The Experts below are selected from a list of 162 Experts worldwide ranked by ideXlab platform
Nguyen Thi Phuong - One of the best experts on this subject based on the ideXlab platform.
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nonlinear static and dynamic buckling analysis of imperfect eccentrically stiffened functionally graded circular cylindrical thin shells under axial compression
International Journal of Mechanical Sciences, 2013Co-Authors: Dao Huy Bich, Dao Van Dung, Nguyen Thi PhuongAbstract:Abstract An analytical approach is presented to investigate the nonlinear static and dynamic buckling of imperfect eccentrically stiffened functionally graded thin circular cylindrical shells subjected to axial compression. Based on the classical thin shell theory with the geometrical nonlinearity in von Karman–Donnell sense, initial geometrical imperfection and the smeared stiffeners technique, the governing equations of motion of eccentrically stiffened functionally graded circular cylindrical shells are derived. The functionally graded cylindrical shells with simply supported edges are reinforced by ring and stringer stiffeners system on internal and (or) external surface. The resulting equations are solved by the Galerkin procedure to obtain the explicit expression of static critical buckling load, post-buckling load–deflection curve and nonlinear dynamic motion equation. The nonlinear dynamic responses are found by using fourth-order Runge–Kutta method. The dynamic critical buckling loads of shells under step loading of infinite duration are found corresponding to the load value of sudden jump in the average deflection and those of shells under linear-time compression are investigated according to Budiansky–Roth criterion. The obtained results show the effects of stiffeners and input factors on the static and dynamic buckling behavior of these structures.
Chongmin Song - One of the best experts on this subject based on the ideXlab platform.
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nonlinear dynamic buckling of the imperfect orthotropic e fgm circular cylindrical shells subjected to the longitudinal constant velocity
International Journal of Mechanical Sciences, 2018Co-Authors: Kang Gao, Wei Gao, Chongmin SongAbstract:Abstract In this study, an analytical approach on the nonlinear dynamic buckling of the orthotropic circular cylindrical shells made of exponential law functionally graded material (E-FGM) subjected to the longitudinal constant velocity is investigated with the incorporation of mercurial damping effect. The material properties are assumed to vary gradually in the thickness direction according to an exponential distribution function of the volume fraction of constituent materials. Theoretical formulations are derived based on improved Donnell shell theory (DST) and accounting for von-Karman strain–displacement relation, initial imperfection and damping effect. By applying Galerkin method and Airy's stress function, the obtained nonlinear differential equations are solved numerically by the fourth-order Runge–Kutta method. The nonlinear dynamic stability of the orthotropic FG cylindrical shell is assessed based on Budiansky–Roth criterion. Additionally, a parametric study is conducted to demonstrate the effects of various velocities, initial imperfections, damping ratios, inhomogeneous parameters on nonlinear dynamic buckling behavior of an imperfect orthotropic FG cylindrical shell. Comparing results with those in other publications validates the proposed method.
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nonlinear dynamic stability of the orthotropic functionally graded cylindrical shell surrounded by winkler pasternak elastic foundation subjected to a linearly increasing load
Journal of Sound and Vibration, 2018Co-Authors: Kang Gao, Wei Gao, Chongmin SongAbstract:Abstract This paper focuses on the dynamic stability behaviors of the functionally graded (FG) orthotropic circular cylindrical shell surrounded by the two-parameter (Winkler-Pasternak) elastic foundation subjected to a linearly increasing load with the consideration of damping effect. The material properties are assumed to vary gradually in the thickness direction based on an exponential distribution function of the volume fraction of constituent materials. Equations of motion are derived from Hamilton's principle and the nonlinear compatibility equation is considered by the means of modified Donnell shell theory including large deflection. Then the nonlinear dynamic buckling equation is solved by a hybrid analytical-numerical method (combined Galerkin method and fourth-order Runge-Kutta method). The nonlinear dynamic stability of the FG orthotropic cylindrical shell is assessed based on Budiansky-Roth criterion. Additionally, effects of different parameters such as various inhomogeneous parameters, loading speeds, damping ratios and aspect ratios and thickness ratios of the structure on dynamic buckling are discussed in details. Finally, the proposed method is validated with published literature.
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nonlinear dynamic characteristics and stability of composite orthotropic plate on elastic foundation under thermal environment
Composite Structures, 2017Co-Authors: Kang Gao, Wei Gao, Chongmin SongAbstract:Abstract An analytical computational scheme for nonlinear dynamic characteristics and stability of an eccentrically composite orthotropic plate on Winkler-Pasternak elastic foundation subjected to different axial velocities is proposed with the incorporation of mercurial damping effects under thermal environment. Incorporating the classical plate theory and Von-Karman strain-displacement relation, the nonlinear compatibility equation is derived. The Galerkin method and Airy’s stress function are implemented to establish the nonlinear dynamic buckling equation accommodating the thermal and damping effects. Then the developed nonlinear differential equations are solved numerically by the fourth-order Runge-Kutta method. The characteristics of natural frequency, linear and nonlinear vibration, frequency-amplitude curve and nonlinear dynamic responses are investigated by the developed approach with validations by other literatures. The nonlinear dynamic buckling loads are determined by using Budiansky-Roth criterion. Additionally, various effects of velocity, damping ratio, temperature change, buckling mode, initial imperfection and foundation parameter on nonlinear dynamic buckling of the orthotropic plate are discussed.
Dao Van Dung - One of the best experts on this subject based on the ideXlab platform.
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nonlinear dynamic analysis of eccentrically stiffened functionally graded circular cylindrical thin shells under external pressure and surrounded by an elastic medium
European Journal of Mechanics A-solids, 2014Co-Authors: Dao Van DungAbstract:Abstract A semi-analytical approach eccentrically stiffened functionally graded circular cylindrical shells surrounded by an elastic medium subjected to external pressure is presented The elastic medium is assumed as two-parameter elastic foundation model proposed by Pasternak. Based on the classical thin shell theory with the geometrical nonlinearity in von Karman–Donnell sense, the smeared stiffeners technique and Galerkin method, this paper deals the nonlinear dynamic problem. The approximate three-term solution of deflection shape is chosen and the frequency–amplitude relation of nonlinear vibration is obtained in explicit form. The nonlinear dynamic responses are analyzed by using fourth order Runge–Kutta method and the nonlinear dynamic buckling behavior of stiffened functionally graded shells is investigated according to Budiansky–Roth criterion. Results are given to evaluate effects of stiffener, elastic foundation and input factors on the frequency–amplitude curves, natural frequencies, nonlinear responses and nonlinear dynamic buckling loads of functionally graded cylindrical shells.
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nonlinear static and dynamic buckling analysis of imperfect eccentrically stiffened functionally graded circular cylindrical thin shells under axial compression
International Journal of Mechanical Sciences, 2013Co-Authors: Dao Huy Bich, Dao Van Dung, Nguyen Thi PhuongAbstract:Abstract An analytical approach is presented to investigate the nonlinear static and dynamic buckling of imperfect eccentrically stiffened functionally graded thin circular cylindrical shells subjected to axial compression. Based on the classical thin shell theory with the geometrical nonlinearity in von Karman–Donnell sense, initial geometrical imperfection and the smeared stiffeners technique, the governing equations of motion of eccentrically stiffened functionally graded circular cylindrical shells are derived. The functionally graded cylindrical shells with simply supported edges are reinforced by ring and stringer stiffeners system on internal and (or) external surface. The resulting equations are solved by the Galerkin procedure to obtain the explicit expression of static critical buckling load, post-buckling load–deflection curve and nonlinear dynamic motion equation. The nonlinear dynamic responses are found by using fourth-order Runge–Kutta method. The dynamic critical buckling loads of shells under step loading of infinite duration are found corresponding to the load value of sudden jump in the average deflection and those of shells under linear-time compression are investigated according to Budiansky–Roth criterion. The obtained results show the effects of stiffeners and input factors on the static and dynamic buckling behavior of these structures.
Dao Huy Bich - One of the best experts on this subject based on the ideXlab platform.
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research on dynamical buckling of imperfect stiffened three layered toroidal shell segments containing fluid under mechanical loads
Acta Mechanica, 2017Co-Authors: Dao Huy Bich, Dinh Gia NinhAbstract:An analytical approach to the nonlinear dynamical buckling of imperfect stiffened three-layered toroidal shell segments containing fluid is performed in this paper. The toroidal shell segments are reinforced by ring and stringer stiffeners system in which the material properties of the shell are assumed to be continuously graded in the thickness direction. Based on the classical thin shell theory with geometrical nonlinearity in von Karman–Donnell sense, Stein and McElman assumption, theoretical formulations are derived with the smeared stiffeners technique. Furthermore, the dynamical pressure of the fluid is taken into account. The fluid is assumed to be non-viscous and ideally incompressible. The dynamical critical buckling loads are evaluated by the Budiansky–Roth criterion in three cases: axial compression and lateral pressure with movable and immovable boundary conditions are obtained using the Galerkin method. Moreover, effects of geometrical and material parameters, imperfection and fluid on the nonlinear dynamical buckling behavior of shells are shown in the obtained results.
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nonlinear static and dynamic buckling analysis of imperfect eccentrically stiffened functionally graded circular cylindrical thin shells under axial compression
International Journal of Mechanical Sciences, 2013Co-Authors: Dao Huy Bich, Dao Van Dung, Nguyen Thi PhuongAbstract:Abstract An analytical approach is presented to investigate the nonlinear static and dynamic buckling of imperfect eccentrically stiffened functionally graded thin circular cylindrical shells subjected to axial compression. Based on the classical thin shell theory with the geometrical nonlinearity in von Karman–Donnell sense, initial geometrical imperfection and the smeared stiffeners technique, the governing equations of motion of eccentrically stiffened functionally graded circular cylindrical shells are derived. The functionally graded cylindrical shells with simply supported edges are reinforced by ring and stringer stiffeners system on internal and (or) external surface. The resulting equations are solved by the Galerkin procedure to obtain the explicit expression of static critical buckling load, post-buckling load–deflection curve and nonlinear dynamic motion equation. The nonlinear dynamic responses are found by using fourth-order Runge–Kutta method. The dynamic critical buckling loads of shells under step loading of infinite duration are found corresponding to the load value of sudden jump in the average deflection and those of shells under linear-time compression are investigated according to Budiansky–Roth criterion. The obtained results show the effects of stiffeners and input factors on the static and dynamic buckling behavior of these structures.
Franzulrich Schafer - One of the best experts on this subject based on the ideXlab platform.
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tmxdi based poly ether urethane polystyrene interpenetrating polymer networks 2 tg behaviour mechanical properties and modulus composition studies
Polymer, 1998Co-Authors: Douglas J. Hourston, Franzulrich Schafer, Michael H S Gradwell, Mo SongAbstract:Abstract In this, the second of two papers on a series of simultaneous polyurethane (PUR)/polystyrene (PS) interpenetrating polymer networks (IPNs), the T g behaviour, mechanical properties and modulus–composition relations have been studied. A gross phase morphology over the full IPN composition range was indicated by two separate loss factor peaks from dynamic mechanical thermal analysis (DMTA). Both DMTA and modulated-temperature differential scanning calorimetry (MT-d.s.c.) measurements revealed that the T g of the PS transition increased with decreasing PS content in the IPN. This was explained by an increase in interactions between the PUR hard segments and the π -electrons of the PS phenyl rings. Despite the phase-separated morphology, materials with good mechanical properties were obtained. The tensile properties and the Shore hardness results were comparable to similar semi-miscible PUR/PEMA IPNs. The Budiansky modulus–composition relation resulted in the best fit with the experimental data, indicating phase inversion at mid-range compositions. Modulus–composition studies, indicating that phase inversion occurred at the 30:70 PUR/PS IPN composition, corroborated the electron microscopy findings from the first paper in this series.
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poly ether urethane poly ethyl methacrylate interpenetrating polymer networks morphology phase continuity and mechanical properties as a function of composition
Polymer, 1996Co-Authors: Douglas J. Hourston, Franzulrich SchaferAbstract:The composition range of polyurethane (PUR)/poly(ethyl methacrylate) (PEMA) interpenetrating polymer networks was investigated with respect to morphology and phase continuity using mechanical and dynamic mechanical methods and transmission electron microscopy (TEM). Dynamic mechanical data revealed one main tanδ transition with a shoulder for the intermediate compositions from 70:30 to 40:60 indicating a semi-miscible system. For the remaining compositions only one peak, indicating a higher degree of miscibility was observed. The storage and elastic moduli were related to the Davies, Kerner and Budiansky modulus-composition models. The Budiansky modulus-composition model, which indicates phase inversion at the mid-range composition, resulted in the best fit. However, it was found that the shape of the modulus versus composition curves was strongly temperature-dependent. In previous studies, not much attention had been given to the temperature at which the modulus-composition studies were conducted. Tensile testing revealed a strong synergistic effect at the 70:30 PUR/PEMA composition with maxima occurring at this composition for both the elongation at break and the toughness index. The tensile strength increased in a three-step regime corroborating the dynamic mechanical thermal analysis results. TEM micrographs confirmed a co-continuous system at the 70:30 to 40:60 PUR/PEMA mid-range compositions.
