The application of fiber reinforced plastic（FRP）,including carbon FRP and glass FRP,for structural repair and strengthening has grown due to their numerous advantages over conventional materials such as externally b...The application of fiber reinforced plastic（FRP）,including carbon FRP and glass FRP,for structural repair and strengthening has grown due to their numerous advantages over conventional materials such as externally bonded reinforcement（EBR） and near-surface mounted（NSM） strengthening techniques.This paper summarizes the results from 21 reinforced concrete beams strengthened with different methods,including externally-bonded and near-surface mounted FRP,to study the strain coordination of the FRP and steel rebar of the RC beam.Since there is relative slipping between the RC beam and the FRP,the strain of the FRP and steel rebar of the RC beam satisfy the quasi-plane-hypothesis;that is,the strain of the longitudinal fiber that parallels the neutral axis of the plated beam within the scope of the effective height（h 0） of the cross section is in direct proportion to the distance from the fiber to the neutral axis.The strain of the FRP and steel rebar satisfies the equation：ε FRP =βε steel,and the value of β is equal to 1.1-1.3 according to the test results.展开更多
In this study,the twinning-detwinning behavior and slip behavior of rolled AZ31 magnesium-alloy plates during a three-step intermittent dynamic compression process along the rolling direction(RD)and normal direction(N...In this study,the twinning-detwinning behavior and slip behavior of rolled AZ31 magnesium-alloy plates during a three-step intermittent dynamic compression process along the rolling direction(RD)and normal direction(ND),are investigated via quasi-in situ electron backscatter diffraction,and the causes of the twinning and detwinning behavior are explained according to Schmid law,local strain coordination,and slip trajectories.It is found that the twins are first nucleated and grow at a compressive strain of 3%along the RD.In addition to the Schmid factor(SF),the strain coordination factor(m’)also influences the selection of the twin variants during the twinning process,resulting in the nucleation of twins with a low SF.During the second and third steps of the application of continuous compressive strains with magnitudes and directions of 3%RD+3%ND and 3%RD+3%ND+2.5%ND,detwinning occurs to different extents.The observation of the detwinning behavior reveals that the order in which multiple twins within the same grain undergo complete detwinning is related to Schmid law and the strain concentration,with a low SF and a high strain concentration promoting complete detwinning.The interaction between slip dislocations and twin boundaries in the deformed grains as well as the pinning of dislocations at the tips of the {1012} tensile twins with a special structure result in incomplete detwinning.Understanding the microstructural evolution and twinning behavior of magnesium alloys under different deformation geometries is important for the development of high-strength and high-toughness magnesium alloys.展开更多
Making exact approximations to solve equations distinguishes applied mathematicians from pure mathematicians, physicists, and engineers. Perturbation problems, both regular and singular, are pervasive in diverse field...Making exact approximations to solve equations distinguishes applied mathematicians from pure mathematicians, physicists, and engineers. Perturbation problems, both regular and singular, are pervasive in diverse fields of applied mathematics and engineering. This research paper provides a comprehensive overview of algebraic methods for solving perturbation problems, featuring a comparative analysis of their strengths and limitations. Serving as a valuable resource for researchers and practitioners, it offers insights and guidance for tackling perturbation problems in various disciplines, facilitating the advancement of applied mathematics and engineering.展开更多
In this paper,we propose a generalized form of the PLK method.To solve weakly nonlinear prob- lems,in straining the related coordinates ,we choose a kind of transformations including nonlinear functionals of de- pende...In this paper,we propose a generalized form of the PLK method.To solve weakly nonlinear prob- lems,in straining the related coordinates ,we choose a kind of transformations including nonlinear functionals of de- pendent variables to linearize asymptotically the original problems,and give more perfect asymptotic solutions with the first-term approximation and the derived transformations.The analysis for some practical examples shows that the generalized method is straightforward and effective and might be applied to more complicated nonlinear problems.展开更多
Discrete element modeling was used to investigate the effect of particle size distribution on the small strain shear stiffness of granular soils and explore the fundamental mechanism controlling this small strain shea...Discrete element modeling was used to investigate the effect of particle size distribution on the small strain shear stiffness of granular soils and explore the fundamental mechanism controlling this small strain shear stiffness at the particle level. The results indicate that the mean particle size has a negligible effect on the small strain shear modulus. The observed increase of the shear modulus with increasing particle size is caused by a scale effect. It is suggested that the ratio of sample size to the mean particle size should be larger than 11.5 to avoid this possible scale effect. At the same confining pressure and void ratio, the small strain shear modulus decreases as the coefficient of uniformity of the soil increases. The Poisson＇s ratio decreases with decreasing void ratio and increasing confining pressure instead of being constant as is commonly assumed. Microscopic analyses indicate that the small strain shear stiffness and Poisson＇s ratio depend uniquely on the soil＇s coordination number.展开更多
基金Consultative Program of the Chinese Academy of Engineeringthe foundation for Excellent Young of Hunan Scientific Committee+1 种基金the National Natural Science Foundation of Hunan Provincethe Science and Research Program of Hunan Province
文摘The application of fiber reinforced plastic（FRP）,including carbon FRP and glass FRP,for structural repair and strengthening has grown due to their numerous advantages over conventional materials such as externally bonded reinforcement（EBR） and near-surface mounted（NSM） strengthening techniques.This paper summarizes the results from 21 reinforced concrete beams strengthened with different methods,including externally-bonded and near-surface mounted FRP,to study the strain coordination of the FRP and steel rebar of the RC beam.Since there is relative slipping between the RC beam and the FRP,the strain of the FRP and steel rebar of the RC beam satisfy the quasi-plane-hypothesis;that is,the strain of the longitudinal fiber that parallels the neutral axis of the plated beam within the scope of the effective height（h 0） of the cross section is in direct proportion to the distance from the fiber to the neutral axis.The strain of the FRP and steel rebar satisfies the equation：ε FRP =βε steel,and the value of β is equal to 1.1-1.3 according to the test results.
基金supported by the General Project of Liaoning Provincial Department of Education(NO:JYTMS20231199)Project of Liaoning Education Department(No:LKMZ20220462 and No:LJKMZ20220467)+1 种基金Basic scientific research project of Liaoning Provincial Department of Education(key research project)(No:JYTZD2023108)Liaoning Nature Fund Guidance Plan(No:42022-BS.179)。
文摘In this study,the twinning-detwinning behavior and slip behavior of rolled AZ31 magnesium-alloy plates during a three-step intermittent dynamic compression process along the rolling direction(RD)and normal direction(ND),are investigated via quasi-in situ electron backscatter diffraction,and the causes of the twinning and detwinning behavior are explained according to Schmid law,local strain coordination,and slip trajectories.It is found that the twins are first nucleated and grow at a compressive strain of 3%along the RD.In addition to the Schmid factor(SF),the strain coordination factor(m’)also influences the selection of the twin variants during the twinning process,resulting in the nucleation of twins with a low SF.During the second and third steps of the application of continuous compressive strains with magnitudes and directions of 3%RD+3%ND and 3%RD+3%ND+2.5%ND,detwinning occurs to different extents.The observation of the detwinning behavior reveals that the order in which multiple twins within the same grain undergo complete detwinning is related to Schmid law and the strain concentration,with a low SF and a high strain concentration promoting complete detwinning.The interaction between slip dislocations and twin boundaries in the deformed grains as well as the pinning of dislocations at the tips of the {1012} tensile twins with a special structure result in incomplete detwinning.Understanding the microstructural evolution and twinning behavior of magnesium alloys under different deformation geometries is important for the development of high-strength and high-toughness magnesium alloys.
文摘Making exact approximations to solve equations distinguishes applied mathematicians from pure mathematicians, physicists, and engineers. Perturbation problems, both regular and singular, are pervasive in diverse fields of applied mathematics and engineering. This research paper provides a comprehensive overview of algebraic methods for solving perturbation problems, featuring a comparative analysis of their strengths and limitations. Serving as a valuable resource for researchers and practitioners, it offers insights and guidance for tackling perturbation problems in various disciplines, facilitating the advancement of applied mathematics and engineering.
基金The project is supported by the National Natural Science Foundation of China
文摘In this paper,we propose a generalized form of the PLK method.To solve weakly nonlinear prob- lems,in straining the related coordinates ,we choose a kind of transformations including nonlinear functionals of de- pendent variables to linearize asymptotically the original problems,and give more perfect asymptotic solutions with the first-term approximation and the derived transformations.The analysis for some practical examples shows that the generalized method is straightforward and effective and might be applied to more complicated nonlinear problems.
基金The work presented in this paper was supported by the National Natural Science Foundation of China （Grant Nos. 51308408, 41272291,51238009） and the Fundamental Research Funds for the Central Universities, and the Open Foundation of State Key Labo- ratory of Hydrology-Water Resources and Hydraulic Engineering （Grant No. 2014492311 ）.
文摘Discrete element modeling was used to investigate the effect of particle size distribution on the small strain shear stiffness of granular soils and explore the fundamental mechanism controlling this small strain shear stiffness at the particle level. The results indicate that the mean particle size has a negligible effect on the small strain shear modulus. The observed increase of the shear modulus with increasing particle size is caused by a scale effect. It is suggested that the ratio of sample size to the mean particle size should be larger than 11.5 to avoid this possible scale effect. At the same confining pressure and void ratio, the small strain shear modulus decreases as the coefficient of uniformity of the soil increases. The Poisson＇s ratio decreases with decreasing void ratio and increasing confining pressure instead of being constant as is commonly assumed. Microscopic analyses indicate that the small strain shear stiffness and Poisson＇s ratio depend uniquely on the soil＇s coordination number.
