Formulation of an improved smeared stiffener theory for buckling analysis of grid-stiffened composite panels

Jaunky, Navin; Knight, Norman F.; Ambur, Damodar R.

doi:10.1016/1359-8368(96)00032-7

Cited by 88 publications

(31 citation statements)

References 2 publications

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“…25. The buckling analysis of local skin segments is also based on a Rayleigh Ritz analysis using a rst-order, sheardeformation theory, and it accounts for material anisotropy.…”

Section: Panel Buckling Analysismentioning

confidence: 99%

Optimal Design of Grid-Stiffened Composite Panels

Jaunky

Knight

Ambur

1998

Journal of Aircraft

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A design strategy for optimal design of composite grid-stiffened panels subjected to global and local buckling constraints is developed using a discrete optimizer. An improved smeared stiffener theory is used for the global buckling analysis. Local buckling of skin segments is assessed using a Rayleigh Ritz method that accounts for material anisotropy and transverse shear exibility. The local buckling of stiffener segments is also assessed. Design variables are the axial and transverse stiffener spacing, stiffener height and thickness, skin laminate, and stiffening con guration, where the stiffening con guration is herein de ned as a design variable that indicates the combination of axial, transverse, and diagonal stiffeners in the stiffened panel. The design optimization process is adapted to identify the lightest-weight stiffening con guration and stiffener spacing for grid-stiffened composite panels given the overall panel dimensions, in-plane design loads, material properties, and boundary conditions of the grid-stiffened panel. Nomenclature a, b = axial and transverse stiffener spacing, respectively F (X, r i ) = modi ed objective function h = stiffener height ICON = design variable for stiffening con guration i = generation or iteration cycle in the optimization procedure LAMI = design variable for stacking sequence of skin laminate M = population size N c = number of design constraints N d = number of design variables Q = normalizing constant r i = penalty parameter [ u g j (X )u 1 g j (X )] 2 N c r ( i j = penalty function t = skin laminate thickness t s = stiffener thickness W (X ) = weight of panel per unit area w s

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“…25. The buckling analysis of local skin segments is also based on a Rayleigh Ritz analysis using a rst-order, sheardeformation theory, and it accounts for material anisotropy.…”

Section: Panel Buckling Analysismentioning

confidence: 99%

Optimal Design of Grid-Stiffened Composite Panels

Jaunky

Knight

Ambur

1998

Journal of Aircraft

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“…The selection of stiffener configuration depends on several factors such as the loading condition, cost, and other factors. The promising future of stiffened cylinders with reinforcing grids or ribs, has led to a wide range of research work [30][31][32][33][34][35][36][37][38].…”

Section: Introductionmentioning

confidence: 99%

Experimental, numerical and analytical investigation of free vibrational behavior of GFRP-stiffened composite cylindrical shells

Hemmatnezhad

Rahimi

Tajik

et al. 2015

Composite Structures

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“…Both global and local buckling behaviours were considered in a weight-minimum design for grid-stiffened panels and cylinders using a genetic algorithm [19,20]. In the work, an improved smeared theory with the offset effect of stiffeners included [21] was employed for the global analysis, while the local skin buckling was assessed by the Rayleigh-Ritz method which accounts for material anisotropy and stiffener crippling was assessed using the method provided in Reddy's work [6]. Then, this method was applied to optimization design of grid-stiffened panels with variable curvature, which were modeled as assemblies of panels with constant curvature [22].…”

Section: Introductionmentioning

confidence: 99%

Buckling Analysis of Grid-Stiffened Composite Shells

Wang

Abdalla

2016

Design and Analysis of Reinforced Fiber Composites

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Abstract. There is a renewed interest in grid-stiffened composite structures; they are not only competitive with conventional stiffened constructions and sandwich shells in terms of weight but also enjoy superior damage tolerance properties. In this paper, both global and local structural instabilities are investigated for grid-stiffened composite panels using homogenization theory. Characteristic cell configurations with periodic boundary constraints are employed for orthogrid-and isogrid-stiffened shells in order to smear the stiffened panel into an equivalent unstiffened shell. Homogenized properties corresponding to classical lamination theory are obtained by matching the strain energy of the stiffened and equivalent cells. Global buckling analysis is carried out based on the homogenized shell properties. Bloch wave theory is adopted to calculate the local buckling load of grid-stiffened shells, where the interaction of adjacent cells is fully taken into account. Moreover, instead of considering skin buckling and stiffener crippling separately, as is commonly done, the skin and stiffeners are assembled together at the level of the characteristic cell. The critical instabilities can be captured whether they are related to the skin or stiffener or their interaction. The proposed combination of global/local models can also be used to predict the material failure of a structure. Numerical examples of orthogrid-and isogrid-stiffened isotropic panels show that the local buckling loads predicted by the proposed method match finite element calculations better than semi-analytical methods based on assumptions and idealisations. The proposed method is further validated using typical configurations of flat composite panels and circular composite cylinders.

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Formulation of an improved smeared stiffener theory for buckling analysis of grid-stiffened composite panels

Cited by 88 publications

References 2 publications

Optimal Design of Grid-Stiffened Composite Panels

Optimal Design of Grid-Stiffened Composite Panels

Experimental, numerical and analytical investigation of free vibrational behavior of GFRP-stiffened composite cylindrical shells

Buckling Analysis of Grid-Stiffened Composite Shells

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