Study On Fracture Behavior Of Microcapsule In Self-healing Composite Material

Self-healing composite material is a kind of smart material which has self-perception and self-healing capability. It provides a new method to prevent potentialstructural damage and repair composite internal micro-cracks in time. Microcapsuleself-healing materials develop rapidly and become a main way for developingself-healing polymeric materials with the maturation of microencapsulationtechnology. Currently, the research of this material focuses on the repair mechanismand repair efficiency, however, there is less research on microcapsule fracturebehavior which is closely related to the completion of repair task.In this paper, in order to reveal the microcapsule fracture behavior, the methodof combining experiment and finite element analysis is used. Meanwhile, a series ofresearch on the mechanical properties of microcapsule wall material, microcapsulefracture reason and the influence of crack location are carried out. The main contentsas follow:1. Microcapsule wall was tested by using nano-indentation, and then dimensionalanalysis theory was employed to analysis the P-h curve. The elastic modulus,yield stress and stress-strain relation of microcapsule wall material were obtainedand they laid the foundation for obtaining ultimate strength of microcapsule wallmaterial.2. The nano-indentation test of microcapsule was simulated by finite elementmethod and then the relationship between microcapsule structure stiffnesscoefficient and microcapsule wall material’s modulus was obtained, furthermore,the ultimate strength of microcapsule wall material was obtained. The abovemechanical parameters laid the foundation for researching the microcapsulefracture and propagation path.3. A finite element model which contained a single microcapsule was founded andthe microcapsule fracture behavior in which case the crack plane and themicrocapsule’s equatorial plane were assumed to be coplanar was studied.Meanwhile, the influence of elastic modulus and ultimate strength change onmicrocapsule fracture behavior was studied.4. The epoxy resin based self-healing composite material sample in which the crackplane and the microcapsule’s equatorial plane were non-coplanar was used for tensile test. What’s more, the influence of crack location was studied by usingfinite element analysis method and it revealed the relationship betweenmicrocapsule fracture behavior and crack offset distance.