دانلود رایگان مقاله زوال فرسودگی ناشی از رابط بین الکل میکرو پلی وینیل (PVA) فیبر و ماتریس سیمان

Abstract

Quality of interfacial bond between fibers and matrix determines the post-cracking behavior of fiber-reinforced composites. Fatigue-induced interface deterioration between fibers and matrix has not been investigated systematically which prevents understanding of premature failure of fiber-reinforced composites subject to fatigue. This study experimentally investigated the deterioration mechanism of flexible fibers in brittle matrix subject to fatigue load. Specifically, the effect of fatigue-induced deterioration of interface between micro-PVA fiber and cement matrix was studied through the single fiber fatigue pullout tests and the micro-structural deterioration mechanism of the fiber-matrix interface under fatigue load was unveiled. It was found that fatigue load leads to fiber debonding which can be described by an empirical relation similar to the Paris' law. Fatigue-induced interface hardening can occur during fiber debonding stage as well as fiber slippage stage. Oil-treatment on surface of micro-PVA fiber was demonstrated as a mean to mitigate such fatigue-induced interface hardening.

4. Conclusions

This study experimentally investigated the deterioration mechanism of flexible fibers in brittle matrix subject to fatigue load. Specifically, the effect of fatigue-induced deterioration of interface between micro-PVA fiber and cement matrix was studied through the single fiber fatigue pullout test and the micro-structural deterioration mechanism of the fiber-matrix interface under fatigue load was unveiled. It was found that fatigue load is able to propagate the tunnel crack along the fiber-matrix interface, i.e. fatigue-induced fiber debonding, and an empirical relation between debonding rate and fatigue loading level similar to the Paris' law was suggested. It was observed that interface chemical bond Gd and the slip-hardening coefficient β were fatigue independent while τ0 increased with fatigue cycles N and fatigue loading levels Pmax. Such fatigue-induced interface hardening can occur during fiber debonding stage, i.e. fatigue debonding hardening, as well as during fiber slippage stage, i.e. fatigue slippage hardening. Oil-treatment on surface of PVA fiber was demonstrated as a mean to mitigate such fatigue-induced interface hardening.