineering and MOE Key Lab of Disaster Forecast and Control in Engineering Jinan UniversityGuangzhou 510632China Shanghai Institute of Applied Mathematics and Mechanics&School of Mechanics and Engineering Science Shanghai UniversityShanghai 200072China

A new approach is proposed to characterize the work-hardening behavior of metals based on the stress-strain data from uniaxial extension *** this new approach,the yield strength as a function of the plastic work can be determined by directly fitting a wellchosen single-variable shape function to any given uniaxial data from the initial yielding up to the strength limit,in an explicit sense with no need to carry out the usual tedious trial-and-error procedures in treating nonlinear elastoplastic rate equations toward identifying numerous unknown *** examples show that the simulation results with the new approach are in accurate agreement with the test data.

关键词： Metals Elastoplasticity Finite strain Work-hardening Yield strength Strength limit Explicit characterization

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Chaotic enhanced colliding bodies optimization algorithm for structural reliability analysis

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ADVANCES IN STRUCTURAL engineering 2020年第3期23卷 438-453页

作者： Cheng, Jiaming Zhao, Wei Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Guangdong Peoples R China

It is of extreme importance to assess the failure probability and safety level of structural system in structural design. Nowadays, many researchers presented several approaches for structural reliability analysis, such as the first-order reliability method, Monte Carlo simulation, and the meta-heuristic algorithm. The meta-heuristic algorithm is not only efficient to solve global optimization problems but also shown to be an effective tool for structural reliability analysis. A recent meta-heuristic optimization approach, enhanced colliding bodies optimization, has emerged as a relatively simple implementation with a fast convergence speed. Chaos theory is characterized by its ergodicity, pseudo-randomness, and irregularity. This article thus presents a novel approach introducing chaotic maps into the enhanced colliding bodies optimization algorithm to promote the performance of convergence, named as chaotic enhanced colliding bodies optimization algorithm. The proposed algorithm uses chaotic maps to change the generation pattern of particles and improve convergence characteristics. A procedure based on the effective use of the represented chaotic enhanced colliding bodies optimization is then applied in structural reliability analysis. A variety of numerical and structural problems are tested in this article to demonstrate that the given method actually improves the performance of enhanced colliding bodies optimization in convergence as well as the accuracy for reliability analysis compared with the other methods existing in the literature.

关键词： chaos enhanced colliding bodies optimization meta-heuristic algorithm optimization algorithm structural reliability

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Flexural performance of reinforced concrete beams strengthened using near-surface-mounted carbon-fiber-reinforced polymer bars: Effects of bonding patterns

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COMPOSITE STRUCTURES 2024年 335卷

作者： Lv, J. B. Lin, D. J. Fu, Bing Liu, S. H. Han, Z. J. Guangdong Univ Technol Sch Civil & Transportat Engn Guangzhou 510643 Peoples R China 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

The near-surface-mounted (NSM) fiber-reinforced polymer (FRP) technique is effective for enhancing the load carrying capacity of strengthened reinforced concrete (RC) beams. However, this technique significantly reduces the deformability of strengthened RC beams. To overcome this, the present study combines the NSM strengthening method with the partial bonding technique: the strengthening FRP reinforcement is partially bonded onto the concrete substrate). Six full-scale 4.3 m long RC beams strengthened with NSM FRPs using various bonding patterns were tested. The results indicated that mechanical interlocking grooves slightly improve the load carrying capacity, but have a negligible effect on the deformability of the strengthened beams. A decrease in the bond length increased deformability by 27.2 %, with only a 7.6 % drop in load capacity compared to that of the beam with full bonding. An advanced finite element model was developed and validated to confirm an optimal bond length of 930 mm for maximum flexural performance.

关键词： Fiber-reinforced polymer Flexural strengthening Reinforced concrete beams Near-surface-mounted Mechanical interlocking groove Partially bonded system

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High-efficiency algorithms for simulating metal failure effects under multiaxial repeated loadings

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INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN engineering 2022年第5期123卷 1277-1293页

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

High-efficiency algorithms are proposed for numerically integrating elasto-plastic rate equations for the purpose of simulating metal failure effects under repeated loading conditions. Results are obtained with a newly established elasto-plasticity model which can automatically simulate both low and high cycle fatigue failure effects, with reference to neither damage-like variables nor ad hoc failure criteria. Novelties are incorporated in a few respects. First, multiaxial loading processes with arbitrarily changing principal stresses and axes can be treated in a broad sense beyond usually treated proportional loading cases. Second, by means of the commonly used J2-invariant of the deviatoric stress, multiaxial loading cases can be directly treated just as in the uniaxial loading case. Third, high cost in time consumption can be considerably reduced in evaluating both low and high cycle failure effects. Numerical examples are presented for simulating uniaxial and multiaxial fatigue failure effects and simulation results are in good agreement with experimental data. Results show that the computation speed with the new algorithms exceeds 600 times faster than usual integration algorithms.

关键词： metals fatigue failure elasto-plastic equations multiaxial repeated loading high-efficiency algorithms

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