Analysis of the strengthening mechanism based on stress-strain hysteresis loop in short fiber reinforced metal matrix composites

The strengthening mechanism of short fiber or whisker reinforced metal matrix composites has been studied by a continuum mechanics treatment utilizing finite element analysis (FEA). To assess the tensile and compressive constitutive responses, a constraint-unconstraint comparative study based on stress-strain hysteresis loop has been performed. For analysis procedures, the aligned axisymmetric single fiber model and the stress grouping technique have been implemented to evaluate the domain-based field quantities. Results indicate that the development of significant triaxial stresses within the matrix both for the tensile and compressive loading, due to the constraint imposed by reinforcements, provide an significant contribution to strengthening. It was also found that fiber stresses are not only sensitive to the fiber/fiber interaction effects but also substantially contribute to the composite strengthening both for the tensile and compressive loading.     

Application of Taguchi and response surface methodologies for surface roughness in machining glass fiber reinforced plastics by PCD tooling

This paper discusses the use of Taguchi and response surface methodologies for minimizing the surface roughness in machining glass fiber reinforced (GFRP) plastics with a polycrystalline diamond (PCD) tool. The experiments have been conducted using Taguchi’s experimental design technique. The cutting parameters used are cutting speed, feed and depth of cut. The effect of cutting parameters on surface roughness is evaluated and the optimum cutting condition for minimizing the surface roughness is determined. A second-order model has been established between the cutting parameters and surface roughness using response surface methodology. The experimental results reveal that the most significant machining parameter for surface roughness is feed followed by cutting speed. The predicted values and measured values are fairly close, which indicates that the developed model can be effectively used to predict the surface roughness in the machining of GFRP composites. The predicted values are confirmed by using validation experiments.