Buckling and postbuckling of stringer stiffened fibre composite curved panels – Tests and computations

Zimmermann, Rolf; Klein, H.; Kling, Alexander

doi:10.1016/j.compstruct.2005.11.050

Cited by 129 publications

(76 citation statements)

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“…The shortening at collapse is 2.28 mm which is quite close to 2.40 mm calculated. The post-buckling ratio is about F max /F cr 1.4, which is relatively low comparing to values ranging from 2.9 to 6.0 for T-stiffened panels [1]. This could be explained by a possible load increase if the gliding conditions would be incorporated at panel borders, as well as a potential for the skin ply lay-up to be optimised.…”

Section: Resultsmentioning

confidence: 97%

“…It is known that opposite buckling waves -symmetric or antisymmetric -are the areas, where delamination initiates [5,6], leading to the loss of connection between skin and stiffeners [1]. In the case of excellent bonding, severe stress concentrations may cause delaminations and fracture in the skin or in the stiffener flanges at these locations [1]. This paper is the experimental investigation of a previous work which was the numerical modelling of this panel [7].…”

Section: Introductionmentioning

confidence: 99%

“…Several studies can be found concerning a compressive post-buckling test of co-cured or co-bonded stiffened panels, manufactured in prepregs. It is known that opposite buckling waves -symmetric or antisymmetric -are the areas, where delamination initiates [5,6], leading to the loss of connection between skin and stiffeners [1]. In the case of excellent bonding, severe stress concentrations may cause delaminations and fracture in the skin or in the stiffener flanges at these locations [1].…”

Section: Introductionmentioning

confidence: 99%

“…A representative test of a panel can be specified in terms of a compressive [1,2] or shear loading state [3]. A pressurised test at the panel level is more difficult to assess since it needs a combined loading [4].…”

Section: Introductionmentioning

confidence: 99%

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Global behaviour of a composite stiffened panel in buckling. Part 2: Experimental investigation

Perret

Mistou

Fazzini

et al. 2012

Composite Structures

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a b s t r a c tThe present study analyses an aircraft composite fuselage structure manufactured by the Liquid Resin Infusion (LRI) process and subjected to a compressive load. LRI is based on the moulding of high performance composite parts by infusing liquid resin on dry fibres instead of prepreg fabrics or Resin Transfer Moulding (RTM). Actual industrial projects face composite integrated structure issues as a number of structures (stiffeners, . . .) are more and more integrated onto the skins of aircraft fuselage.A post-buckling test of a composite fuselage representative panel is set up, from numerical results available in previous works. Two stereo Digital Image Correlation (DIC) systems are positioned on each side of the panel, that are aimed at correlating numerical and experimental out-of-plane displacements (corresponding to the skin local buckling displacements of the panel). First, the experimental approach and the test facility are presented. A post-mortem failure analysis is then performed with the help of Non-Destructive Techniques (NDT). X-ray Computed Tomography (CT) measurements and ultrasonic testing (US) techniques are able to explain the failure mechanisms that occured during this post-buckling test. Numerical results are validated by the experimental results.

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Section: Resultsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Global behaviour of a composite stiffened panel in buckling. Part 2: Experimental investigation

Perret

Mistou

Fazzini

et al. 2012

Composite Structures

View full text Add to dashboard Cite

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“…Stiffened panels are a common design strategy to obtain high stiffness in shell structures, keeping the lightness of the component and ensure the required buckling strength of the shell structure. As many others commonly used structural subcomponents these structures are frequently analysed [1][2][3][4] using the so-called virtual tests, which aims to reduce the design cost by reducing the number of test on real components.…”

Section: Introductionmentioning

confidence: 99%

Damage tolerance optimization of composite stringer run-out under tensile load

Badalló

Trias

Lindgaard

2015

Composite Structures

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Please cite this article as: Badalló, P., Trias, D., Lindgaard, E., Damage tolerance optimization of composite stringer run-out under tensile load, Composite Structures (2015), doi: http://dx.doi.org/10. 1016/j.compstruct.2015.07.025 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. AbstractStringer run-outs are a common solution to achieve the necessary strength, stiffness and geometric requirements of some structural solutions. The mechanical behaviour and complexity of such design details requires careful and thorough studies to ensure the structural integrity of the structure. The influence of some geometric variables of the run-out in the interface of the set stringer-panel is crucial to avoid the onset and growth of delamination cracks. In this study, a damage tolerant design of a stringer run-out is achieved by a process of design optimization and surrogate modelling techniques. A parametric finite element model created with python was used to generate a number of different geometrical designs of the stringer run-out. The relevant information of these models was adjusted using Radial Basis Functions (RBF). Finally, the optimization problem was solved using Quasi-Newton method and Genetic Algorithms. In the solution process, the RBF were used to compute the objective function: ratio between the energy release rate and the critical energy release rate according to the Benzeggagh-Kenane mixed mode criterion. Some design guidelines to obtain a damage tolerant stringer-panel interface have been derived from the results.

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Post‐buckling optimization of composite structures using Koiter's method

Henrichsen

Lindgaard

Lund

2016

Numerical Meth Engineering

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SUMMARYThin-walled structures, when compressed, are prone to buckling. To fully utilize the capabilities of such structures, the post-buckling response should be considered and optimized in the design process. This work presents a novel method for gradient based design optimization of the post-buckling performance of structures. The post-buckling analysis is based on Koiter's asymptotic method. To perform gradient based optimization, the design sensitivities of the Koiter factors are derived and new design optimization formulations based on the Koiter factors are presented. The proposed optimization formulations are demonstrated on a composite square plate and a curved panel where the post-buckling stability is optimized. Copyright c 0000 John Wiley & Sons, Ltd. Thin-walled structures are often designed such that buckling does not occur during service. To ensure a structure does not buckle, the specified buckling load is often much greater than the design load. If a structure can be allowed to buckle during operation, thus operating in the post-buckling regime, it enables the possibility to design lighter and more efficient structures. To enable such an approach, the engineer must optimize the post-buckling response of the structure. Fiber reinforced polymers are ideally suited for such design tasks, as these materials allow a high degree of tailoring of the considered structure, and thus applied here for the post-buckling design optimization of structures. When optimizing structures, robustness of the resulting structure is of major importance, as the imperfection sensitivity can increase during the optimization process [1]. One method is to collect these into an equivalent geometric imperfection and use that to evaluate the knockdown in performance. Refs. [2,3] demonstrate robust design optimization by combining "worst" shape imperfection optimization and laminate optimization, thereby efficiently decreasing the imperfection sensitivity of laminated composite structures. A different approach is to handle all imperfections simultaneously by modeling the uncertainties using statistics, therefore quantifying * Correspondence to: Department of Mechanical and Manufacturing Engineering, Aalborg University (AAU), the imperfections arising from material, geometry, load etc., and perform robust buckling optimization based on the uncertainties, see e.g., [4] for a review of different approaches. Many textbooks describe the coupling between imperfections, buckling load factor, and post-buckling stability, see e.g., [5]. Focusing on simple i.e., distinct buckling load factors, the sensitivity towards imperfections relates to the stability of the post-buckling response. Generally speaking, a stable post-buckled structure is less sensitive towards imperfections than an unstable post-buckled structure. Because of these considerations, the post-buckling stability can be utilized to design robust structures.Post-buckling analysis of plates and shells has been subject to much research. Driven by the aerospace industry, large re...

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Buckling and postbuckling of stringer stiffened fibre composite curved panels – Tests and computations

Cited by 129 publications

References 1 publication

Global behaviour of a composite stiffened panel in buckling. Part 2: Experimental investigation

Global behaviour of a composite stiffened panel in buckling. Part 2: Experimental investigation

Damage tolerance optimization of composite stringer run-out under tensile load

Post‐buckling optimization of composite structures using Koiter's method

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