Effect of nitrile butadiene rubber hardness on the sealing characteristics of hydraulic O-ring rod seals

The nitrile butadiene rubber (NBR) hardness effect on the sealing characteristics of hydraulic O-ring rod seals is analyzed based on a mixed lubrication elastohydrodynamic model. Parameterized studies are conducted to reveal the mechanism of the influence of rubber hardness on the static and dynamic behavior of seals. The optimized selections of rubber hardness are then investigated under different conditions. Results show that the low hardness seal is prone to stress concentration due to the extrusion effect under high pressure conditions; it is also more prone to leaking. A high hardness seal can better prevent leakage by reducing film thickness but it will cause large frictional power loss and increase the probability of wear failure. The choice of low hardness is recommended to reduce friction with the premise that leakage requirements are met.