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A novel WOA-based structural damage identification using weighted modal data and flexibility assurance criterion

STRUCTURAL engineering AND MECHANICS 2020年第4期75卷 445-454页

作者： Chen, Zexiang Yu, Ling Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China

Structural damage identification (SDI) is a crucial step in structural health monitoring. However, some of the existing SDI methods cannot provide enough identification accuracy and efficiency in practice. A novel whale optimization algorithm (WOA) based method is proposed for SDI by weighting modal data and flexibility assurance criterion in this study. At first, the SDI problem is mathematically converted into a constrained optimization problem. Unlike traditional objective function defined using frequencies and mode shapes, a new objective function on the SDI problem is formulated by weighting both modal data and flexibility assurance criterion. Then, the WOA method, due to its good performance of fast convergence and global searching ability, is adopted to provide an accurate solution to the SDI problem, different predator mechanisms are formulated and their probability thresholds are selected. Finally, the performance of the proposed method is assessed by numerical simulations on a simply-supported beam and a 31-bar truss structures. For the given multiple structural damage conditions under environmental noises, the WOA-based SDI method can effectively locate structural damages and accurately estimate severities of damages. Compared with other optimization methods, such as particle swarm optimization and dragonfly algorithm, the proposed WOA-based method outperforms in accuracy and efficiency, which can provide a more effective and potential tool for the SDI problem.

关键词： structural damage identification whale optimization algorithm constrained optimization problem objective function flexibility assurance criterion

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Progressive Failure Analysis of Laminates with Embedded Wrinkle Defects Based on an Elastoplastic Damage Model

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MATERIALS 2020年第10期13卷 2422页

作者： Ning, Zhi Hua Huo, Guan Liang Liu, Ren Huai Wu, Wei Lin Xie, Jia Ming Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China

Out-of-plane wrinkling has a significant influence on the mechanical performance of composite laminates. Numerical simulations were conducted to investigate the progressive failure behavior of fiber-reinforced composite laminates with out-of-plane wrinkle defects subjected to axial compression. To describe the material degradation, a three-dimensional elastoplastic damage model with four damage modes (i.e., fiber tensile failure, matrix failure, fiber kinking/splitting, and delamination) was developed based on the LaRC05 criterion. To improve the computational efficiency in searching for the fracture angle in the matrix failure analysis, a high-efficiency and robust modified algorithm that combines the golden section search method with an inverse interpolation based on an existing study is proposed. The elastoplastic damage model was implemented in the finite-element code Abaqus using a user-defined material subroutine in Abaqus/Explicit. The model was applied to the progressive failure analysis of IM7/8552 composite laminates with out-of-plane wrinkles subjected to axial compressive loading. The numerical results showed that the compressive strength prediction obtained by the elastoplastic damage model is more accurate than that derived with an elastic damage model. The present model can describe the nonlinearity of the laminate during the damage evolution and determine the correct damage locations, which are in good agreement with experimental observations. Furthermore, it was discovered that the plasticity effects should not be neglected in laminates with low wrinkle levels.

关键词： elastoplastic damage model wrinkle defect progressive failure analysis fiber kinking fracture plane

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

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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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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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Propagation Characteristics of Flexural Wave in One-Dimensional Phononic Crystals Based on Lattice Dynamics Model

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Journal of Applied Mathematics and Physics 2022年第5期10卷 1416-1431页

作者： Hao Wu Youdi Kuang School of Mechanics and Construction Engineering MOE Key Laboratory of Disaster Forecast and Control in Engineering Jinan University Guangzhou China School of Civil Engineering and Architecture Wuyi University Jiangmen China

In this paper, we establish discrete flexural lattice chain models of Bragg and locally resonant phononic crystals by setting mass defect atoms and local resonant elements on the flexural lattice chain. The bandgap characteristics of flexural wave in phononic crystals are studied by establishing the governing equations of the model. The results from models show that with the change of the mass ratio of defective atoms to normal atoms, the bandgap of the flexural wave produced by Bragg scattering shows a certain rule. When the local resonant bandgap and Bragg scattering bandgap are close to each other, the two bandgaps will be coupled to form a wider flexural wave bandgap. The effect of axial strain on bending wave propagation is only the shift of bandgap position. The effect of material damping on the propagation of a bending wave is only energy dissipation at high frequency. In addition, we use finite element simulation to calculate the bandgap of flexural wave in phononic crystals with mass defects, and the results are consistent with lattice chain model. This shows that lattice chain model can effectively guide the bandgap design of phononic crystals. This comprehensive study may help to elucidate the rule of bandgap generation of flexural wave in one-dimensional phononic crystals.

关键词： Phononic Crystals Local Resonance Bragg Scattering Damping Strain Flexural Wave

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Study on Band Gap Characteristics of Boat-Shaped Phononic Crystal

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Journal of Applied Mathematics and Physics 2022年第12期10卷 3693-3699页

作者： Jia Xu Yabing Li Youdi Kuang School of Mechanics and Construction Engineering MOE Key Laboratory of Disaster Forecast and Control in Engineering Jinan University Guangzhou China School of Civil Engineering and Architecture Wuyi University Jiangmen China

In this paper, we analyze the two-dimensional Boat-shaped structure based on the finite element method. We calculated its energy band structure and vibration transmission properties and found that the structure has band gaps at both high and low frequencies. Compared with common traditional two- dimensional phononic crystals, the boat-shaped phononic crystal has the advantage of larger bandgap design and modulation parameter space due to their structural complexity. In order to obtain better bandgap characteristics, we studied the influence of four key parameters, such as the rod length and the angle between the rods, on the bandgap. The results show that: for low frequency band gaps, the width of the band gap can be effectively changed by changing the size of the angle between the rods while rod length greatly affects the bandgap position;for high band gaps, the length of rods has a large effect on the band gap position. These laws have guiding significance for the bandgap regulation of boat-shaped phononic crystal.

关键词： Phononic Crystal Band Gap Boat-Shaped Finite Element Simulation

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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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Alternating iterative method for moving force identification 10

Alternating iterative method for moving force identification

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10th International Conference on Bridge Maintenance, Safety and Management (IABMAS)

作者： Liu, H. L. Li, C. Yu, L. Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou Peoples R China State Key Lab Hlth & Safety Bridge Struct Wuhan Peoples R China

ISBN: (纸本)9780429279119;9780367232788

Moving force identification (MFI) has attracted increasing attentions in recent years. However, the MFI results obtained from the existing methods are inaccurate under measurement noises. One of reasons is fact that the characteristics of moving forces are not properly explored. To fix the problem, a novel MFI method is proposed by combining an alternating iterative method (AIM) and regularizations here. Firstly, each of moving forces is decomposed into constant force and time varying force components respectively. The prior knowledge that time-varying force component usually fluctuates around constant force component is then adopted. Rather than convex optimization problem, a semi-convex constrained estimation problem is defined and solved by the AIM. Numerical simulations on MFI in a simply supported beam are conducted to assess its effectiveness. The results show that the proposed method can provide a higher MFI accuracy than the truncated generalized singular value decomposition method and the prior knowledge is reasonable.

关键词： Iterative methods

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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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