Constitutive Modeling Of Softening In Swollen Elastomers Under Long Term Cyclic Loading

Nowadays, engineering rubber components such as gasket, seals, bumpers, cushions and tubing are essential in mechanical operations due to their simple yet efficient solution for various engineering problems. This is due to its properties such as hyperelasticity, high strain and resilience. Unfortunately, the urge of the market for biodiesel and organic based lubricants jeopardize the life of engineering rubber products due to susceptibility of rubber components to swell under organic solutions especially those served under dynamic forces as in automotive engines and machine tools. Existing models are insufficient to explain behaviour of swollen rubber filled components. Rubbers were immersed in both biodiesel and conventional diesel until reaching 5% swelling percentage. Afterwards the rubbers underwent multiaxial cyclic load until failure with two different elongation percentage which is 75% and 100% elongation. From the peak stress values obtained of corresponding cyclic load, a fitting plot was done to ascertain the suitability of the model with experimental values. Two models were considered based on previous study of modelling swollen elastomers. Computer software MATLAB was used to determine better fit achieved between the two models. The relationship between interaction parameter χ, swelling percentage with the coefficient of the models were also studied. Adjustments were done on the coefficients in order to achieve a suitable numerical relationship between interaction parameter χ and swelling percentage Js with model’s coefficients. The model was then plotted against the experimental values. Validation of the model was achieved from the good coefficient of determination R2 achieved