A Numerical Study on the Effect of Urea Formaldehyde Microcapsules Filling Ratio on the Deformation of Epoxy Composites using Finite Element Method (FEM)

In recent years, many new material configurations have emerged from which hybrid materials such as microcomposites have shown promising applications. In the current study, the microencapsulated-based epoxy composites were simulated in micro and macro-scales using numerical modeling. A single-microcapsule was simulated by finite element method  (FEM) to estimate the effect of compression on a representative equivalent volume (REV). FEM sensitivity analysis was conducted for different conditions of encapsulation efficiency, i.e., full, half-full and empty, varied diameter (50, 100, 200 μm) and thickness (2, 6, 10 μm) of capsules to study the influence of each governing parameter on the load-deformation behavior of the composite. The composites containing microcapsules with full content showed an improvement in the elastic modulus in comparison with the neat epoxy, while half-full and empty composites exhibited lower elastic moduli. Moreover, the results showed that the diameter of the capsules significantly influences the stiffness of the composite. Indeed, the overall elastic modulus of the 50 μm microcapsules was slightly affected by the encapsulation efficiency while the 200 μm microcapsules showed a drop of 28% in their elastic modulus from the full to the empty capsule condition. Finally, the load-deformation behavior of the composite was studied in macro-scale based on the elastic moduli calculated from micro-scale modeling of an REV.