اسماعيل فاطمي

Today, short fiber rubber composites (SFRCs) are used in a wide range of applications in the industry, and fatigue loading is one of the most common failure factors in this type of material. Therefore, it is important to predict the fatigue life of these composites and reduce the possible risks of sudden failure and reduce replacement costs. In this research, the fatigue life of natural rubber composites without fibers and containing short glass fibers under tensile fatigue loading was investigated experimentally and numerically. For this purpose, a model based on the damage entropy approach was developed using thermodynamic laws, which predicts the fatigue life by characterizing the viscoelastic properties of SFRCs and using thermographic data. During the fatigue process, this model calculates the damage entropy cycle by cycle, and by calculating the accumulated damage entropy and comparing it with the critical value (fracture fatigue entropy), it estimates the fatigue life of SFRCs. In addition, an extensive experimental program was conducted to eva‎luate the presented model, and the effect of adding fibers to rubber on viscoelastic properties, self-heating, fatigue life, and strain stress behavior was investigated. The fatigue test was performed on a dumbbell-shaped specimen at five different strain levels for rubber without and containing 4% and 8% fiber, and thermography data were recorded during the test by a thermal camera. The experimental results showed that the presented model can accurately predict the fatigue life of SFRCs at strain levels below 88% for different mass percentages of fibers. Also, the model shows sensitivity to specimen thickness and ambient temperature and can consider their effect.

عمر خستگي , كامپوزيت‌هاي لاستيكي الياف كوتاه , آنتروپي آسيب , خودگرمايشي , مدل‌سازي , آزمايش‌هاي تجربي

fatigue life , short fiber rubber composites , damage entropy , self-heating , modeling , experimental tests

Esmaeil Fatemi

Mahmood Mehrdad Shokrieh