Developing a finite element beam theory for nanocomposite shape-memory polymers with application to sustained release of drugs

In this paper, a thermodynamically consistent constitutive model, recently proposed for nanocomposite Shape-Memory Polymers (SMPs), is used as a basis for development of SMP beam element in a finite element framework. The beam theory utilized here is the Euler-Bernoulli beam theory with its basic assumptions. Effects of different materials as well as the geometric structural parameters, e.g. reinforcement (nano/micro-particles) volume fraction, viscosity coefficients, and external loads, on the thermomechanical response of the structure are studied in this work. The beam element numerical results are compared to those of 3D finite element modeling to verify validity of the beam element formulation and the assumptions made therein. This beam element provides us with a fast and reliable tool for simulation of structures, consisting of reinforced SMP beams. As an application, the developed nanocomposite SMP beam element could be used for numerical modeling of thermomechanical response of the drugs (e.g., theophylline) coated by films of SMP nanocomposites. It is shown that the numerical results are in correspondence with those of the experiments reported for sustained release of SMP-nanocomposite based drugs.