Electro-thermo-mechanical instability study of fiber-reinforced bimorph convex dielectric elastomer

Intelligent electroactive polymer-based dielectric elastomer actuators (DEAs) are capable of geometrical disorientation. These actuators are susceptible to electro-thermo-mechanical instability due to their ability to be electrically powered at various stresses and temperatures. This proposed work provides mathematical derivations for the study of instability in coupled electro-thermo-mechanical anisotropic bimorph convex DEAs. The equilibrium equations are formulated assuming the taper ratio because of the convex structure and the ply angles due to anisotropy. MATLAB is employed to numerically solve the complicated equations for critical stretch, nominal electric field, and entropy under a variety of mechanical, electrical, and thermal loads. The observations indicate that under conditions of Cb=Ch=0.1, θ1=θ2=45∘ and T=300K, an increase in nominal stress from σ˜=0.05MPa to σ˜=5MPa leads to a corresponding increase in the peak point of the nominal electric field, specifically from E˜=0.4×104V/m to E˜=4×104V/m for axial stretch values of 2.107 and 2.159, respectively. When the nominal electric field is reported against nominal electric displacement, it enhances with the rise in temperature and reduces with the hike in nominal stress and taper ratio. When the fibers are arranged parallel to the axial stretch direction then the failure point of stretch is least, compared to that oriented in a perpendicular direction. The present study demonstrates that elevated temperature and nominal stress result in an increase in entropy, leading to a corresponding increase in system disorder. Furthermore, the perpendicular alignment of fibers with respect to axial stretch is found to decrease the degree of system randomness.