Variable-stiffness skin concept for camber-morphing airfoils

Raither, Wolfram; Furger, Emian; Zündel, Manuel; Bergamini, Andrea; Ermanni, Paolo

doi:10.1177/1045389x14546780

Cited by 11 publications

(8 citation statements)

References 20 publications

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“…EBLs are well‐suited for applications in which the bending stiffness of a structure must be dynamically changed. Example applications of stiffness modulation via electroadhesive laminates are shape‐morphing and structural modification of airfoils, [ 59,60 ] as well as, dynamic vibration suppression in large structures and vehicles. [ 61–63 ] EBLs have also been used in applications where soft materials are programmed to stiffen for high‐force operation.…”

Section: Electroprogrammable Stiffness Via Electrostaticsmentioning

confidence: 99%

Materials with Electroprogrammable Stiffness

Levine

Turner

2021

Advanced Materials

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Stiffness is a mechanical property of vital importance to any material system and is typically considered a static quantity. Recent work, however, has shown that novel materials with programmable stiffness can enhance the performance and simplify the design of engineered systems, such as morphing wings, robotic grippers, and wearable exoskeletons. For many of these applications, the ability to program stiffness with electrical activation is advantageous because of the natural compatibility with electrical sensing, control, and power networks ubiquitous in autonomous machines and robots. The numerous applications for materials with electrically driven stiffness modulation has driven a rapid increase in the number of publications in this field. Here, a comprehensive review of the available materials that realize electroprogrammable stiffness is provided, showing that all current approaches can be categorized as using electrostatics or electrically activated phase changes, and summarizing the advantages, limitations, and applications of these materials. Finally, a perspective identifies state‐of‐the‐art trends and an outlook of future opportunities for the development and use of materials with electroprogrammable stiffness.

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Section: Electroprogrammable Stiffness Via Electrostaticsmentioning

confidence: 99%

Materials with Electroprogrammable Stiffness

Levine

Turner

2021

Advanced Materials

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“…21 Due to the predominance of the capacitive behaviour in its energy balance, the electro-bonded laminate is generally characterized by low energy requirements. …”

Section: Concept Of Adaptive-twist Airfoil With Variable Stiffnessmentioning

confidence: 99%

Adaptive-Twist Airfoil Based on Electrostatic Stiffness Variation

Raither

Simoni

Lillo

et al. 2014

22nd AIAA/ASME/AHS Adaptive Structures Conference

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Shape-adaptable airfoils with variable shear center location and torsional stiffness represent a promising solution for controlling the aerodynamic loads on a wing by continuous deformations instead of rigid-body attachments. In the present article, a structural concept for an adaptive-twist airfoil based on wing spars with variable mechanical topology is investigated. The integration of a smart material system relying on controllable electrostatic attraction forces in the spars allows for reversible opening of the wing box and thusfor controlling the airfoil's twist. While finite element simulations and static testing of an experimental airfoil demonstrate the concept's effectiveness, a numerical upscaling to the dimensions of a glider wing evaluates its potential with respect to a realistic application. Under the considered conditions, the upscaled adaptive-twist airfoil permits changes in lift coefficient by around 20% in such an implementation.

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“…From the work of Di Lillo et al, the high levels of achievable holding force are clear, particularly for less rigid electrode elements [6]. Raither et al considered some other uses of these thin film electroadhesive devices within larger structures, utilising the devices for the opening and closing of discrete bays of an aerofoil section to confer variations in the torsional stiffness of the section, and thus the lift/drag response of the aerofoil [7,8]. This study considers the introduction of electrostatic adhesive elements in a lower level of the overall structural hierarchy, within the elements of a cellular core structure.…”

Section: Introductionmentioning

confidence: 99%

Morphing hybrid honeycomb (MOHYCOMB) within situPoisson’s ratio modulation

Heath

Neville

Scarpa

et al. 2016

Smart Mater. Struct.

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Electrostatic adhesion can be used as a means of reversible attachment. Through application of high voltage (~2kV) across closely spaced parallel plate electrodes, significant shear stresses (11 kPa) can be generated. The highest levels of electrostatic holding force can be achieved through close contact of connection surfaces; this is facilitated by flexible electrodes which can conform to reduce air gaps. Cellular structures are comprised of thin walled elements, making them ideal host structures for electrostatic adhesive elements. The reversible adhesion provides control of the internal connectivity of the cellular structure, and determines the effective cell geometry. This would offer variable stiffness and control of the effective Poisson's ratio of the global cellular array. Using copper-polyimide thin film laminates and PVDF thin film dielectrics, double lap shear electrostatic adhesive elements have been introduced to a cellular geometry. By activating different groups of reversible adhesive interfaces, the cellular array can assume four different cell configurations. A maximum stiffness modulation of 450 % between the "All off" and "All on" cell morphologies has been demonstrated. This structure is also capable of in-situ effective Poisson's ratio variations, with the ability to switch between values of -0.45 and 0.54. Such a structure offers the potential for tuneable vibration absorption (due to its variable stiffness properties), or as a smart honeycomb with controllable curvature and is termed MOHYCOMB (MOrphing HYbrid honeyCOMB).

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Variable-stiffness skin concept for camber-morphing airfoils

Cited by 11 publications

References 20 publications

Materials with Electroprogrammable Stiffness

Materials with Electroprogrammable Stiffness

Adaptive-Twist Airfoil Based on Electrostatic Stiffness Variation

Morphing hybrid honeycomb (MOHYCOMB) within situPoisson’s ratio modulation

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