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SSRN 2022年

作者： Li, Kunmao Liu, Xiaochun Liu, Yujing Wu, Xiang Zhang, Wencai Yang, Junjie Li, Wei Zhou, Shengfeng Institute of Advanced Wear & Corrosion Resistance and Functional Materials MOE Key Lab of Disaster Forecast and Control in Engineering Jinan University Guangzhou510632 China Hunan Changsha410004 China Department of Orthopedics First Affiliated Hospital Jinan University Guangzhou510632 China The state Key Laboratory of Mechanical Transmissions Chongqing University Chongqing400044 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 μm, 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 and producing excellent strain hardening. 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. © 2022, The Authors. All rights reserved.

关键词： Titanium alloys

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Recycled Aggregate Concrete-Filled Steel Tube Columns with Small-Diameter Circular Frp-Confined Sea-Sand Concrete Cores: Conceptual and Experimental Investigations

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SSRN 2023年

作者： Zeng, Lan Wu, Liqi Li, Boqin Fang, Shu Mohamed, Hazem Samih Fang, Zhuangcheng Yuan, Hong MOE Key Laboratory of Disaster Forecast and Control in Engineering School of Mechanics and Construction Engineering Jinan University Guangdong Guangzhou510632 China Guangdong Architectural Design and Research Institute Co. Ltd. Guangzhou510006 China Guangdong Key Laboratory of Earthquake Engineering & Applied Technique Earthquake Engineering Research & Test Centre Guangzhou University Guangzhou510006 China School of Architectural Engineering Guangzhou Institute of Science and Technology Guangzhou510540 China Fujian Agriculture and Forestry University China

Recycled aggregate concrete (RAC) prepared from waste concrete can achieve the green recycling of resources;however, its inferior material properties hinder its applications. Sea-sand concrete (SSC) can help alleviate the resource shortage of fresh water and river sands but is prone to steel corrosion. To address these challenges, this study developed a new RAC-filled steel tube column with a small-diameter circular fibre-reinforced polymer (FRP)-confined SSC core. This paper presents and discusses the results of the axial compression tests conducted on RAC-filled steel tube columns, with and without small-diameter circular FRP-confined SSC cores. The study investigated the effects of the configuration of the FRP-confined SSC core, diameter-to-thickness ratio of the FRP tubes, compressive strength of RAC and SSC, and cross-sectional shape of the column. The results revealed that using small-diameter circular FRP-confined SSC cores to partially replace RAC was effective in improving the compressive performance of RAC-filled steel tube columns. The increase in the number of FRP tubes, in-filled concrete strength, and confinement stiffness of the steel and FRP tubes contributed to improvements in the structural strength and ductility, resulting in progressive ladder-shaped declines in the post-peak curve. Finally, a reasonable load–capacity model is presented for the proposed columns. © 2023, The Authors. All rights reserved.

关键词： Steel corrosion

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Compressive and thermal properties of foamed concrete at high temperature

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JOURNAL OF SUSTAINABLE CEMENT-BASED MATERIALS 2022年第6期11卷 353-369页

作者： Xi, Huifeng Yao, Yiming Sun, Yuanfeng Mobasher, Barzin Liu, Yiping Ma, Hongwei Jinan Univ Coll Mech & Construct Engn Guangzhou Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou Peoples R China Xi An Jiao Tong Univ State Key Lab Strength & Vibrat Mech Struct Xian Peoples R China Southeast Univ Minist Educ Engn Res Ctr Safety & Protect Explos & Impact Nanjing Peoples R China Southeast Univ Sch Civil Engn Nanjing Peoples R China Arizona State Univ Sch Sustainable Engn & Built Environm Tempe AZ USA South China Univ Technol Sch Civil Engn & Transportat Guangzhou Peoples R China Dongguan Univ Technol Sch Environm & Civil Engn Dongguan Peoples R China

Foamed concrete is an attractive material for structural use and insulation of buildings, which can replace flammable organic insulating materials on the market. This study investigated the compressive and thermal properties of the plain, fly ash and expanded polystyrene (EPS) foamed concrete ranging widely in density from 180 to 1800 kg/m(3). Furthermore, the compressive strength of the plain foamed concrete was analyzed at four density levels of 180, 325, 450, and 595 kg/m(3) and at four temperatures of room temperature, 300, 600, and 900 degrees C to quantify its fire resistance. The compressive strength of the foamed concrete dramatically declined, and it suffered severe damage when the temperature was higher than 300 degrees C. A constitutive stress-strain model incorporating the compressive strength-density relationship and the temperature effects was also proposed for the plain foamed concrete. The findings may provide new perspectives on the existing design codes for energy efficiency and fire protection.

关键词： Foamed concrete compressive behavior thermal conductivity elevated temperature constitutive relation

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A cost-efficient UHPC incorporated with coarse aggregates and macro fibres recycled from waste GFRP

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JOURNAL OF BUILDING engineering 2023年 73卷

作者： Yuan, Hong Lin, Wei-Lin You, Xue-Min Fu, Bing Zou, Qi-Qi Xiang, Yu 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 Guangzhou Inst Sci & Technol Sch Architectural Engn Guangzhou 510540 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

High production cost is a key impediment to the broader applications of UHPC materials. In the present study, a concept has been therefore proposed on jointly incorporating coarse aggregates and macro fibres recycled from waste GFRP in the UHPC system to produce a cost-efficient UHPC. The coarse aggregates were respectively incorporated into UHPC using the modified Andreasen and Andreasen model (MAAM) leading to the cement added in per m3 UHPC being as low as 668 kg. Compression and flexural tests were first carried out to examine the effects of incorporating both coarse aggregates and macro fibres on the properties of such a UHPC. The tensile stressstrain curves were then obtained from the data results of bending tests through a twice inverse analysis. A cost analysis was performed as well to quantitatively compare the production costs of different UHPCs, justifying the proposed concept. The test results and discussion revealed that the UHPC incorporated coarse aggregates have a compressive strength of about 150 MPa, and the presence of macro fibres of 6% in volume results in about 20% decrease in the compressive strength of UHPC, but significantly enhances the flexural properties of UHPC, including peak strength, residual strength, and toughness. The production cost of the UHPC mixture has been lowered to about 1700 CNY/m3 by jointly incorporating coarse aggregates and macro fibres. The maximum value of the efficiency index (E) is achieved when utilizing aggregate with a maximum particle size of 9.5 mm and 6% macro fibre.

关键词： Ultra-high-performance concrete Recycling GFRP waste Coarse aggregate Production cost

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An explicit and accurate approach toward simulating plastic-to-pseudoelastic transitions of SMAs under multiple loading and unloading cycles

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INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES 2020年 185卷 104-115页

作者： Zhan, Lin Wang, Xiao-Ming Wang, Si-Yu Xi, Hui-Feng Xiao, Heng Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn West Huangpu Ave 601 Guangzhou 510632 Peoples R China Ningbo Polytech Ningbo Peoples R China Shanghai Univ Shanghai Inst Appl Math & Mech Yanchang Rd 149 Shanghai 200072 Peoples R China

New finite elastoplastic J(2)-flow equations are proposed for the purpose of explicitly simulating continuous transitions from plastic to pseudo-elastic effects of SMAs under multiple loading-unloading cycles. Novelties of such models are as follows: (i) New hardening effects are incorporated by introducing interplay between the changing of the yield surface radius and the moving of the yield surface center;(ii) extensive experimental data may be accurately simulated for any given number of loading-unloading cycles;(iii) the complicated task for simulating extensive data may be accomplished by independently fitting certain single-variable functions;and (iv) such single-variable functions may be presented in explicit forms for the purpose of automatically, accurately fitting extensive data, thus bypassing uncertainties and undue complexities usually involved in iteratively solving a coupled system of nonlinear constitutive rate equations toward identifying numerous unknown parameters. Numerical examples for model validation are presented and in good agreement with stress-strain data up to 20 loading-unloading cycles given in literature. (C) 2019 Published by Elsevier Ltd.

关键词： Shape memory alloys Plasticity Pseudo-elasticity Loading cycles Continuous transitions Explicit simulation

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Buckling of composite laminates with multiple delaminations: Part I Theoretical and numerical analysis

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COMPOSITE STRUCTURES 2020年 250卷 112491-112491页

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

Buckling of composite laminates containing multiple delaminations are analyzed theoretically based on the proposed equivalent model. From the exact analysis in which the nonlinear contact effect between the two portions above and beneath the delamination is included, it is found that (1) the two portions above and below the delamination undergoes exactly identical global deflection;(1) the composite laminate is subjected to Mode II delamination propagation due to in-plane slipping. According to such observations, an equivalent model which is perfect, delamination free is proposed to replace the delaminated portion of the laminate. The substitute model has the same geometric size and is stacked in the same sequence as that of the delaminated portion. The exact solution of the global deflection mode also suggests that the stiffness of the substitute model is taken as the sum of the stiffness of the two portions above and beneath the delamination. Buckling of composite laminates simply supported at the four sides with a single delamination is examined for different delamination length and depth using equivalent model, exact model and the finite element model. A good agreement between them demonstrates the efficiency and accuracy of the presented equivalent model. Using the established equivalent model, buckling of composite laminates with multiple delaminations along thickness and horizontal directions are investigated. Parametric studies are executed analytically and numerically to inspect the influence of delamination conditions, such as the number of delamination as well as the depth, the position and the length of each delamination, on the buckling performance of the composite laminates.

关键词： Multiple delaminations Equivalent model Contact effect Laminated composites Buckling analysis

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Metal failure effects predicted accurately with a unified and explicit criterion

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ZAMM-ZEITSCHRIFT FUR ANGEWANDTE MATHEMATIK UND MECHANIK 2021年第11期101卷

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

A new criterion for predicting metal failure effects under cyclic loading conditions is derived from an innovative elastoplasticity model established most recently. As compared with usual approaches, novel results with this new criterion are presented in four respects: (i) both low and high cycle fatigue effects can be simultaneously simulated in a unified and direct manner;(ii) cumbersome trial-and-error procedures in identifying numerous unknown parameters can be bypassed;(iii) time-consuming numerical procedures are not involved in treating responses in cyclic loading processes;and, for the first time, (iv) data sets for fatigue failure can be simultaneously matched for various cases of the cyclic stress ratio. Numerical examples show that model predictions are in accurate agreement with test data.

关键词： elastoplasticity model fatigue failure effects metals unified criterion

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Recycled aggregate concrete-filled steel tube columns with small-diameter circular FRP-confined sea-sand concrete cores: Conceptual and experimental investigations

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CONSTRUCTION AND BUILDING MATERIALS 2023年第1期401卷

作者： Zeng, Lan Wu, Liqi Li, Boqin Fang, Shu Mohamed, Hazem Samih Fang, Zhuangcheng Yuan, Hong Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Guangdong Peoples R China Guangdong Architectural Design & Res Inst Co Ltd Guangzhou 510006 Peoples R China Guangzhou Univ Earthquake Engn Res & Test Ctr Guangdong Key Lab Earthquake Engn & Appl Tech Guangzhou 510006 Peoples R China Fujian Agr & Forestry Univ Coll Transportat & Civil Engn Fuzhou Peoples R China Guangzhou Inst Sci & Technol Sch Architectural Engn Guangzhou 510540 Peoples R China

Recycled aggregate concrete (RAC) prepared from waste concrete can achieve the green recycling of resources;however, its inferior material properties hinder its applications. Sea-sand concrete (SSC) can help alleviate the resource shortage of fresh water and river sands but is prone to steel corrosion. To address these challenges, this study developed a new RAC-filled steel tube column with a small-diameter circular fibre-reinforced polymer (FRP)-confined SSC core. This paper presents and discusses the results of the axial compression tests conducted on RAC-filled steel tube columns, with and without small-diameter circular FRP-confined SSC cores. The study investigated the effects of the configuration of the FRP-confined SSC core, diameter-to-thickness ratio of the FRP tubes, compressive strength of RAC and SSC, and cross-sectional shape of the column. The results revealed that using small-diameter circular FRP-confined SSC cores to partially replace RAC was effective in improving the compressive performance of RAC-filled steel tube columns. The increase in the number of FRP tubes, in-filled concrete strength, and confinement stiffness of the steel and FRP tubes contributed to improvements in the structural strength and ductility, resulting in progressive ladder-shaped declines in the post-peak curve. Finally, a reasonable load-capacity model is presented for the proposed columns.

关键词： Recycled aggregate concrete Concrete-filled steel tube columns Sea-sand concrete (SSC) Fiber-reinforced polymer (FRP)-confined concrete core Axial compressive performance

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Analysis of the Effect of Urban Geometric Form Factors on Heat Islands in Guangzhou

Analysis of the Effect of Urban Geometric Form Factors on He...

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2020 International Conference on Green Energy, Environment and Sustainable Development, GEESD 2020

作者： Zheng, Langtao Tang, Jian Chen, Xiong Guangdong Eng. Technology Research Center for Green Building Materials and Fabricated Architecture Maoming China MOE Key Laboratory of Disaster Forecast and Control in Engineering School of Mechanics and Construction Engineering Jinan University Guangzhou510632 China

The geometric form factors of urban space include height width ratio (H/W), sky view factor (SVF) and street direction, which directly affect the incidence of solar radiation, and then affect the temperature change of the block. In this study, the representative hot island and cold island streets in Guangzhou are selected as the research objects. According to the intensity and range distribution map of Guangzhou heat island in summer of 2014-2017 issued by Guangzhou Meteorological Bureau, the intersection area with high intensity of 4-year continuous heat island is found out by two-dimensional image superposition. In the region, the typical measurement points and comparison points are selected in groups, the temperature of each measurement point is monitored, and the urban geometry data is collected for comparative analysis. The results show that under the condition of the same underlying surface factor and no significant difference in artificial heat factor, the urban geometry can alleviate the heat island effect, and the measuring points with smaller sky view factor and larger height width ratio (H/W) have lower temperature, and the temperature of each measuring point has higher correlation with the size of SVF. In addition, the direction defined by the long axis of the valley will also affect the solar radiation equivalent of the street pavement, and the reclamation open land is also easy to become a heat island area. © Published under licence by IOP Publishing Ltd.

关键词： Landforms

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Buckling of composite laminates with multiple delaminations: Part II experiments

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COMPOSITE STRUCTURES 2020年 247卷 112498-112498页

作者： Zhu, Zhipeng Yang, Peng Xia, Fei Jin, Fusong Liang, Haofeng He, Zanhang Xue, Jianghong Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China

This paper focus on the experimental study of the buckling of composite laminates with multiple delamina- tions, as a succession to the theoretical and numerical studies in Part I. Test specimens containing delamina- tions of different length and different depth were fabricated by embedding Te flon plastic film using hot pressing machine. Compressive tests were carried out to investigate the in fluence of the delamination condi- tions on the buckling and post -buckling performances of the composite laminates. It was found that a surface delamination deteriorates the stiffness of the laminate less than a deep -buried delamination does, while iso- thickness-spaced multiple delaminations damage the stiffness severely compared with non -equal -thickness - spaced delamination for the same number of delamination. In general the larger the length and the number of delamination, the smaller the buckling load. Nevertheless, when the total length and the number of the delamination are fixed, the laminates containing multiple delaminations of equal length have a higher buckling load. Furthermore, it was observed that regardless of the number of delamination, all laminates are suffered to a global buckling. Local buckling does not occur until global buckling occurs. The experimental results justify the theoretical prediction;thereby con firm the correctness and validity of the theoretical approach proposed in Part I.

关键词： Experimental study Composite laminates Multiple delaminations Equivalent model Buckling and post-buckling

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