Journal articles: 'Stiffened structures'

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Sirajudeen, Rahima Shabeen, and Alagusundaramoorthy P. "GFRP Stiffened Plate with Square Cutout under Axial and Out-of-Plane Load." Polymers 13, no. 8 (April 7, 2021): 1185. http://dx.doi.org/10.3390/polym13081185.

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The high-strength-to-weight ratio and corrosion resistance properties of glass-fiber-reinforced polymer (GFRP) composites makes them potentially well-suited for application in ship structures, bridges and off-shore oil platforms. These structures are often formed by stiffened plates and are subjected to axial load and out-of-plane load. Cutouts and openings are provided in the plates for access and maintenance. The main objective of this study was to examine the buckling behavior of GFRP-stiffened composite plates with square cutouts under a combination of axial and out-of-plane load up to failure. Four blade-stiffened composite plates without a cutout and four with square cutout were fabricated with stiffeners as a continuous layup of the flange plate using glass fiber and epoxy resin. The initial geometric imperfections were measured, and plate imperfections (Δx), stiffener imperfections (Δsy) and overall imperfections (Δsx) were calculated from the measurements. All fabricated-stiffened composite plates were tested up to failure. The finite element model was developed in ANSYS software and validated with the experimental results. It was observed that GFRP-stiffened composite plates failed by stiffener compression/stiffener tension mode of failure. The presence of out-of-plane loads and cutouts reduced the axial load carrying capacity of the stiffened composite plates.

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Abdel Nasser, Yehia, Aly Aliraqi, and Bader El Din Ali. "Collision Analysis of Ship Side." Advanced Materials Research 199-200 (February 2011): 119–25. http://dx.doi.org/10.4028/www.scientific.net/amr.199-200.119.

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Structural design of ships against collision requires prediction of the extent of damage to stiffened plates subjected to impact. In ship structures, stiffened plates are furnished with vertical or horizontal stiffeners to sustain conventional loads such as shearing, bending and local buckling. The consideration of collision in ship structural design is especially important for tankers where accidents may cause serious environmental pollution. In predicting the extent of collision damage, FE modeling of stiffened plates using ABAQUS software is applied to demonstrate different collision scenario. Typical stiffened plates of tankers in service with different configurations of stiffeners are used to examine absorbed energy in each case. The aim of this paper is to examine the stiffener shape that absorbs more deformation energy.

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KALNINS, KASPARS, ROLANDS RIKARDS, JANIS AUZINS, CHIARA BISAGNI, HAIM ABRAMOVICH, and RICHARD DEGENHARDT. "METAMODELING METHODOLOGY FOR POSTBUCKLING SIMULATION OF DAMAGED COMPOSITE STIFFENED STRUCTURES WITH PHYSICAL VALIDATION." International Journal of Structural Stability and Dynamics 10, no. 04 (October 2010): 705–16. http://dx.doi.org/10.1142/s0219455410003695.

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A metamodeling methodology has been proposed for postbuckling simulation of stiffened composite structures with integrated degradation scenarios. The presence of artificial damage between the outer skin and stiffeners has been simulated as softening of the material properties in predetermined regions of the structure. The proposed methodology for the fast design procedure of axially or torsionally loaded stiffened composite structures is based on response surface methodology (RSM) and design and analysis of computer experiments (DACE). Numerical analyses have been parametrically sampled by means of the ANSYS/LS-DYNA probabilistic design toolbox extracting the load-shortening response curves in the preselected domain of interest. These response curves have been simplified using piecewise linear approximation identifying the buckling and postbuckling stiffness ratios along with the values of the skin and the stiffener buckling loads. Three stiffened panel designs and a closed box structure with preselected damage scenarios have been elaborated and validated with the tests performed within the COCOMAT project. The resulting design procedure provides a time-effective design tool for preliminary study and for elaboration of the optimum design guidelines for composite stiffened structures with material degradation restraints.

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Elsayed, Tarek, and Alaa Mansour. "Reliability-Based Specification of Welding Distortion Tolerances for Stiffened Steel Panels." Journal of Ship Research 47, no. 01 (March 1, 2003): 39–47. http://dx.doi.org/10.5957/jsr.2003.47.1.39.

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The purpose of this study is to analytically derive a simple and reasonably accurate expression for the maximum allowable unfairness tolerance of longitudinally stiffened panels in ship structures. The stiffened panels under consideration are typical of those found in the deck, bottom, or side shell of longitudinally stiffened ships. They are assumed to be under still water and wave-induced loads, resulting in predominantly compressive loads. A plate-stiffener combination model is used as representative of the stiffened panel. Ultimate strength is determined based on a strut approach taking into account the effects of initial stiffener deflection and welding residual stresses in the stiffener. A series of stiffener reliability analyses relative to the ultimate failure strength of the stiffener for varying proportions of column slenderness ratios is carried out. Based on the computed results, a simple expression for predicting the maximum allowable unfairness tolerance of the stiffener is derived. The developed expression, expressed in terms of the stiffener slenderness ratio, can be useful for the assessment of fairness limits of plating with frames, or as a design guideline in ship structures during construction.

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Wang, Wei Yuan, Yuan Yuan Li, and Hai Sheng Shu. "Sound Insulation Property of Bionic Thin-Walled Stiffened Plate Based on Plants Venations Growth Mechanism." Journal of Biomimetics, Biomaterials and Biomedical Engineering 20 (June 2014): 35–44. http://dx.doi.org/10.4028/www.scientific.net/jbbbe.20.35.

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The leaf can be seen as shin plate structures with stiffener(vein) and the venation distributions are closed related to the external environment load. Leaf venation growing algorithm (VGA) is the abstract description of vein growing process and reflects an ideological of learning from nature. This article concerns the sound insulation property of thin-walled stiffened plates. Numerical method is used to analyze three types of plants: non-stiffened plate, traditional stiffened plate and VGA stiffened plate. The VGA stiffened plate optimized by leaf venations growth algorithm method can reflect the influence of venations layout structure on the noise reduction performance of forest belts. The computational model of sound transmission through a stiffened plate excited by a harmonic oblique incident plane wave and mounted in an infinite baffle using the coupled finite element/boundary element approach is presented. The proposed model also takes the acoustic fluid- structure coupling into account. The results show that the sound transmission losses are closely dependent on the natural frequency. The sound transmission losses of bionic thin-walled stiffened plate are 0.17-2.45dB more than that of traditional stiffened plate in the range of 900-2000Hz. It indicated that the layout of stiffeners is an influence factor for noise reduction for plate structures, just like that of vein layout for tree belts. There is a certain merit to use the method of bionic plant leaves for acoustic optimization.

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Sheikh, Abdul Hamid, and Madhujit Mukhopadhyay. "Transverse Vibration of Plate Structures With Elastically Restrained Edges by the Spline/Finite Strip Method." Journal of Vibration and Acoustics 115, no. 3 (July 1, 1993): 295–302. http://dx.doi.org/10.1115/1.2930348.

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The newly developed spline finite strip method has been applied to determine the natural frequencies of plates and stiffened plates with edged elastically restrained against translation and rotation. The stiffener has been modelled so that it can be situated anywhere within the plate strip. The formulation has been generalized in such a manner that it can handle general shaped plates and stiffeners having arbitrary orientation and eccentricity. A consistent formulation has been adopted to incorporate the contribution of the edge restraints in the structural stiffness matrix. Numerical examples as available in the literature are solved and the comparison of the results indicates good accuracy of the method. New results in the form of natural frequencies corresponding to the higher modes particularly for plates/stiffened plates with nonclassical boundaries are presented.

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Wang, Wei Yuan, Yuan Yuan Li, and Ping Wang. "Mechanical Analysis for Thin-Walled Stiffened Plates on the Base of Plants Venations Growth Algorithm." Applied Mechanics and Materials 541-542 (March 2014): 299–302. http://dx.doi.org/10.4028/www.scientific.net/amm.541-542.299.

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The reinforced shin shell structures are widely used in many fields such as mechanical, architecture, aerospace and shipbuilding, etc. The leaf can be seen as shin plate structures with stiffener (vein) and the venation distributions are closed related to the external environment load. Leaf venation growing algorithm is the abstract description of vein growing process and reflects an ideological of learning from nature. This article concerns the mechanical analysis for thin-walled stiffened plates, which consist of static mechanical behavior and dynamic performance. Numerical method is used to analyze three types of plants: non-stiffened plate, traditional stiffened plate and stiffened plate optimized by leaf venations growth algorithm (VGA) method. The calculation results proved that the VGA stiffened plate has better mechanical performances than traditional method and illustrated the effectiveness of the bionic venations layout method for stiffened structures.

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Roberts, J. C., and G. J. White. "Experimental Results for Bending and Buckling of Rectangular Orthotropic Fiber-Reinforced Plastic Plate Structures." Marine Technology and SNAME News 36, no. 01 (January 1, 1999): 22–28. http://dx.doi.org/10.5957/mt1.1999.36.1.22.

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Solid unstiffened, sandwich, and hat-stiffened rectangular orthotropic fiber-reinforced plastic (FRP) plates were tested in uniaxial in-plane compression and out-of-plane uniform pressure. The two short edges of all plates were clamped, whereas the two long edges of the unstiffened and sandwich plates were simply supported and the same edges of the hat-stiffened plate were left free. Unstiffened plates reached global buckling at about 688 kN (155 klb); however, the plates did not collapse up to the machine load limit of 1334 kN (300 klb). Sandwich plates never reached the overall elastic buckling load; they collapsed in local buckling by face sheet delamination and core shear failure at loads of about 939 kN (211 klb). Hat-stiffened plates exhibited local buckling of the outer unsupported flanges at a load of about 356 kN (80 klb). All hat-stiffened plates collapsed under uniaxial compression due to a combination of face sheet to stiffener delamination followed by hat-stiffener local buckling at loads of about 939 kN (211 klb). The stresses and deflections due to out-of-plane uniform pressure were compared between the unstiffened, sandwich, and hat-stiffened plates from pressures of 6.895 kPa (1 psi) to 34 kPa (5 psi). With the plates under uniaxial compression and out-of-plane uniform pressure simultaneously, there was a general decrease in buckling and collapse with an increase in out-of-plane uniform pressure.

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Chen, Hao, Yuanming Xu, Junhao Hu, and Xi Wang. "Optimization of lightweight sub-stiffened panels with buckling analysis and imperfection sensitivity analysis." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, no. 15 (June 13, 2019): 5507–21. http://dx.doi.org/10.1177/0954410019856782.

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On the purpose of improving the structural efficiency of stiffened panels, which is widely used in engineering, three promising layouts of sub-stiffened thin-walled structures were optimized in view of structure's initial buckling and further analyzed through post-buckling and imperfection-sensitivity analysis. The optimization tasks were carried out using an integrated framework, which is based on the multidisciplinary optimization platform Model Center and finite element method software ABAQUS. The particle swarm optimization algorithm was applied to optimize layout parameters. Three optimal sub-stiffened panels were then evaluated based on their performance on critical buckling loads and post-buckling ultimate strength under uniaxial loading. Imperfection-sensitivity analysis was also conducted to investigate the stability behavior of the proposed panels with defect. The results indicate that the introduction of sub-stiffeners into the traditional stiffened panel can achieve significant improvements on the panel's buckling loads and ultimate strength under uniaxial loading, which are favorable to expand design space for engineering structures under requirements of lightweight with high bending stiffness and bucking resistance.

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Shojaee, T., B. Mohammadi, and R. Madoliat. "Experimental and numerical investigation of stiffener effects on buckling strength of composite laminates with circular cutout." Journal of Composite Materials 54, no. 9 (September 23, 2019): 1141–60. http://dx.doi.org/10.1177/0021998319874101.

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In the notched structures, to achieve maximum buckling resistance in comparison with structural weight, the optimal design of a stiffener is very important. In this research, after a review of the existing literature, nonlinear buckling behavior of composite plates containing the cutout with three different designs of stringer was investigated. The considered stiffeners are planer, longitudinal, and ring types. The buckling experiments were carried out on the stiffened plates containing a circular notch. Moreover, to achieve an efficient prediction of the buckling in the stiffened laminate with the hole, a finite strip method is developed based on the Airy stress function and von Karman’s large deformation equations. Studies show that there is a good agreement between the postbuckling behaviors derived from developed finite strip method with experimental results. Fast convergence of the considered finite strip method compared with the finite element results shows its efficiency for prediction of buckling behavior in laminated composites. The results show that the buckling load-bearing capacities of perforated plates with a longitudinal and planer stiffener are higher compared with the other stiffener, respectively. The detailed parametric study on the effects of thickness of the plate and stiffener and opening diameter on buckling behavior was performed using experiments and modeling.

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Zhu, Xiang, Gong Yu Xiao, Tian Yun Li, and Xiao Fang Hu. "Vibrational Power Flow Analysis of Stiffened Plate and Shell Structures." Applied Mechanics and Materials 66-68 (July 2011): 1897–901. http://dx.doi.org/10.4028/www.scientific.net/amm.66-68.1897.

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In this paper, the vibration and power flow characteristics of stiffened plate and cylindrical shell structures are investigated by using finite element method. The power flow formulas of basic shell structural elements are given at first. Then a simply supported plate and stiffened plate’s input power flow characteristics and power flow vectors are investigated. The effects of stiffeners in plates are discussed. For a simply supported cylindrical shell, the influence of the structural damping, viscous damper and stiffeners on the cylindrical shell’s input power flow characteristics and propagated power flow characteristics are discussed in detail. The power flow vectors are visualized to reveal the distribution of energy in the shell structures. Some useful conclusions are drown and helpful for the vibration control of plate and shell structures.

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Yuan, Guo-qing, and Wei-Kang Jiang. "Vibration analysis of stiffened multi-plate structure based on a modified variational principle." Journal of Vibration and Control 23, no. 17 (December 21, 2015): 2767–81. http://dx.doi.org/10.1177/1077546315621855.

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In order to study the vibration characteristics of flow-induced open cavity structures, the dynamic model of stiffened multi-plate is established. The first-order shear deformable plate theory and the Timoshenko beam theory are used to model the displacement fields of isotropic plates and stiffeners, respectively. A modified variational principle combined with a multi-segment partitioning procedure is employed to formulate the discretized equations of motion. The stiffeners are considered as discrete elements, and the energy contributions are included into the system energy functional by using the displacement compatibility conditions. The displacement and rotation components of each plate segment are expanded by a duplicate series of Chebyshev orthogonal polynomials of first kind. The convergence and accuracy of the present results for isotropic stiffened plates with different boundary conditions have been validated using comparisons with the published data and those obtained from the finite element analyses. Free vibration and dynamic responses of stiffened multi-plates with either longitudinal or orthogonally oriented stiffeners are discussed. The mathematical model and methodology presented in this paper may be used as an appropriate numerical tool in the analysis and design of stiffened multi-plate structures.

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Nam, Vu Hoai, Nguyen Thi Phuong, Dao Huy Bich, and Dao Van Dung. "Nonlinear static and dynamic buckling of eccentrically stiffened functionally graded cylindrical shells under axial compression surrounded by an elastic foundation." Vietnam Journal of Mechanics 36, no. 1 (February 28, 2014): 27–47. http://dx.doi.org/10.15625/0866-7136/36/1/3470.

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This paper presents an analytical approach to investigate the nonlinear buckling of imperfect eccentrically stiffened functionally graded thin circular cylindrical shells subjected to axial compression and surrounded by an elastic foundation. Based on the classical thin shell theory with the geometrical nonlinearity in von Karman-Donnell sense, initial geometrical imperfection, the smeared stiffeners technique and Pasternak’s two-parameter elastic foundation, the governing equations of eccentrically stiffened functionally graded cylindrical shells are derived. The functionally graded cylindrical shells are reinforced by homogeneous ring and stringer stiffener system on internal and (or) external surface. The resulting equations are solved by the Galerkin method 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 are considered for step loading of infinite duration and linear-time compression. The obtained results show the effects of foundation, stiffeners and input factors on the nonlinear buckling behavior of these structures.

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Gupta, Mohit, and Massimo Ruzzene. "Dynamics of Quasiperiodic Beams." Crystals 10, no. 12 (December 16, 2020): 1144. http://dx.doi.org/10.3390/cryst10121144.

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Quasiperiodic metastrucures are characterized by edge localized modes of topological nature, which can be of significant technological interest. We here investigate such topological modes for stiffened and sandwich beams, which can be employed as structural members with inherent vibration localization capabilities. Quasiperiodicity is achieved by altering the geometric properties and material properties of the beams. Specifically, in the stiffened beams, the geometric location of stiffeners is modulated to quasiperiodic patterns, while, in the sandwich beams, the core’s material properties are varied in a step-wise manner to generate such patterns. The families of periodic and quasiperiodic beams for both stiffened and sandwich-type are obtained by varying a projection parameter that governs the location of the center of the stiffener or the alternating core, respectively. The dynamics of stiffened quasiperiodic beams is investigated through 3-D finite element simulations, which leads to the observation of the fractal nature of the bulk spectrum and the illustration of topological edge modes that populate bulk spectral bandgaps. The frequency spectrum is further elucidated by employing polarization factors that distinguish multiple contributing modes. The frequency response of the finite stiffened cantilever beams confirms the presence of modes in the non-trivial bandgaps and further demonstrates that those modes are localized at the free edge. A similar analysis is conducted for the analysis of sandwich composite beams, for which computations rely on a dynamic stiffness matrix approach. This work motivates the use of quasiperiodic beams in the design of stiffened and sandwich structures as structural members in applications where vibration isolation is combined with load-carrying functions.

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Badran, Sherif Farouk, Ashraf O. Nassef, and Sayed M. Metwalli. "A Comparison of Buckling Strength of Y and T Stiffeners in Ship Plating." Marine Technology and SNAME News 45, no. 03 (July 1, 2008): 125–31. http://dx.doi.org/10.5957/mt1.2008.45.3.125.

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One aim of naval architects is to design structures that are strong enough and capable of absorbing impact energy. Therefore, ship plates are stiffened using different stiffeners to withstand compressive and other loads resulting from loads due to collisions, stranding, or grounding. There are also uniform stresses that are most typically induced in deck or bottom flange by longitudinal hull girder bending. In this paper, the T stiffener that has been widely used in shipbuilding and the Y stiffener that is starting to be used in inland waterway tankers in The Netherlands are considered. The aim of this paper is to compare the buckling strength of the T and Y stiffeners in combination with the effective width of ship plating under the action of uniformly distributed compressive loads. Two different groups of boundary conditions are considered for both T and Y stiffeners, and the elastic buckling coefficient is obtained and then the critical buckling loads are calculated. The obtained results showed that the critical buckling loads for Y stiffener are larger than that for equivalent T stiffener by about 40% for the first group of boundary conditions. The second group showed that the Y stiffener plate combination is five times stronger in compression than the equivalent T stiffener plate combination.

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Mukherjee, Kenneth Sunil, and Tetsuya Yao. "Buckling/Elastoplastic Collapse Behavior and Strength of Continuous Tee-Bar Stiffened Plates." Journal of Offshore Mechanics and Arctic Engineering 128, no. 2 (December 8, 2005): 145–55. http://dx.doi.org/10.1115/1.2185131.

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The influence of residual stress distributions should be properly taken into account in the structural analysis of stiffened plates. The generally assumed residual stress distributions in the analyses often have constant values across their cross sections. This approximation is also applied to identical stiffeners that are constructed by different methods, such as rolled and built-up tee-bar stiffened plates. This paper focuses on buckling/plastic collapse behavior of rolled and built-up tee-bar stiffened plates with experimentally determined residual stress distributions in their cross sections. The structural behavior until collapse of these two types of tee-bar stiffeners is analyzed in detail, using residual stresses measured from experimental results. Various numerical modelling aspects of stiffened plated structures are briefly discussed and finally the influence of differences in residual stress distributions on buckling/plastic collapse behavior of continuous stiffened plates is studied based on selected results, using the Finite Element Method.

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Hao, Peng, Bo Wang, Kuo Tian, Gang Li, and Xi Zhang. "Optimization of Curvilinearly Stiffened Panels with Single Cutout Concerning the Collapse Load." International Journal of Structural Stability and Dynamics 16, no. 07 (August 3, 2016): 1550036. http://dx.doi.org/10.1142/s0219455415500364.

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The motivation of this study is to meet the requirement of cutout reinforcements in aerospace industry by using the design flexibility of curvilinearly stiffened panels. The reason is that the load path and tension field caused by curvilinear stiffeners can increase the load-carrying capacity of stiffened panels. The inherent superiority of such structures was examined in detail by comparison with those having straight stiffeners. Due to the large computational burden caused by post-buckling analysis, the optimum design of curvilinearly stiffened panels with single cutout was obtained based on surrogate model. On this basis, variable symmetrization and reduction methods were developed for different design cases, aimed at reducing the number of dependent variables in the optimization. Illustrative examples show the superiority of curvilinearly stiffened panels for cutout reinforcement, and demonstrate the effectiveness of the proposed optimization framework.

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Sim, Chang-Hoon, Han-Il Kim, Jae-Sang Park, and Keejoo Lee. "Derivation of knockdown factors for grid-stiffened cylinders considering various shell thickness ratios." Aircraft Engineering and Aerospace Technology 91, no. 10 (November 4, 2019): 1314–26. http://dx.doi.org/10.1108/aeat-11-2018-0272.

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PurposeThe purpose of this paper is to derive knockdown factor functions in terms of a shell thickness ratio (i.e. the ratio of radius to thickness) for conventional orthogrid and hybrid-grid stiffened cylinders for the lightweight design of space launch vehicles. Design/methodology/approachThe shell knockdown factors of grid-stiffened cylinders under axial compressive loads are derived numerically considering various shell thickness ratios. Two grid systems using stiffeners – conventional orthogrid and hybrid-grid systems – are used for the grid-stiffened cylinders. The hybrid-grid stiffened cylinder uses major and minor stiffeners having two different cross-sectional areas. For modeling grid-stiffened cylinders with various thickness ratios, the effective thickness (teff) of the cylinders is kept constant, and the radius of the cylinder is varied. Thickness ratios of 100, 192 and 300 are considered for the orthogrid stiffened cylinder, and 100, 160, 200 and 300 for the hybrid-grid stiffened cylinder. Postbuckling analyses of grid-stiffened cylinders are conducted using a commercial nonlinear finite element analysis code, ABAQUS, to derive the shell knockdown factor. The single perturbation load approach is applied to represent the geometrical initial imperfection of a cylinder. Knockdown factors are derived for both the conventional orthogrid and hybrid-grid stiffened cylinders for different shell thickness ratios. Knockdown factor functions in terms of shell thickness ratio are obtained by curve fitting with the derived shell knockdown factors for the two grid-stiffened cylinders. FindingsFor the two grid-stiffened cylinders, the derived shell knockdown factors are all higher than the previous NASA’s shell knockdown factors for various shell thickness ratios, ranging from 100 to 400. Therefore, the shell knockdown factors derived in this study may facilitate in the development of lightweight structures of space launch vehicles from the aspect of buckling design. For different shell thickness ratios of up to 500, the knockdown factor of the hybrid-grid stiffened cylinder is higher than that of the conventional orthogrid stiffened cylinder. Therefore, it is concluded that the hybrid-grid stiffened cylinder is more efficient than the conventional orthogrid-stiffened cylinder from the perspective of buckling design. Practical implicationsThe obtained knockdown factor functions may provide the design criteria for lightweight cylindrical structures of space launch vehicles. Originality/valueDerivation of shell knockdown factors of hybrid-grid stiffened cylinders considering various shell thickness ratios is attempted for the first time in this study.

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Troina, Grégori, Marcelo Cunha, Vinícius Pinto, Luiz Rocha, Elizaldo dos Santos, Cristiano Fragassa, and Liércio Isoldi. "Computational Modeling and Constructal Design Theory Applied to the Geometric Optimization of Thin Steel Plates with Stiffeners Subjected to Uniform Transverse Load." Metals 10, no. 2 (February 4, 2020): 220. http://dx.doi.org/10.3390/met10020220.

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Stiffened thin steel plates are structures widely employed in aeronautical, civil, naval, and offshore engineering. Considering a practical application where a transverse uniform load acts on a simply supported stiffened steel plate, an approach associating computational modeling, Constructal Design method, and Exhaustive Search technique was employed aiming to minimize the central deflections of these plates. To do so, a non-stiffened plate was adopted as reference from which all studied stiffened plate’s geometries were originated by the transformation of a certain amount of steel of its thickness into longitudinal and transverse stiffeners. Different values for the stiffeners volume fraction (φ) were analyzed, representing the ratio between the volume of the stiffeners’ material and the total volume of the reference plate. Besides, the number of longitudinal (Nls) and transverse (Nts) stiffeners and the aspect ratio of stiffeners shape (hs/ts, being hs and ts, respectively, the height and thickness of stiffeners) were considered as degrees of freedom. The optimized plates were determined for all studied φ values and showed a deflection reduction of over 90% in comparison with the reference plate. Lastly, the influence of the φ parameter regarding the optimized plates was evaluated defining a configuration with the best structural performance among all analyzed cases.

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Kim, Han-Il, Chang-Hoon Sim, Jae-Sang Park, Keejoo Lee, Joon-Tae Yoo, and Young-Ha Yoon. "Numerical Derivation of Buckling Knockdown Factors for Isogrid-Stiffened Cylinders with Various Shell Thickness Ratios." International Journal of Aerospace Engineering 2020 (May 11, 2020): 1–14. http://dx.doi.org/10.1155/2020/9851984.

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This study is aimed at providing a numerical derivation of the shell knockdown factors of isogrid-stiffened cylinders under axial compressive loads. The present work uses two different analysis models such as the detailed model with modeling of numerous stiffeners and the equivalent model without modeling of stiffeners for isogrid-stiffened cylinders. The single perturbation load approach is used to represent the geometrically initial imperfection of the cylinder. Postbuckling analyses using the displacement control method are conducted to calculate the global buckling loads of a cylinder. The shell knockdown factor is numerically derived using the obtained global buckling loads without and with the initial imperfection of the isogrid-stiffened cylinder. The equivalent model is more efficient than the detailed model in terms of modeling time and computation time. The present knockdown factor function in terms of the shell thickness ratio (radius to thickness) for the isogrid-stiffened cylinder is significantly higher than NASA’s knockdown factor function; therefore, it is believed that the present knockdown factor function can facilitate in developing lightweight launch vehicle structures using isogrid-stiffened cylinders.

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Harth, Péter, and Pál Michelberger. "Symmetric Stiffened Shell Structures." Periodica Polytechnica Transportation Engineering 43, no. 1 (2015): 27–34. http://dx.doi.org/10.3311/pptr.7542.

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Li, Wei, Yingbin Chai, Xiangyu You, and Qifan Zhang. "An Edge-Based Smoothed Finite Element Method for Analyzing Stiffened Plates." International Journal of Computational Methods 16, no. 06 (May 27, 2019): 1840031. http://dx.doi.org/10.1142/s0219876218400315.

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In this paper, an edge-based smoothed finite element method with the discrete shear gap using triangular elements (ES-DSG3) is presented for static, free vibration and sound radiation analyses of plates stiffened by eccentric and concentric stiffeners. In the present model, the ES-DSG3 for the plate element with the isoparametric thick-beam element is employed to formulate stiffened plate structures. The deflections and rotations of the plates and the stiffeners are connected at tying positions. By using Rayleigh integral, sound radiation of stiffened plates subjected to a point load can be obtained. The edge-based gradient smoothing technique is employed to perform the related numerical integrations over the edge-based smoothing domains. Compared with the original DSG3 model, the present ES-DSG3 model is relatively softer as a result of the edge-based gradient smoothing technique. From several numerical examples, it is observed that the ES-DSG3 can produce more accurate numerical solutions than the original DSG3 for stiffened plates.

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Yuan, Fang, Hong Huang, and Mengcheng Chen. "Behaviour of square concrete-filled stiffened steel tubular stub columns under axial compression." Advances in Structural Engineering 22, no. 8 (February 8, 2019): 1878–94. http://dx.doi.org/10.1177/1369433218819584.

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As China’s infrastructure grows rapidly, the use of concrete-filled steel tubular structures for engineering applications is attracting increasing interest owing to their high section modulus, high strength and good seismic performance. However, for concrete-filled steel tubular members with large width-to-thickness ratio, steel tubes are prone to outward buckling when they are subjected to axial compression. Welding of longitudinal stiffeners on the steel tubes is one of the most efficient approaches for delaying local buckling and thus improving the mechanical performance of such type of concrete-filled steel tubular members. This study attempts to investigate the axial compression behaviour of concrete-filled stiffened steel tubular members with square sections through experimental study and finite element analysis. First, 14 concrete-filled steel tubular stub columns, with different width-to-thickness ratios of steel tube and depth-to-thickness ratios of stiffener, were subjected to axial compression loads and tested. It was found that the use of stiffeners increases the ultimate strength and improves the stability of the stub columns. Later, an investigation on the behaviour of the stiffened concrete-filled steel tubular stub columns was carried out through a three-dimensional finite element analysis. The accuracy of the finite element analysis model was verified by the test results. A parametric study was conducted to further evaluate the stiffening schemes that influence the axial compression strength. Finally, the research findings were synthesized into a new simplified model to predict the load-carrying capacity of stiffened concrete-filled steel tubular stub columns that allows for large width-to-thickness ratios.

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Khvyiuzov, Arsenii, and Yuan Ming Xu. "Initial Buckling of Compressed Rectangular Panels with Variable Stiffener Sizes." Advanced Materials Research 915-916 (April 2014): 150–64. http://dx.doi.org/10.4028/www.scientific.net/amr.915-916.150.

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Recent advancement in manufacturing technology has initiated a new phase of buckling structures analysis and structural design research development. As the ability to manufacture stiffeners in complex shapes has become increasingly more sophisticated, researchers are able to further enhance the design of thin-walled stiffeners. This paper presents an attempt to discover a structural design which employs the use of sub-stiffeners and the ability to retain maximal buckling load. FEM analysis was performed on compression loaded rectangular stiffened panels clamped on all sides to determine optimal attributes of two panel concepts: (1) stiffeners height changes according to sinusoidal law across the panel width, (2) stiffeners area changes according to sinusoidal law across the panel width. In both cases, total volume of the material was held constant. Non-dimensional parameters of the optimal panels were obtained. It was found that there was a positive correlation between the amount of change in buckling patterns caused by a sub-stiffener, and the amount of initial buckling load which could be obtained.

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Chen, Xing Hua, and Lian Chun Long. "Buckling Analysis and Optimization of Stiffened Cylindrical Shells under Uniform Axial Compression." Key Engineering Materials 462-463 (January 2011): 88–93. http://dx.doi.org/10.4028/www.scientific.net/kem.462-463.88.

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Thin cylindrical shells are widely used in modern structures. When the structures are under axial compression, inflectional destruction happens early. In order to design reasonable and reliable shell structures, stiffened cylindrical shells are applied in the dissertation, ANSYS, an valid finite element analysis software, is employed to redevelop and set up parameter calculation model, subjected to volume and variables value range restriction, the structure’s critical buckling load is the objective, and the serial linear programming optimization procedure is executed as well as the optimized thickness of shell and the size of stiffeners are gained accordingly. The critical buckling load of the structure is obviously increased after optimization, and the feasibility of this method is validated due to the comparison with the numerical and theoretical result.

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Yetman, J. E., A. J. Sobey, J. I. R. Blake, and R. A. Shenoi. "Investigation into skin stiffener debonding of top-hat stiffened composite structures." Composite Structures 132 (November 2015): 1168–81. http://dx.doi.org/10.1016/j.compstruct.2015.06.061.

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Dai, Wei Liang, Xu Guang Li, and Qing Chun Wang. "Energy-Absorbing Characteristics of the Stiffened Thin-Walled Tubes Subjected to Axial Crushing." Applied Mechanics and Materials 437 (October 2013): 158–63. http://dx.doi.org/10.4028/www.scientific.net/amm.437.158.

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Energy absorbing characteristics of the non-stiffened and stiffened single hat sections subjected to quasi-static axial crushing were experimentally investigated. First non-stiffened hat sections were axially crushed, then structures with different stiffened methods (stiffened in hat and stiffened in the plate) were tested, finally energy absorption capacities of these structures were compared. Test results showed that, for the appropriate designed stiffened tube, the mean crush force and mass specific energy absorption were increased significantly compared to the non-stiffened. Stiffened in hat section showed a little more energy absorption capacity than that stiffened in the plate, but the structure may sustain a global bending.

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Yang, Weizhu, Zhufeng Yue, Lei Li, Fan Yang, and Peiyan Wang. "Optimization design of unitized panels with stiffeners in different formats using the evolutionary strategy with covariance matrix adaptation." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 231, no. 9 (June 13, 2016): 1563–73. http://dx.doi.org/10.1177/0954410016654023.

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Curvilinear stiffener concept has been introduced to aircraft panel structures most recently for possible further weight reduction during optimization design. However, due to enlarged design space and high design complexity, more computational time is needed to optimize curvilinearly stiffened panels. Considering the requirement for both lighter structure and less design time, optimization designs of a unitized panel with stiffeners in three different formats, i.e. curvilinear, oblique, and evenly distributed straight, are conducted under various loading conditions to figure out which stiffener format should be selected in a real design environment. Four single loading cases with different compression-shear ratios and a set of multiple load cases are considered. Evolution strategy with covariance matrix adaption is combined with sequential quadratic programming to seek out the optimum structure with minimum mass taking into account buckling and strength constraints. Comparative analysis of the optimization results indicates that evenly distributed straight format is suitable for compression-dominant loading conditions whereas curvilinear format become superior in case that shear loading is considerable or multiple biaxial compression and shear loads are applied. Besides, curvilinear format adds more design flexibilities to the stiffeners, which enables them to play a more important role in the optimized structures. Furthermore, evolution strategy with covariance matrix adaption is found to be more efficient than particle swarm optimization for this optimization problem. This study can provide a useful guidance for future optimization design of aircraft structures.

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Loov, Robert, and Narayana Parthasarathi. "Study of shear provisions for stiffened plate girders." Canadian Journal of Civil Engineering 31, no. 1 (January 1, 2004): 160–67. http://dx.doi.org/10.1139/l03-096.

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Steel design in Canada generally follows the provisions of CSA-S16-01 "Limit states design of steel structures" (CSA 2001). The provisions in this standard governing the shear design of stiffened plate girders set limits to the choice of web thickness, girder depth, and the spacing of intermediate stiffeners. This paper reviews the influence of each of the equations that govern the shear design of stiffened plate girders. The study reveals that many of the equations are unlikely to have any effect. Of the 13 equations that could restrict the design, only 3 are likely to have any influence on a typical design. This reveals avenues for possible simplification of design procedures.Key words: anchor panel, shear design, stiffened plate girder, tension field panel.

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Tao, Jie, Feng Li, Qilin Zhao, Dongdong Zhang, and Zhibo Zhao. "In-plane compression properties of a novel foam core sandwich structure reinforced by stiffeners." Journal of Reinforced Plastics and Composites 37, no. 2 (November 8, 2017): 134–44. http://dx.doi.org/10.1177/0731684417737631.

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A novel foam core sandwich structure was proposed to prevent skin wrinkling by inserting glass fibre-reinforced plastic stiffeners attached to the sandwich skins. A modified vacuum-assisted resin infusion method was used to manufacture the sandwich panels. To investigate the in-plane compression strengths and failure modes of the new foam core sandwich panels, experimental tests were performed on a series of specimens with different cross-sectional configurations, including thin skin, thick skin, and stiffened ones. In addition, analytical modelling was conducted, the results of which agreed well with the experimental results. Results indicate that upon the insertion of stiffeners, the failure mode of the foam core sandwich composite structures changed from skin wrinkling to compressive microbuckling or global buckling. Compared to thin-skin and thick-skin specimens, the average ultimate load and specific strength of the stiffened specimen were markedly improved. Thus, the concept of inserting glass fibre-reinforced plastic stiffeners might be desirable to prevent skin wrinkling in foam core sandwich structures for engineering applications.

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Li, L. Y., I. Applegarth, J. W. Bull, P. Bettess, and T. J. Bond. "Adaptive analysis of stiffened structures using stiffened plate bending elements." International Journal of Pressure Vessels and Piping 65, no. 2 (January 1996): 117–25. http://dx.doi.org/10.1016/0308-0161(94)00164-e.

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Xie, Miaoxia, Lixia Li, Xiangtao Shang, and Jianping Zhao. "Initial Investigation of Energy Finite Element Validation on High-Frequency Flexural Vibration of Stiffened Thin Orthotropic Plates." Shock and Vibration 2018 (2018): 1–10. http://dx.doi.org/10.1155/2018/1461086.

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Energy finite element analysis (EFEA) has unique advantages in solving high-frequency dynamic responses of orthotropic structures, due to its ability to obtain detailed local response information. In order to accurately predict high-frequency vibration response of the stiffened orthotropic plate, EFEA theory on the propagation of bending wave in the orthotropic structure and the energy transfer coefficient which express the energy transfer at the stiffener was investigated. Based on the EFEA theory presented, high-frequency dynamic responses of a stiffened orthotropic plates were predicted. Furthermore, tests were done for the same problem, and differences between prediction and test were discussed. Finally, the future works were pointed out.

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Ekhande, Shantaram G., and George Abdel-Sayed. "Application of compound finite strip method in soil–steel structures." Canadian Journal of Civil Engineering 16, no. 4 (August 1, 1989): 426–33. http://dx.doi.org/10.1139/l89-072.

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The method of compound finite strip is applied for the three-dimensional analysis of corrugated soil–steel structures with and without curved stiffeners. Displacement functions are suggested for the analysis of soil–steel structures during and after backfilling. The eccentricity between the middle surfaces of stiffened elements and the adjacent shell elements is considered in the displacement functions so that the continuity of the shell is satisfied between the strips. The formulation presented herein incorporates the stiffness contribution of surrounding soil media directly in the strip element stiffness matrix. Examples of soil–steel structures are analyzed by the proposed method and the results are compared with experimental results. Key words: cylindrical shells, finite strip, soil–steel structures, stiffeners.

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Wang, Dan, Mostafa M. Abdalla, and Weihong Zhang. "Buckling optimization design of curved stiffeners for grid-stiffened composite structures." Composite Structures 159 (January 2017): 656–66. http://dx.doi.org/10.1016/j.compstruct.2016.10.013.

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McGrattan, R. J. "Weight and Cost Optimization of Hydrostatically Loaded Stiffened Flat Plates." Journal of Pressure Vessel Technology 107, no. 1 (February 1, 1985): 68–76. http://dx.doi.org/10.1115/1.3264408.

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Plates with longitudinal or orthogonal tee-stiffeners subjected to differential pressure are used in many structures. Equations to achieve minimum weight and cost are presented. Energy methods and plate gridwork theory are used. The accuracy of the technique is verified for typical designs by excellent comparison with stresses calculated by finite-element analysis. Minimum weight and cost studies using an optimization program are presented. Numerous small stiffeners minimize weight, whereas fewer, large stiffeners minimize cost. Fifteen independent structural variables are used for orthogonally stiffened plates. Stress, deflection, stability, and minimum thickness constraints are applied. Rapid optimum designs are achieved economically.

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Liu, Tie Jun, Yong Zhang, Gang Li, and Feng Hui Wang. "Dynamic Response Analysis for the Solar-Powered Aircraft Composite Wing Panel with Viscoelastic Damping Layer." Applied Mechanics and Materials 105-107 (September 2011): 491–94. http://dx.doi.org/10.4028/www.scientific.net/amm.105-107.491.

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In design of solar powered aircraft wing panel, vibration properties of wing panel should be considered, especially for the peak value of dynamic response. In this research, a viscoelastic damping layer is built for vibration isolation, wing panel finite element models of stiffened and no-stiffened structures base on fiber-reinforced laminates with damping layer in the middle are built. Natural frequency and displacement response are analyzed with different thickness of damping layer and structures. Result shows natural frequencies decrease as thickness increased, and that of laminates are lower than stiffened structure. The maximum displacement response value decreased when thickness increased and that of laminates is higher than structured with stiffer. The presented work is helpful for type selection and designing of solar powered aircraft wing panel.

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Playdon, David K., and Sidney H. Simmonds. "Behavior of slab-stiffened culvert structures." Canadian Journal of Civil Engineering 15, no. 4 (August 1, 1988): 726–31. http://dx.doi.org/10.1139/l88-093.

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Large span elliptical culverts stiffened over the upper portion with a concrete cap can be used economically in highway construction at locations where only a small soil cover is possible. The behavior of such structures based on analyses obtained using the finite element program ADINA is presented. Primary variables are the thickness of the concrete cap and the depth of the soil. The effects of both the construction sequence and highway loading are considered.The load-carrying mechanism for the composite structure is dependent primarily on the amount of lateral deformation permitted by the adjacent soil and the thickness of the concrete cap. It is concluded that the behavior of the structure is that of a flat arch; but, with the lateral deformations likely to occur, the concrete section should be proportioned as a simple beam. Key words: concrete cap, culverts, construction loads, deformations, finite element analysis, stresses.

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Zhang, Xiangyang, Suong Van Hoa, Yong Li, Jun Xiao, and Yan Tan. "Effect of Z-pinning on fatigue crack propagation in composite skin/stiffener structures." Journal of Composite Materials 52, no. 2 (May 26, 2017): 275–85. http://dx.doi.org/10.1177/0021998317710708.

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The skin/stiffener interface debonding has been a longstanding problem for composite stiffened panels. Proper crack-arresting reinforcements become a necessity for the wide application on large-scale framed structures. Z-pinning was employed to strengthen composite skin/stiffener bond in this study. Herein, static and fatigue tensile tests were conducted on a generic configuration to characterize the improvement of Z-pinning on skin/stiffener debonding resistance to skin stretching. Results show that the improvements on ultimate debonding strength and fatigue life are significant, even though the effect on crack onset is marginal under either monotonic or cyclic loading. Z-pinning changes the unstable continuous crack growth into a propagation-suspension-propagation evolution pattern. The crack growth rate is decreased by up to three orders of magnitude due to Z-pinning. Effects of pin distribution were experimentally studied. A locally densified distribution is found to be more effective than the traditional uniform distribution.

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Pham, Quoc Hoa, and Phu-Cuong Nguyen. "Static Analysis of Stiffened Shells Using an Edge-Based Smoothed MITC3 (ES-MITC3) Method." Mathematical Problems in Engineering 2021 (September 21, 2021): 1–9. http://dx.doi.org/10.1155/2021/3996485.

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A novel approach for solving the stiffened shell structures by using an edge-based smoothed MITC3 finite element method (ES-MITC3) is presented in this paper. The ES-MITC3 method is an efficient finite element method by combining the edge-based smoothed finite element method (ES-FEM) with the original MITC3 triangular element to not only significantly improve the accuracy but also overcome the shear-locking phenomenon in the Reissner–Mindlin shell analysis. In this study, the ES-MITC3 method is applied for shell structures and then reinforced by stiffeners based on the Timoshenko beam theory to achieve more durability and strength structures. The transverse displacements of the shell structures and stiffeners at the contact positions are assumed compatible. Numerical results of the ES-MITC3 element are compared with those of available other numerical results to demonstrate a good convergence and accuracy of the present method.

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Cho, Dae Seung, Nikola Vladimir, and Tae Muk Choi. "Simplified Procedure For The Free Vibration Analysis Of Rectangular Plate Structures With Holes And Stiffeners." Polish Maritime Research 22, no. 2 (April 1, 2015): 71–78. http://dx.doi.org/10.1515/pomr-2015-0019.

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Abstract Thin and thick plates, plates with holes, stiffened panels and stiffened panels with holes are primary structural members in almost all fields of engineering: civil, mechanical, aerospace, naval, ocean etc. In this paper, a simple and efficient procedure for the free vibration analysis of such elements is presented. It is based on the assumed mode method and can handle different plate thickness, various shapes and sizes of holes, different framing sizes and types as well as different combinations of boundary conditions. Natural frequencies and modes are determined by solving an eigenvalue problem of a multi-degree-of-freedom system matrix equation derived by using Lagrange’s equations. Mindlin theory is applied for a plate and Timoshenko beam theory for stiffeners. The applicability of the method in the design procedure is illustrated with several numerical examples obtained by the in-house developed code VAPS. Very good agreement with standard commercial finite element software is achieved.

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Kumar, Y. V. Satish, M. Mukhopadhyay, and T. Sarkar. "Development of a new efficient stiffened plate element for dynamic analysis of a three-dimensional ship structure." Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment 216, no. 1 (June 1, 2002): 45–56. http://dx.doi.org/10.1243/147509002320382130.

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The dynamic analysis of a complete ship structure is presented using a new stiffened plate element to model the hull plating, bulkheads, decks and other parts. The analysis is based on three-dimensional modelling of the complete vessel, and the hydrodynamic loads are computed using a panel method (based on linear diffraction theory). The stiffened plate element can elegantly accommodate any number of arbitrarily oriented stiffeners and obviates the use of mesh lines along the longitudinals and transverses. It enhances the flexibility in mesh generation over the hull components. Analysis is limited to zero forward speed and head sea conditions only. As an example, three-dimensional dynamic analysis of a bulk carrier with an accurate treatment of stiffeners is presented. Results in terms of stress amplitudes are presented for several wave frequencies. The present method provides a unique, elegant and economic way for three-dimensional dynamic analysis of complete ship structures.

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Hosseinpour, Emad, Shahrizan Baharom, and Yasser Yadollahi. "Evaluation of Steel Shear Walls Behavior with Sinusoidal and Trapezoidal Corrugated Plates." Advances in Civil Engineering 2015 (2015): 1–11. http://dx.doi.org/10.1155/2015/715163.

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Reinforcement of structures aims to control the input energy of unnatural and natural forces. In the past four decades, steel shear walls are utilized in huge constructions in some seismic countries such as Japan, United States, and Canada to lessen the risk of destructive forces. The steel shear walls are divided into two types: unstiffened and stiffened. In the former, a series of plates (sinusoidal and trapezoidal corrugated) with light thickness are used that have the postbuckling field property under overall buckling. In the latter, steel profile belt series are employed as stiffeners with different arrangement: horizontal, vertical, or diagonal in one side or both sides of wall. In the unstiffened walls, increasing the thickness causes an increase in the wall capacity under large forces in tall structures. In the stiffened walls, joining the stiffeners to the wall is costly and time consuming. The ANSYS software was used to analyze the different models of unstiffened one-story steel walls with sinusoidal and trapezoidal corrugated plates under lateral load. The obtained results demonstrated that, in the walls with the same dimensions, the trapezoidal corrugated plates showed higher ductility and ultimate bearing compared to the sinusoidal corrugated plates.

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Zhu, Xin Ming, Hao Zhan, and Zhi Gang Jiang. "Numerical Simulation of the Influence of Weld Model on the Response of Stiffened Plates under Blast Loading." Applied Mechanics and Materials 204-208 (October 2012): 943–48. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.943.

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Stiffened plates are used in a wide variety of engineering structures. Based on the published experiments, two kinds of weld models were established in simulation and the influence of weld model on the response of stiffened plates under blast loading was analyzed. The results show that the deflections and failure modes of stiffened plates from simulation are in good agreement with those from experiments, and that the weld model has little influence on the deformation and the critical charge of the plates. A simple model can be used for analyzing the large stiffened structures under blast loading.

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Li, Baotong, Jun Hong, Suna Yan, and Zhifeng Liu. "Multidiscipline Topology Optimization of Stiffened Plate/Shell Structures Inspired by Growth Mechanisms of Leaf Veins in Nature." Mathematical Problems in Engineering 2013 (2013): 1–11. http://dx.doi.org/10.1155/2013/653895.

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Biological structures with preeminent performance in nature endow inexhaustible inspiration for creative design in engineering. In this paper, based on the observation of the natural morphogenesis of leaf veins, we put forward a simple and practical multidiscipline topology optimization method to produce the stiffener layout for plate/shell structures. This method simulates the emergence of complex branching patterns copying the self-optimization of leaf veins which always try to grow into a configuration with global optimal performances. Unlike the conventional topology optimization methods characterized by “subtraction mode,” the proposed method is based on the “addition mode,” giving great potential for designers to achieve more clear stiffener layout patterns rather than vague material distributions and, consequently, saving computational resources as well as enhancing availability of design outputs. Numerical studies of both static and dynamic problems considered in this paper clearly show the suitability of the proposed method for the optimal design of stiffened plate/shell structures.

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Chen, Wen Su, and Hong Hao. "Numerical Studies on the Blast-Resistant Capacity of Stiffened Multiple-Arch Panel." Key Engineering Materials 535-536 (January 2013): 514–17. http://dx.doi.org/10.4028/www.scientific.net/kem.535-536.514.

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Blast-resistant structures are traditionally designed and fabricated with solid materials of heavy weight to resist blast loadings. This not only increases the material and construction costs, but also undermines the operational performance of protective structures. To overcome these problems, new designs with either new structural forms or new materials are demanded against blast loads. A multi-arch double-layered unstiffened panel has been proposed as a new structural form in the previous study[1]. Its performance has been numerically demonstrated better than other forms of double-layered panels in resisting blast loads. In this study, to further improve the effectiveness of the multi-arch double-layered panel in resisting blast loads, responses of a five-arch double-layered panel with rectangular stiffeners to blast loads are investigated by using finite element code Ls-Dyna. Peak displacement, internal energy absorption, boundary reaction forces and plastic strain are extracted and used as response parameters to demonstrate the effectiveness of stiffened panel on the blast resistance capacities. The numerical results show that the stiffened panel outperforms the unstiffened panel of the same weight on the blast-resistant capacity. The stiffened multi-arch double-layered panel has great potential applications in the blast-resistant panel design.

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DAOUD, FERNASS, and MIRCEA CALOMFIRESCU. "OPTIMIZATION OF COMPOSITE AIRCRAFT STRUCTURES IN CONSIDERATION OF POSTBUCKLING BEHAVIOR." International Journal of Structural Stability and Dynamics 10, no. 04 (October 2010): 905–16. http://dx.doi.org/10.1142/s0219455410003804.

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An approach is presented to determine the design that minimizes the weight in consideration of the postbuckling behavior of stiffened composite panels. Since, due to computational expense, for optimization purposes a nonlinear finite element approach is not appropriate, a semianalytical approach is implemented in the EADS MAS software LAGRANGE. A gradient-based optimization scheme is employed to determine the ply thicknesses and fiber orientation of the composite skins and the cross-sectional areas of the stiffeners. Strength and stability constraints are used. Based on two examples of different complexity, weight savings are shown to be due to the fact, that skin buckling is allowed above a certain load level.

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Sanchez-Carmona, Alejandro, and Cristina Cuerno-Rejado. "Composite stiffened panel sizing for conceptual tail design." Aircraft Engineering and Aerospace Technology 90, no. 8 (November 5, 2018): 1272–81. http://dx.doi.org/10.1108/aeat-05-2017-0129.

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Purpose A conceptual design method for composite material stiffened panels used in aircraft tail structures and unmanned aircraft has been developed to bear compression and shear loads. Design/methodology/approach The method is based on classical laminated theory to fulfil the requirement of building a fast design tool, necessary for this preliminary stage. The design criterion is local and global buckling happen at the same time. In addition, it is considered that the panel does not fail due to crippling, stiffeners column buckling or other manufacturing restrictions. The final geometry is determined by minimising the area and, consequently, the weight of the panel. Findings The results obtained are compared with a classical method for sizing stiffened panels in aluminium. The weight prediction is validated by weight reductions in aircraft structures when comparing composite and aluminium alloys. Research limitations/implications The work is framed in conceptual design field, so hypotheses like material or stiffeners geometry shall be taken a priori. These hypotheses can be modified if it is necessary, but even so, the methodology continues being applicable. Practical implications The procedure presented in this paper allows designers to know composite structure weight of aircraft tails in commercial aviation or any lifting surface in unmanned aircraft field, even for unconventional configurations, in early stages of the design, which is an aid for them. Originality/value The contribution of this paper is the development of a new rapid methodology for conceptual design of composite panels and the feasible application to aircraft tails and also to unmanned aircraft.

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Belblidia, F., S. M. B. Afonso, E. Hinton, and G. C. R. Antonino. "Integrated design optimization of stiffened plate structures." Engineering Computations 16, no. 8 (December 1999): 934–52. http://dx.doi.org/10.1108/02644409910304185.

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Huybrechts, Steven M., Troy E. Meink, Peter M. Wegner, and Jeff M. Ganley. "Manufacturing theory for advanced grid stiffened structures." Composites Part A: Applied Science and Manufacturing 33, no. 2 (February 2002): 155–61. http://dx.doi.org/10.1016/s1359-835x(01)00113-0.

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Puckett, Jay A., Robert G. Erikson, and John P. Peiffer. "Fatigue Testing of Stiffened Traffic Signal Structures." Journal of Structural Engineering 136, no. 10 (October 2010): 1205–14. http://dx.doi.org/10.1061/(asce)st.1943-541x.0000229.

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Journal articles on the topic 'Stiffened structures'

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