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

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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The Effects of RF Power and Cavity Structure on the Plasma Discharge Characteristics of RPS

The Effects of RF Power and Cavity Structure on the Plasma D...

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Electronics and Devices, Computational Science (ICEDCS), International Conference on

作者： Hai Lin Wei Su Ming Chen Renhuai Liu 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

In this paper, a two-dimensional model of plasma diffusion in remote plasma source discharge chamber is established by COMSOL plasma module. The electron density and electron temperature distributions inside the discharge cavity were obtained by adjusting the thickness of alumina coating and the magnitude of RF power parameters. Based on the results, the authors discuss the effects of different alumina coating thickness and RF power on the electron density and electron temperature inside the discharge cavity, which provide theoretical guidance for the subsequent optimization of the internal structure of the discharge cavity and the discharge parameters.

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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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Fault structure, seismicity, and magmatism of the Littoral Fault zone, northern South China sea: Insights from high-resolution seismic reflection data

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MARINE AND PETROLEUM GEOLOGY 2024年 160卷

作者： Zhang, Yanxin Ye, Xiuwei Wan, Kuiyuan Lv, Zuoyong Wen, Genggeng Xu, Shunshan Guangdong Earthquake Agcy CEA Key Lab Earthquake Monitoring & Disaster Mitig Guangzhou 510070 Peoples R China Guangdong Sci & Technol Collaborat Innovat Ctr Ear Guangzhou 510070 Peoples R China Urban Earthquake Safety Lab MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510070 Peoples R China Chinese Acad Sci South China Sea Inst Oceanol CAS Key Lab Ocean & Marginal Sea Geol Guangzhou 510301 Peoples R China Southern Marine Sci & Engn Guangdong Lab Guangzhou Guangzhou 511458 Peoples R China Univ Nacl Autonoma Mexico Ctr Geociencias Queretaro 76230 Mexico

Four destructive M7+ earthquakes and 18 M6+ earthquakes demonstrate that the Littoral Fault Zone (LFZ) is one of the most seismically active regions in the offshore area of South China. However, the location, geometry, and structural characteristics of the LFZ, which spans over 1000 km, have not been properly examined. In this study, we investigate the precise position of the LFZ offshore East Guangdong (EGD) and map the fault structure using recently acquired high-resolution multi-channel seismic (MCS) reflection data. The LFZ consists of an array of normal faults that collectively form a terraced sidewall fault zone linked to the continental rifting of the South China Sea (SCS). This fault zone is approximately 35-75 km wide and runs parallel to the shoreline. The primary faults of the LFZ EGD segment correlate to a high-gravity gradient zone and serve as the northern boundary of the Zhu-I Depression. During the syn-rift phase, the LFZ experienced significant intra-plate deformation, resulting in fault throws of up to 1000 m. This deformation was locally influenced by pre-existing structures, giving rise to a listric geometry at depth. In the post-rift period, the LFZ exhibited inherited activity along its rift-related faults. The presence of growth fault structures suggests that the LFZ remained active throughout the Cenozoic, with numerous active faults extending practically to the seafloor. The negative flower structure confirms the strikeslip character of the LFZ, which is influenced by the modern tectonic stress field. Intense multi-phase Cenozoic magmatism, including igneous intrusion, volcanism, and lava flows, has been detected in the offshore area of Nan'ao Island. The frequent earthquakes in the study area are primarily attributed to far-field stress release resulting from the subduction of the Philippine Sea Plate beneath the Eurasian Plate. Additionally, the intense magmatism weakens crustal structures, further facilitating stress release and the frequ

关键词： Littoral Fault zone Active fault Magmatism Multi-channel seismic profile Northern South China sea

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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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Buckling and post-buckling of delaminated Reissner-Mindlin panels subjected to hygro-thermal-mechanical multi-field loading

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THIN-WALLED STRUCTURES 2021年 162卷 107583-107583页

作者： Xia, Fei Xue, Jianghong He, Zanhang Yao, Sishi Jin, Fusong Yuan, Hong Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China

This paper proposed a theoretical study on buckling and post-buckling responses for delaminated Reissner- Mindlin composite panels under hygrothermal environment based on the first order shear deformation theory. Constitutive equations of the laminated panel which takes into consideration of the transverse shear and the hydrothermal effects were conducted. Using the von-Kaman nonlinear displacement-strain relationship governing equations in terms of displacements and the slope functions were derived in which the nonlinear contact effect at the interface of delamination was included. Asymptotic solutions of the delaminated composite panel were obtained using perturbation approach and the post-buckling equilibrium paths of the panel characterized by the in-plane load vs deflection amplitude curves were determined via Galerkin approach. By developing Matlab programs, theoretical solutions were computed and parametric studies were carried out to examine the effect of the temperature, the hygroscopic concentration and the delamination conditions on the buckling and post-buckling behaviors of the delaminated panel. It is found that increasing the environmental temperature and hygroscopic concentration will significantly reduce the load carrying capacity of the delaminated composite panels in buckling and post-bucking stage. Solutions from the analysis were validated against finite element results from ABAQUS analysis and were found in good agreement with the latter.

关键词： Hygrothermal effect Transverse shear deformation Buckling and post-buckling analysis Contact effect Delamination

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Offset parameter cancellation produces countless coexisting attractors

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CHAOS 2022年第12期32卷 121104-121104页

作者： Li, Chunbiao Lei, Tengfei Liu, Zuohua Nanjing Univ Informat Sci & Technol Sch Artificial Intelligence Nanjing 210044 Peoples R China Nanjing Univ Informat Sci & Technol Collaborat Innovat Ctr Forecast & Evaluat Meteorol Nanjing 210044 Peoples R China Qilu Inst Technol Collaborat Innovat Ctr Memrist Comp Applicat CICMC Jinan 250200 Peoples R China Chongqing Univ State Key Lab Coal Mine Disaster Dynam & Control Chongqing 400044 Peoples R China

The average value of a system variable determines the position of its attractor. When the offset parameters come together and get disappeared after an algebraic operation, the location of the attractor is then governed by an initial condition only. In this case, parameter-dominated offset control turns out to be the initial condition-defined coexisting attractors. In this Letter, a special mechanism for generating countless coexisting attractors is disclosed. Furthermore, a new regime of multistability is revealed, which explains where and how countless coexisting attractors are born and arranged. Published under an exclusive license by AIP Publishing.

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Dynamics of a Gaussian and Non-Gaussian Vibration Excited Discrete Product Packaging System with Hyperbolic Tangent Nonlinearity

SSRN

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SSRN 2023年

作者： Yang, Song-Ping Deng, Pei-Chang Wang, Zhi-Wei Packaging Engineering Institute College of Packaging Engineering Jinan University Zhuhai519070 China MOE Key Laboratory of Disaster Forecast and Control in Engineering School of Mechanics and Construction Engineering Jinan University Guangzhou510632 China Key Laboratory of Product Packaging and Logistics of Guangdong Higher Education Institutes Jinan University Zhuhai519070 China

This paper reveals the dynamical properties of a Gaussian and non-Gaussian vibration excited multi-degree-of-freedom (MDOF) discrete product packaging system (DPPS) with hyperbolic tangent nonlinearity base on a more systematic acceleration response analysis. Firstly, the product package considering multiple critical components is modeled as a general model of MDOF DPPS, centered around the opposite designed purpose with the similar multiple tuned mass damper (MTMD) model, in which the hyperbolic tangent nonlinearity is rarely considered, then approximate solution theory is established to effectively predicate the acceleration response spectrum of the hyperbolic tangent MDOF DPPS under Gaussian random vibration. Secondly, Hermite polynomial is adopted to simulate non-Gaussian vibration excitation, and verified by the actual road excitation signal. On this basis, the non-Gaussian random vibration analysis method is introduced to analyze the acceleration non-Gaussian stochastic response of the system, the sensitivity of the response to the external excitation and system parameters is discussed. Finally, the reliability analysis via the first-passage distribution of the acceleration stochastic response is given. Approximate solution theory can effectively predict acceleration response spectrum of the system under Gaussian random vibration. The proposed non-Gaussian vibration analysis approach can conveniently reproduce actual non-Gaussian vibration excitation and analyze the dynamic properties, the investigation provides a guidance for packaging vibration absorption design. © 2023, The Authors. All rights reserved.

关键词： Reliability analysis

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A semi-convex function for both constant and time-varying moving force identification

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MECHANICAL SYSTEMS AND SIGNAL PROCESSING 2021年 146卷 107062-107062页

作者： Liu, Huanlin Luo, Ziwei Yu, Ling Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China

In recent years, many moving force identification (MFI) methods have been proposed to monitor moving forces indirectly from structural responses. However, the prior knowledge about moving forces has not been reasonably considered in the existing methods, so the identified moving forces are not accurate enough. To improve the accuracy of MFI results, a novel MFI method is proposed based on a semi-convex function in this study. Firstly, a model of a simply-supported beam subjected to moving forces is taken as an example to establish the relationship between moving forces and structural responses. Then, the prior knowledge that time-varying force component of a moving force usually fluctuates around its static weight in the time domain is adopted. Thus, the moving force is decomposed into constant and time-varying force components. The constant force component is unchanged over time and the time-varying force component is changed over time. Based on this prior knowledge, a semi-convex function is defined for MFI, which is inspired by an alternating iterative method (AIM) and regularization techniques. As a result, the semi-convex function is solved by the AIM, so the constant and time-varying force components can be respectively obtained through iterations, and the moving forces are identified from structural responses. Finally, to evaluate the effectiveness of the proposed method, both numerical simulations and experimental verifications are carried out. The identified results show that the proposed method can further improve the MFI results by comparing with the L-2 regularization and the moving average Tikhonov regularization. The characteristics of the identified moving forces are consistent with that described in the given prior knowledge. Moreover, the proposed method can provide a good ability to estimate the total weight of the model car. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： Moving force identification (MFI) Alternating iterative method (AIM) Semi-convex function Regularization technique

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