Geometrically Nonlinear Dynamic Analysis of an Imperfect, Stiffened, Functionally Graded, Doubly Curved Shell

An analytical study of the nonlinear response of imperfect stiffened doubly curved shells made of functionally graded material (FGM) is presented. The formulation of the problem is based on the first-order shear deformation shell theory in conjunction with the von Kármán geometrical nonlinear strain...

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Main Authors: Boutros Azizi, Habib Eslami, Kais Jribi
Format: Article
Language:English
Published: MDPI AG 2025-05-01
Series:Dynamics
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Online Access:https://www.mdpi.com/2673-8716/5/2/18
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author Boutros Azizi
Habib Eslami
Kais Jribi
author_facet Boutros Azizi
Habib Eslami
Kais Jribi
author_sort Boutros Azizi
collection DOAJ
description An analytical study of the nonlinear response of imperfect stiffened doubly curved shells made of functionally graded material (FGM) is presented. The formulation of the problem is based on the first-order shear deformation shell theory in conjunction with the von Kármán geometrical nonlinear strain–displacement relationships. The nonlinear equations of the motion of stiffened double-curved shells based on the extended Sanders’s theory were derived using Galerkin’s method. The material properties vary in the direction of thickness according to the linear rule of mixture. The effect of both longitudinal and transverse stiffeners was considered using Lekhnitsky’s technique. The fundamental frequencies of the stiffened shell are compared with the FE solutions obtained by using the ABAQUS 6.14 software. A stepwise approximation technique is applied to model the functionally graded shell. The resulting nonlinear ordinary differential equations were solved numerically by using the fourth-order Runge–Kutta method. Closed-form solutions for nonlinear frequency–amplitude responses were obtained using He’s energy method. The effect of power index, functionally graded stiffeners, geometrical parameters, and initial imperfection on the nonlinear response of the stiffened shell are considered and discussed.
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spelling doaj-art-4c2064d7a15c4d04ba4485ca9c68bc0b2025-06-25T13:43:37ZengMDPI AGDynamics2673-87162025-05-01521810.3390/dynamics5020018Geometrically Nonlinear Dynamic Analysis of an Imperfect, Stiffened, Functionally Graded, Doubly Curved ShellBoutros Azizi0Habib Eslami1Kais Jribi2Department of Engineering Fundamentals, Embry Riddle Aeronautical University, 1 Aerospace BLVD, Daytona Beach, FL 32114, USADepartment of Aerospace Engineering, Embry Riddle Aeronautical University, 1 Aerospace BLVD, Daytona Beach, FL 32114, USADepartment of Mechanical Engineering, Florida Polytechnic University, 4700 Research Way, Lakeland, FL 33805, USAAn analytical study of the nonlinear response of imperfect stiffened doubly curved shells made of functionally graded material (FGM) is presented. The formulation of the problem is based on the first-order shear deformation shell theory in conjunction with the von Kármán geometrical nonlinear strain–displacement relationships. The nonlinear equations of the motion of stiffened double-curved shells based on the extended Sanders’s theory were derived using Galerkin’s method. The material properties vary in the direction of thickness according to the linear rule of mixture. The effect of both longitudinal and transverse stiffeners was considered using Lekhnitsky’s technique. The fundamental frequencies of the stiffened shell are compared with the FE solutions obtained by using the ABAQUS 6.14 software. A stepwise approximation technique is applied to model the functionally graded shell. The resulting nonlinear ordinary differential equations were solved numerically by using the fourth-order Runge–Kutta method. Closed-form solutions for nonlinear frequency–amplitude responses were obtained using He’s energy method. The effect of power index, functionally graded stiffeners, geometrical parameters, and initial imperfection on the nonlinear response of the stiffened shell are considered and discussed.https://www.mdpi.com/2673-8716/5/2/18functionally graded materialsdouble-curved stiffened shellLekhnitsky’s techniquenonlinear static analysisnonlinear dynamic analysisGalerkin’s method
spellingShingle Boutros Azizi
Habib Eslami
Kais Jribi
Geometrically Nonlinear Dynamic Analysis of an Imperfect, Stiffened, Functionally Graded, Doubly Curved Shell
Dynamics
functionally graded materials
double-curved stiffened shell
Lekhnitsky’s technique
nonlinear static analysis
nonlinear dynamic analysis
Galerkin’s method
title Geometrically Nonlinear Dynamic Analysis of an Imperfect, Stiffened, Functionally Graded, Doubly Curved Shell
title_full Geometrically Nonlinear Dynamic Analysis of an Imperfect, Stiffened, Functionally Graded, Doubly Curved Shell
title_fullStr Geometrically Nonlinear Dynamic Analysis of an Imperfect, Stiffened, Functionally Graded, Doubly Curved Shell
title_full_unstemmed Geometrically Nonlinear Dynamic Analysis of an Imperfect, Stiffened, Functionally Graded, Doubly Curved Shell
title_short Geometrically Nonlinear Dynamic Analysis of an Imperfect, Stiffened, Functionally Graded, Doubly Curved Shell
title_sort geometrically nonlinear dynamic analysis of an imperfect stiffened functionally graded doubly curved shell
topic functionally graded materials
double-curved stiffened shell
Lekhnitsky’s technique
nonlinear static analysis
nonlinear dynamic analysis
Galerkin’s method
url https://www.mdpi.com/2673-8716/5/2/18
work_keys_str_mv AT boutrosazizi geometricallynonlineardynamicanalysisofanimperfectstiffenedfunctionallygradeddoublycurvedshell
AT habibeslami geometricallynonlineardynamicanalysisofanimperfectstiffenedfunctionallygradeddoublycurvedshell
AT kaisjribi geometricallynonlineardynamicanalysisofanimperfectstiffenedfunctionallygradeddoublycurvedshell