Postbuckling optimisation of a variable angle tow composite wingbox using a multi-modal Koiter approach

Liguori, Francesco S.; Zucco, Giovanni; Madeo, Antonio; Magisano, Domenico; Leonetti, Leonardo; Garcea, Giovanni; Weaver, Paul M.

doi:10.1016/j.tws.2019.01.035

Cited by 79 publications

(38 citation statements)

References 53 publications

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“…Overall, the layup is more constraint-driven than that of a fully optimised design. Therefore, there remains scope for improvement in buckling and postbuckling behaviour for this wingbox, as discussed by Liguori et al (12) The design process of the wingbox is elaborated with more details in Ref. [11].…”

Section: Design and Manufacture Of The Wingboxmentioning

confidence: 99%

Static test of a variable stiffness thermoplastic composite wingbox under shear, bending and torsion

et al. 2020

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Automated manufacturing of thermoplastic composites has found increased interest in aerospace applications over the past three decades because of its great potential in low-cost, high rate, repeatable production of high performance composite structures. Experimental validation is a key element in the development of structures made using this emerging technology. In this work, a $750\times640\times240$ mm variable-stiffness unitised integrated-stiffener out-of-autoclave thermoplastic composite wingbox is tested for a combined shear-bending-torsion induced buckling load. The wingbox is manufactured by in-situ consolidation using a laser-assisted automated tape placement technique. It is made and tested as a demonstrator section located at 85% of the wing semi-span of a B-737/A320 sized aircraft. A bespoke in-house test rig and two aluminium dummy wingboxes are also designed and manufactured for testing the wingbox assembly which spans more than 3m. Prior to testing, the wingbox assembly and the test rig were analysed using a high fidelity finite element method to minimise the failure risk due to the applied load case. The experimental test results of the wingbox are also compared with the predictions made by a numerical study performed by nonlinear finite element analysis showing less than 5% difference in load-displacement behaviour and buckling load and full agreement in predicting the buckling mode shape.

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Section: Design and Manufacture Of The Wingboxmentioning

confidence: 99%

Static test of a variable stiffness thermoplastic composite wingbox under shear, bending and torsion

et al. 2020

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“…Jin et al [36] used parallel GA for large wingbox optimizations. More recently, Liguori et al [37] applied GA in the optimization of a variableangle tow wingbox construction considering post-buckling constraints.…”

Section: Optimization Through a Genetic Algorithmmentioning

confidence: 99%

Overlap-Stiffened Panels for Optimized Buckling Performance Under Minimum Steering Radius Constraints

Ummels¹,

Castro²

2020

Preprint

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Recent research on variable stiffness laminates have shown both numerically and experimentally that further improvement on the buckling behaviour is possible by incorporating overlaps that result in variable thickness profiles, with the thickness non-linearly coupled with the local steering angle. We present the concept of overlap-stiffened panels, developing a design method that allows for incorporating higher-stiffness regions into individual plies of a variable-angle tow (VAT) laminate, taking advantage of the non-linear coupling between the tow steering angles and the local thickness. The proposed method naturally copes with minimum steering radius constraints of different manufacturing processes, and the present study considers two tow steering processes: automated fiber placement (AFP) and continuous tow shearing (CTS). The minimum radius constraint is satisfied by connecting two transition regions of thickness specified on each ply by means of circular fiber tow arcs, of which the radius of curvature always exceed the minimum manufacturing constraint. Each individual ply exploring the overlap-stiffened design is described using 5 design variables. Laminates made up of these overlap-stiffened plies are optimized for a maximum volume-normalized buckling performance under bi-axial compression, measured through FEM, by a genetic algorithm and benchmarked against a straight fiber panel optimized for the same load case. The conclusion can be drawn that both AFP and CTS overlap-stiffened VAT panels can at least achieve the double of the volume-normalized buckling performance of an optimized straight fiber panel, demonstrating the potential of the proposed design method.

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“…With a similar strategy based on stochastic simulations, Liguori et al [37], produced a tool to optimise the stacking sequence of slender composite shells detecting both the best layup and the worst shape of geometrical imperfection and its effect on the collapse load. Moreover, in their most recent work, Liguori et al [38] applied this Koiter-inspired method, coupled with Monte-Carlo and stochastic algorithm, to optimise the post-buckling behaviour of a variable angle tow (VAT) wingbox. As a matter of fact, they achieved more than 80% reduction in the out-of-lane displacement in the post-buckling regime of the examined structure.…”

Section: Eigenvalue/eigenmode Analysismentioning

confidence: 99%

“…In all, these studies can be useful to assess the most critical set of impacted cases considering the number, relative sizes and damage implantation location on the panels with a low computational cost. It is the author's opinion that more holistic tools [36], [37], [38] could be implemented for achieving the optimum structure considering the initial imperfection. However, this is beyond the scope of this study and a simpler eigenvalue/eigenmode analysis is applied to obtain an insight on the criticality of the induced damage on the post-buckling behaviour of the examined panels.…”

Section: Eigenvalue/eigenmode Analysismentioning

confidence: 99%

Numerical FEA parametric analysis of CAI behaviour of CFRP stiffened panels

Gaitanelis

Giannopoulos

Theotokoglou

2019

Thin-Walled Structures

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This paper examined the effect of numerical modelling parameters on the accuracy and computational efficiency of Carbon Fibre Reinforced Polymer (CFRP) stiffened panels under Compression After Impact (CAI). Pristine and damaged CFRP stiffened panels were subjected to compression in Abaqus ® software using Cohesive Zone Model (CZM) method. Various case studies were examined and the effect of the stiffness parameters of the cohesive elements was critically assessed. Moreover, the required number of cohesive zones to fully capture the damage mechanisms of the impacted and pristine panels under compressive loading was examined. The results showed that a wrong set of parameters can even lead to neglecting the induced damage and can cause severe convergence problems in the numerical model. The importance of the Overall Meshing Factor (OMF) was highlighted and a user-defined subroutine (USDFLD) was applied to capture the decrease in the load bearing capability of an impacted panel prior to the compressive loading, since CZM was found insufficient for this scope. The above-mentioned remarks illustrated the process of investigating the optimum numerical parameters set to achieve an accurate and efficient finite element modelling of the stiffened panels structural performance and maximum load-carrying capability, when subjected to CAI loading.

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Postbuckling optimisation of a variable angle tow composite wingbox using a multi-modal Koiter approach

Cited by 79 publications

References 53 publications

Static test of a variable stiffness thermoplastic composite wingbox under shear, bending and torsion

Static test of a variable stiffness thermoplastic composite wingbox under shear, bending and torsion

Overlap-Stiffened Panels for Optimized Buckling Performance Under Minimum Steering Radius Constraints

Numerical FEA parametric analysis of CAI behaviour of CFRP stiffened panels

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