5 - Failure analysis and the optimal toughness design of sheep–wool reinforced epoxy composites

Abstract

Wool fiber is soft, durable, safe in nature, and has high wear and tear resistance. It has good characteristics such as elasticity, resilience, poor resistance to alkalis with good resistance to acids, and good insulation property. This study focuses on the failure analysis of wool fiber–reinforced composites. This composite material contains 60% sheep wool fabric (reinforcement) and 40% epoxy (matrix), and processing is carried out by the conventional hand lay-up method. The open-hole tensile (OHT) test was conducted following ASTM D 5766. A statistical method of Taguchi design was used for the design of experiments to study and describe optimal toughness of natural fiber composite. The control factors such as width, thickness, and hole diameter were used to evaluate the tensile strength and fracture toughness of the composites. An L9 orthogonal array, main effect plots, analysis of variance (ANOVA), response surface methodology (RSM), and linear regressions are used to analyze the effect of control factors. It was found that thickness having a high percentage of contribution about 55.91% on tensile strength, and hole diameter contributes more to fracture toughness about 50.46% of the time. The Taguchi method is suited well for optimizing the control factors with the minimum number of trials. A good agreement between experimental results with predicted values was observed. The holes induced in fiber-reinforced polymer composites resulted in high rate of rejected parts which affects the performance of the composite product. Hence, OHT testing of the composite will satisfy the industrial applications.