TY - JOUR

T1 - Snap-through of bistable variable stiffness laminates using MFC actuators

AU - Anilkumar, P. M.

AU - Haldar, A.

AU - Jansen, E. L.

AU - Rao, B. N.

AU - Rolfes, R.

N1 - Funding Information: The first author would like to acknowledge the German Academic Exchange Service: Deutscher Akademischer Austauschdienst – DAAD, and Prime Minister’s Research Fellowship, India during the course of this research. The authors gratefully acknowledge the helpful comments and discussions with Dr.-Ing. Sven Scheffler for the revision of the manuscript.

PY - 2021/6/15

Y1 - 2021/6/15

N2 - Unsymmetric composite laminates exhibit two or more stable equilibrium shapes with opposite curvature as a result of residual thermal stresses induced during the curing process. Surface bonded Macro Fibre Composite (MFC) actuators are generally employed to trigger snap-through between one stable shape to another by applying external voltages. However, these actuators require high actuation voltage input to change from one stable shape to another, especially when used in morphing applications. If the snap-through voltage is too high, morphing becomes infeasible or may require several actuators, which is contrary to the weight requirements. Variable Stiffness (VS) laminates provide the possibility for an enlarged design space with the possibility to tailor stiffness parameters, leading to lower snap-through loads and consequently reducing the size of the actuators. On the prediction of snap-through voltages, the existing semi-analytical models have shown reasonably high discrepancies between numerical and experimental results. An improved analytical model is proposed in this study to predict the snap-through of bistable VS laminates with MFC actuators. In the improved model, the equations resulting from the compatibility and the in-plane equilibrium are described equivalent to a standard plane elasticity problem which can be solved using a standard finite element (FE) approach. In addition, the total potential energy is written in terms of curvatures. The improved semi-analytical results are compared with a full geometrically nonlinear FE calculation.

AB - Unsymmetric composite laminates exhibit two or more stable equilibrium shapes with opposite curvature as a result of residual thermal stresses induced during the curing process. Surface bonded Macro Fibre Composite (MFC) actuators are generally employed to trigger snap-through between one stable shape to another by applying external voltages. However, these actuators require high actuation voltage input to change from one stable shape to another, especially when used in morphing applications. If the snap-through voltage is too high, morphing becomes infeasible or may require several actuators, which is contrary to the weight requirements. Variable Stiffness (VS) laminates provide the possibility for an enlarged design space with the possibility to tailor stiffness parameters, leading to lower snap-through loads and consequently reducing the size of the actuators. On the prediction of snap-through voltages, the existing semi-analytical models have shown reasonably high discrepancies between numerical and experimental results. An improved analytical model is proposed in this study to predict the snap-through of bistable VS laminates with MFC actuators. In the improved model, the equations resulting from the compatibility and the in-plane equilibrium are described equivalent to a standard plane elasticity problem which can be solved using a standard finite element (FE) approach. In addition, the total potential energy is written in terms of curvatures. The improved semi-analytical results are compared with a full geometrically nonlinear FE calculation.

KW - Bistability

KW - Finite elements

KW - MFC actuators

KW - Semi-analytical

KW - Snap-through

UR - http://www.scopus.com/inward/record.url?scp=85102647441&partnerID=8YFLogxK

U2 - 10.1016/j.compstruct.2021.113694

DO - 10.1016/j.compstruct.2021.113694

M3 - Article

AN - SCOPUS:85102647441

VL - 266

JO - Composite structures

JF - Composite structures

SN - 0263-8223

M1 - 113694

ER -