Experimental Study on the Mechanical Properties of Nylon Fabric-Reinforced Elastomeric Isolators (N-FREIs)

In recent decades, carbon fiber, glass fiber, polyester and Kevlar fiber have been utilized to replace the steel shims in conventional steel-reinforced elastomeric isolators (SREIs). This study chose nylon fabrics owing to their extreme low cost, low elastic modulus and good adhesion to rubber, and nine nylon fabric-reinforced elastomeric isolators (N-FREIs) were manufactured with different design parameters. Compression and compression shear tests were, respectively, conducted to investigate the mechanical properties together with their influential factors of the N-FREIs. Results show that the vertical load-carrying capacity of the isolator is high enough to sustain a compressive stress of 10MPa without visible damage. The compressive stiffness of N-FREI is much smaller than that of SREI, and the vertical damping ratio under cyclic compression reaches up to 7%. In the compression shear tests, the shear stiffness of the isolator first decreases and then increases as the shear strain increases within 300%, and the equivalent damping ratio varies between 9% and 14% for different sizes of the isolator. Additionally, due to the flexibility and extensibility of the low modulus nylon fabric, both vertical and horizontal stiffness decrease a bit with an increase in the number of fabric layers. Finally, a formula for calculating the horizontal stiffness of N-FREI is proposed, it provides a comprehensive mathematical model to predict the behavior of the N-FREI under horizontal shear conditions.