Fracture model of polymer - matrix composites

Abstract

Polymer-matrix composites are of great interest in both academic and industrial research. Their light weight coupling with superior mechanical properties makes them competitive in Aerospace Engineering and other industries, e.g. transportation, sports and medical equipments. Along with the development of nanotechnology, nanosized filler polymer-based composites have been attracted numerous studies. However, these research are primarily on intact state of composites and comparatively few studies on fracture behavior. Furthermore, it has been reported that the interface and interphase behavior governs the properties in the bulk as well as fracture related properties of nano-sized clay reinforcement polymer-matrix composites (NCR-PMCs). The goal of the M.Sc.- thesis is to develop a model for NCR-PMCs to predict fracture related material properties such as tensile strength and fracture toughness. The model should account for the interphase and interface behavior of PMCs. Secondly, the model should be used to qualitatively determine the influence of the interphase-properties on the PMCs. Structure of NCR-PMCs is simulated as a model compounded by clays that arbitrarily dispersed into the matrix base. The element in matrix and interphase are defined as normal triangular element with additional phase-field while the clay element is considered as linear elastic material with very high stiffness. The results reveals that the most influencing factor on nanocomposite property is the interphase (IP) thickness. It could control the tensile strength as well as the failure critical point of deflection curve. The elastic modulus of interphase also affects the fracture mechanism, the stiffer interphase is, the more stable the stress-strain curve becomes, while the energy release rate Gc seems to be rather small effect on overall system.