检索结果-南通市图书馆

Science China(Technological Sciences) 2020年第7期63卷 1177-1187页

作者： LI Chao LI HongNan ZHANG Hao SU JunSheng LI RouHan DING YiMing State Key Laboratory of Coastal and Offshore Engineering Faculty of Infrastructure EngineeringDalian University of TechnologyDalian 116024China School of Civil Engineering Shenyang Jianzhu UniversityShenyang 110168China Key Laboratory of Coast Civil Structure Safety of Ministry of Education Tianjin UniversityTianjin 300350China

This paper presents a novel and precise seismic performance evaluation method for large-span offshore cable-stayed(LSOCS)bridge by considering the strain rate effect of RC materials and the spatial variation effect of seafloor seismic motions. Threedimensional finite element(FE) model of a LSOCS bridge located in the southeast coast of China is constructed in the ABAQUS platform. The non-uniform ground motions at the offshore site beneath the bridge are stochastically simulated and used as seismic inputs. Moreover, a subroutine for considering the rate-dependent properties of RC materials in a fiber-based beamcolumn element model is developed to account for the strain rate effect of RC materials in the nonlinear time-history *** numerical results indicate that seismic responses and fragilities of the LSOCS bridge are both considerably affected by the non-uniform seafloor seismic motions and strain rate effect. The seismic performance evaluation approach presented in this paper can provide vital support for earthquake resistant design of LSOCS bridges.

关键词： large-span offshore cable-stayed bridges spatially varying seafloor seismic motions strain rate effect seismic fragility

Modeling strain rate effect for Heterogeneous Brittle Materials

在线全文

学校读者我要写书评

暂无评论

Transactions of Tianjin University 2006年第B9期12卷 79-82页

作者： MA Guowei DONG Aiai LI Jianchun School of Civil and Environmental Engineering Nanyang Technological University Singapore 639798

Rocks are heterogeneous from the point of dynamic failure behavior. Both the compressive and microstructure which is of significance to their tensile strength of rock-like materials is regarded different from the static strength. The present study adopts smoothed particle hydrodynamics （SPH） which is a virtual particle based meshfree method to investigate strain rate effect for heterogeneous brittle materials. The SPH method is capable of simulating rock fracture, free of the mesh constraint of the traditional FEM and FDM models. A pressure dependent J-H constitutive model involving heterogeneity is employed in the numerical modeling. The results show the compressive strength increases with the increase of strain rate as well as the tensile strength, which is important to the engineering design.

关键词： heterogeneous strain rate effect SPH method

strain-rate effect on initial crush stress of irregular honeycomb under dynamic loading and its deformation mechanism

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2018年第1期34卷 117-129页

作者： Peng Wang Zhijun Zheng Shenfei Liao Jilin Yu CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern Mechanics University of Science and Technology of China Institute of Systems Engineering China Academy of Engineering Physics Institute of Fluid Physics China Academy of Engineering Physics

The seemingly contradictory understandings of the initial crush stress of cellular materials under dynamic loadings exist in the literature, and a comprehensive analysis of this issue is carried out with using direct information of local stress and strain. Local stress/strain calculation methods are applied to determine the initial crush stresses and the strain rates at initial crush from a cell-based finite element model of irregular honeycomb under dynamic loadings. The initial crush stress under constant-velocity compression is identical to the quasi-static one, but less than the one under direct impact, i.e. the initial crush stresses under different dynamic loadings could be very different even though there is no strain-rate effect of matrix material. A power-law relation between the initial crush stress and the strain rate is explored to describe the strain-rate effect on the initial crush stress of irregular honeycomb when the local strain rate exceeds a critical value, below which there is no strain-rate effect of irregular honeycomb. Deformation mechanisms of the initial crush behavior under dynamic loadings are also *** deformation modes of the initial crush region in the front of plastic compaction wave are different under different dynamic loadings.

关键词： Cellular material Constant-velocity compression Direct impact Cross-sectional stress Initial crush stress strain rate effect

effects of Temperature and strain rate on Dynamic Properties of Concrete

在线全文

学校读者我要写书评

暂无评论

Transactions of Tianjin University 2008年第B10期14卷 511-513页

作者：贾彬陶俊林李正良王汝恒张誉 School of Civil Engineering Chongqing University School of Civil Engineering and Architecture Southwest University of Science and Technology

To study the dynamic properties of the concrete subjected to impulsive loading, stress-time curves of concrete in different velocities were measured using split Hopkinson pressure bar (SHPB).effects of temperature and strain rate on the dynamic yield strength and constitutive relation of the con-crete were analyzed. The dynamic mechanical properties of the reinforced concrete are subjected to high strain rates when it is at a relatively low temperature. But with temperature increasing, the temperature softening effect makes the strength of the concrete weaken and the impact toughness of the concrete is saliently relative to strain rate effect. So, strain rate effect, strain hardening and temperature softening work together on the dynamic mechanical capability of concrete and the relation between them is relatively complex.

关键词： concrete temperature effect strain rate effect SHPB

Numerical study on dynamic properties of rubberised concrete with different rubber contents

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2023年第6期24卷 228-240页

作者： Lei Pan Hong Hao Jian Cui Thong M.Pham Guangzhou University-Curtin University Joint Research Centre for Structural Monitoring and Protection Against Multi-Dynamic Hazards School of Civil EngineeringGuangzhou UniversityChina Guangzhou University-Curtin University Joint Research Centre for Structural Monitoring and Protection Against Multi-Dynamic Hazards School of Civil and Mechanical EngineeringCurtin UniversityAustralia School of Civil Engineering Tianjin UniversityChina Centre for Infrastructural Monitoring and Protection School of Civil and Mechanical EngineeringCurtin UniversityAustralia

As a green environmentally-friendly material,rubberised concrete(Ru C),which has the characteristics of low elastic modulus,large deformation capacity,high damping,good energy dissipation and good crack resistance,has attracted extensive attention and research in the civil engineering ***,most of existing studies are based on experimental tests on Ru C material properties,and there has been no numerical study based on meso-scale modelling of Ru C *** more comprehensively investigate the Ru C dynamic material properties without conducting intensive experimental tests,this study developed a high-fidelity meso-scale model considering coarse and fine aggregates and rubber crumbs to numerically investigate the mechanical properties of rubberised concrete under different strain *** meso-scale model was verified against both quasi-static compressive testing data and Split Hopkinson Pressure Bar(SHPB)dynamic testing *** the verified numerical model,the dynamic properties of rubberised concrete with various rubber content(0%-30%)under different strain rates were *** numerical results show that the developed meso-scale model can use to predict the static and dynamic properties of rubberised concrete with high *** dynamic compressive strength of the rubberised concrete increases with the increment of the strain rate,and the strain rate sensitivity increases with the rubber content ranging from 0 to 30%.Based on intensive numerical simulation data,empirical DIFs is used as a function of strain rate and rubber content to predict the dynamic strength of rubberised concrete.

关键词： Rubberised concrete Meso-scale model Numerical simulation strain rate effect Dynamic increase factor

Dynamic Compression Behavior and Microstructure of a Novel Low-Carbon Quenching-Partitioning-Tempering Steel

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2014年第3期27卷 444-451页

作者： Qingguo Hao Ying Wang Xiaoshuai Jia Xunwei Zuo Nailu Chen Yonghua Rong School of Materials Science and Engineering Shanghai Jiao Tong University School of Mechanical Engineering Shanghai Dianji University

A 0.2C-1.5Mn-1.5Si-0.6Cr-0.05Nb （wt%） steel is treated respectively by novel quenching-partitioning-tempering （Q-P-T） process and traditional quenching and tempering （Q＆T） process for comparison. X-ray diffraction analysis indicates that Q-P-T steel has about 10% retained austenite, but Q＆T steel hardly has one. With the increase of com- pression strain rate from 7 × 10^2 to 5 × 10^3 s^-1, the flow stress of Q-P-T steel increases, which demonstrates the positive strain rate effect, but does not exist in Q＆T steel. The characterization of scanning electron microscopy indicates that a large number of long, straight martensite laths in Q-P-T steel will bend or be destroyed by large compressive strain of 35% at 5 × 10^3 s^-1. However, relative small compressive s^xain of about 5% at 7× 10^2 s^-1 almost does not have any effect on the original lath morphology. The characterization of transmission electron microscopy further reveals the origin of the positive strain rate effect and the microstructural evolution during dynamic compressive deformation.

关键词： Quenching-partitioning-tempering (Q-P-T) steel Retained austenite strain rate effect Microstructural characterization

Dynamic tensile and failure behavior of bi-directional reinforced GFRP materials

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2020年第2期36卷 460-471页

作者： Zishang Liu Zhe Yang Yuchao Chen Yangyang Yu Yanpeng Wei Maohui Li Chenguang Huang Institute of Mechanics Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China CRRC Qingdao Sifang Co. LTDQingdao 266111China The Quartermaster Research Institute of Engineering and Technology Beijing 100010China

In this paper,a series of static/dynamic tensile tests are performed for glass fiber reinforced plastic(GFRP)*** the combination of high-speed photography and digital image correlation(DIC)technology,true stress-strain curves in different directions and strain rates are *** also obtained the dynamic failure strain of the material in different directions,which are used to accurately describe the dynamic tensile and failure behavior of the *** experimental results show that there is a stiffness change point N in three directions under different strain rate(10-3 s-1,10 s-1,100 s-1)tensile *** stiffness before and after N point is recorded as Einitial and Echanged *** values of Echanged in weft direction and warp direction are about 30%to 50%of Einitial,while Echanged in tilt direction is only about 10%of *** fiber has the highest strength in the weft direction and the tilt direction has the lowest *** the combination of high-speed photography and DIC technology,the dynamic failure parameters of different directions under the strain rate of 100 s-1 are *** dynamic failure strains in three directions are 0.245,0.373 and 0.341,*** parameters are verified by impact three-point bending *** works can more accurately describe the dynamic mechanical behavior of glass fiber reinforced plastic(GFRP)composites and provide reference for the design of GFRP structures.

关键词： Solid mechanics Dynamic failure strain Digital image correlation strain rate effect Stiffness

Elasto-plastic constitutive model of aluminum alloy foam subjected to impact loading

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2011年第3期21卷 449-454页

作者：王志华敬霖赵隆茂太原理工大学应用力学与生物医学工程研究所山西太原030024

A multi-parameter nonlinear elasto-plastic constitutive model which can fully capture the three typical features of stress-strain response, linearity, plasticity-like stress plateau and densification phases was developed. The functional expression of each parameter was determined using uniaxial compression tests for aluminum alloy foams. The parameters of the model can be systematically varied to describe the effect of relative density which may be responsible for the changes in yield stress and hardening-like or softening-like behavior at various strain rates. A comparison between model predictions and experimental results of the aluminum alloy foams was provided to validate the model. It was proved to be useful in the selection of the optimal-density and energy absorption foam for a specific application at impact events.

关键词： elasto-plastic constitutive model metallic foam strain rate effect energy absorption

rate efect and coupled evolution of atomic motions and potential landscapes

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2013年第5期29卷 676-681页

作者： Pan Xiao Jun Wang Rong Yang Fu-Jiu Ke Meng-Fen Xia Yi-Long Bai State Key Laboratory of Nonlinear Mechanics (LNM) Institute of Mechanics Chinese Academy of Sciences School of Physics and Nuclear Energy Engineering Beihang University

Since rate effect of materials plays a key role in impact engineering, the microscopic mechanism of rate effect is investigated at molecular level in this paper. The results show that rate effect on the strength of atomic system is closely related to the coupled evolution of atomic motions and potential landscapes. Accordingly, it becomes possible to develop a new algorithm of molecular simulation, which could properly and efficiently demonstrate strain rate effect under a wide range of loading rates and unveil the mecha- nisms underlying the strain rate effects.

关键词： strain rate effect Atomic motions - Potential landscape Molecular simulation

Experimental investigation of rigid confinement effects of radial strain on dynamic mechanical properties and failure modes of concrete

在线全文

学校读者我要写书评

暂无评论

International Journal of Mining Science and Technology 2021年第5期31卷 939-951页

作者： Pengfei Liu Xiaoping Zhou Qihu Qian School of Civil Engineering Chongqing UniversityChongqing 400044China School of Civil Engineering Wuhan UniversityWuhan 430072China PLA University of Science and Technology Nanjing 210007China

In this study,to confirm the effect of confining pressure on dynamic mechanical behavior and failure modes of concrete,a split Hopkinson pressure bar dynamic loading device was utilized to perform dynamic compressive experiments under confined and unconfined *** confining pressure was achieved by applying a lateral metal sleeve on the testing specimen which was loaded in the axial *** experimental results prove that dynamic peak axial stress,dynamic peak lateral stress,and peak axial strain of concrete are strongly sensitive to the strain rate under confined ***,the failure patterns are significantly affected by the stress-loading rate and confining *** shows stronger strain rate effects under an unconfined condition than that under a confined *** cracks are created in concrete subjected to uniaxial dynamic compression at a higher strain rate,which can be explained by a thermal-activated *** contrast,crack generation is prevented by *** formulas of the dynamic peak stress and dynamic peak axial strain are established by considering strain rate effects(50–250 s-1)as well as the dynamic confining increase factor(DIFc).

关键词： strain rate effect Multiaxial loading Dynamic peak axial stress Thermo-activated mechanism Dynamic increase factor