Flexural Stiffness Control of Multilayered Beams
This paper focuses on the ability to introduce change in the flexural bending stiffness of a niultilayered beam. The multilayered beam comprises a base layer with polymer layers on the upper and lower surfaces and stiff cover layers. The flexural stiffness can be reduced by effecting a reduction in the shear modulus of the polymer layers by heating through glass transition. Stiffer polymer layers strongly couple the cover layers to the base beam and the entire multilayered beam bends more as an integral unit On heating, a reduction in the shear modulus of the polymer layer results in its undergoing shear deformation as the base beam undergoes flexural bending and results in the cover layers decoupling from the base beam. This reduces the overall flexural bending stiffness. A finite element analysis is developed for the multilayered beam, and after experimentally verifying its ability to predict change in flexural bending deflection under load with a change in the polymer-layer shear modulus, it is used to conduct parametric studies. The results of the parametric studies provide broad insights into how the achievable change in flexural bending stiffness with a change in the polymer-layer modulus varies with design parameters such as the modulus and thickness of both the cover layers and the polymer layers. Changes in flexural bending stiffness by a factor of over 70 for a clamped-free beam and by a factor of over 130 for a pinned-pinned beam were observed for certain configuration designs.