Air-Tightness of Rubber O-Ring Seal in Ball Valve of Vacuum Toilet: A Simulation Study

The mechanical properties at the contact of rubber O-ring and polypropylene(PP) ball-valve of vacuum toilet were empirically approximated,mathematically modeled,theoretically analyzed,numerically simulated with MATLAB software and experimentally evaluated.The influence of the key variables,including the low pressure,friction coefficient and geometric tolerance,on the contact-stress was investigated for design optimization of rubber O-ring. The simulated results show that the friction coefficient and geometric tolerance have a major impact.For instance,as the friction coefficient increases,the contact-stress changes in an increase-decrease mode,peaking at 0.25;and as the tolerance increases,the contact stress varies in an increase-constant manner,leveling off at 0.23 mm,because the deformation enhances contact-stress.A prototyped O-ring,with the optimized friction coefficient(0.26) and tolerance(0.23 mm),was fabricated and tested.As shown in the test results,the contact-stress meets the sealing requirements.