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Bending Failure Mode and Prediction Method of the Compressive Strain Capacity of A Submarine Pipeline with Dent Defects
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作者 HOU Fu-heng JIA Lu-sheng +3 位作者 CHEN Yan-fei ZHANG Qi ZHONG Rong-feng WANG Chun-sha 《China Ocean Engineering》 SCIE EI CSCD 2024年第4期636-647,共12页
A dent is a common type of defects for submarine pipeline.For submarine pipelines,high hydrostatic pressure and internal pressure are the main loads.Once pipelines bend due to complex subsea conditions,the compression... A dent is a common type of defects for submarine pipeline.For submarine pipelines,high hydrostatic pressure and internal pressure are the main loads.Once pipelines bend due to complex subsea conditions,the compression strain capacity may be exceeded.Research into the local buckling failure and accurate prediction of the compressive strain capacity are important.A finite element model of a pipeline with a dent is established.Local buckling failure under a bending moment is investigated,and the compressive strain capacity is calculated.The effects of different parameters on pipeline local buckling are analyzed.The results show that the dent depth,external pressure and internal pressure lead to different local buckling failure modes of the pipeline.A higher internal pressure indicates a larger compressive strain capacity,and the opposite is true for external pressure.When the ratio of external pressure to collapse pressure of intact pipeline is greater than 0.1,the deeper the dent,the greater the compressive strain capacity of the pipeline.And as the ratio is less than 0.1,the opposite is true.On the basis of these results,a regression equation for predicting the compressive strain capacity of a dented submarine pipeline is proposed,which can be referred to during the integrity assessment of a submarine pipeline. 展开更多
关键词 submarine pipeline dent defect bending load local buckling compressive strain capacity
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Bending Strength of Glass Materials under Strong Dynamic Impact and Its Strain Rate Effects
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作者 LIU Xiaogen QI Shuang +2 位作者 WEI Shaoshan WAN Detian JIN Chunxia 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2024年第6期1358-1364,共7页
Based on the structural characteristics of the high-speed loading tester,a four-point bending test device was designed to carry out the four-point bending strength test of glass under the action of static load and dif... Based on the structural characteristics of the high-speed loading tester,a four-point bending test device was designed to carry out the four-point bending strength test of glass under the action of static load and different impact velocities,and the formulae for calculating the maximum dynamic stress and strain rate of glass specimens under the action of impact loads were derived.The experimental results show that the bending strength values of the glass under dynamic impact loading are all higher than those under static loading.With the increase of impact speed,the bending strength value of glass specimens generally tends to increase,and the bending strength value increases more obviously when the impact speed exceeds 0.5 m/s or higher.By increasing the impact velocity,higher tensile strain rate of glass specimens can be obtained because the load action time becomes shorter.The bending strength of the glass material increases with its tensile strain rate,and when the tensile strain rate is between 0 and 2 s^(-1),the bending strength of the glass specimen grows more obviously with the strain rate,indicating that the glass bending strength is particularly sensitive to the tensile strain rate in this interval.As the strain rate increases,the number of cracks formed after glass breakage increases significantly,thus requiring more energy to drive the crack formation and expansion,and showing the strain rate effect of bending strength at the macroscopic level.The results of the study can provide a reference for the load bearing and structural design of glass materials under dynamic loading. 展开更多
关键词 glass materials strong dynamic impact bending strength strain rate effect dynamic enhancement factor
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Analysis of plane strain bending of a strain hardening curved beam based on unified yield criterion 被引量:1
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作者 傅军 庞苗 +2 位作者 宋广远 张永强 杨博 《Journal of Southeast University(English Edition)》 EI CAS 2016年第3期339-345,共7页
The analysis of plane strain elastic-plastic bending of a linear strain hardening curved beam with a narrow rectangular cross section subjected to couples at its end is conducted based on a unified yield criterion. Th... The analysis of plane strain elastic-plastic bending of a linear strain hardening curved beam with a narrow rectangular cross section subjected to couples at its end is conducted based on a unified yield criterion. The solutions for the mechanical properties of plane strain bending are derived, which are adapted for various kinds of non-strength differential materials and can be degenerated to those based on the Tresca, von Mises, and twin-shear yield criteria. The dependences of the two critical bending moments, the radii of the interfaces between the elastic and plastic regions and the radial displacements of the points at the symmetrical plane on different yield criteria and Poisson’s ratios are discussed. The results show that the influences of different yield criteria and Poisson’s ratio on the two critical bending moments, the radii of the interfaces between the elastic and plastic regions and the radial displacements of the points at the symmetrical plane of the curved beam are significant. Once the value of bis obtained by experiments, the yield criterion and the corresponding solution for the materials of interest are then determined. 展开更多
关键词 curved beam plane strain strain hardening elastic-plastic bending unified yield criterion
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Effect of Pre-strain on Microstructure and Stamping Performance of High-strength Low-alloy Steel
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作者 刘坡 WEN Zhicheng +1 位作者 LIU Zheng 许峰 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2024年第3期774-780,共7页
In this study,pre-strain ranging from 0 to 0.12 was applied through uniaxial tension on high-strength low-alloy(HSLA)specimens with four kinds of grain size.Effect of pre-strain and grain size on me-chanical property ... In this study,pre-strain ranging from 0 to 0.12 was applied through uniaxial tension on high-strength low-alloy(HSLA)specimens with four kinds of grain size.Effect of pre-strain and grain size on me-chanical property was investigated through tensile tests.Microstructures of the pre-strained and tensile tested samples were analyzed,respectively.The 30.8°v-bending and following flattening,as well as Erichson cupping tests,were performed on the pre-strained samples.Results show the elongation ratio of grain and dislocation density increases with pre-strain.Yielding platform is removed when pre-strain is larger than 0.06 while yielding plateau period decreases with pre-strain less than 0.06 due to reduction of pinning effect.The 30.8°v-bending and the following flattening tests are successfully accomplished on all the pre-strained samples with different grain size.Decrease in grain size,along with increase in pre-strain,causes increase in strength and decrease in elongation rate as well as cupping value.Pre-strain causes very slight effect on bending ability,much less than that on mechanical property and cupping test value.Reciprocal impact of the pre-strain and grain size on HSLA steel deformability is inconspicuous. 展开更多
关键词 strain hardening DISLOCATION TEXTURE bending erichson cupping test
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Variational principles for buckling and vibration of MWCNTs modeled by strain gradient theory 被引量:1
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作者 徐晓建 邓子辰 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2014年第9期1115-1128,共14页
Variational principles for the buckling and vibration of multi-walled carbon nanotubes (MWCNTs) are established with the aid of the semi-inverse method. They are used to derive the natural and geometric boundary con... Variational principles for the buckling and vibration of multi-walled carbon nanotubes (MWCNTs) are established with the aid of the semi-inverse method. They are used to derive the natural and geometric boundary conditions coupled by small scale parameters. Hamilton's principle and Rayleigh's quotient for the buckling and vibration of the MWCNTs are given. The Rayleigh-Ritz method is used to study the buckling and vibration of the single-walled carbon nanotubes (SWCNTs) and double-walled carbon nanotubes (DWCNTs) with three typical boundary conditions. The numerical results reveal that the small scale parameter, aspect ratio, and boundary conditions have a profound effect on the buckling and vibration of the SWCNTs and DWCNTs. 展开更多
关键词 variational principle strain gradient theory buckling VIBRATION carbonnanotube
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Study on size-dependent bending behavior of axially functionally graded microbeams via nonlocal strain gradient theory 被引量:1
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作者 Kang Zetian Wang Zhiyong +1 位作者 Zhou Bo Xue Shifeng 《Journal of Southeast University(English Edition)》 EI CAS 2019年第4期453-463,共11页
Based on the nonlocal strain gradient theory(NSGT),the static bending behaviors of an axially functionally graded(AFG)Bernoulli-Euler microbeam subjected to concentrated and distributed loads are studied.The material ... Based on the nonlocal strain gradient theory(NSGT),the static bending behaviors of an axially functionally graded(AFG)Bernoulli-Euler microbeam subjected to concentrated and distributed loads are studied.The material property of the AFG microbeam changes continuously along the longitudinal direction.On the basis of the minimum potential energy principle,the equations of motion and associated classical and non-classical boundary conditions are derived.Then,Galerkin’s weighted residual method in conjunction with the normalization technique are utilized to solve the governing differential equations.The transverse deformations of the AFG microbeam suffering the sinusoidal distributed load within the framework of NSGT,nonlocal elasticity theory(NET),strain gradient theory(SGT)and classical elasticity theory(CET)are compared.It is observed that the bending flexibility of the microbeam decreases with the increase in the ratio of the material length scale parameter to the beam height.However,the bending flexibility increases with the increase in the material nonlocal parameter.The functionally graded parameter plays an important role in controlling the transverse deformation.This study provides a theoretical basis and a technical reference for the design and analysis of AFG micro-beams in the related regions. 展开更多
关键词 axially functionally graded microbeam nonlocal strain gradient theory bending Galerkin method normalization method
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Ultimate Bending Capacity of Strain Hardening Steel Pipes
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作者 陈严飞 张娟 +3 位作者 张宏 李昕 周晶 曹静 《China Ocean Engineering》 SCIE EI CSCD 2016年第2期231-241,共11页
Based on Hencky's total strain theory of plasticity,ultimate bending capacity of steel pipes can be determined analytically assuming an elastic-linear strain hardening material,the simplified analytical solution is p... Based on Hencky's total strain theory of plasticity,ultimate bending capacity of steel pipes can be determined analytically assuming an elastic-linear strain hardening material,the simplified analytical solution is proposed as well.Good agreement is observed when ultimate bending capacities obtained from analytical solutions are compared with experimental results from full-size tests of steel pipes.Parametric study conducted as part of this paper indicates that the strain hardening effect has significant influence on the ultimate bending capacity of steel pipes.It is shown that pipe considering strain hardening yields higher bending capacity than that of pipe assumed as elastic-perfectly plastic material.Thus,the ignorance of strain hardening effect,as commonly assumed in current codes,may underestimate the ultimate bending capacity of steel pipes.The solutions proposed in this paper are applicable in the design of offshore/onshore steel pipes,supports of offshore platforms and other tubular structural steel members. 展开更多
关键词 steel pipes ultimate bending capacity strain hardening Hencky's total strain
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Analysis of bending mechanism in multi-scanning laser bending process based on plastic strain development
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作者 Wang Chao Wu Chunbiao +1 位作者 Xu Benlian Kim Jaewoong 《China Welding》 CAS 2022年第4期28-36,共9页
By using multi-pass straight-line scan strategies,a larger bending angle can be achieved.There is,however,a limited understanding of the variation in bending angle per pass during multi-pass under various process para... By using multi-pass straight-line scan strategies,a larger bending angle can be achieved.There is,however,a limited understanding of the variation in bending angle per pass during multi-pass under various process parameters.In multi-pass laser scanning,the bending angle cannot always linearly increase with scanning passes and this phenomenon can be observed mostly in low heat input.Strain hardening is the common explanation for this phenomenon.However,it could not explain why this bending angle reduction phenomenon occurs at low heat input scanning rather than at high heat input scanning.In this study,this phenomenon is discussed based on strain development in experiments and numerical simulation.The different growing mechanism of plastic strain is analyzed to reveal the effects of laser power and scanning velocity.Furthermore,the opposite bending trend that occurred at larger laser power is discussed in comparison to the plastic strain development.The study shows that relatively larger heat input below 6.7 J/mm can help to avoid the bending angle reduction phenomenon and the opposite bending trend is highly dependent on the larger laser power.For achieving the expected cumulative bending angle in multi-pass laser bending,it is recommended to decrease the scanning velocity at a relatively low laser power level while increase the scanning velocity at a high level of laser power. 展开更多
关键词 bending angle reduction phenomenon opposite bending trend multi-pass laser bending plastic strain development
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STRAIN-GRADIENT STRESS ANALYSIS IN SAINT-VENANT BENDING
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作者 Friedrich Wilhelm Hecker Jerzy Tadeusz Pindera 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 1996年第3期225-242,共18页
Light beam deflections caused by stress or strain gradients are inves- tigated analytically and experimentally in homogeneous beam specimens which are subjected to a particular case of flexure with shear. This study i... Light beam deflections caused by stress or strain gradients are inves- tigated analytically and experimentally in homogeneous beam specimens which are subjected to a particular case of flexure with shear. This study is a generalization of the prior an alytical-experimental examination of strain-gradient light deflections produced in stressed plates, which had concentrated on the simplest case where in- formation of interest is collected along a line of symmetry of the stress field. Main purpose of the present investigation is to document the efficacy of the strain-gradient method in analysis of the general case of stress state. The most interesting stress state is that in a beam subjected to the Saint-Venant bending, where the transversal and the longitudinal axes of the beam are in pure shear. The obtained results are compared with the predictions of the developed analytical models and with the pre- dictions of Filon's stress function. The procedures of evaluating the photoelastic and material coefficients using strain-gradient techniques were tested positively. 展开更多
关键词 experimental stress analysis applied mechanics optical methods light propagation strain-gradient light bending testing mathematical models
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DISTRIBUTED MICROBEND FIBER-OPTIC STRAIN SENSOR
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作者 孟爱东 骆飞 袁慎芳 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2000年第2期224-227,共4页
The distributed strain sensor has significant application in real time measurement of strain status for large and important engineering structures such as aircraft, bridge and dam. In this paper, a quasi distributed... The distributed strain sensor has significant application in real time measurement of strain status for large and important engineering structures such as aircraft, bridge and dam. In this paper, a quasi distributed optical fiber strain sensor system is set up using optical time domain reflect technique. The local strain sensors based on a novel microbend configuration are designed and applied to measure local strains along the optical fiber. As the result of the experimental research, the microbend sensors show high sensitivity, good linearity and repeatability in certain operation range. 展开更多
关键词 strain measurement strain sensor optical fiber sensor DISTRIBUTED micro bend
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Experimental study on uplift mechanism of pipeline buried in sand using high-resolution fiber optic strain sensing nerves 被引量:8
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作者 Haojie Li Honghu Zhu +2 位作者 Yuanhai Li Chunxin Zhang Bin Shi 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2022年第4期1304-1318,共15页
Reliable assessment of uplift capacity of buried pipelines against upheaval buckling requires a valid failure mechanism and a reliable real-time monitoring technique.This paper presents a sensing solution for evaluati... Reliable assessment of uplift capacity of buried pipelines against upheaval buckling requires a valid failure mechanism and a reliable real-time monitoring technique.This paper presents a sensing solution for evaluating uplift capacity of pipelines buried in sand using fiber optic strain sensing(FOSS)nerves.Upward pipe-soil interaction(PSI)was investigated through a series of scaled tests,in which the FOSS and image analysis techniques were used to capture the failure patterns.The published prediction models were evaluated and modified according to observations in the present study as well as a database of 41 pipe loading tests assembled from the literature.Axial strain measurements of FOSS nerves horizontally installed above the pipeline were correlated with the failure behavior of the overlying soil.The test results indicate that the previous analytical models could be further improved regarding their estimations in the failure geometry and mobilization distance at the peak uplift resistance.For typical slip plane failure forms,inclined shear bands star from the pipe shoulder,instead of the springline,and have not yet reached the ground surface at the peak resistance.The vertical inclination of curved shear bands decreases with increasing uplift displacements at the post-peak periods.At large displacements,the upward movement is confined to the deeper ground,and the slip plane failure progressively changes to the flow-around.The feasibility of FOSS in pipe uplift resistance prediction was validated through the comparison with image analyses.In addition,the shear band locations can be identified using fiber optic strain measurements.Finally,the advantages and limits of the FOSS system are discussed in terms of different levels in upward PSI assessment,including failure identification,location,and quantification. 展开更多
关键词 Pipe-soil interaction(PSI) Upheaval buckling Distributed strain sensing Image analysis Uplift resistance prediction Interfacial behavior
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Effects of pre-deformation mode and strain on creep aging bend-forming process of Al-Cu-Li alloy 被引量:6
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作者 Jian-guo TANG Bo YU +2 位作者 Jin ZHANG Fu-shun XU Chong-jun BAO 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2020年第5期1227-1237,共11页
The bending deformation method was adopted to characterize the creep deformation behavior of Al-Cu-Li alloy in the creep aging forming(CAF) process based on a series of CAF tests, and the evolution laws of its mechani... The bending deformation method was adopted to characterize the creep deformation behavior of Al-Cu-Li alloy in the creep aging forming(CAF) process based on a series of CAF tests, and the evolution laws of its mechanical properties and microstructures under different pre-deformation conditions were studied. The results show that the bending creep strain characterization method can intuitively describe the creep variation. With the increase of the pre-deformation strain, the creep strain of the specimen firstly increases and then decreases. The increase of the pre-deformation strain can promote the course of aging precipitation, and improve the formed alloy’s tensile properties at room temperature, the Kahn tearing properties, and the fatigue propagation properties. Pre-rolled specimens produce a slightly weaker work hardening than pre-stretched specimens, but they also create a stronger aging-strengthening effect;thus the strength, toughness and damage performance can be improved to some extent. Among all the types of specimens, the specimen with 3% rolling after CAF treatment has the best comprehensive mechanical properties. 展开更多
关键词 Al-Cu-Li alloy creep aging forming PRE-DEFORMATION bending creep strain microstructure evolution mechanical properties
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Finite element analysis of stress and strain distributions in mortise and loose tenon furniture joints 被引量:6
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作者 Mohammad Derikvand Ghanbar Ebrahimi 《Journal of Forestry Research》 SCIE CAS CSCD 2014年第3期677-681,共5页
We studied the effect of loose tenon dimensions on stress and strain distributions in T-shaped mortise and loose tenon (M&amp;LT) furni-ture joints under uniaxial bending loads, and determined the effects of loose ... We studied the effect of loose tenon dimensions on stress and strain distributions in T-shaped mortise and loose tenon (M&amp;LT) furni-ture joints under uniaxial bending loads, and determined the effects of loose tenon length (30, 45, 60, and 90 mm) and loose tenon thickness (6 and 8 mm) on bending moment capacity of M&amp;LT joints constructed with polyvinyl acetate (PVAc) adhesive. Stress and strain distributions in joint elements were then estimated for each joint using ANSYS finite element (FE) software. The bending moment capacity of joints increased significantly with thickness and length of the tenon. Based on the FE analysis results, under uniaxial bending, the highest shear stress values were obtained in the middle parts of the tenon, while the highest shear elastic strain values were estimated in glue lines between the tenon sur-faces and walls of the mortise. Shear stress and shear elastic strain values in joint elements generally increased with tenon dimensions and corre-sponding bending moment capacities. There was consistency between predicted maximum shear stress values and failure modes of the joints. 展开更多
关键词 bending moment capacity failure mode finite element furniture mortise and loose tenon joint stress and strain distributions
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Strain concentration caused by the closed end contributes to cartridge case failure at the bottom 被引量:2
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作者 Song Cai Jie Feng +3 位作者 Hui Xu Kun Liu Zhong-xin Li Zhi-lin Wu 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2020年第6期1151-1159,共9页
Ruptures at the bottom of cartridges are a common cause of failure of ammunitions,which directly threatens the safety of weapons and shooters.Based on plastic tube theory,this study analyses the radial and axial defor... Ruptures at the bottom of cartridges are a common cause of failure of ammunitions,which directly threatens the safety of weapons and shooters.Based on plastic tube theory,this study analyses the radial and axial deformation of a cartridge,considering the radial constraint of the closed end at the bottom of the cartridge.Owing to the influence of the closed end,the bottom of a cartridge does not establish complete contact with the chamber.Owing to strain concentration in the non-contact area,this area is more amenable to the occurrence of cartridge rupture.This theory predicts the location of the fracture more accurately than the traditional theory.The maximum axial deformation of a cartridge comprises bending and friction deformation.The maximum strain at the bottom of the cartridge increased by 135%owing to the introduction of bending strain caused by the closed end.The strain distribution of a cartridge was measured using digital image correlation technology,and the measured result was consistent with the predicted results of the bending deformation theory and rupture case.The effects of wall thickness,radial clearance,friction coefficient,and axial clearance on the axial deformation of the cylinder were studied.Increasing the wall thickness and reducing radial clearance were found to reduce bending deformation;furthermore,lubrication and reduction in axial clearance reduce frictional deformation,which in turn reduce cartridge rupture. 展开更多
关键词 Closed end Cartridge case failures strain concentration bending deformation
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Steel Design by Advanced Analysis: Material Modeling and Strain Limits
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作者 Leroy Gardner Xiang Yun +1 位作者 Andreas Fieber Lorenzo Macorini 《Engineering》 SCIE EI 2019年第2期243-249,共7页
Structural analysis of steel frames is typically performed using beam elements. Since these elements are unable to explicitly capture the local buckling behavior of steel cross-sections, traditional steel design speci... Structural analysis of steel frames is typically performed using beam elements. Since these elements are unable to explicitly capture the local buckling behavior of steel cross-sections, traditional steel design specifications use the concept of cross-section classification to determine the extent to which the strength and deformation capacity of a cross-section are affected by local buckling. The use of plastic design methods are restricted to Class 1 cross-sections, which possess sufficient rotation capacity for plastic hinges to develop and a collapse mechanism to form. Local buckling prevents the development of plastic hinges with such rotation capacity for cross-sections of higher classes and, unless computationally demanding shell elements are used, elastic analysis is required. However, this article demonstrates that local buckling can be mimicked effectively in beam elements by incorporating the continuous strength method (CSM) strain limits into the analysis. Furthermore, by performing an advanced analysis that accounts for both geometric and material nonlinearities, no additional design checks are required. The positive influence of the strain hardening observed in stocky cross-sections can also be harnessed, provided a suitably accurate stress–strain relationship is adopted;a quad-linear material model for hot-rolled steels is described for this purpose. The CSM strain limits allow cross-sections of all slenderness to be analyzed in a consistent advanced analysis framework and to benefit from the appropriate level of load redistribution. The proposed approach is applied herein to individual members, continuous beams, and frames, and is shown to bring significant benefits in terms of accuracy and consistency over current steel design specifications. 展开更多
关键词 Advanced analysis CONTINUOUS STRENGTH method LOCAL buckling MATERIAL modeling strain limits
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Effect of Strain Rate on the Mechanical Properties of Ti-24Al-11Nb
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作者 Guoliang CHEN Yandong WANG Wangyue YANG Zhuqing SUN Runrong REN Dept.of Materials Science and Engineering,Beijing University of Science and Technology,Beijing,100083,ChinaShijie ZHU Suhua AI Lab.of Fatigue and Fracture for Materials,Institute of Metal Research Academia Sinica,Shenyang,110015,China 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 1993年第3期219-222,共4页
The effect of strain rate on the bend ductility and notch fracture toughness of Ti-24Al-11 Nb was studied,it was found that the strain rate with a range of 1.17×10^(-5)~1.17 ×10^(-3) at 20℃ had nega- tive ... The effect of strain rate on the bend ductility and notch fracture toughness of Ti-24Al-11 Nb was studied,it was found that the strain rate with a range of 1.17×10^(-5)~1.17 ×10^(-3) at 20℃ had nega- tive influence on both properties based on different microstructures. 展开更多
关键词 bend ductility notch fracture toughness strain rate
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Static and dynamic stability responses of multilayer functionally graded carbon nanotubes reinforced composite nanoplates via quasi 3D nonlocal strain gradient theory
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作者 Ahmed Amine Daikh Mohamed Sid Ahmed Houari +2 位作者 Mohamed Ouejdi Belarbi Salwa A.Mohamed Mohamed A.Eltaher 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2022年第10期1778-1809,共32页
This manuscript presents the comprehensive study of thickness stretching effects on the free vibration,static stability and bending of multilayer functionally graded(FG)carbon nanotubes reinforced composite(CNTRC)nano... This manuscript presents the comprehensive study of thickness stretching effects on the free vibration,static stability and bending of multilayer functionally graded(FG)carbon nanotubes reinforced composite(CNTRC)nanoplates.The nanoscale and microstructure influences are considered through a modified nonlocal strain gradient continuum model.Based on power-law functions,four different patterns of CNTs distribution are considered in this analysis,a uniform distribution UD,FG-V CNTRC,FG-X CNTRC,and FG-O CNTRC.A 3D kinematic shear deformation theory is proposed to include the stretching influence,which is neglected in classical theories.Hamilton's principle is applied to derive the governing equations of motion and associated boundary conditions.Analytical solutions are developed based on Galerkin method to solve the governing equilibrium equations based on the generalized higher-order shear deformation theory and the nonlocal strain gradient theory and get the static bending,buckling loads,and natural frequencies of nanoplates.Verification with previous works is presented.A detailed parametric analysis is carried out to highlight the impact of thickness stretching,length scale parameter(nonlocal),material scale parameter(gradient),CNTs distribution pattern,geometry of the plate,various boundary conditions and the total number of layers on the stresses,deformation,critical buckling loads and vibration frequencies.Many new results are also reported in the current study,which will serve as a benchmark for future research. 展开更多
关键词 3D shear deformation theory Free vibration buckling bending Galerkin method Functionally graded nanotube Nonlocal strain gradient theory
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Analytical solutions for buckling of size-dependent Timoshenko beams 被引量:4
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作者 Xiaojian XU Mulian ZHENG 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2019年第7期953-976,共24页
The inconsistences of the higher-order shear resultant expressed in terms of displacement(s) and the complete boundary value problems of structures modeled by the nonlocal strain gradient theory have not been well add... The inconsistences of the higher-order shear resultant expressed in terms of displacement(s) and the complete boundary value problems of structures modeled by the nonlocal strain gradient theory have not been well addressed. This paper develops a size-dependent Timoshenko beam model that considers both the nonlocal effect and strain gradient effect. The variationally consistent boundary conditions corresponding to the equations of motion of Timoshenko beams are reformulated with the aid of the weighted residual method. The complete boundary value problems of nonlocal strain gradient Timoshenko beams undergoing buckling are solved in closed forms. All the possible higher-order boundary conditions induced by the strain gradient are selectively suggested based on the fact that the buckling loads increase with the increasing aspect ratios of beams from the conventional mechanics point of view. Then, motivated by the expression for beams with simply-supported (SS) boundary conditions, some semiempirical formulae are obtained by curve fitting procedures. 展开更多
关键词 buckling strain GRADIENT theory BOUNDARY condition
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Local buckling failure analysis of high-strength pipelines 被引量:3
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作者 Yan Li Jian Shua +2 位作者 Zhong-Li Jin Ya-Tong Zhao Kui Xu 《Petroleum Science》 SCIE CAS CSCD 2017年第3期549-559,共11页
Pipelines in geological disaster regions typically suffer the risk of local buckling failure because of slender structure and complex load. This paper is meant to reveal the local buckling behavior of buried pipelines... Pipelines in geological disaster regions typically suffer the risk of local buckling failure because of slender structure and complex load. This paper is meant to reveal the local buckling behavior of buried pipelines with a large diameter and high strength, which are under different conditions, including pure bending and bending combined with internal pressure. Finite element analysis was built according to previous data to study local buckling behavior of pressurized and unpressurized pipes under bending conditions and their differences in local buckling failure modes. In parametric analysis, a series of parameters,including pipe geometrical dimension, pipe material properties and internal pressure, were selected to study their influences on the critical bending moment, critical compressive stress and critical compressive strain of pipes.Especially the hardening exponent of pipe material was introduced to the parameter analysis by using the Ramberg–Osgood constitutive model. Results showed that geometrical dimensions, material and internal pressure can exert similar effects on the critical bending moment and critical compressive stress, which have different, even reverse effects on the critical compressive strain. Based on these analyses, more accurate design models of critical bending moment and critical compressive stress have been proposed for high-strength pipelines under bendingconditions, which provide theoretical methods for highstrength pipeline engineering. 展开更多
关键词 Local buckling High-strength pipeline Finiteelement analysis Critical bending moment Criticalcompressive stress Critical compressive strain
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Thermal buckling analysis of ceramic-metal functionally graded plates 被引量:3
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作者 Ashraf M. Zenkour Daoud S. Mashat 《Natural Science》 2010年第9期968-978,共11页
Thermal buckling response of functionally graded plates is presented in this paper using sinusoidal shear deformation plate theory (SPT). The material properties of the plate are assumed to vary according to a power l... Thermal buckling response of functionally graded plates is presented in this paper using sinusoidal shear deformation plate theory (SPT). The material properties of the plate are assumed to vary according to a power law form in the thickness direction. Equilibrium and stability equations are derived based on the SPT. The non-linear governing equations are solved for plates subjected to simply supported boundary conditions. The buckling analysis of a functionally graded plate under various types of thermal loads is carried out. The influences of many plate parameters on buckling temperature difference will be investigated. Numerical results are presented for the SPT, demonstrating its importance and accuracy in comparison to other theories. 展开更多
关键词 Thermal buckling NON-LINEAR strainS Functionally GRADED MATERIAL Sinusoidal PLATE
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