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چكيده انگليسي :

Design of High Pressure Seal Fariba Zeinali Ghotbabad f zeinali@me iut ac ir Date of Submission 2015 06 16 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor Mahmoud Farzin farzin@cc iut ac irAbstract Nowadays in various industries such as aerospace industry gas and oil chemical industry refineriesand petrochemical industries etc mechanisms at high high pressure are required to allow the process to becompleted Pressure rise of the fluid occurs inside the chamber which has usually a cylindrical shape Therefore it is vital to design a sealing system in order to prevent the leakage of the fluid The leakagehappens when the fluid pressure is increased The reason for this is that as the process progresses the pressuredifferences between the outside and inside of the system goes up and consequently the tendency of the fluidleakage increases in a way that the tank turns into a kind of un controllable vessel chamber that even the leastdisruption in sealing system causes fluid leakage and it s damage of which maybe irreparable Therefore forsuch processes high pressure processes sealing secure is an extremely important prerquisite This research aims at designing a high pressure seal based on the Bridgman plan by means of whichthe fluid pressure is increased through a sealing system as a result of which the sealing operation is carriedout securely Bridgman has stated that the key development which enabled him to reach higher pressureswithout leaks was his invention of the unsupported area seal now called the Bridgman seal The principle ofits operation is that pressure in the contained fluid produces an over pressure in the seal which preventsleakage In order to check the sealing system operation ABAQUS simulation software was used Different sealingrings o ring u ring c ring and v ring were simulated A sealing ring is acceptable that can create enoughsealing pressure which is greater than the fluid pressure In addition the shape of the ring should be such thatthe sealing ring pressure distribution is more uniform to prevent seal damage The choice of a proper material is probably the most critical factor in the design of seals able to withstandextremely high pressure and knowledge of material mechanical properties is essential for the finite elementmodel FEM simulations needed to understand and optimize seal behavior Based on very few commercialsolutions proposed for high pressure applications five materials potentially suitable for ultrahigh pressuresealing systems have been selected for testing Nitrile Nutadiene Rubber NBR Silicone Rubber Polyamide6 PA6 and Ultrahigh Molecular Weight Polyethylene UHMWPE reinforced with glass and ceramicmicrospheres to enhance wear resistance have been considered suitable to be used in the sealing ring for theirgood pressure carrying capability combined with wear life Properties of PA6 UHMWPE glass andUHMWPE ceramic obtained from previous research Uniaxial tension and stress relaxation tests wereperformed to obtain properties of NBR and silicone rubber Uniaxial tension tests showed that the behaviorof NBR and silicone rubber were hyperelastic but PA6 and UHMWPE materials exhibited a typical elasto plastic behavior Combination of viscoelastic and hyperelastic models were used to simulate the behavior ofNBR and silicone rubber and a combination of elastic and viscoelastic models were used to simulate thebehavior of PA6 UHMWPE glass and UHMWPE ceramic Keywords Sealing High Pressure Bridgman Polymers Hyperelastic

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آب بندي , بريجمن , پليمرها , هايپرالاستيك