The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
D G Xiao - One of the best experts on this subject based on the ideXlab platform.
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non linear thermal buckling for Local Delamination near the surface of laminated cylindrical shell
International Journal of Mechanical Sciences, 2002Co-Authors: Xi Wang, Guoxing Lu, D G XiaoAbstract:A solving method is applied to conduct research on the non-linear thermal buckling behavior of Local Delamination near the surface of fiber-reinforced laminated cylindrical shell. The shape of delaminated region considered is elliptic, triangular and lemniscates. Young's modulus and the thermal expansion coefficient of material are treated as a function of temperature, which leads to the force in the middle plane of the sub-laminated shells a non-linear function of temperature. The critical temperatures of laminated cylindrical shells with various shaped Local Delamination, different stacking patterns and different radius of the laminated cylindrical shells are obtained by making use of the energy principle. It has been found that linear solution of the critical buckling temperature gives a higher value than that of non-linear consideration.
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a study of buckling of near surface Local Delamination in a cylindrical laminated shell
Journal of Reinforced Plastics and Composites, 2001Co-Authors: Xi Wang, D G XiaoAbstract:In this paper, an energy method is applied to study the buckling problem of near surface triangular, elliptical and lemniscated Delamination in a cylindrical laminated shell. The relationships between critical strain value and the geometrical and physical parameters of base laminated shell and sub-laminated shell are investigated.
T K Obrien - One of the best experts on this subject based on the ideXlab platform.
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analysis of matrix cracking and Local Delamination in 0 ϑ ϑ s graphite epoxy laminates under tensile load
Journal of Composites Technology & Research, 1993Co-Authors: S A Salpekar, T K ObrienAbstract:Several three-dimensional element analyses of (0/ϑ/−ϑ), graphite epoxy laminates, where ϑ = 15, 20, 25, 30, and 45°, subjected to axial tensile load, were performed. The interlaminar stresses in the ϑ/−ϑ interface were calculated with and without a matrix crack in the central −ϑ plies. The interlaminar normal stress changes from a small compressive stress when no matrix crack is present to a high tensile stress at the intersection of the matrix crack and the free edge. The analysis of Local Delamination from the −ϑ matrix crack indicates a high strain energy release rate and a Localized Mode I component near the free edge, within one-ply distance from the matrix crack. To examine the stress state causing the matrix cracking, the maximum principal normal stress in a plane perpendicular to the fiber direction in the −ϑ ply was calculated in an uncracked laminate. The corresponding shear stress parallel to the fiber was also calculated. The principal normal stress at the laminate edge increased through the ply thickness and reached a very high tensile value at the ϑ/−ϑ interface indicating that the crack in the −ϑ ply may initiate at the ϑ/−ϑ interface. Predicted crack profiles on the laminate edge in the −ϑ ply were constructed from the principal stress directions. The cracks were found to be more curved for layups with smaller ϑ angles, which is consistent with experimental observations in the literature.
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Local Delamination in laminates with angle ply matrix cracks part ii delamlnation fracture analysis and fatigue characterization
1993Co-Authors: T K ObrienAbstract:Abstract : Constant amplitude tension-tension fatigue tests were conducted on AS4/3501-6 graphite/epoxy (02/theta2/-theta2)s laminates, where theta was 15, 20, 25, or 30 degrees. Fatigue tests were conducted at a frequency of 5 Hz and an R-ratio of 0.1. Dye penetrant enhanced X-radiography was used to document the onset of matrix cracking in the central -theta degree plies, and the subsequent onset of Local Delaminations in the theta/-theta interface at the intersection of the matrix cracks and the free edge, as a function of the number of fatigue cycles. Two strain energy release rate solutions for Local Delamination from matrix cracks were derived: one for a Local Delamination growing from an angle ply matrix crack with a uniform Delamination growing from an angle ply matrix crack with a triangular shaped Delamination area that extended only partially into the laminate width from the free edge. Plots of Gmax vs. N were generated to assess the accuracy of these G solutions. ne influence of residual thermal and moisture stresses on G were also quantified. However, a detailed analysis of the G components and a mixed-mode fatigue failure criterion for this material may be needed to predict the fatigue behavior of these laminates.
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Local Delamination in laminates with angle ply matrix cracks part 1 tension tests and stress analysis
Ndt & E International, 1992Co-Authors: T K Obrien, S J HooperAbstract:Quasi-static tension tests were conducted on AS4/3501-6 graphite epoxy laminates. Dye penetrant enhanced x-radiography was used to document the onset of matrix cracking and the onset of Local Delaminations at the intersection of the matrix cracks and the free edge. Edge micrographs taken after the onset of damage were used to verify the location of the matrix cracks and Local Delamination through the laminate thickness. A quasi-3D finite element analysis was conducted to calculate the stresses responsible for matrix cracking in the off-axis plies. Laminated plate theory indicated that the transverse normal stresses were compressive. However, the finite element analysis yielded tensile transverse normal stresses near the free edge. Matrix cracks formed in the off-axis plies near the free edge where in-plane transverse stresses were tensile and had their greatest magnitude. The influence of the matrix crack on interlaminar stresses is also discussed.
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Residual thermal and moisture influences on the strain energy release rate analysis of Local Delaminations from matrix cracks
1991Co-Authors: T K ObrienAbstract:An analysis utilizing laminated plate theory is developed to calculate the strain energy release rate associated with Local Delaminations originating at off-axis, single ply, matrix cracks in laminates subjected to uniaxial loads. The analysis includes the contribution of residual thermal and moisture stresses to the strain energy released. Examples are calculated for the strain energy release rate associated with Local Delaminations originating at 90 degrees and angle-ply (non-90 degrees) matrix ply cracks in glass epoxy and graphite epoxy laminates. The solution developed may be used to assess the relative contribution of mechanical, residual thermal, and moisture stresses on the strain energy release rate for Local Delamination for a variety of layups and materials.
Guoxing Lu - One of the best experts on this subject based on the ideXlab platform.
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Local buckling of composite laminar plates with various delaminated shapes
Thin-walled Structures, 2003Co-Authors: Xiansong Wang, Guoxing LuAbstract:An investigation is carried out to understand the buckling behaviour of Local Delamination near the surface of fiber reinforced laminated plates under mechanical and thermal loads. The shape of the delaminated region considered is rectangular and triangular. The displacement expression is composed of items with the effect of tension-shear coupling and the effect of bend-torsion coupling. The critical strains of laminated plates with various shaped Local Delamination and different stacking patterns are obtained by making use of the energy principle. Analytical predictions for Delamination buckling loads are shown to correlate well with experimental results for a number of different Delamination shapes.
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non linear thermal buckling for Local Delamination near the surface of laminated plates
Journal of Reinforced Plastics and Composites, 2003Co-Authors: Xiansong Wang, D Su, Guoxing Lu, C WangAbstract:An investigation is carried out to understand the non-linear thermal buckling behaviour of Local Delamination near the surface of fiber reinforced laminated plates. The shape of the delaminated region considered is rectangular, elliptic or triangular. The mechanical properties and the thermal expansion coefficient of the fiber material are treated as a function of temperature, which leads to the force in the middle plane of the laminated plates a non-linear function of temperature. The critical temperatures of laminated plates with variously shaped Local Delamination and different stacking patterns are obtained by making use of the energy principle. It has been found that linear solutions of the critical buckling temperature give a higher value than that from non-linear consideration.
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non linear thermal buckling for Local Delamination near the surface of laminated cylindrical shell
International Journal of Mechanical Sciences, 2002Co-Authors: Xi Wang, Guoxing Lu, D G XiaoAbstract:A solving method is applied to conduct research on the non-linear thermal buckling behavior of Local Delamination near the surface of fiber-reinforced laminated cylindrical shell. The shape of delaminated region considered is elliptic, triangular and lemniscates. Young's modulus and the thermal expansion coefficient of material are treated as a function of temperature, which leads to the force in the middle plane of the sub-laminated shells a non-linear function of temperature. The critical temperatures of laminated cylindrical shells with various shaped Local Delamination, different stacking patterns and different radius of the laminated cylindrical shells are obtained by making use of the energy principle. It has been found that linear solution of the critical buckling temperature gives a higher value than that of non-linear consideration.
F. K. Chang - One of the best experts on this subject based on the ideXlab platform.
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Structural health monitoring from fiber-reinforced composites to steel-reinforced concrete
Smart Materials and Structures, 2001Co-Authors: C.s. Wang, F Wu, F. K. ChangAbstract:Accurate interpretation of sensor measurements in terms of physical changes in structures is a major challenge for the development of robust structural health monitoring systems. An active diagnostic system was proposed to detect embedded damage in fiber-reinforced composites and steel-reinforced concrete. Due to the inherent difference in material characteristics, changes in sensor measurements resulting from damage for the two material systems were found considerably different. For a given excitation, it was found that Local Delamination in fiber-reinforced composites reduced the measured signal strength of a nearby sensor, while rebar debond in concrete increased signal strength. Techniques based on the characteristics of these material responses to damage are being developed for adequate active sensing diagnostic systems for each material.
Lijuan He - One of the best experts on this subject based on the ideXlab platform.
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thermal regime of the north china craton implications for craton destruction
Earth-Science Reviews, 2015Co-Authors: Lijuan HeAbstract:Abstract This paper presents an overview of the thermal studies dealing with heat flow data, lithospheric thermal thickness, basin thermal history, and thermal modeling in the North China Craton (NCC), with aim to provide ideas for geodynamical mechanism on the NCC destruction. Heat flow investigations show that only a small cold core is still preserved in the Ordos, western NCC, with low heat flow value of The sedimentary basins in the NCC have recorded distinct thermal histories since the Mesozoic. The Ordos Basin located in the western NCC experienced its maximum paleo-temperature in the Mesozoic, associated with compression, uplift and erosion. In contrast, most depressions of the Bohai Bay Basin in the eastern NCC experienced their maximum heat flow at the Cenozoic era, accompanied by episodic extension, rapid subsidence and sedimentation. Few boreholes in the Jiyang Depression recorded high heat flow of > 80 mW/m2 and surface denudation of ~ 2 km in the Mesozoic. The paper summarizes several dynamical models related to lithospheric thinning, including the mantle plume, Delamination, subduction and lithospheric extension, and analyzes their near-surface tectono-thermal responses. Present results suggest that the regional thermal–chemical erosion by vigorous mantle convection within the big mantle wedge (BMW), possibly together with Local Delamination, may play a key role in the Mesozoic thinning, and the Cenozoic thinning is probably related to rifting and/or mantle plume. The thermal regime, combined with magmatism and numerical modeling, indicates that the NCC evolution has involved four distinct stages: modification in the Jurassic by Pacific Plate subduction; destruction during the Early Cretaceous under combined convective erosion, peridotite–melt interaction, and possible Local Delamination; multi-phase extension perhaps together with plume in the Late Cretaceous–Cenozoic; and cooling since the Late Cenozoic.