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SSRN 2023年

作者： Fu, Bing Xu, Guang-Ti Peng, Wei-Sen Huang, Jizhi Zou, Qiqi Kuang, You-Di School of Mechanics and Construction Engineering Jinan University Guangzhou510632 China MOE Key Lab of Disaster Forecast and Control in Engineering Jinan University Guangzhou510632 China College of Water Conservancy and Civil Engineering South China Agricultural University Guangzhou510642 China Department of Ocean Science and Engineering Southern University of Science and Technology Shenzhen518000 China School of Civil Engineering and Architecture Wuyi University Jiangmen529020 China

Reprocessing into coarse aggregates of concrete is a sustainable solution for the disposal of construction and demolition (C&D) waste. Use of recycled coarse aggregates however leads to a degradation in the mechanical properties of the resulting concrete, which then limits the use of recycled aggregates concrete (RAC) in structural elements. The incorporation of discrete fibers shows to be effective in eliminating the mechanical degradation problem of RAC, and this paper has therefore proposed to use macro fibers recycled from waste glass fiber reinforced polymer (GFRP) to reinforce RAC, thus improving the robustness of RAC in structural elements. The effect of macro fibers on the mechanical properties of RAC has been first examined through a series of compression and bending tests. Then, the tensile constitutive law of concrete was derived based on the load-deflection response of the beam specimens using an inverse analysis. The results revealed that the mechanical properties (e.g., compressive toughness, flexural strength, flexural toughness) of RAC can be significantly enhanced by the fiber addition. For concrete with 50% recycled aggregate (RA), the increase of macro fibers (from 0% to 0.5%, 1%, and 1.5%) leads to the enhancement of flexural strength from 3.13 MPa to 3.54, 4.69, and 5.97 MPa, and the toughness (T150) from 1.4 J to 35.5, 59.2 and 77.6 J, respectively. Such enhancements in the mechanical properties of RAC demonstrate the feasibility of the proposed method. © 2023, The Authors. All rights reserved.

关键词： Bending strength

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Valorization of macro fibers recycled from decommissioned turbine blades as discrete reinforcement in concrete

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JOURNAL OF CLEANER PRODUCTION 2022年第Part2期379卷

作者： Xu, Guang-Ti Liu, Ming-Jie Xiang, Yu Fu, Bing Jinan Univ Sch Mech & Construct Engn Guangzhou 510632 Peoples R China Hong Kong Polytech Univ Dept Civil & Environm Engn Hong Kong Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China

The extensive use of glass fiber-reinforced polymer (GFRP) composites has inevitably resulted in a large amount of FRP waste, posing a significant environmental threat. A recent study performed by the authors' group of the present study pioneered a new mechanical method of recycling GFRP wind turbine blades into macro fibers, in which the macro fibers characterized by a fixed-length have been produced using a manual process of low efficiency and high cost, making it impossible for use in a practical application. In the present study, a shredding machine has been therefore used to efficiently process waste GFRP wind turbine blades into macro fibers of hybrid lengths lesser than 100 mm for being incorporated into concrete. A series of tests were carried out to investigate the properties of the resulting concrete, and the test results of beam specimens were then analyzed using a twice inverse analysis approach. The results of compression tests and four-point bending tests showed that the incorporation of recycled macro fibers led to a slump loss of 54%, a compressive strength reduction of 14.07%, a flexural strength improvement of 37.85% and a significant flexural toughness enhancement of 36.8 times at a fiber volume ratio of 2.5%, as compared to those of plain concrete. The direct-tensile strength and the corresponding tensile strain obtained by a twice inverse analysis approach were about 2.26 MPa and 134 mu epsilon, respectively, as predicted by the inverse analysis based on flexural load-deflection curves. The macro fibers processed using a shredding machine are feasible for enhancing the performance of the resulting concrete, and can be economic-efficiently used for industrial scale applications.

关键词： Fiber -reinforced concrete (FRC) Fiber -reinforced polymer (FRP) Recycled Macro fibers Concrete

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Shear transferring mechanism of the FPR-to-concrete bonded joint with end U-jacketing: A theoretical study

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STRUCTURES 2023年 56卷

作者： Lu, Tianhao Li, Peilong Cui, Chuying Wu, Jiayu Fu, Bing Jinan Univ Sch Mech & Construct Engn Guangzhou 510632 Peoples R China Southern Univ Sci & Technol Dept Ocean Sci & Engn Shenzhen 518000 Peoples R China Hong Kong Polytech Univ Dept Civil & Environm Engn Hong Kong Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China

Installation of fiber reinforced polymer (FRP) U-jackets is an effective method for improving the low utilization rate of the expensive FRP material in the application of flexural strengthening of the reinforced concrete (RC) beam. The stress transfer mechanism of the FPR-to-concrete bonded joint with end U-jacket still remains poorly understood. This study proposed a new analytical model to predict the interfacial debonding process and the load carrying capacity of the joint with end U-jacket. The failure process of the FRP-to-concrete joint with an inclined U-jacket features five stages including elastic, elastic-softening, elastic-softening-debonding, softening-debonding and completely debonding stages. Expressions for the interfacial shear stress distribution and load-displacement relation are derived for these five stages. The load-displacement curve predicted by the analytical model, indicating that the bearing capacity of the joint with end U-jacket has increased by 200%, is in good agreement with the experimental and FE analysis results. Finally, the results from analytical solutions are presented to clarify the effects of the bond length, the FRP plate stiffness and the elasticity coefficient of end U-jacket on the load-displacement relations, the ultimate load and the effective bond length.

关键词： FRP Reinforced concrete beams Flexural strengthening Debonding Anchorages

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Monitoring abnormal vibration and structural health conditions of an in-service structure from its SHM data

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JOURNAL OF SOUND AND VIBRATION 2022年 537卷

作者： Li, X. Y. Guan, Y. H. Law, S. S. Zhao, W. Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China Jinan Univ Sch Mech & Construct Engn Guangzhou 510632 Peoples R China Chongqing Univ Sch Civil Engn Chongqing 400044 Peoples R China

Vortex-induced vibration occurred recently in several important engineering structures in China. Very large mono-frequency periodic vibration was noted. This study reports on the analysis of recorded data from the structural health monitoring (SHM) system of a suspension bridge with the aim to develop some indicators that may be useful to evaluate if there is any abnormal vibration or change of health conditions of a structure in future. The power spectrum of measured acceleration responses is plotted in three-dimensions of time, frequency and power. Acceleration responses from 16 sensors on the target bridge deck in 233 days are analyzed. The evolution of different dynamic parameters in the period encompassing the occurrences of large vortex-induced vibration are reported. The changes in these parameters are identified to be closely associated with some temporary installations on the deck and temporary measures for vibration suppression. The changes in vibration power at different natural frequencies of the structure can be used to demonstrate the evolution of the unexpected event. The trend and abrupt changes of natural frequencies and modal components show the flow of vibration energy between different vibration modes. In addition to the intuitive three-dimension power spectral plot, two state vectors are also developed from the power spectrum. The identification of abnormal vibration and structural state can then be carried out automatically with the novelty detection method and a threshold. The analysis of the SHM acceleration responses of the bridge deck demonstrates the implementation procedure and the effectiveness of the proposed method.

关键词： Abnormal vibration Long-term monitoring Vibration power Power spectral density Novelty detection

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Investigation of nonlinear torsional guided wave mixing in pipes buried in soil

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engineering STRUCTURES 2022年 273卷 1页

作者： Ng, Ching Tai Yeung, Carman Yin, Tingyuan He, Yuncheng Chen, Liujie Univ Adelaide Sch Civil Environm & Min Engn Adelaide SA 5005 Australia Guangzhou Univ Res Ctr Wind Engn & Engn Vibrat Guangzhou 510006 Guangdong Peoples R China Guangzhou Univ Key Lab Disaster Forecast & Control Engn 3MOE Guangzhou Guangdong Peoples R China

Pipes have been widely applied in different engineering areas, such as drainage and the conveyance of chemical products and they are usually installed underground. This makes the structural integrity inspection becomes challenging. Numerous studies investigated the phenomenon of guided wave propagation in buried pipes and the wave interaction with different types of damage, e.g. corrosion and thermal damage. However, very limited studies focused on studying guided wave mixing in embedded pipes, which has recently attracted significant research interest for damage detection. This study develops a three-dimensional (3D) finite element (FE) model incorporating strain energy function to analyse wave mixing phenomena in pipes embedded in the soil. To characterise nonlinear features, such as combinational harmonic generation, due to guided wave mixing, the 3D FE model is used to simulate two torsional guided waves interacting with each other. The numerical results are then verified by experimentally measured data and the results show that the amplitude in the frequency-domain exhibits a sharp drop due to the energy leakage in the existence of soil medium at fundamental frequencies, second and combinational harmonics.

关键词： Guided wave mixing Combinational harmonic Second harmonic Material nonlinearity Finite element Buried pipes

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Method of Analyzing Coating Structure Under Conical Concave Contact

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SSRN 2022年

作者： Huang, Shi-Qing Tang, Pan-Jun Hou, Peng-Fei 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 State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan University Changsha410082 China Department of Engineering Mechanics Hunan University Changsha410082 China

The evaluation of mechanical performance for a coating structure is important in the fields of mechanics and materials. The general theories of the contact mechanics for transversely isotropic elasticity coating structures under conical concave contact are presented in this paper. Based on the Green's function of semi-infinite bodies, the Green's function of coating structures are obtained with mirror image method. The general solution obtained indicates the displacement and stress at any position of the coating, substrate, and interface, which provide the code basis for the analysis of interface failure and determination of material parameters in numerical analysis software. This paper presents accurate solutions in the elastic stage, and there are stress singularities in the contact center and contact boundary, which provide a reference for future research on the relationships between stress singularities and plastic mechanical behavior. © 2022, The Authors. All rights reserved.

关键词： Finite element method

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Experimental analysis and prediction of mechanical properties of soft palate using machine learning 10

Experimental analysis and prediction of mechanical propertie...

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10th Australasian Congress on Applied Mechanics, ACAM 2021

作者： Chen, Liujie He, Chaobo Yao, Haodong Ng, Ching Tai Xiao, Tan Zhang, Xiangming School of Civil Engineering Guangzhou University Guangdong Guangzhou China MOE Key Lab of Disaster Forecast and Control in Engineering Guangdong Guangzhou China School of Civil Environmental & Mining Engineering The University of Adelaide SA Australia Center for Mechanical Teaching and Testing Guangdong University of Petrochemical Technology Guangdong Maoming China The sixth Affiliated Hospital of Sun Yat-sen University Guangdong Guangzhou China

ISBN: (纸本)9781925627596

The mechanical properties of the soft palate are nonlinear and anisotropic, which are important for explaining the occurrence of Obstructive Sleep Apnea Hypopnea Syndrome (OSAHS). The thick and hypertrophic soft palate in the upper airway cavity can easily lead to OSAHS. Therefore, understanding the mechanical properties of the soft palate is essential for further analysis of the mechanical mechanism of OSAHS. Previous studies on the mechanical properties of soft tissue established the constitutive relation between material deformation and internal force by constructing explicit function to fit experimental data for obtaining the related mechanical parameters. However, this process inevitably introduces errors and uncertainties, and some of the information in the data is lost. In this study, we used a pig soft palate as an example and carried out uniaxial tension and stress relaxation experiments for understanding the nonlinear and viscoelastic mechanical characteristics of the soft palate. Furthermore, the experimental data was used to construct the Multi-Layer Perceptron (MLP) model for studying the stress-strain relationship. To verify the proposed method, the predicted elastic modulus of the fitted data using the MLP model were compared with that calculated by the experimental data. The results show that the elastic modulus of soft palate predicted by MLP model is very close to that obtained by the experimental results. Therefore, the machine learning model based on MLP can provide a better prediction on the elastic modulus of the soft palate. In particular, there are three key findings: (i) the stress-strain curves of the soft palate with different sections have small variation and different sections have similar tensile properties;(ii) the soft palate has obvious stress relaxation phenomenon, and smaller magnitude of the initial stress has faster rate of decrease and larger reduction in stress over time;(iii) the initial stress of the soft palate is linearly c

关键词： Stress-strain curves

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Pullout behavior of recycled macro fibers in the cementitious matrix: Analytical model and experimental validation

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COMPOSITE STRUCTURES 2024年 328卷

作者： Yuan, Hong Fan, Y. C. You, X. M. Fu, Bing Zou, Q. Q. Jinan Univ Sch Mech & Construct Engn Guangzhou 510632 Peoples R China Jinan Univ Key Lab Disaster Forecast & Control Engn MOE Guangzhou 510632 Peoples R China Guangzhou Inst Sci & Technol Sch Architectural Engn Guangzhou 510632 Peoples R China Harbin Inst Technol Sch Astronaut Harbin 150001 Peoples R China Southern Univ Sci & Technol Dept Ocean Sci & Engn Shenzhen 518055 Peoples R China

A novel mechanical recycling method has been recently developed in the authors' group for processing waste glass fiber-reinforced polymer (GFRP) composites into macro fibers, which are then incorporated into concrete to produce green fiber-reinforced concrete (FRC). The present study has been conducted for facilitating the characterization of the tensile properties of macro fiber reinforced concrete (MFRC). A trilinear bond-slip model based on the shear-lag theory has first been refined by introducing a slip coefficient to consider different slip behaviors at the final pullout stages. Such a refined trilinear bond-slip model is suitable for describing the bond-slip behavior of the recycled macro fibers embedded in the cementitious matrix. The bond parameters are obtained through an inverse analysis, in which an improved particle swarm optimization algorithm (PSO) is used. The predicted force-end slip curves are compared with the pullout test results, and a good agreement is observed counterparts with the integral absolute error (IAE) ranging from 3.05% to 5.52%, demonstrating the feasibility of the proposed analytical model. A parametric study is finally conducted to examine the sensitivity of different parameters including the fiber geometries and bond properties on the pullout behavior of the macro fibers.

关键词： Analytical models

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Enhancing the Tribological Properties of Ta1 Titanium Alloy Via Surface Mechanical Composite Strengthening

SSRN

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SSRN 2022年

作者： Dai, Yan Li, Mao Kun Liu, Gang Ou, Gui Mei Yang, Feng Liu, Jing School of Materials and Architectural Engineering Guizhou Normal University Guiyang550025 China School of Materials and Metallurgy Guizhou University Guiyang550025 China Institute of Advanced Wear & Corrosion Resistance and Functional Materials MOE Key Lab of Disaster Forecast and Control in Engineering Jinan University Guangzhou510632 China

The main factor hindering the application of TA1 titanium alloy is its poor wear resistance. In this study, surface mechanical composite strengthening technology was proposed to prepare a gradient structure composite layer on the surface of TA1 titanium alloy to enhance the friction and wear properties. Experimental results show that the gradient structure composite layer can be effectively prepared using the surface mechanical composite strengthening technology on the surface of TA1 titanium alloy. Moreover, the microstructure and properties of the composite-strengthening layer were characterised using scanning electron microscopy, X-ray diffraction, electron backscatter diffraction, metallography microscopy, micro-scratch and friction wear tester . The composite-strengthening layer comprised an ~60-μm-thick mechanical deformation layer and a 20-μm-thick WC ( Tungsten Carbide , WC) particle-reinforced coating that formed a mechanical bond with the matrix. The mechanical deformation layer comprised the surface fine-grain zone and subsurface deformation twinning. The nano-hardness of the coating area is 21.771 GPa, ~8.3 times the TA1 matrix nano -hardness. Under the same conditions, the wear rate of the composite-strengthening layer is 4.03 × 10−4 (mm3·N−1·m−1), which is only 24.8% of the matrix wear rate. The wear mechanisms of the composite-strengthening layer are mainly abrasion wear and oxidation wear. The formation of the composite-strengthening layer improves the friction and wear properties of the TA1 titanium alloy. © 2022, The Authors. All rights reserved.

关键词： Wear resistance

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Microstructure refinement and improvement of mechanical properties of Ti46Al8Nb0.9B alloys by electromagnetic cold crucible continuous solidification

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INTERMETALLICS 2022年 140卷 107391-107391页

作者： Wang, Yongzhe Li, Wei Yuan, Hong Ding, Hongsheng Chen, Ruirun Guo, Jingjie Fu, Hengzhi Jinan Univ Inst Adv Wear & Corros Resistance & Funct Mat Guangzhou 510632 Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China Harbin Inst Technol Sch Mat Sci & Engn Harbin 150001 Peoples R China

Microalloying with boron is effective and economical for refining microstructures of as-cast TiAl alloy. However, microstructural refinement is easily affected by the alloy composition and cooling rate, leading to inhomogeneous grain size in different areas of the ingot. In this study, the Ti46Al8Nb0.9B alloys are continuously solidified by the electromagnetic cold crucible, aiming to obtain homogeneous and fine microstructure. After electromagnetic cold crucible continuous solidification (EMCS), the obtained ingot shows finer and more homogeneous microstructure with lamellar colony size of about 50 mu m. The results of tensile test show that the EMCS ingot exhibited improved properties with yield strength (00.2) of 548 MPa and plastic elongation of 0.6%.

关键词： TiAl alloy Microstructure refinement Solidification Mechanical properties

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