The Experts below are selected from a list of 264 Experts worldwide ranked by ideXlab platform
Huishen Shen - One of the best experts on this subject based on the ideXlab platform.
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buckling and postbuckling of anisotropic laminated cylindrical shells under Combined Axial Compression and torsion
Composite Structures, 2008Co-Authors: Huishen Shen, Yang XiangAbstract:Abstract A postbuckling analysis is presented for an anisotropic laminated cylindrical shell of finite length subjected to Combined loading of Axial Compression and torsion. The governing equations are based on classical shell theory with von Karman–Donnell-type of kinematic nonlinearity and including the extension–twist, extension–flexural and flexural–twist couplings. The nonlinear prebuckling deformations and initial geometric imperfections of the shell are both taken into account. A singular perturbation technique is employed to determine interactive buckling loads and postbuckling equilibrium paths. The numerical illustrations concern the postbuckling response of perfect and imperfect, anisotropic laminated cylindrical shells for different values of load-proportional parameters. The results show that the postbuckling characteristics depend significantly upon the load-proportional parameter. The results reveal that in Combined loading cases the postbuckling equilibrium path is unstable and the shell structure is imperfection-sensitive.
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buckling and postbuckling of single walled carbon nanotubes under Combined Axial Compression and torsion in thermal environments
Physical Review B, 2007Co-Authors: Chenli Zhang, Huishen ShenAbstract:The buckling behavior of single-walled carbon nanotubes under Combined Axial Compression and torsion is investigated by using molecular dynamics simulations, to evaluate interactive buckling loads, and to assess the effect of temperature changes on bucking and postbuckling responses. Simulation results show that both the armchair and zigzag tubes exhibit nonlinear interaction curves at different temperature considered, and the interactive buckling loads are strongly size dependent. The buckling and postbuckling behavior of single-walled carbon nanotubes depends strongly on the temperature. Rise in temperature results in decrease of interactive buckling loads and postbuckling equilibrium paths, and the effect of temperature varies with the value of load-proportional parameter. The results also reveal that the single-walled carbon nanotubes may display two kinds of typical buckling configurations under Combined loads, which are characterized by notable features distinct from those presented in pure Axial Compression or torsion.
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Thermomechanical postbuckling of composite laminated cylindrical shells with local geometric imperfections
International Journal of Solids and Structures, 1999Co-Authors: Huishen ShenAbstract:Abstract The effect of local geometric imperfections on the buckling and postbuckling of composite laminated cylindrical shells subjected to Combined Axial Compression and uniform temperature loading was investigated. The two cases of compressive postbuckling of initially heated shells and of thermal postbuckling of initially compressed shells are considered. The formulations are based on a boundary layer theory of shell buckling, which includes the effects of the nonlinear prebuckling deformation, the nonlinear large deflection in the postbuckling range and the initial geometric imperfection of the shell. The analysis uses a singular perturbation technique to determine buckling loads and postbuckling equilibrium paths. Numerical examples are presented that relate to the performances of cross-ply laminated cylindrical shells with or without initial local imperfections, from which results for isotropic cylindrical shells follow as a limiting case. Typical results are presented in dimensionless graphical form for different parameters and loading conditions.
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Thermomechanical postbuckling analysis of imperfect laminated plates of softening nonlinear elastic foundations
Composite Structures, 1997Co-Authors: Huishen Shen, Frederic Ward WilliamsAbstract:Using the classical laminated plate theory, including plate-foundation interaction and thermal effects, thermal postbuckling perturbation analysis is presented for a simply supported, composite laminated plate subjected to Combined Axial Compression and uniform temperature loading and resting on a softening nonlinear elastic foundation. The two cases of thermal postbuckling of initially compressed plates and of compressive postbuckling of initially heated plates are considered. The initial geometrical imperfection of the plate is taken into account. Numerical examples are presented. The effects of foundation stiffness, plate aspect ratio, fiber orientation, total number of layers and initial geometrical imperfection are studied. Typical results are presented in dimensionless graphical form and exhibit interesting imperfection sensitivity.
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Thermomechanical postbuckling of imperfect moderately thick plates on two-parameter elastic foundations
Structural Engineering and Mechanics, 1996Co-Authors: Huishen ShenAbstract:A postbuckling analysis is presented for a simply supported, moderately thick rectangular plate subjected to Combined Axial Compression and uniform temperature loading and resting on a two-parameter elastic foundation. The two cases of thermal postbuckling of initially compressed plates and of compressive postbuckling of initially heated plates are considered. The initial geometrical imperfection of the plate is taken into account. The formulations are based on the Reissner-Mindlin plate theory considering the first order shear deformation effect, and including the plate-foundation interaction and thermal effect. The analysis uses a deflection-type perturbation technique to determine the buckling loads and postbuckling equilibrium paths. Numerical examples cover the performances of perfect and imperfect, moderately thick plates resting on Winkler or Pasternak-type elastic foundations. Typical results are presented in dimensionless graphical form.
A H Sofiyev - One of the best experts on this subject based on the ideXlab platform.
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on the buckling of composite conical shells resting on the winkler pasternak elastic foundations under Combined Axial Compression and external pressure
Composite Structures, 2014Co-Authors: A H SofiyevAbstract:Abstract The article discusses the buckling analysis of composite orthotropic truncated conical shells under a Combined Axial Compression and external pressure and resting on a Pasternak foundation. The governing equations have been obtained for the orthotropic truncated conical shell resting on a Pasternak foundation and solved by applying the Superposition and Galerkin methods. The novelty of present work is to achieve closed-form solutions for critical Combined loads. Finally, the effects of the Winkler and Pasternak elastic foundations, shell characteristics and material orthotropy on the values of critical Combined loads have been studied. Comparison of results with those available in the literature has been presented.
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On the buckling of composite conical shells resting on the Winkler–Pasternak elastic foundations under Combined Axial Compression and external pressure
Composite Structures, 2014Co-Authors: A H SofiyevAbstract:Abstract The article discusses the buckling analysis of composite orthotropic truncated conical shells under a Combined Axial Compression and external pressure and resting on a Pasternak foundation. The governing equations have been obtained for the orthotropic truncated conical shell resting on a Pasternak foundation and solved by applying the Superposition and Galerkin methods. The novelty of present work is to achieve closed-form solutions for critical Combined loads. Finally, the effects of the Winkler and Pasternak elastic foundations, shell characteristics and material orthotropy on the values of critical Combined loads have been studied. Comparison of results with those available in the literature has been presented.
Togay Ozbakkaloglu - One of the best experts on this subject based on the ideXlab platform.
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behavior of square fiber reinforced polymer high strength concrete steel double skin tubular columns under Combined Axial Compression and reversed cyclic lateral loading
Engineering Structures, 2016Co-Authors: Yunita Idris, Togay OzbakkalogluAbstract:Abstract This paper presents an experimental study on seismic behavior of square fiber reinforced polymer (FRP)–concrete–steel columns. Six hybrid double-skin tubular columns (DSTCs) manufactured using high-strength concrete (HSC) were tested under Combined Axial Compression and reversed-cyclic lateral loading. The main parameters under investigation were the Axial load level, size of inner steel tube, provision (or absence) of a concrete-filling inside the steel tube, and the column aspect ratio. The results indicate that, in general, square DSTCs exhibit very ductile behavior under Combined Axial Compression and reversed-cyclic lateral loading. However, the important influence of the Axial load level on the column behavior is evident, with an increase in the load level leading to a significant decrease in the lateral deformation capacity of DSTCs. The results also indicate that a DSTC with a larger inner steel tube exhibits lower lateral displacement capacity than that of a companion DSTC with a smaller inner steel tube. It is shown, however, that provision of a concrete-filling inside the inner steel tube leads to a significant increase in the lateral deformation capacity of a DSTC with a larger inner steel tube to a level that is higher than that seen in a companion DSTC with a smaller hollow inner steel tube. Experimental results are presented together with accompanying discussions on the influence of the investigated parameters on the seismic behavior of square DSTCs.
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Behavior of square fiber reinforced polymer–high-strength concrete–steel double-skin tubular columns under Combined Axial Compression and reversed-cyclic lateral loading
Engineering Structures, 2016Co-Authors: Yunita Idris, Togay OzbakkalogluAbstract:Abstract This paper presents an experimental study on seismic behavior of square fiber reinforced polymer (FRP)–concrete–steel columns. Six hybrid double-skin tubular columns (DSTCs) manufactured using high-strength concrete (HSC) were tested under Combined Axial Compression and reversed-cyclic lateral loading. The main parameters under investigation were the Axial load level, size of inner steel tube, provision (or absence) of a concrete-filling inside the steel tube, and the column aspect ratio. The results indicate that, in general, square DSTCs exhibit very ductile behavior under Combined Axial Compression and reversed-cyclic lateral loading. However, the important influence of the Axial load level on the column behavior is evident, with an increase in the load level leading to a significant decrease in the lateral deformation capacity of DSTCs. The results also indicate that a DSTC with a larger inner steel tube exhibits lower lateral displacement capacity than that of a companion DSTC with a smaller inner steel tube. It is shown, however, that provision of a concrete-filling inside the inner steel tube leads to a significant increase in the lateral deformation capacity of a DSTC with a larger inner steel tube to a level that is higher than that seen in a companion DSTC with a smaller hollow inner steel tube. Experimental results are presented together with accompanying discussions on the influence of the investigated parameters on the seismic behavior of square DSTCs.
K Y Xu - One of the best experts on this subject based on the ideXlab platform.
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curvature effects on buckling of double walled carbon nanotubes under Combined Axial Compression and lateral pressure
Smart Materials and Structures, 2007Co-Authors: H Qian, K Y XuAbstract:Based on a curvature model for van der Waals (vdW) pressure between the interlayer of a double-walled carbon nanotube (DWNT), explicit expressions are derived for the critical buckling load of a DWNT which is modeled as a double-elastic shell under Combined Axial Compression and lateral pressure. The critical load is calculated for various radii, length-to-radius ratios and load combinations. New results show that the curvature effects play a significant role in buckling problems for DWNTs of small radii. Neglecting the curvature effect usually leads to an under-estimate of the critical load for DWNTs when lateral pressure dominates. In addition, unlike Wang et al (2003b Int. J. Solids Struct. 40 3893) and Qian et al (2005 Int. J. Solids Struct. 42 5426), the buckling mode corresponding to the minimum Axial buckling strain is unique, even when the lateral pressure is very small. For the DWNTs under Combined Axial Compression and lateral pressure, the critical Axial strain is reduced due to the external pressure.
Tao Yu - One of the best experts on this subject based on the ideXlab platform.
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experimental behavior of hybrid frp concrete steel double skin tubular columns under Combined Axial Compression and cyclic lateral loading
Engineering Structures, 2015Co-Authors: Bo Zhang, J G Teng, Tao YuAbstract:Abstract Hybrid FRP–concrete–steel double-skin tubular columns (DSTCs) are a new form of hybrid columns, consisting of an outer tube made of fiber reinforced polymer (FRP) and an inner tube made of steel, with the space between filled with concrete. In hybrid DSTCs, the three constituent materials are optimally Combined to achieve several advantages not available with existing columns, including their excellent corrosion resistance and seismic performance. Although two existing studies have examined the seismic performance of circular hybrid DSTCs, they have been limited to normal strength concrete, small column dimensions, and small void ratios (ratios between the inner diameter and the outer diameter of the annular concrete section). Against this background, this paper presents the first experimental study on hybrid DSTCs filled with HSC subjected to Axial Compression in combination with cyclic lateral loading. A relatively large column section (with a diameter of 300 mm) was chosen to allow reliable experimental modeling of real columns. The test results indicate that hybrid DSTCs possess excellent ductility and seismic resistance even when high strength concrete with a cylinder compressive strength of around 120 MPa is used; column damage is concentrated in a small plastic hinge region near the column bottom end; and the performance of hybrid DSTCs can be enhanced by filling the inner void in the plastic hinge region. The test results provide valuable data needed for the formulation and verification of a theoretical model for the hysteric behavior of hybrid DSTCs, particularly when they are filled with HSC.
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behaviour of hybrid double skin tubular columns subjected to Combined Axial Compression and cyclic lateral loading
2012Co-Authors: Bing Zhang, J G Teng, Tao YuAbstract:Hybrid FRP-concrete-steel double-skin tubular columns (hybrid DSTCs) are a new form of hybrid columns developed at The Hong Kong Polytechnic University. They consist of an outer tube made of fibre reinforced polymer (FRP) and an inner tube made of steel, with the space between filled with concrete. In these hybrid DSTCs, the three constituent materials are optimally Combined to achieve several advantages not available with existing forms of columns, including their superior corrosion and seismic performance. This paper presents the test results of a series of large-scale hybrid DSTCs subjected to Combined Axial and cyclic lateral loads, with an emphasis on the effect of a high strength concrete infill. All column specimens had a circular section with a diameter of 300 mm and a height of 1350 mm (from the point of lateral loading to the top surface of the stiff RC footing). The parameters examined include the concrete strength, the confinement stiffness of the GFRP tube and the Axial load ratio. The test results showed that these hybrid DSTCs possess excellent ductility and hence excellent seismic resistance even when high strength concrete with a cylinder compressive strength of around 120 MPa is used.