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Material behavior modeling with multi-output support vector regression

APPLIED MATHEMATICAL MODELLING 2015年第17期39卷 5216-5229页

作者： Zhao, W. Liu, J. K. Chen, Y. Y. Jinan Univ Key Lab Disaster Forecast & Control Engn Minist Educ China Guangzhou 510632 Guangdong Peoples R China Sun Yat Sen Univ Dept Mech Guangzhou 510275 Guangdong Peoples R China Guangzhou Univ Earthquake Engn Res & Test Ctr Guangzhou 510405 Guangdong Peoples R China

Based on neural network material-modeling technologies, a new paradigm, called multi-output support vector regression, is developed to model complex stress/strain behavior of materials. The constitutive information generally implicitly contained in the results of experiments, i.e., the relationships between stresses and strains, can be captured by training a support vector regression model within a unified architecture from experimental data. This model, inheriting the merits of the neural network based models, can be employed to model the behavior of modern, complex materials such as composites. Moreover, the architectures of the support vector regression built in this research can be more easily determined than that of the neural network. Therefore, the proposed constitutive models can be more conveniently applied to finite element analysis and other application fields. As an illustration, the behaviors of concrete in the state of plane stress under monotonic biaxial loading and compressive uniaxial cycle loading are modeled with the multi-output and single-output support regression respectively. The excellent results show that the support vector regression provides another effective approach for material modeling. (C) 2015 Elsevier Inc. All rights reserved.

关键词： Multi-support vector regression Training Material modeling

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A novel two-step intelligent algorithm for damage detection of beam-like structures

A novel two-step intelligent algorithm for damage detection ...

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International Conference on Natural Computation (ICNC)

作者： Zepeng Chen Ling Yu Department of Mechanics and Civil Engineering Jinan University Guangzhou China MOE Key Lab of Disaster Forecast and Control in Engineering Jinan University Guangzhou China

A novel two-step intelligent algorithm is proposed for structural damage detection (SDD) by combining particle swarm optimization and Nelder-Mead (PSO-NM) algorithm, in which two steps are deployed for exploring a better balance between computational efficiency and accuracy. In the first step, a modal strain energy based index (MSEBI) is defined and used to precisely locate damages of structures. In the second step, structural damage extent is determined by PSO-NM algorithm. Some beam-like structures are adopted to assess its applicability. A parametric study and the effect of measurement noise on the method are also considered. The illustrated numerical simulation results show that the novel method can not only locate structural damage but also identify damage extent of beam-like structures with a good robustness to noises.

关键词： Optimization Shape Algorithm design and analysis Strain Computational efficiency Particle swarm optimization Indexes

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Experimental and numerical studies of the oblique defects in the pipes using a chaotic oscillator based on ultrasonic guided waves

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JOURNAL OF SOUND AND VIBRATION 2015年 347卷 218-231页

作者： Yang, Fei Jing, Lin Zhang, Weiwei Yan, Yinzhong Ma, Hongwei Jinan Univ Coll Sci & Engn Guangzhou 510632 Guangdong Peoples R China Southwest Jiaotong Univ State Key Lab Tract Power Chengdu 610031 Sichuan Peoples R China Taiyuan Univ Sci & Technol Dept Mech Taiyuan 030024 Peoples R China Jinan Univ Moe Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Guangdong Peoples R China Qinghai Univ Sch Civil Engn Xining 810016 Peoples R China

The longitudinal ultrasonic guided waves in oblique defects pipes were investigated experimentally and numerically in the paper. A novel method of the defect detection for pipes is proposed based on the Duffing -Holmes chaotic oscillator. Five kinds of defects with inclined angle of 0 degrees, 30 degrees, 45 degrees, 60 degrees and 90 degrees were discussed arid analyzed, respectively. Based on the experiment, the corresponding simulations were conducted by using finite element software [S-DYNA. Both experimental arid numerical results show that this proposed method could be used to inspect the weaker guided waves;and the reflection coefficient of echo increases with the decrease of the inclined angle. (C) 2015 Elsevier Ltd. All rights reserved.

关键词： POINT defects CHAOS theory ULTRASONIC waves PHYSICS experiments NUMERICAL analysis FINITE element method

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Elastoplastic analysis of tunnel surrounding rocks based on the statistical damage constitutive model

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Journal of engineering Science and Technology Review 2016年第3期9卷 27-34页

作者： Zhu, C.Q. Yin, Z.Q. Li, C.M. Feng, R.M. Anhui Province Key Lab. of Mining Response and Disaster Prevention and Control in Deep Coal Mine Anhui University of Science and Technology Huainan Anhui232001 China School of Resource and Safety Engineering Anhui University of Science and Technology Huainan Anhui232001 China Department of Mining and Mineral Resources Engineering Southern Illinois University Carbondale CarbondaleIL62901 United States

Accurately determining the stress status of surrounding rocks is difficult as stress in surrounding rocks is redistributed after tunneling. A constitutive model selection of surrounding rocks based on the pre-peak strain hardening characteristics of surrounding rocks is considered to further analyze the mechanical characteristics of tunnel surrounding rocks. Theoretical analysis and analytic calculation were conducted on the stress distribution and the deformation characteristics of tunnel surrounding rocks in this study. The evolution laws of stress, as well as the strain of the elastoplastic zone of tunnel surrounding rocks, and the plastic zone radius along with strain hardening and other relevant factors were also analyzed. Results show that, in view of strain hardening, the mechanical characteristics of surrounding rocks increasingly approaches that of reality and the plastic zone radius achieved is larger than the result of the Kastner solution. Moreover, when the strain hardening stage is shortened, the plastic zone radius initially decreases and then slightly increases;tangential strain and displacement increase in varying degrees as the radial strain gradually decreases;tangential stress peak gradually increases and the sudden change of its distribution curve becomes increasingly evident although radial stress changes are less obvious;and sensitivity of the radius and displacement of the surrounding rock plastic zone that support resistance increase with the increase in mining depth. As a result, the research findings solve, to a certain degree, the problem that the constitutive model of surrounding rocks failed to reflect the true characteristics of surrounding rocks, providing the theoretical foundation of stability analysis and supporting the design of tunnel surrounding rocks.

关键词： Strain hardening

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Residual strength of slip zone soils

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LANDSLIDES 2014年第2期11卷 305-314页

作者： Chen, X. P. Liu, D. Jinan Univ Coll Sci & Engn Key Lab Disaster Forecast & Control Engn Guangzhou Guangdong Peoples R China

Slip zones of ancient landslides are commonly composed of fine-grained soils with amount of coarse-grained particle. Residual strength of slip zone soil is an important parameter for evaluating reactivation potential and understanding progressive failure mechanism. In this study, the residual strength is examined by in situ direct shear tests, improved laboratory reversal shear box test, precut specimen triaxial shear test and ring shear test. Some residual shear behaviors are recognized. Field residual strength is the average operational resistance along the sliding surface not an ideal drained strength, which is less than peak and greater than residual strength measured in laboratory. Stress-displacement curves obtained from in situ shear and laboratory reversal direct shear demonstrate strain-hardening which have no significant peak, but the shear stress is decreased gradually with increasing displacement. Residual friction coefficient depends on the normal stress, and this dependence is relevant to the interaction of rolling and sliding of particles. Residual friction angle is closely related to coarse fraction and dry density, appearing a linear increase with increasing coarse fraction and a form of polynomial function with increasing dry density. The influence of shearing rate on residual strength can be negligible.

关键词： Slip zone soils Residual strength Fine-grained soils with coarse-grained particle Shear test

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Study on Prediction for Fracturing Operation Noise and Impact Assessment

Study on Prediction for Fracturing Operation Noise and Impac...

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2016 IEEE International Conference of Online Analysis and Computing Science(ICOACS 2016)

作者： Liu Jingcheng Jiang Junlong Mei Lin Liu Jumei Wang Yu Institute of Petroleum & Gas Engineering Chongqing University of Science and Technology School of Aerospace Mechanical&Manufacturing EngineeringRMIT University Chongqing gas field Southwest Oil and Gas Field BranchPetro China Company Limited Key Lab for Exploitation of China Southwestern Resources & Environmental Disaster Control Engineering Ministry of EducationChongqing University Research Institute of safety and environmental protection and technology supervision Petro China Company Limited

Fracturing is one of the key stimulation treatment techniques with wide application prospect for oil-gas well and is a kind of main form of natural gas exploitation currently,which is especially important for development of shale ***,the noise generated in the process of fracturing operation may impact the site operators and residents in the *** typical fracturing operation process is selected in this paper to implement the actual measurement of noise and record such relevant parameters as operation condition and ambient *** on the computation method of outdoor acoustic transmission attenuation,Cadna/A ambient noise simulation software is utilized to establish the acoustic environment simulation simplification model for certain oil well fracturing operation,implement the simulation study for noise impact distribution condition in the process of fracturing operation construction and perform the contrastive analysis for actually-measured value on the *** result shows that the site operator's contact noise value is higher than the occupational exposure limit in National Occupational Sanitary Standard GBZ 2.2-2007 Occupational Exposure Limit for Harmful Factors in Workplace and the noise produced during operation in the daytime doesn't meet the emission limit in National Standard GB 12348-2008 Emission Standard for Ambient Noise at the Boundary of Industrial ***,in combination with the actual fracturing operation,the reasonable noise prevention and control measures are *** study result of this paper has certain reference value for prediction and assessment of fracturing operation noise.

关键词： Fracturing noise prediction assessment prevention and control measures

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Seismic fragility analysis of steel-concrete composite bridges excited by near-fault ground motions

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Tumu Gongcheng Xuebao/China Civil engineering Journal 2016年 49卷 56-60and77页

作者： Liu, Yang Lu, Dagang Yu, Xiaohui Key Lab of Structural Dynamic Behavior and Control of China Ministry of Education Harbin Institute of Technology Harbin150090 China School of Civil Engineering Harbin Institute of Technology Harbin150090 China State Key Laboratory for Disaster Reduction in Civil Engineering Tongji University Shanghai200092 China

The seismic fragility analysis was conducted for a steel-concrete composite bridge (SCCB) including the effects of the near-fault pulse-like ground motions. A total of 60 real ground motions were selected from the PEER strong earthquake database as the inputs. The global fragility curves and local fragility curves of the bridge were obtained through the fragility analysis. Compared to the fragility results of the far-field earthquake records, it is found that the demands due to the near-fault ground motions are significantly larger than that due to the far-field ground motions. Under the near-fault pulse-like ground motions, the pier is the most fragile component, while the concrete crossbeam and the studs are less fragile. © 2016, Editorial Office of China Civil engineering Journal. All right reserved.

关键词： Concretes

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Nonlinear characteristics of pendulum model with negative stiffness suspension

Nonlinear characteristics of pendulum model with negative st...

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第十五届全国非线性振动暨第十二届全国非线性动力学和运动稳定性学术会议

作者：李媛萍 CHEN Si-yu Key Lab of Disaster Forecast and Control in Engineering Ministry of Education of the People's Republic of China(Jinan University) Department of Mechanics and Civil Engineering Jinan University State Key Laboratory of High Performance Complex Manufacturing Central South University

Vibration and noise are important engineering problem and many methods have been developed to control and/or absorb the *** to now,there are a number of strategies to control the response of a system such as passive control,active control,semi-active control and hybrid *** achieve perfect performance of target system,the structures or mechanical systems should be designed to suit for different types of loading such as particularly dynamic and transient loads,and to obtain high static stiffness resulting in a small static deflection and a small dynamic stiffness resulting in a low natural *** mainaim of this paper is to improve the nonlinear pendulum system with negative stiffness suspension element with external excitation,and to explore the bifurcation and chaos characteristics contained in the pendulum *** governing equations of pendulum are derived by Lagrange *** analyze the bifurcation of nonlinear response of pendulum system,the phase portrait and bifurcation diagram are obtained ***,the Floquet multipliers are obtained by solving the perturbation equation with original equation with numerical *** results show that the main responses of pendulum system are periodic,and through saddle node bifurcation the system come into chaotic *** parametric resonance may occur when the excitation frequency closed to the natural frequency at vertical direction of whole *** variation of stiffness and excitation frequency has a large influence on the performance of the pendulum,and the amplitude of excitation may deduce unbounded motion in the resonance region.

关键词： Pendulum Bifurcation Floquet multiplier chaotic motion Suspension

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A Global Energy Approach for Analysis of a Propagating Buckle in Submarine Pipelines

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JOURNAL OF OFFSHORE MECHANICS AND ARCTIC engineering-TRANSACTIONS OF THE ASME 2014年第4期136卷 041701-1-041701-8页

作者： Tang, Mingqiao Xue, Jianghong Liu, Renhuai Jinan Univ Minist Educ Key Lab Disaster Forecast & Control Engn Dept Mech & Civil Engn Guangzhou 510632 Guangdong Peoples R China

This paper presents a unique approach to analyze the steady-state buckle propagation phenomenon in underwater pipelines. In previous work, we restudied the buckling of a very long pipeline subjected to external pressure and found that buckling happens only over a certain length of the pipeline. In this paper, the collapse mode of the pipeline obtained in previous studies is taken as the transition zone during steady-state buckle propagation. Kinematics in the transition zone is analyzed based on von Karman-Donnell type of nonlinearity. Assuming linear elastic rigid plastic material properties, the mechanical responses in the transition zone are examined using the deformation theory. Two parameters, the yield coefficient and the membrane stretching factor, are introduced to depict the effects of transversal bending and the membrane stretching, respectively. Analytical solution of buckle propagation pressure is derived by considering the energy conversation calculated from shell theory. It is found that the buckle propagation performance is governed by the transversal bending, including the circumferential bending and longitudinal bending. The membrane stretching is significant only for thick wall pipeline, in particular when the ratio of radius-to thickness is small than ten. The analysis is in effect by comparing the obtained solutions with the well-established predictions and the experimental results.

关键词： offshore pipelines reliability of offshore structures and pipelines structural safety and risk analysis system integrity assessment

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A comprehensive study on a propagating buckle in externally pressurized pipelines

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JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY 2014年第12期28卷 4907-4919页

作者： Xue, Jianghong Gan, Neng Jinan Univ Dept Mech & Civil Engn Minist Educ Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Guangdong Peoples R China

Buckle propagation is a unique phenomenon occurring in deep-sea pipelines. In previous works, this phenomenon was investigated using a ring technique in which the pipeline was assumed to be in plane strain condition and the energies absorbed in membrane stretching and longitudinal bending were ignored. This paper presents a three-dimensional analysis of the buckle propagation phenomenon with an emphasis to address more complete factors that were not accounted for in the ring analysis. The analyses are based on the available solutions of the transition zone obtained in our previous works. A comprehensive mechanism for buckle propagation phenomenon is described from the point view of plastic stability theory for shells which enables the incorporation of the effects of transverse and longitudinal bending, membrane stretching and material strain hardening. The nondimensionalized buckle propagation pressure is represented in terms of yield coefficient, strain hardening coefficient and membrane stretching factor. It is found that a buckle once initiated in a pipeline may or may not propagate along the pipeline depending on its radius-to-thickness ratio. By comparing with various experimental results the theoretical predictions from this analysis are shown to provide very accurate estimations of the buckle propagation pressure for different materials with diverse geometric parameters and material properties. This paper points to the need for more complete information regarding the effects of transverse bending, membrane stretching and material strain-hardening on the buckle propagation pressure. Upon the requirement of application variations of the yield coefficient, strain hardening coefficient and membrane stretching factor with respect to the radius-to-thickness ratio are sketched out. This eliminates the need for recourse the curves and allows a fast and convenient resolution of buckle propagation pressure for certain pipeline. Most importantly, the present analysis of

关键词： Buckle propagation Shells and membranes Plastic collapse Length of transition zone Stability and bifurcation

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