Nonlinear Postbuckling of Eccentrically Oblique-Stiffened Functionally Graded Doubly Curved Shallow Shells Based on Improved Donnell Equations

The nonlinear buckling and postbuckling of eccentrically oblique-stiffened doubly curved shallow functionally graded shells is investigated based on improved Donnell equations. The improved Lekhnitskii smeared stiffeners technique is employed to found the stiffness matrix of the stiffened shells. The shells are reinforced by eccentrically oblique stiffeners with an arbitrary inclination angle. Using the Galerkin method, an analytical approximate solution for the deflection of reinforced FGM doubly curved shallow shells is obtained. The influence of geometrical parameters, oblique stiffeners, and temperature on the postbuckling behavior of the shells is analyzed.

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Acknowledgment

This research was funded by the National Science and Technology Program of Vietnam for the period of 2016-2020 “Research and development of science education to meet the requirements of fundamental and comprehensive reform education of Vietnam” under the Grant KHGD/16-20.DT.032. The authors are grateful for this support.

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Correspondence to N. D. Duc.

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Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 55, No. 6, pp. 1059-1080, November- December, 2019.

Appendix

Appendix

$$ {\displaystyle \begin{array}{c}{I}_{11}={A}_{11}-\frac{D_{11}}{R_x^2}{I}_{12}={A}_{66}-\frac{D_{66}}{R_x^2},{I}_{13}={A}_{16}+{A}_{61}-\frac{1}{R_x^2}\left({D}_{61}+{D}_{16}\right),\\ {}{I}_{21}={A}_{16}+{B}_{16}\left(\frac{1}{R_y}-\frac{1}{R_x}\right)-\frac{D_{16}}{R_x{R}_y},{I}_{22}={A}_{62}+{B}_{62}\left(\frac{1}{R_y}-\frac{1}{R_x}\right)-\frac{D_{62}}{R_x{R}_y},\\ {}{I}_{23}={A}_{12}+{A}_{66}+\left({B}_{12}+{B}_{66}\right)\left(\frac{1}{R_y}-\frac{1}{R_x}\right)-\frac{1}{R_x{R}_y}\left({D}_{12}+{D}_{66}\right),\\ {}{I}_{31}=\left({A}_{11}-{B}_{11}\frac{1}{R_x}\right)\frac{1}{R_x}+\left({A}_{12}-\frac{1}{R_x}{B}_{12}\right)\frac{1}{R_y},{I}_{32}=\left({A}_{61}-\frac{1}{R_x}{B}_{61}\right)\frac{1}{R_x}\left({A}_{62}-\frac{D_{62}}{R_x}\right)\frac{1}{R_y},\\ {}{I}_{33}={A}_{16}-\frac{1}{R_x}{B}_{16},{I}_{34}={A}_{66}-\frac{1}{R_x}{B}_{66},{I}_{35}=\left({B}_{11}-\frac{1}{R_x}{D}_{11}\right),\\ {}\begin{array}{l}{I}_{130}=\frac{1}{2{R}_x}{A}_{11}+\frac{1}{2{R}_y}{A}_{21},{I}_{131}=\frac{1}{2{R}_x}{A}_{12}+\frac{1}{2{R}_y}{A}_{22},{I}_{132}=\frac{A_{16}}{R_{,x}}+\frac{A_{26}}{R_y}0,\\ {}\end{array}\\ {}\begin{array}{l}{I}_{133}={A}_{11}\frac{1}{R_x}+{A}_{12}\frac{1}{R_y},{I}_{134}={A}_{11}\frac{1}{R_x}+{A}_{12}\frac{1}{R_y},{I}_{135}={A}_{61}\frac{1}{R_x}+{A}_{62}\frac{1}{R_y},\\ {}\begin{array}{c}{I}_{136}={A}_{61}\frac{1}{R_x}+{A}_{62}\frac{1}{R_y},{I}_{137}={A}_{21}\frac{1}{R_x}+{A}_{22}\frac{1}{R_y},{I}_{138}={A}_{21}\frac{1}{R_x}+{A}_{22}\frac{1}{R_y},\end{array}\end{array}\\ {}{I}_{139}={A}_{61}\frac{1}{R_x}+{A}_{62}\frac{1}{R_y},{I}_{140}\left({A}_{61}\frac{1}{R_x}+{A}_{62}\frac{1}{R_y}\right),{I}_{51}^{\ast }=\frac{8}{9}\left(\frac{3}{2{R}_x}{A}_{11}+\frac{1}{2{R}_y}{A}_{21}+{A}_{12}\frac{1}{R_y}\right),\\ {}{I}_{52}^{\ast }=\frac{8}{9}\left(\frac{1}{2{R}_x}{A}_{12}+\frac{3}{2{R}_y}{A}_{22}+{A}_{21}\frac{1}{R_x}\right),\\ {}{I}_{53}^{\ast }=\frac{16}{9}\frac{{\lambda_m}^3}{\delta_n}{B}_{11}+\frac{4}{9}{B}_{12}{\lambda}_m{\delta}_n+\frac{16}{9}\frac{{\delta_n}^3}{\lambda_m}{B}_{22}-\frac{8}{9}{B}_{66}{\lambda}_m{\delta}_n\\ {}{I}_{36}={B}_{62}-\frac{1}{R_x}{D}_{62},{I}_{37}={B}_{12}+2{B}_{66}-\frac{1}{R_x}\left(2{D}_{66}+{D}_{12}\right),{I}_{38}=2{B}_{16}+{B}_{61}-\frac{1}{R_x}\left({D}_{61}+2{D}_{16}\right),\\ {}{I}_{41}=\frac{1}{2}{A}_{61}-\frac{1}{2{R}_x}{B}_{61},{I}_{42}=\frac{1}{2}{A}_{62}-\frac{1}{2{R}_x}{B}_{62},{I}_{43}=\frac{1}{2}{A}_{11}-\frac{1}{2{R}_x}{B}_{11},{I}_{44}=\frac{1}{2}{A}_{12}-\frac{1}{2{R}_x{B}_{12},}\\ {}{I}_{51}={A}_{61}+{B}_{61}\left(\frac{1}{R_x}-\frac{1}{R_y}\right)-\frac{D_{61}}{R_y{R}_x},{I}_{52}={A}_{26}+{B}_{26}\left(\frac{1}{R_x}-\frac{1}{R_y}\right)-\frac{D_{26}}{R_x{R}_y},\\ {}\end{array}} $$
$$ {\displaystyle \begin{array}{c}{I}_{53}={A}_{21}+{A}_{66}+\left({B}_{21}+{B}_{66}\right)\left(\frac{1}{R_x}-\frac{1}{R_y}\right)-\frac{\left({D}_{66}+{D}_{21}\right)}{R_x{R}_y},\\ {}{I}_{61}=\left({A}_{66}-\frac{D_{66}}{R_y^2}\right),{I}_{62}\left({A}_{22}-\frac{D_{22}}{R_y^2}\right),{I}_{63}\left[{A}_{26}+{A}_{62}-\frac{\left({D}_{62}+{D}_{26}\right)}{R_y^2}\right],\\ {}{I}_{71}=\frac{1}{2}{A}_{21}-\frac{1}{2{R}_y},{I}_{72}=\frac{1}{2}{A}_{22}-\frac{1}{2{R}_y}{B}_{22},{I}_{73}=\frac{1}{2}{A}_{61}-\frac{1}{2{R}_y}{B}_{61},{I}_{74}=\frac{1}{2}{A}_{62}-\frac{1}{2{R}_y}{B}_{62},\\ {}{I}_{81}={A}_{21}\frac{1}{R_x}-\frac{1}{R_y}\left({B}_{21}\frac{1}{R_x}+{B}_{22}\frac{1}{R_y}-{A}_{22}\right),{I}_{82}={B}_{21}+2{B}_{66}-\frac{1}{R_y}\left({D}_{21}+2{D}_{66}\right),\\ {}{I}_{83}={B}_{22}-\frac{1}{R_y}{D}_{22},{I}_{84}=2{B}_{26}+{B}_{62}-\frac{1}{R_y}\left({D}_{62}+2{D}_{26}\right),\\ {}{I}_{85}={A}_{61}\frac{1}{R_x}+{A}_{62}\frac{1}{R_y}-\frac{1}{R_y}\left({B}_{61}\frac{1}{R_x}+{D}_{62}\frac{1}{R_y}\right),{I}_{86}={B}_{61}-\frac{1}{R_y}{D}_{61},\\ {}{I}_{87}={A}_{26}-\frac{1}{R_y}{B}_{26},{I}_{88}={A}_{66}-\frac{1}{R_y}{B}_{66},\\ {}{I}_{91}={B}_{11}+{D}_{11}\frac{1}{R_x},{I}_{92}={B}_{26}+{D}_{26}\frac{1}{R_x},{I}_{93}={B}_{16}+{D}_{16}\frac{1}{R_x}+2\left({B}_{61}+{D}_{61}\frac{1}{R_x}\right),\\ {}{I}_{94}={B}_{21}+{D}_{21}\frac{1}{R_x}+2\left({B}_{66}+{D}_{66}\frac{1}{R_x}\right),{I}_{95}=\frac{1}{R_x}\left({A}_{11}+{B}_{11}\frac{1}{R_x}\right)+\frac{1}{R_y}\left({A}_{21}+{B}_{21}\frac{1}{R_x}\right),\\ {}{I}_{96}=\frac{1}{R_x}\left({A}_{16}+{B}_{16}\frac{1}{R_x}\right)+\frac{1}{R_y}\left({A}_{26}+{B}_{26}\frac{1}{R_x}\right),{I}_{110}={B}_{16}+{D}_{16}\frac{1}{R_y},{I}_{111}={B}_{22}+{D}_{22}\frac{1}{R_y},\\ {}{I}_{112}={B}_{26}+{D}_{26}\frac{1}{R_y}+2\left({B}_{62}+{D}_{62}\frac{1}{R_y}\right),{I}_{113}={B}_{12}+{D}_{12}\frac{1}{R_y}+2\left({B}_{66}+{D}_{66}\frac{1}{R_y}\right),\\ {}{I}_{114}=\frac{1}{R_x}\left({A}_{12}+{B}_{12}\frac{1}{R_y}\right)+\frac{1}{R_y}\left({A}_{22}+{B}_{22}\frac{1}{R_y}\right),{I}_{115}=\frac{1}{R_x}\left({A}_{16}+{B}_{16}\frac{1}{R_y}\right)+\frac{1}{R_y}\left({A}_{26}+{B}_{26}\frac{1}{R_y}\right),\\ {}{P}_3(w)={I}_{130}{\left({w}_{,x}\right)}^2+{I}_{131}{\left({w}_{,y}\right)}^2+\frac{1}{2}{B}_{11}{\left({w}_{,x}^2\right)}_{,x\;x}+\frac{1}{2}{B}_{12}{\left({w}_{,y}^2\right)}_{,x\;x}+\frac{1}{2}{B}_{21}{\left({w}_{,x}^2\right)}_{,y\;y}+\frac{1}{2}{B}_{22}{\left({w}_{,y}^2\right)}_{,y\;y}\\ {}+{B}_{61}{\left({w}_{,x}^2\right)}_{,x\;y}+{B}_{62}{\left({w}_{,y}^2\right)}_{,x\;y}+2{B}_{66}{\left({w}_{,x}{w}_{,y}\right)}_{,x\;y}+{B}_{16}{\left({w}_{,x}{w}_{,y}\right)}_{,x\;x}+{B}_{26}{\left({w}_{,x}{w}_{,y}\right)}_{,y\;y}+{I}_{132}{w}_{,x}{w}_{,y}\\ {}-{w}_{,x}^2{I}_{133}-w{w}_{,x\;x}{I}_{134}+\frac{1}{2}{A}_{11}{\left({w}_{,x}^3\right)}_{,x}+\frac{1}{2}{A}_{12}{\left({w}_{,y}^2\right)}_{,x}+{w}_{,x}+\frac{1}{2}{A}_{12}{w}_{,y}^2{w}_{,x\;x}+{A}_{16}{w}_{,x}^2{w}_{,x\;y}+{A}_{16}{\left({w}_{,x}^2\right)}_{,x}{w}_{,y}\\ {}+{B}_{11}{w}_{, xx x}{w}_{,x}+{B}_{11}{w}_{, xx}^2+{B}_{12}{w}_{,x\;x}{w}_{,y\;y}+{B}_{12}{w}_{,x}{w}_{,x\; yy}+2{B}_{16}{w}_{,x\;x}{w}_{, xy}+2{B}_{16}{w}_{,x}{w}_{, xx y}+2{B}_{66}{w}_{, xy y}{w}_{,x}\\ {}\frac{1}{2}{A}_{61}{\left({w}_{,x}^2\right)}_{,x}{w}_{,y}+\frac{1}{2}{A}_{61}{w}_{,x}^2{w}_{,x\;y}+\frac{1}{2}{A}_{62}{\left({w}_{,y}^3\right)}_{,x}+{A}_{66}{w}_{,x\;x}{w}_{,y}^2+{A}_{66}{w}_{,x}{\left({w}_{,y}^2\right)}_{,x}+2{B}_{66}{w}_{, xy}{w}_{, xy}\\ {}-{w}_{,x}{w}_{,y}{I}_{135}-w{w}_{,x\;y}{I}_{136}+{B}_{61}{w}_{, xx x}{w}_{,y}+{B}_{62}{w}_{,x\; yy}{w}_{,y}+{B}_{62}{w}_{, yy}{w}_{,x\;y}+2{B}_{66}{w}_{, xx y}{w}_{,y}\end{array}} $$
$$ {\displaystyle \begin{array}{c}+2{B}_{66}{w}_{, xy}{w}_{,x\;y}-{w}_{,y}^2{I}_{137}-w{w}_{, yy}{I}_{138}+\frac{1}{2}{A}_{21}{\left({w}_{,x}^2\right)}_{,y}{w}_{,y}+\frac{1}{2}{A}_{21}{w}_{,x}^2{w}_{, yy}+\frac{1}{2}{A}_{22}{\left({w}_{,y}^3\right)}_{,y}+{A}_{26}{w}_{, xy}{w}_{,y}^2\\ {}+{A}_{26}{w}_{,x}{\left({w}_{,y}^2\right)}_{,y}+{B}_{21}{w}_{, xx y}{w}_{,y}+{B}_{21}{w}_{, xx}{w}_{, yy}+{B}_{22}{w}_{, yy y}{w}_{,y}+{B}_{22}{w}_{, yy}^2+2{B}_{26}{w}_{, xy y}{w}_{,y}+2{B}_{26}{w}_{, xy}{w}_{, yy}\\ {}-{w}_{,y}{w}_{,x}{I}_{139}-w{w}_{, xy}{I}_{139}^{\ast }+\frac{1}{2}{A}_{61}{\left({w}_{,x}^3\right)}_{,y}+\frac{1}{2}{A}_{62}{w}_{,x}{\left({w}_{,y}^2\right)}_{,y}+{A}_{66}{\left({w}_{,x}^2\right)}_{,y}{w}_{,y}\\ {}+{A}_{66}{w}_{,x}^2{w}_{, yy}+{B}_{61}{w}_{, xx y}{w}_{,x}+{B}_{61}{w}_{, xx}{w}_{, xy}+{B}_{62}{w}_{, yy y}{w}_{,x}+{B}_{62}{w}_{, yy}{w}_{xy},\\ {}{Q}_3\left(u,w\right)={u}_{,x\;x}{w}_{,x}\left({A}_{11}+{B}_{11}\frac{1}{R_x}\right)+{u}_{,x}{w}_{,x\;x}\left({A}_{11}+{B}_{11}\frac{1}{R_x}\right)\\ {}+{u}_{,y}{w}_{,x\;x}\left({A}_{16}+{B}_{16}\frac{1}{R_x}\right){u}_{,y\;x}{w}_{,y}\left({A}_{21}+{B}_{21}\frac{1}{R_x}\right)+{u}_{,x}{w}_{, yy}\left({A}_{21}+{B}_{21}\frac{1}{R_x}\right)\\ {}+{u}_{yy}{w}_{,y}\left({A}_{26}+{B}_{26}\frac{1}{R_x}\right)+{u}_{,y}{w}_{, yy}\left({A}_{26}+{B}_{26}\frac{1}{R_x}\right)+{u}_{, xx}{w}_{,y}\left({A}_{61}+{B}_{61}\frac{1}{R_x}\right)\\ {}+{u}_{,x}{w}_{, xy}\left({A}_{61}+{B}_{61}\frac{1}{R_x}\right)+{u}_{, xy}{w}_{,y}\left({A}_{66}+{B}_{66}\frac{1}{R_x}\right)+{u}_{,y}{w}_{, xy}\left({A}_{66}+{B}_{66}\frac{1}{R_x}\right)\\ {}+{u}_{xy}{w}_{,x}\left({A}_{61}+{B}_{61}\frac{1}{R_x}\right)+{u}_{,x}{w}_{, xy}\left({A}_{61}+{B}_{61}\frac{1}{R_x}\right)+{u}_{, yy}{w}_{,x}\left({A}_{66}+{B}_{66}\frac{1}{R_x}\right)\\ {}+{u}_{,y}{w}_{xy}\left({A}_{66}+{B}_{66}\frac{1}{R_x}\right)+{u}_{, xy}{w}_{,x}\left({A}_{16}+{B}_{16}\frac{1}{R_x}\right),\\ {}{R}_3\left(v,w\right)={v}_{,y}{w}_{,x\;x}\left({A}_{12}+{B}_{12}\frac{1}{R_y}\right)+{v}_{,x\;y}{w}_{,x}\left({A}_{12}+{B}_{12}\frac{1}{R_y}\right)\\ {}+{v}_{, xx}{w}_{,x}\left({A}_{16}+{B}_{16}\frac{1}{R_y}\right)+{v}_{,x}{w}_{,x\;x}\left({A}_{16}+{B}_{16}\frac{1}{R_y}\right)\\ {}+{v}_{y\;y}{w}_{,y}\left({A}_{22}+{B}_{22}\frac{1}{R_y}\right)+{v}_{,y}{w}_{, yy}\left({A}_{22}+{B}_{22}\frac{1}{R_y}\right)\\ {}+{v}_{, xy}{w}_{,y}\left({A}_{26}+{B}_{26}\frac{1}{R_y}\right)+{v}_{,x}{w}_{, yy}\left({A}_{26}+{B}_{26}\frac{1}{R_y}\right)\\ {}+{v}_{,x\;y}{w}_{,y}\left({A}_{62}+{B}_{62}\frac{1}{R_y}\right)+{v}_{,y}{w}_{,x\;y}\left({A}_{62}+{B}_{62}\frac{1}{R_y}\right)\\ {}+{v}_{, xx}{w}_{,y}\left({A}_{66}+{B}_{66}\frac{1}{R_y}\right)+{v}_{,x}{w}_{,x\;y}\left({A}_{66}+{B}_{66}\frac{1}{R_y}\right)\\ {}+{v}_{,y\;y}{w}_{,x}\left({A}_{62}+{B}_{62}\frac{1}{R_y}\right)+{v}_{,y}{w}_{, yx}\left({A}_{62}+{B}_{62}\frac{1}{R_y}\right)\\ {}+{v}_{xy}{w}_{,x}\left({A}_{66}+{B}_{66}\frac{1}{R_y}\right)+{v}_{,x}{w}_{, xy}\left({A}_{66}+{B}_{66}\frac{1}{R_y}\right).\end{array}} $$

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Duc, N.D., Nam, V.H. & Cuong, N.H. Nonlinear Postbuckling of Eccentrically Oblique-Stiffened Functionally Graded Doubly Curved Shallow Shells Based on Improved Donnell Equations. Mech Compos Mater 55, 727–742 (2020). https://doi.org/10.1007/s11029-020-09847-9

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Keywords

  • nonlinear postbuckling
  • oblique stiffeners
  • doubly curved shallow functionally graded shell
  • improved Donnell equations