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T Weller - One of the best experts on this subject based on the ideXlab platform.
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calculation of the collapse load of an axially compressed laminated composite Stringer stiffened curved panel an engineering approach
Composite Structures, 2008Co-Authors: P Pevzner, Haim Abramovich, T WellerAbstract:Abstract The effective width method that is widely applied for the analysis of isotropic planar Stringer-stiffened panels has been extended to laminated composite Stringer-stiffened circular cylindrical panels. The approach was modified and adapted to handle curved composite structures. Panels stiffened by blade type stiffeners, J-form stiffeners and T-form stiffeners were considered in the present study. Bending buckling of the stiffeners, their torsional buckling, combined bending and torsion buckling and local buckling of the Stringers were accounted for in the investigation. Using the proposed extended effective width method, a MATLAB based software code TEW 1 was developed and implemented. To validate this code, predictions obtained by it were compared with experimental results and with finite element calculations. Good agreement between the present proposed method, experiments and finite element simulations was found, thus yielding an efficient, simple to apply and fast engineering code to be used in design and optimization stages.
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failure in Stringer interfaces in postbuckled composite stiffened panels
Twelfth Australian Aeronautical Conference, 2007Co-Authors: Adrian C Orifici, T Weller, I Herszberg, Rodney S Thomson, Andrey Kotler, Javid BayandorAbstract:The application of composite materials for post-buckling blade-stiffened structures requires capturing the initiation of delamination, which is particularly critical in the interface of the skin and stiffener. This paper presents an investigation into such failure for a skin-stiffener interface of a typical composite fuselage structure with the aim to develop an improved design methodology. In the experimental investigation, thin strips consisting of a skin and single stiffener were cut from a large stiffened panel to form T-sections. These sections were loaded until failure in two separate test rigs, which aimed to simulate the symmetric and anti-symmetric loads on skin-stiffener interfaces in a post-buckling panel. Two-dimensional finite element models were analysed, and strength criteria applied in order to predict the initiation of delamination in these specimens. Based on these predictions, recommendations are made for the application of the two-dimensional analysis approach to predict skin-Stringer interface failure in large fuselage-representative structures.
Haim Abramovich - One of the best experts on this subject based on the ideXlab platform.
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calculation of the collapse load of an axially compressed laminated composite Stringer stiffened curved panel an engineering approach
Composite Structures, 2008Co-Authors: P Pevzner, Haim Abramovich, T WellerAbstract:Abstract The effective width method that is widely applied for the analysis of isotropic planar Stringer-stiffened panels has been extended to laminated composite Stringer-stiffened circular cylindrical panels. The approach was modified and adapted to handle curved composite structures. Panels stiffened by blade type stiffeners, J-form stiffeners and T-form stiffeners were considered in the present study. Bending buckling of the stiffeners, their torsional buckling, combined bending and torsion buckling and local buckling of the Stringers were accounted for in the investigation. Using the proposed extended effective width method, a MATLAB based software code TEW 1 was developed and implemented. To validate this code, predictions obtained by it were compared with experimental results and with finite element calculations. Good agreement between the present proposed method, experiments and finite element simulations was found, thus yielding an efficient, simple to apply and fast engineering code to be used in design and optimization stages.
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dynamic buckling of cylindrical Stringer stiffened shells
Computers & Structures, 2003Co-Authors: Ronith Yaffe, Haim AbramovichAbstract:Abstract The dynamic buckling of cylindrical Stringer stiffened shells was investigated both numerically and experimentally. A new criterion to define the numerical “dynamic” buckling load was developed yielding consistent results. The ADINA finite element code was applied to simulate the static and dynamic buckling loads of the shells. It was shown numerically that when the period of the applied loading (half-wave sine) equals half the lowest natural period of the shell, there is a slight drop in the dynamic load amplification factor (DLF). The DLF is defined, as the ratio of the dynamic buckling to the static buckling of the shell. This factor drops below unity, when the ratio of the given sound speed in solids, c , to the velocity developed axially due to the applied dynamic loading, approaches unity. It means that, for this particular loading period, the dynamic buckling load would be lower than the static one. It was shown numerically that the shape of the loading period, half-wave sine, a shape encountered during the tests, as well as the initial geometric imperfections have a great influence on the dynamic buckling of the shells. The relatively simple test set-up design to cause a shell to buckle dynamically did not fulfill our expectations. Although, the process leading to eventually the dynamic buckling of the shell worked properly, still no test results were obtained to form a sound experimental database for this phenomenon. Based on the numerical predictions, correct guidelines were formulated for better test procedures to be applied in future tests, which will be reported in due time.
Hota V S Gangarao - One of the best experts on this subject based on the ideXlab platform.
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Experimental evaluation of stressed timber bridge systems : Modern timber bridges
Transportation Research Record, 1994Co-Authors: L S Barger, Roberto Lopez-anido, Hota V S GangaraoAbstract:The stiffness and transverse load distribution variations of stressed timber bridge system, including the shear lag phenomenon for the Tee and Box superstructure configurations, two Stringer spacings, and two prestress levels, were examined. The tests were carried out for static loads that were applied at midspan on both interior and exterior Stringer locations. Deflections and strains at different transverse locations on the deck and Stringers were obtained. the analysis of the data provides helpful information to evaluate stiffnesses of stressed Tee and box timber bridges. Composite moments of inertia of the Stringers were obtained from the experimental flexibility coefficients. Shear lag in flanges was evaluated by accounting for the effective flange width of an individual composite beam. The experimental strain variations were used to validate this model.
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experimental evaluation of stressed timber bridge systems
Transportation Research Record, 1993Co-Authors: L S Barger, Roberto Lopezanido, Hota V S GangaraoAbstract:The stiffness and transverse load distribution variations of stressed timber bridge systems, including the shear lag phenomenon for the Tee and Box superstructure configurations, two Stringer spacings, and two prestress levels, were examined. The tests were carried out for static loads that were applied at midspan on both interior and exterior Stringer locations. Deflections and strains at different transverse locations on the deck and Stringers were obtained. The analysis of the data provides helpful information to evaluate stiffnesses of stressed Tee and Box timber bridges. Composite moments of inertia of the Stringers were obtained from the experimental flexibility coefficients. Shear lag in flanges was evaluated by accounting for the effective flange width of an individual composite beam. The experimental strain variations were used to validate this model.
Wenhao Wang - One of the best experts on this subject based on the ideXlab platform.
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effects of connective parts on stability of folded Stringers stiffened composite panel
Composite Structures, 2016Co-Authors: Wenhao Wang, Wenxuan Gou, Fusheng Wang, Jiu Wang, Zhufeng YueAbstract:Abstract In this paper, in order to select a better material between aluminum alloy and composite for the connective parts which is on a folded omega Stringers stiffened composite panel under an axial compression, numerical investigation is conducted. The axial compression is divided into two stages which are buckling and post-buckling. By using software ABAQUS, 9 models were analyzed respectively. By comparing among the 9 models, firstly, composite joints have the highest collapse load with the same T Stringer or without T Stringer and next are aluminum alloy joints. Secondly, aluminum alloy T Stringer has the highest buckling load and collapse load than composite one with the same joints or without joints and the composite T Stringer the second. Thirdly, the joints and the T Stringer are compulsory, because either the joints or the T Stringer or both of them can enhance buckling load and collapse load remarkably. An important question for future studies is that the failure mechanisms occurring at the connective parts including their surrounding areas and choosing reasonable failure criterion for the material of these sections have to be researched by numerical methods and experimental tests.
Jiangfan Zhou - One of the best experts on this subject based on the ideXlab platform.
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experiment and analysis of hat Stringer stiffened composite curved panels under axial compression
Composite Structures, 2015Co-Authors: Jiangfan ZhouAbstract:Abstract An experimental and numerical study on the buckling and post-buckling behaviors of hat-Stringer-stiffened composite curved panel under axial compression load was carried out. Several influence factors, such as skin thickness, panel radius, and distance between two adjacent Stringers were studied. Three groups of stiffened curved panel buckling and postbuckling behaviors were obtained. An engineering approach was proposed to predict the initial buckling load of curved panel. Finite element analysis was used to investigate these tests and the FE models were performed by ABAQUS. The experiment results compared with that of numerical are presented. The capability and feasibility of numerical predictions in post-buckling field was assessed by comparing with experimental data. Good agreement between experimental and numerical results was observed.
