Harnessing springs to tune thermally induced snap-through instabilities in bi-layer beams

The snap-through behavior is one in which an elastic system abruptly transitions from one equilibrium state to a non-adjacent one. In this work, we employ moderate rotations theory, which is an extension of linear elasticity, to investigate the thermally induced snap-through response of constrained polymeric bi-layer beams. To enable one to control the snap-through behavior, we propose to connect one end of the beam to a spring. We begin with a homogeneous beam and show that by tuning the spring constant, one can control the buckling temperature. Bi-layer beams bend in respond to thermal excitation and the snap-through is manifested through a reversal in the direction of bending. This can occur due to the mismatch between the thermo-mechanical properties or the changes in the thermo-mechanical properties due to the glass-transition temperature. The snap-through typically requires an activation energy to enable the beam to transition through non-equilibrium high energy states. We show that by using springs, this activation energy and the snap-through behavior can be attenuated. The findings from this work provide tools that can be used to enhance the performance of applications that employ the snap-through phenomenon, such as in soft robotics and deployable structures.