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Behavior of confined concrete with recycled glass fiber-reinforced polymer needles as coarse aggregates under axial compression

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JOURNAL OF BUILDING engineering 2023年 71卷

作者： Cheng, Cai-Shu Xu, Yuan-Bin Xiao, Cong-Yue Fu, Bing Gao, Ruo-Fan Kuang, You-Di 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 Wuyi Univ Sch Civil Engn & Architecture Jiangmen 529020 Peoples R China

Cutting waste GFRP into needles as part of coarse aggregates in concrete shows to be a promising approach for recycling the waste GFRP composites. However, the resulting concrete has its compressive strength lower than that of normal concrete, and is therefore limited for use in nonstructural elements. The present study proposes a method to improve the robustness of such concrete in structural elements by utilizing the confined concrete concept, in which the concrete with GFRP needles is confined with carbon fiber-reinforced polymer wraps. A series of compression tests under concentric loading were conducted with the ratio of GFRP needles to the total coarse aggregates (i.e., replacement ratio) and the confining jacket stiffness as the two test parameters. The test results indicate that the compressive strength of unconfined concrete decreased by approximately 10% due to replacing 15% coarse aggregates with GFRP needles, while the confining jackets of the same stiffness applied resulted the compressive performance of the confined concrete with needles comparable to or even slightly higher than that of its counterpart without needles. Two widely-used theoretical models were used to predict the compressive performance of the confined concrete, finding that both of them overestimated the axial stress but underestimated the axial strain of the confined concrete with GFRP needles. Therefore, a refined model is required to predict the behavior of confined concrete with GFRP needles under axial compression.

关键词： Recycling Glass fiber-reinforced polymer (GFRP) needles Carbon fiber-reinforced polymer (CFRP) Confined concrete Compressive behavior

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Molecular mechanics mechanisms for ultralow bending stiffness of monolayer silicene

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MATERIALS TODAY COMMUNICATIONS 2022年 33卷

作者： Yang, Mengyu Kuang, Youdi Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou Peoples R China Wuyi Univ Sch Civil Engn & Architecture Jiangmen Peoples R China

Monolayer silicene, as one-atom thick membrane, has a bending stiffness of about 0.31 eV, even much lower than that of monolayer graphene for which only weak out-of-plane p-bonding interactions contribute to the elastic constant. To clarify the underlying mechanisms, we explore the origin of bending stiffness for silicene from the viewpoint of molecular mechanics. An approach to achieve high precision atomic interaction potential parameters are developed by combining independent deformation modes of lattices with quantum mechanical calculations. For comparison, the corresponding studies are also conducted for graphane and graphene. It is found that, different with the out-of-plane p-bonding interactions for graphene, the bending stiffness of silicene and graphane origins from the covalent angle interactions, the covalent bond interactions contribute little to their bending stiffness. The reasons for the significant discrepancy of bending stiffness value between these monolayers are clarified by means of the quantitative comparison of atomic interaction strength. Present work has a general implication in understanding nanomechanics of one atom thick monolayers.

关键词： Ultrathin monolayer Quantum mechanics calculations Lattice dynamics calculations Molecular mechanics mechanism Origin of bending stiffness

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New finite strain elastoplastic equations for accurately and explicitly simulating pseudoelastic-to-plastic transition effects of shape memory alloys

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Applied Mathematics and Mechanics(English Edition) 2020年第10期41卷 1583-1596页

作者： Siyu WANG Lin ZHAN Huifeng XI Heng XIAO School of Mechanics and Construction Engineering MOE Key Lab of Disaster Forecast and Control in EngineeringJinan University601 West Huangpu AvenueGuangzhou 510632China Shanghai Institute of Applied Mathematics and Mechanics Shanghai Key Laboratory of Mechanics in Energy EngineeringSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai 200072China

A new finite strain elatoplastic J2-flow model with coupling effects of both isotropic and anisotropic hardening is proposed with the co-rotational logarithmic *** terms of certain single-variable shape functions representing uniaxial loading and unloading curves,explicit multi-axial expressions for the three hardening quantities incorporated in the new model proposed are derived in unified forms for the purpose of automatically and accurately simulating complex pseudoelastic-to-plastic transition effects of shape memory alloys(SMAs)under multiple loading-unloading *** examples show that with only a single parameter of direct physical meaning for each cycle,accurate and explicit simulations may be achieved for extensive data from multiple cycle tests.

关键词： shape memory alloy(SMA) finite deformation pseudo-elasticity plasticity cyclic loading transition effect elastoplastic equation explicit and accurate approach

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Transverse Free Vibration of Axisymmetric Functionally Graded Circular Nanoplates with Radial Loads

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JOURNAL OF VIBRATION engineering & TECHNOLOGIES 2021年第6期9卷 1253-1268页

作者： Luo, Qiuyang Li, Cheng Li, Shuang Soochow Univ Sch Rail Transportat Dept Vehicle Engn Suzhou 215131 Jiangsu Peoples R China Guilin Univ Elect Technol Guangxi Key Lab Cryptog & Informat Secur Guilin 541004 Guangxi Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Guangdong Peoples R China

Purpose The functionally graded circular nanoplate is a commonly seen component in the nano-electromechanical system. It is indispensable to examine free vibration behaviors of such an axisymmetric nanostructure subjected to uniformly distributed loads in the radial direction. Although the vibration engineering and technology have been fully studied at the macro-scale, there are still many unsolved problems at the micro-scale. The present research aims to promote the theoretical characterization of vibration behaviors at micro/nano-scale and further provide a basis for the development of vibration testing technologies. Methods Using the nonlocal strain gradient approach and Mindlin plate theory, we develop the theoretical model describing the transverse free vibration of the axisymmetric functionally graded circular nanoplate. First, by considering the nonlocal strain gradient constitutive relation, we derive the equation of motion via Hamilton's principle in polar coordinate system. Subsequently, the differential quadrature method is employed to solve the equation of motion numerically. Results The natural frequencies of circular nanoplates decrease with an increase of a radial compression while increase with an increase of a radial tension. The first-mode natural frequency reduces to zero under a certain radial compression, bringing about the dynamical instability. The natural frequencies are sensitive to the radial compression, and the clamped boundary constraint is more resistant to external loads than the simply supported one. An increase in the nonlocal parameter results in lower natural frequencies, while an increase in the strain gradient characteristic parameter results in higher ones. Conclusions It is demonstrated that the strain gradient characteristic parameter has a threshold in the present model for functionally graded circular nanoplates. In the circumstance of a lower nonlocal parameter than the strain gradient characteristic parameter, the circular

关键词： Nonlocal strain gradient Functionally graded Axisymmetric Circular nanoplate Vibration

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Regularization Strategies for Contiguous and Noncontiguous Damage Detection of Structures

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INTERNATIONAL JOURNAL OF COMPUTATIONAL METHODS 2021年第6期18卷

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

Regularization strategies have attracted attention in the structural damage detection (SDD) field. However, there is lack of studies on regularization strategies for damage patterns in the existing methods. This paper proposes regularization strategies for contiguous and noncontiguous damages of structures and performs comparative studies. The objective functions are first defined to consider effects of strategies on SDD by adding distinct norm penalties, and then are solved by the particle swarm optimization (PSO). Three numerical simulation models are employed to assess the applicability of three strategies. The results show that the l(2) norm regularization is suitable for detecting multiple damages, the l(1) norm regularization performs well in contiguous damages, and the sparsest solutions can be obtained by the l(1/2) norm regularization.

关键词： Structural damage detection (SDD) regularization strategy norm penalty sensitivity analysis particle swarm optimization (PSO)

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Screws Fixation for Oblique Lateral Lumbar Interbody Fusion (OL-LIF): A Finite Element Study

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BIOMED RESEARCH INTERNATIONAL 2021年第0期2021卷 000-000页

作者： Ling, Qinjie Zhang, Huanliang He, Erxing Guangzhou Med Univ Dept Spinal Surg Affiliated Hosp 1 151 Yanjiang West Rd Guangzhou 510120 Guangdong Peoples R China Jinan Univ Inst Appl Mech MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Guangdong Peoples R China

Background. The combination of screw fixation and cage can provide stability in lumbar interbody fusion (LIF), which is an important technique to treat lumbar degeneration diseases. As the narrow surface cage is developed in oblique lateral lumbar interbody fusion (OL-LIF), screw fixation should be improved at the same time. We used the finite element (FE) method to investigate the biomechanics response by three different ways of screw fixation in OL-LIF. Methods. Using a validated FE model, OL-LIF with 3 different screw fixations was simulated, including percutaneous transverterbral screw (PTVS) fixation, percutaneous cortical bone trajectory screw (PCBTS) fixation, and percutaneous transpedical screw (PPS) fixation. Range of motion (ROM), vertebral body displacement, cage displacement, cage stress, cortical bone stress, and screw stress were compared. Results. ROM in FE models significantly decreased by 84-89% in flexion, 91-93% in extension, 78-89% in right and left lateral bending, and 73-82% in right and left axial rotation compared to the original model. The maximum displacement of the vertebral body and the cage in six motions except for the extension of model PTVS was the smallest among models. Meanwhile, the model PTVS had the higher stress of screw-rods system and also the lowest stress of cage. In all moments, the maximum stresses of the cages were lower than their yield stress. Conclusions. Three screw fixations can highly restrict the surgical functional spinal unit (FSU). PTVS provided the better stability than the other two screw fixations. It may be a good choice for OL-LIF.

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Vibration Characteristic Measurement Method of MEMS Gyroscopes in Vacuum, High and Low Temperature Environment and Verification of Excitation Method

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IEEE ACCESS 2021年 9卷 129582-129593页

作者： Luo, Wenhao Su, Wei Nie, Zhenhua Huang, Qinwen Li, Shiyuan Dong, Xianshan MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China China Elect Prod Reliabil & Environm Testing Res Sci & Technol Reliabil Phys & Applicat Technol El Guangzhou 510610 Peoples R China Jinan Univ Sch Mech & Construct Engn Guangzhou 510632 Peoples R China

A method for measuring vibration characteristics of MEMS (Micro Electro Mechanical System) is presented. This method aims to simulate a real environment where MEMS operates. At first, the method of applying high and low temperature in a vacuum environment is studied. And the excitation method applying to movable microstructures of MEMS in this environment is found. Based on the above environmental conditions, the vibration characteristics of MEMS movable microstructure are measured by micro-laser vibration measurement. The base excitation method is used to measure the vibration characteristics of MEMS movable microstructures outside the plane. ANSYS 14.0 was used for finite element simulation to verify this method. The electrostatic excitation method is used to measure the inside of the plane. The stroboscopic method is used to verify the electrostatic excitation by fitting the displacement signal of the movable microstructure and the excitation output signal. The results show that the out-of-plane first-order frequency is 11.926 kHz, and the error is 0.30% compared with the experimental results. The amplitude is 44.218 nm, and the error is 0.59%. The in-plane first-order frequency is 5715.7Hz, which achieves the requirement of design precision. Both the numerical simulation and the stroboscopic method verify the excitation method well. The effect of temperature on the natural frequency of the structure is negatively correlated. And as the temperature drops, the motion of the structure becomes increasingly violent. The findings of this study provide important guidance for maintenance, reliable operation and optimal design of MEMS.

关键词： Temperature measurement Vibrations Micromechanical devices Microstructure Resistance heating Vibration measurement Heat transfer MEMS reliability vibration measurement with laser vacuum large temperature range

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Stress-strain behaviour of carbon fibre reinforced polymer-confined concrete containing macro fibres recycled from waste glass fibre reinforced polymer

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ADVANCES IN STRUCTURAL engineering 2024年第7期27卷 1189-1208页

作者： Zou, Qi-Qi Fu, Bing Chen, Jian-Fei Teng, Jin-Guang Harbin Inst Technol Sch Astronaut Harbin Peoples R China Southern Univ Sci & Technol Dept Ocean Sci & Engn Shenzhen Peoples R China Jinan Univ Sch Mech & Construct Engn Guangzhou Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou Peoples R China Hong Kong Polytech Univ Dept Civil & Environm Engn Hong Kong Peoples R China Jinan Univ Sch Mech & Construct Engn 601 Whampoa Ave West Guangzhou 510632 Peoples R China Southern Univ Sci & Technol Dept Ocean Sci & Engn 1088 Xuanyuan Ave Shenzhen 518055 Peoples R China

Glass fibre-reinforced polymer (GFRP) wastes may be mechanically processed into small strips called "macro fibres," which were used as short reinforcement fibres to produce macro fibre reinforced concrete (MFRC). The addition of such macro fibres into concrete has proven to be effective in enhancing the flexural strength and toughness of concrete, but it also slightly reduces the compressive strength of concrete. This paper presents a study on the behaviour of CFRP-confined MFRC. A total of 84 CFRP-confined MFRC cylinders were prepared and tested in axial compression. The test parameters included the CFRP confinement stiffness, macro fibre content, and fibre length. The test results show that the compressive strength and ultimate axial strain can be significantly enhanced through the use of CFRP confinement. The ultimate axial strain of CFRP-confined concrete with macro fibres is slightly higher than that without macro fibres. The test results were compared with two well-known stress-strain models for FRP-confined concrete, including Teng et al.'s design-oriented model and Jiang and Teng's analysis-oriented model. A comparative analysis showed that both models slightly underestimate the compressive strength and slightly overestimate the ultimate axial strain for CFRP-confined MFRC.

关键词： macro fibres mechanical recycling glass fibre-reinforced polymer waste confinement carbon fibre reinforced polymer concrete

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Machine learning-based design and optimization of double curved beams for multi-stable honeycomb structures

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EXTREME MECHANICS LETTERS 2023年 65卷

作者： Yu, Jizhou Shi, Xinlai Feng, Yuxuan Chang, Jinke Liu, Junbang Xi, Huifeng Huang, Shiqing Zhang, Wenhua 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 UCL Div Surg & Intervent Sci London NW3 2PF England

Curved beams with bistable and negative stiffness properties can be used to design multi-stable metamaterials or honeycomb structures. Consequently, the deformation patterns and mechanical properties of curved beams under load have attracted many attentions. However, due to the nonlinear characteristics of variable thickness double curved beams, it is impossible to exhaust all possible structural forms through experimental and theoretical approaches. This paper presents a machine learning (ML) method for designing and optimizing double curved beam structures. The ML model is used to establish the underlying mapping relationship between thickness parameters and mechanical properties. After optimizing the double curved beam in different directions, the optimal thickness distributions of the backward snapping force and energy absorption are obtained. Double curved beams with optimal thickness distributions are used to construct multi-stable honeycomb structures, demonstrating the optimization process from single cell structure to periodic structure. Under the same mass, compared to the constant thickness honeycomb structure, the optimized variable thickness honeycomb structures exhibit a 140% increase in backward snapping force and a 57% increase in energy absorption. The objective of this study is to utilize machine learning technique to obtain a general approach for optimizing model of 'multiparameter input' to 'single-parameter output', which is valuable for guiding the optimization and design of metamaterial structures in the future. This paper is a good case study of the mechanical structure performance optimization, whose implementation path is given detailly in appendix. Other disciplines with similar optimization goals can also use this method to carry out researches.

关键词： Double curved beam Multi-stable structures Backward snapping force Energy absorption Structural optimization Machine learning

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Numerical Simulation of Harmonic Response Analysis for Small Out-Line Package

Numerical Simulation of Harmonic Response Analysis for Small...

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Software engineering, Social Network Analysis and Intelligent Computing (SSAIC), Asia-Pacific Conference on

作者： Hai Lin Xianshan Dong Wei Su Qinwen Huang Agam Tomar School of Mechanics and Construction Engineering Jinan University Guangzhou China Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory China Electronic Product Reliability and Environmental Testing Research Institute Guangzhou China MOE Key lab of Disaster Forecast and Control in Engineering Guangzhou China Faculty of Engineering and Mathematical Sciences University of Western Australia Australia

ISBN: (数字)9798350393682

ISBN: (纸本)9798350393699

In order to discuss the influence of the number of sheets on acceleration and frequency curve of sample surface, the finite element model of clamp, SOP sample and metal sheet is firstly established with Solidworks. Different number of sheets are laid on the surface of SOP sample. Then changing the number of the paper sheets, harmonic response analysis is converted based on modal analysis. The influence of different number of sheet on acceleration and frequency curve is discussed. The results show the relation between acceleration-frequency curve of different thickness of paper, which provides reference for packaging design.

关键词： Solid modeling Social networking (online) Modal analysis Metals Packaging Harmonic analysis Numerical simulation

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