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Modified micro-mechanics based multiscale model for progressive failure prediction of 2D twill woven composites

Chinese Journal of Aeronautics 2020年第7期33卷 2070-2087页

作者： Meng WANG Peiwei ZHANG qingguo fei fei GUO Institute of Aerospace Machinery and Dynamics Southeast UniversityNanjing 211189China Department of Engineering Mechanics Southeast UniversityNanjing 211189China

To consider fiber random distribution at the microscale for the multiscale model based on the micro-mechanics failure(MMF)theory,clustering method is used for the extraction of amplification *** the clustering method is a kind of unsupervised machine learning method,the elements with similar mechanical behavior under external loading can be included in a cluster automatically at the *** this modification,the fiber random distribution model can be used for multiscale damage analysis in the framework of MMF *** validate the modified multiscale analysis method,progressive damage analysis of a kind of 2D twill woven composites is conducted based on different microscale *** stress values for microscale models with fiber hexagonal and random distribution patterns are compared *** higher stress concentration is generated in the fiber random distribution model due to the smaller inter-fiber distance especially under longitudinal shear *** obtained cluster distribution results exhibit the characters of the stress distribution in the two microscale ***,tensile and compressive responses of the 2D twill woven composite are predicted with the modified multiscale analysis method and accuracy of the method is verified through comparison with published experimental *** the simulation results,it can be found that the matrix damage initiation from the model based on the fiber random distribution model is premature compared with that from the model based on the fiber hexagonal distribution ***,under tensile loading,the damage all initiates from the fill tows and propagates to the wrap ***,under compressive loading,the matrix damage initiates from the wrap tows in the model based on the fiber random distribution model.

关键词： 2D twill woven composites Clustering analysis Fiber distribution patterns Micro-mechanics failure theory Multiscale damage model

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Strain-Rate-Dependent In-Plane Compressive Properties of 3D Fine Weave Pierced C/C Composite:Failure Mechanism and Constitutive Model

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Acta Mechanica Solida Sinica 2022年第1期35卷 63-78页

作者： fei Guo qingguo fei Yanbin LiL Nikhil Gupta Jiangsu Engineering Research Center of Aerospace Machinery Southeast UniversityNanjing 211189China Department of Engineering Mechanics Southeast UniversityNanjing 211189China School of Mechanical Engineering Southeast UniversityNanjing 211189China Composite Materials and Mechanics Laboratory Department of Mechanical and Aerospace EngineeringTandon School of EngineeringNew York UniversityBrooklynNY 11201USA

In-plane compression experiments are performed on 3D fine weave pierced C/C composite at a wide strain rate range of 0.0001/s-1000/*** in-plane compressive failure mechanism of the composite at quasi-static and high strain rates is analyzed by a scanning electron *** results show that the in-plane compressive modulus,maximum stress and the corresponding strain increase with increasing strain *** quasi-static in-plane compressive failure mode of the 3D fine weave pierced C/C composite is characterized by the shear failure at the angle of 45°and the local buckling of the^direction fiber *** comparison,the high strain rate in-plane compression failure mode of the composite is characterized by the compressive fracture of the interlaminar matrix and the progressive compression failure of the a>direction fiber bundles.A strain-rate-dependent in-plane compressive constitutive model is proposed to predict the dynamic in-plane compressive response of the *** proposed constitutive model is verified by experimental data.

关键词： C/C composite Compression Failure mechanism Constitutive model

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Fatigue Life of a 2.5D C/SiC Composite Under Tension–Tension Cyclic Loading:Experimental Investigation and Sensitivity Analysis

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Acta Mechanica Solida Sinica 2021年第5期34卷 645-657页

作者： Jingwei Yu qingguo fei Peiwei Zhang Yanbin Li Qiang Chen School of Mechanical Engineering Southeast UniversityNanjing211189China Jiangsu Engineering Research Center of Aerospace Machinery Southeast UniversityNanjing211189China

Engineering structures made of ceramic matrix composites(CMCs)usually suffer from cyclic loads during service,which could lead to disastrous *** work focuses on the fatigue behavior of a 2.5D C/SiC composite under tension–tension cyclic *** of the 2.5D C/SiC composite are firstly carried out to determine the fatigue lifetime of the material at different stress *** fracture surfaces examined by a scanning electronic microscope indicate that the damage mechanisms under cyclic loading are closely related to crack propagation,fiber/matrix interfacial degradation,and fiber *** the damage evolution of fibers and interfacial resistance,a micromechanical model is adopted to describe the fatigue behavior of 2.5D C/SiC composite,and the numerical results are compared with the experimental ***,a sensitivity analysis is performed as a function of the interfacial shear stress,fiber Weibull modulus,and fiber *** calculation of sensitivity factors shows that the variations of the fiber Weibull modulus and fiber strength have the most significant influence and,thereafter,the variation of interfacial shear stress.

关键词： Ceramic matrix composites(CMCs) 2.5D C/SiC composite Fatigue Mechanical properties Sensitivity

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Mesenchymal stem cells in progression and treatment of cancers

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Frontiers in Biology 2014年第3期9卷 186-194页

作者： qingguo ZHAO fei LIU Institute for Regenerative Medicine at Scott & White MCMD Texas A&M Health Science Center Temple TX 76502 USA

Mesenchymal stem or stromal cells （MSCs） from bone marrow or local tissues are recruited to stroma of almost all types of cancers during initiation and/or progression of cancer. The recruited MSCs and their derivative cancer-associated fibroblasts interact with cancer cells to promote sternness, invasion and metastasis of cancer cells. Targeting these cancer-recruited MSCs and/or the interaction between MSCs and cancer cells are promising strategies to improve cancer therapy. On the other hand, the unique tumor-homing capacity of MSCs makes them a promising vehicle to deliver various anti-cancer agents. This review summarized the recent advancement of our understanding on the interaction between MSCs and cancer ceils, as well as the potential of MSCs for cancer therapy.

关键词： mesenchymal stem or stromal cells cancer cancer-associated fibroblasts gene therapy cell therapy

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Frequency-dependent random fatigue of panel-type structures made of ceramic matrix composites

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Acta Mechanica Solida Sinica 2017年第2期30卷 165-173页

作者： Yadong Zhou Xiaochen Hang Shaoqing Wu qingguo fei Natasa Trisovic Department of Engineering Mechanics Southeast University Nanjing 210096 PR China Department of Civil and Environmental Engineering and Department of Mechanical Engineering NorthwesternUniversity Evanston IL 60208 USA Department of Aerospace Engineering and Mechanics University of Alabama Tuscaloosa AL 35487 USA School of Mechanical Engineering Southeast University Nanjing 210096 PR China Faculty of Mechanical Engineering Department of Mechanics University of Belgrade Belgrade 11120 Serbia

The panel-type structures used in aerospace engineering can be subjected to severe highfrequency acoustic loadings in service. This paper evaluates the frequency-dependent random fatigue of panel-type structures made of ceramic matrix composites（CMCs） under acoustic loadings. Firstly, the high-frequency random responses from the broadband random excitation will result in more stress cycles in a deinite period of time. The probability density distributions of stress amplitudes will be different in different frequency bandwidths, though the peak stress estimations are identical. Secondly, the fatigue properties of CMCs can be highly frequency-dependent. The fatigue evaluation method for the random vibration case is adopted to evaluate the fatigue damage of a representative stiffened panel structure. The frequency effect through S-N curves on random fatigue damage is numerically veriied. Finally, a parameter is demonstrated to characterize the mean vibration frequency of a random process, and hence this parameter can further be considered as a reasonable loading frequency in the fatigue tests of CMCs to obtain more reliable S-N ***, the inluence of vibration frequency can be incorporated in the random fatigue model from the two perspectives.

关键词： Random fatigue Frequency effect Ceramic matrix composites(CMCs) S-N curve Loading frequency

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Modal identification of long-span Runyang Bridge using ambient responses recorded by SHMS

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Science China(Technological Sciences) 2009年第12期52卷 3632-3639页

作者： qingguo fei AiQun Li XiaoLin Han ChangQing Miao School of Civil Engineering Southeast University Nanjing 210096 China Key Laboratory of Concrete and Prestressed Concrete Structures of Ministry of Education Southeast University Nanjing 210096 China

Runyang Bridge is a newly built cable-supported bridge that crosses the Yangtze River in *** bridge is composed of one suspension bridge and one cable-stayed *** the construction of the bridge,a structural health monitoring system(SHMS)was installed,which was designed by the Southeast *** the bridge was open to traffic,quantities of structural ambient responses have been recorded by the ***,it’s really important to extract structrural information from these records for health *** paper presents the study on modal identification of the *** dynamic properites including modal frequencies,mode shapes and damping ratios are extracted from the ambient *** identification methods are employed including the enhanced frequency domain decomposition and the stochastic subspace *** identified modal parameters from the two methods are *** show that modal frequencies and mode shapes from the two methods are almost the same while the damping ratios are different.

关键词： cable-supported bridge Runyang Bridge structural health monitoring modal identification ambient response analysis

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Numerical-experimental method for elastic parameters identification of a composite panel

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Theoretical & Applied Mechanics Letters 2014年第6期4卷 20-25页

作者： Dong Jiang Rui Ma Shaoqing Wu qingguo fei Jiangsu Key Laboratory of Engineering Mechanics Southeast University Department of Engineering Mechanics Southeast University

A hybrid numerical-experimental approach to identify elastic modulus of a textile composite panel using vibration test data is proposed and investi- gated. Homogenization method is adopted to predict the initial values of elastic parameters of the composite, and parameter identification is transformed to an optimization problem in which the objective function is the minimization of the discrepancies between the experimental and numerical modal data. Case study is conducted employing a woven fabric reinforced composite panel. Three parameters （Ell, E22, G12） with higher sensitivities are selected to be identified. It is shown that the elastic parameters can be accurately identified from experimental modal data.

关键词： composite panel elastic modulus parameter identification modal data,numerical-experimental method

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Temperature-dependence of acoustic fatigue life for thermal protection structures

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Theoretical & Applied Mechanics Letters 2014年第2期4卷 27-31页

作者： Yadong Zhou Shaoqing Wu Zhiyong Tan qingguo fei Department of Engineering Mechanics Southeast University Jiangsu Key Laboratory of Engineering Mechanics Southeast University State Key Laboratory of Space Physics

Acoustic fatigue life evaluation is essential for thermal protection struc- tures due to the severe thermo-acoustic load in service. A study on temperature- dependence of acoustic fatigue life for a C/SiC panel is presented in this paper. Effects of temperature on both the structural responses and the S-N curves are investigated. The Dirlik method is adopted to predict the fatigue life of a C/SiC panel at three different temperatures respectively. Significant differences are ob- served from the results of numerical simulations between the fatigue lives of the panel in the three cases. The temperature-dependence of acoustic fatigue life of a C/SiC panel is verified, and fatigue test of the material needs to be more atten- tively performed.

关键词： C/SiC panel S-N curve acoustic fatigue temperature-dependence

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Static analysis of elastic cable structures under mechanical load using discrete catenary theory

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Fundamental Research 2023年第6期3卷 967-973页

作者： Weicheng Huang Dongze He Dezhong Tong Yuzhen Chen Xiaonan Huang Longhui Qin qingguo fei School of Mechanical Engineering Southeast UniversityNanjing 211189China Jiangsu Engineering Research Center of Aerospace Machinery Southeast UniversityNanjing 211189China Department of Mechanical and Aerospace Engineering University of CaliforniaLos AngelesCA 90095USA Department of Mechanical Engineering and Materials Science Yale UniversityNew HavenCT 06511USA

In this paper,the nonlinear mechanical response of elastic cable structures under mechanical load is studied based on the discrete catenary theory.A cable net is discretized into multiple nodes and edges in our numerical approach,which is followed by an analytical formulation of the elastic energy and the associated Hessian matrix to realize the dynamic simulation.A fully implicit framework is proposed based on the discrete differential geometry(DDG)*** equilibrium configuration of a target object is derived by adding damping force into the system,known as the dynamic relaxation *** mechanical response of a single suspended cable is investigated and compared with the analytical solution for cross-validation.A more intricate scenario is further discussed in detail,where a structure consisting of multiple slender cables is connected through *** the robustness and efficiency of our discrete numerical framework,a systematic parameter sweep is performed to quantify the force displacement relationships of nets with the different number of cables and different directions of ***,an empirical scaling law is provided to account for the rigidity of elastic cable net in terms of its geometric properties,material characteristics,component numbers,and cable *** results would provide new insight in revealing the connections between flexible structures and tensegrity structures,and could motivate innovative designs in both mechanical and civil engineered equipment.

关键词： Cable structures Rigidity Solid mechanics Computational mechanics Numerical simulation Nonlinearity

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基于正交检验法的颤振分析模态跟踪技术

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振动与冲击 2017年第19期36卷 84-89,134页

作者：蒋令闻杭晓晨费庆国江苏省工程力学分析重点实验室南京210096 东南大学工程力学系南京210096

模态跟踪是颤振分析的关键问题之一。常见的基于模态置信度的跟踪方法在颤振点附近常会出现错误导致跟踪失败。通过探究该方法的数学机理,阐明了基于模态置信度跟踪方法存在的缺陷,进而引入左特征向量,研究了一种基于正交检验法的模态... 详细信息

模态跟踪是颤振分析的关键问题之一。常见的基于模态置信度的跟踪方法在颤振点附近常会出现错误导致跟踪失败。通过探究该方法的数学机理,阐明了基于模态置信度跟踪方法存在的缺陷,进而引入左特征向量,研究了一种基于正交检验法的模态跟踪技术。采用一悬臂直翼盒模型开展仿真研究,在状态空间下进行颤振分析,基于正交检验法得到其根轨迹图,并将模态跟踪结果与MAC值法进行对比,证明了正交检验法具有更好的模态跟踪效果。

关键词：颤振状态空间特征向量模态跟踪模态置信度

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