A large deformation isogeometric approach for flexoelectricity and soft materials

We propose an isogeometric approach for flexoelectricity in soft dielectric materials at finite deformations accounting for Maxwell stresses on the surface between two different media. In contrast to piezoelectricity where there is a linear dependence between mechanical strain and electric polarization, in flexoelectricity the polarization is related to strain gradients which requires a C1 continuous finite element framework. In electro-mechanical materials, the Maxwell stress emerges as a consequence of the coupling effect between electrostatics and mechanics. If a solid body is embedded in a surrounding medium such as air or vacuum, the Maxwell stress acting on the surfaces governs the interaction between electric fields and deformable media. This is quite difficult to handle due to the surface discontinuity and the traction electrical forces still have to satisfy some certain continuity conditions, hence an appropriate numerical framework is required for the treatment. Here, we employed Non-Uniform Rational B-spline (NURBS) functions with knot insertion technique in order to introduce discontinuities across material interfaces while still maintaining C1 continuity in the domain to evaluate the coupling effect of strain gradient and electric polarization in the regime of finite deformation. The accuracy and robustness of our IGA approach for flexoelectric soft materials are demonstrated in some benchmark numerical examples.