Numerical modeling of nonlinear photoelasticity

Abstract

Abstract When molecular photo‐switches, such as azobenzene or norbornadiene, are embedded into a sufficiently soft polymer matrix the resulting compound can undergo a mechanical deformation induced by light of a specific wavelength. These photo‐sensitive compounds have the potential to be applied as soft actuators without the need for hard wired electronics or a separate energy source. Such characteristics are especially attractive in the design of micro‐scale robots but also other applications such as high‐speed data transfer or the conversion of photonic energy into a mechanical response holds great promise. Despite these almost futuristic possibilities, photo‐sensitive polymers have not yet experienced a sufficient attention in industrial applications. One important factor to increase the acceptance of this group of soft smart materials is the formulation of a rigorous constitutive modeling approach in combination with numerical simulation methods. Thus, in this contribution we present a photo‐mechanical modeling approach, departing from the fundamentals published previously. We briefly introduce the necessary constitutive equations which are subsequently utilized in combination with the respective balance laws into a finite element implementation. Finally, the capabilities of the numerical solution approach are illustrated by a simple two‐dimensional bench‐mark example and subsequently extended to a more complex three‐dimensional problem.