Wear of Elastomer Seals Analysis of Seal Profile Devin Murray MANE 6960 Friction, Wear & Lubrication

Project Goal Evaluate different elastomer seal profiles to determine characteristics which increase resistance to abrasive wear.

Seal Profiles O-RingQuad-O-Dyn SealQuad Ring

Analysis Results Standard O-Ring The standard o-ring profile has the lowest overall peak contact stress in large part due to the contact area of the deformed seal and the cylinder being the greatest of the three seals evaluated. This results in a seal which is the weakest initially in overall sealing strength (i.e. the standard o-ring is the least capable of the three seals in withstanding differential pressure without leakage). The large contact area of the seal with the cylinder also presents the worst prospect with regard to abrasive wear during dynamic travel. As the standard o-ring wears and material is removed, a significant decrease in seal compression can be expected which ultimately leads to failure of the o-ring to contain differential pressure and leakage rates will reach unacceptable levels.

Analysis Results Quad Ring Seal The Quad Ring seal has the highest overall peak contact stress which is due to this seal profile having the smallest contact area with the cylinder of all profiles evaluated. The high contact stress results in a very strong seal strength; however this will also result in increased wear of the sealing ‘lobes’ when compared with the Quad-O-Dyn seal. With all facts considered, the Quad Ring should perform better than the standard o-ring due to the small contact area of the seal exposed to abrasive wear and the geometry of the seal being such that wear at the two ‘lobes’ should not greatly decrease the seal compression. This is because the majority of the compressed seal material resides in the ‘main body’ of the seal and is unaffected by wear. Conversely, the Quad Ring is likely to fail sooner due to wear than the Quad-O-Dyn seal due to the comparatively higher contact stress.

Analysis Results Quad-O-Dyn Seal The peak contact stress of the Quad-O-Dyn seal profile falls roughly in the middle of the standard o-ring and Quad Ring stresses. As the general seal geometry of the Quad- O-Dyn seal profile is very similar to the Quad Ring, it is apparent that the same positive aspects of the engineered profile are maintained (strong seal strength, low contact area exposed to abrasive wear, and maintaining seal compression despite wear at seal ‘lobes’). Therefore, due to the decreased contact stress when compared to the Quad Ring, the Quad-O-Dyn seal is expected to wear at a decreased rate resulting in a greater seal life prior to failure.

Conclusion Quad-O-Dyn seal offers the best sealing strength with the most resistance to abrasive wear during seal travel. Further study should be pursued regarding seals with additional ‘lobes’ to find the optimal engineered seal profile.