Debonding Damage in Glass-Particle-Reinforced Nylon 66 Composites and Micromechanics Approach

摘要

This paper deals with the influence of debonding damage between particles and matrix on mechanicalrnperformance of particle-reinforced composites and its micromechanics. Tensile strength and fracture toughness werernexamined on seven kinds of glass-particle-reinforced nylon 66 composites in which a volume fraction of glassrnparticles and interface treatment between particles and matrix were changed. Although the main damage mode isrndebonding damage between particles and matrix in both interface-treated and untreated composites, in the interfacetreatedrncomposite the debonding damage is hard to occur because of high interfacial strength. The interface-treatedrncomposites are superior on the tensile strength, and inferior on the fracture toughness to the interface-untreatedrncomposite. In order to make clear the influence of the debonding damage on the mechanical performance of therncomposites, an incremental damage theory, which describe the progressive debonding or cracking damage of thernparticles, was developed based on the micromechanics approach. This damage theory was applied to the numericalrnanalyses of the stress-strain response and crack-tip field of the glass-particle-reinforced nylon 66 composites. Therninfluence of the debonding damage is summarized as follows. The load carrying capacity of the composites, namelyrntensile strength, is enhanced by the intact hard particles and is reduced by the debonding damage. On the crack-tiprnfield, however, the hard particles lower the resistance to crack initiation and growth because of high stressrnconcentration, while the debonding damage acts as a toughening mechanism due to the stress release and energyrndissipation.