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Goal-adaptive Meshing of Isogeometric Kirchhoff–Love Shells

Verhelst, H.M. (author), Mantzaflaris, A. (author), Möller, M. (author), den Besten, J.H. (author)

Mesh adaptivity is a technique to provide detail in numerical solutions without the need to refine the mesh over the whole domain. Mesh adaptivity in isogeometric analysis can be driven by Truncated Hierarchical B-splines (THB-splines) which add degrees of freedom locally based on finer B-spline bases. Labeling of elements for refinement is...

journal article 2024

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Skin-stringer separation in post-buckling of butt-joint stiffened thermoplastic composite panels

van Dooren, K.S. (author), Tijs, B.H.A.H. (author), Waleson, J. E.A. (author), Bisagni, C. (author)

Two aeronautical thermoplastic composite stiffened panels are analysed and tested to investigate the buckling behaviour, the skin-stringer separation and the final failure mode. The panels are made of fast crystallising polyetherketoneketone carbon composite, have three stringers with an angled cap on one side, and are joined to the skin by a...

journal article 2023

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Application of column buckling theory to steel aluminium foam sandwich panels

Vidwans, Aditya (author), Trovalusci, Patrizia (author), Fantuzzi, Nicholas (author), Correia, J.A.F.O. (author)

In steel structures, a lot of attention is paid to lightweight structures, i.e. reduction of dead load without compromising structural safety, integrity and performance. Thanks to modern steel aluminium foam sandwich panel manufacturing technology a new possibility became available for lightweight structural design. Assessment and...

journal article 2023

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Design, analysis and testing of thermoplastic welded stiffened panels to investigate skin-stringer separation in post-buckling

van Dooren, K.S. (author), Bisagni, C. (author)

Thermoplastic composite three-stringer panels with omega stiffeners and conduction welded joints are designed, analysed and tested until final failure to investigate the performance of the welded joint in post-buckling. The three-stringer panels are designed to be structurally representative of the fuselage demonstrator of the Clean Sky 2...

journal article 2023

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Stiffness Compensation Through Matching Buckling Loads in a Compliant Four-Bar Mechanism

Numic, A. (author), Blad, Thijs (author), van Keulen, A. (author)

In this paper, a novel alternative method of stiffness compensation in buckled mechanisms is investigated. This method involves the use of critical load matching, i.e., matching the first two buckling loads of a mechanism. An analytical simply supported five-bar linkage model consisting of three rigid links, a prismatic slider joint, and four...

journal article 2022

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Investigation on buckling and mode jumping of composite plates under thermomechanical loads

Gutierrez Alvarez, J. (author), Bisagni, C. (author)

This paper presents an experimental and numerical study of composite plates, analyzing the interaction between mechanical and thermal loads related to buckling and the occurrence of mode jumping. A novel experimental setup for thermomechanical testing was developed. The setup is conceived around a frame with a low coefficient of thermal...

journal article 2022

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Experimental and numerical study of bending-induced buckling of stiffened composite plate assemblies

Telford, R. (author), Peeters, D.M.J. (author), Rouhi, M. (author), Weaver, P. M. (author)

Despite their importance in benchmarking numerical simulations, buckling tests still feature compromises between component-level and high-fidelity large-scale tests. For example, compression-induced buckling tests cannot capture the through-thickness or span-wise stress gradients in wing skins. Consequently, the results obtained often require...

journal article 2022

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Lightweight design of variable-angle filament-wound cylinders combining Kriging-based metamodels with particle swarm optimization

Wang, Z. (author), Almeida, José Humberto S. (author), Ashok, Aravind (author), Wang, Zhonglai (author), Castro, Saullo G.P. (author)

Variable-angle filament-wound (VAFW) cylinders are herein optimized for minimum mass under manufacturing constraints, and for various design loads. A design parameterization based on a second-order polynomial variation of the tow winding angle along the axial direction of the cylinders is utilized to explore the nonlinear steering-thickness...

journal article 2022

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Micro Energy Harvesting from Low-Frequency Vibrations: Towards Powering Pacemakers with Heartbeats

Blad, Thijs (author)

Miniaturized vibration energy harvesters can provide an alternative to batteries in powering the billions of low power devices we use today by extracting power from ambient motion. Especially for implanted medical devices, these alternative power sources may be an attractive option to overcome the limitations on longevity and the replacement...

doctoral thesis 2021

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Buckling-driven mechanisms for twisting control in adaptive composite wings

Zhang, J. (author), Bisagni, C. (author)

This study aims to design novel tailorable and effective mechanisms by controlling buckling behaviour in structural elements of a composite wing for future morphing application. Instead of the traditional design against buckling, the idea is to embrace this built-in instability by using the nonlinear post-buckling response to control...

journal article 2021

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Support Vector Machine Applied to the Optimal Design of Composite Wing Panels

dos Santos, Rogério Rodrigues (author), Machado, Tulio Gomes de Paula (author), Castro, Saullo G.P. (author)

One of the core technologies in lightweight structures is the optimal design of laminated composite stiffened panels. The increasing tailoring potential of new materials added to the simultaneous optimization of various design regions, leading to design spaces that are vast and non-convex. In order to find an optimal design using limited...

journal article 2021

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Displacement-based formulation of Koiter's method: Application to multi-modal post-buckling finite element analysis of plates

Castro, Saullo G.P. (author), Jansen, E. L. (author)

Koiter's asymptotic method enables the calculation and deep understanding of the initial post-buckling behaviour of thin-walled structures. For the single-mode asymptotic analysis, Budiansky (1974) presented a clear and general formulation for Koiter's method, based on the expansion of the total potential energy function. The formulation from...

journal article 2021

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Design, modeling, optimization, manufacturing and testing of variable-angle filament-wound cylinders

Almeida, José Humberto S. (author), St-Pierre, Luc (author), Wang, Z. (author), Ribeiro, Marcelo L. (author), Tita, Volnei (author), Amico, Sandro C. (author), Castro, Saullo G.P. (author)

This work demonstrates the potential of manufacturing variable-angle composite cylinders via filament winding (FW), called VAFW. The proposed design strategy allows different filament angles along the axial direction by dividing the cylinder into regions of constant angle called frames. Designs using two, four, or eight frames are herein...

journal article 2021

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Overlap-stiffened panels for optimized buckling performance under minimum steering radius constraints

Ummels, R. (author), Castro, Saullo G.P. (author)

Recent research on variable stiffness laminates have shown both numerically and experimentally that further improvement on the buckling performance is possible by incorporating overlaps that result in variable thickness profiles. We present the concept of overlap-stiffened designs that take advantage of the non-linear coupling between the tow...

journal article 2021

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Flexible piezoelectric AlN transducers buckled through package-induced preloading for mechanical energy harvesting

Mariello, M. (author), Blad, Thijs (author), Mastronardi, V. M. (author), Madaro, F. (author), Guido, F. (author), Staufer, U. (author), Tolou, N. (author), De Vittorio, M. (author)

There is a high demand for novel flexible micro-devices for energy harvesting from low-frequency and random mechanical sources. The research of new functional designs is required to strategically enhance the performances and to increase the control on mechanical flexibility. In this work we report the fabrication and characterization of bi...

journal article 2021

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Achievements in the buckling of thin-walled composite launcher structures

Degenhardt, Richard (author), Franzoni, Felipe (author), Castro, Saullo G.P. (author)

For most structural parts of real launcher structures buckling is the critical design criterion. Due to the high imperfection sensitivity of these structures and to the unknown geometric imperfections during the design phase, it is still today a challenge to predict a reliable design buckling load and to experimentally and non-destructively...

conference paper 2021

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A method for tuning the stiffness of building blocks for statically balanced compliant ortho-planar mechanisms

Blad, Thijs (author), van Ostayen, R.A.J. (author), Tolou, N. (author)

In this paper a method is demonstrated for tuning the stiffness of building blocks for statically balanced compliant ortho-planar mechanisms. Three post-buckled mechanisms are proposed where the flexural rigidity can be manipulated over a part of their length in order to tune the ratio between the first two critical loads. A sensitivity...

journal article 2021

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Reliability-based buckling optimization with an accelerated Kriging metamodel for filament-wound variable angle tow composite cylinders

Wang, Z. (author), Almeida, José Humberto S. (author), St-Pierre, Luc (author), Wang, Zhonglai (author), Castro, Saullo G.P. (author)

A reliability-based optimization framework is introduced and used to design filament-wound cylindrical shells with variable angle tow. Seven design cases are investigated to enable a comparison between constant-stiffness and variable angle tow designs, also considering effects of thickness variation created due to overlapping tow paths,...

journal article 2020

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

Zucco, G. (author), Oliveri, V. (author), Rouhi, M. (author), Telford, R. (author), Clancy, G. (author), McHale, C. (author), O'Higgins, R. (author), Young, T. M. (author), Weaver, P. M. (author), Peeters, D.M.J. (author)

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...

journal article 2020

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Non-linear bending compliance of thin ply composite beams by local compression flange buckling

Schadt, F. (author), Rueppel, M. (author), Brauner, C. (author), Courvoisier, Y. (author), Masania, K. (author), Dransfeld, C.A. (author)

Passive spanwise bending shape-adaption has the potential to increase the efficiency and manoeuvrability of vehicles with wing-like structures. By utilisation of compression flange buckling, the in-plane stiffness can be tuned to design beams with contrasting pre-buckling and post-buckling bending stiffness. The investigated concept is...

journal article 2020