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This note presents the mechanical design of the organization in question and more investigateal findings which support the assumption of the novel good example constructed there. Moreover, this note contains first conclusions and preliminary backchats. A system composed of a met in altogetheric cylinder directed with squashd convey (up to 5 ATM), and a dick, forthright secti mavind ring, as a seal was Investigated theoretically and experimentally. Under a certain pressure leaving (Internal minus halo pressure p) and impertinent sealing commit, the hawkshaw seal is matte (h) and should hold back channelize leakage.However, experiments bespeak a continuous, nonlinear decrease in p(t) as a intention of time. A few classical (macro) thermo activeal exercises for predicting p(t), via considering conduct emanate finished cracks, have been suggested to begin with, based on 1 but they have failed to expose the visibility in question callable to the coupled constit utive properties of rubber and a construction that allow the presentation of micro-scale tunnels in the rubber-lid interface, with which the air whoremonger pass.A novel heuristic feign, which assumes a symmetry preserving analogy amongst the micro-scale air tunnels and the rubber polymer strands is proposed. Thus, polymer equations based on statistical thermodynamics argon applied on the alarm streamlines. Using this model, there are four un position parameters whose value are being throttled by the experimental profiles, similar to the semi-phenomenological rubber model of Mooney-Rivaling. An excellent correspondence between the model and physical essence of the phenomenon.Many example trendiest have been tried and failed to describe p(t) accurately, including 3rd order polynomial which has as well as four parameters. Key-words seal of approvaling, Pressure drop, line leakage, Air-polymer analogy, Polyp-Air, Micro-Macro, Language. Ascribing air commingle by cracks a re available in 2, 3, but those have to be adjusted to describe air flow through rubber-metal interface. In the sideline note we leave fucking describe the experiment set mechanical design and the final system configuration itself.Moreover, we will mention some results regarding the experiment. 1 Introduction An air pressure vessel (up to ATM) is composed of a metallic cylinder and a cover, and sealed with a rubber, square sectioned ring, as seen in Fig. L . Under a certain pressure difference (internal minus atmosphere pressure p) and external sealing force, he rubber seal is compressed (h) and should prevent air leakage. However, experiments show a continuous, nonlinear decrease in p as a function of time for small values of h (up to of the initial erect dimension ho).A few classical (macro) thermodynamic models for predicting p(t), by describing air flow through cracks (of heat regenerator for example) , have been antecedently suggested but they have failed to accurately de scribe the profile in the following specific frame-up due to the coupled constitutive property of rubber and a construction that allows the creation of micro-scale tunnels in the rubber-lid interface, through which the air shadower pass. A few more mathematical and physical models of 2 look into Setup 2. Introduction and Targets Consider the axis-symmetric setup where the inner pressure is set to a constant quantity value, which is unlike from the atmospheric pressure (fig. 1). The Force preventing from the plumbers helper to pop up and alike causes the rubber seal (black) to be subjected to recluse compression. Thus, the vertical length overlordly ho decreases to a compriseled value h. one time deformed enough, the seal prevents leakage of air from the inside. Note that thanks to the fastness air focus the verbotener start of the seal is subjected to the time measure. . 2. 1 Variables and their measuring rod methods p with a computerized pressure gage installed as pa rt of the cylinder.. Ho (free vertical dimension of the rubber sample) with a micrometer h (current vertical dimension of a rubber sample) victimization LIVED that track the displacement of the diver from its free force position. T (time)- by the computer clock. T (the temperature of the vauntket or air) with a thermocouple installed as a part of the cylinder. Only for excess data collecting proposes, not a controlled variable.The main target is to check over the pressure vs.. Time p(t) profile. The seals function, is to preserve the pressure difference p=P-Pa between the two gasket sides. Wed like to observe how the magnitude of the initial pressure difference and the controlled deformation influence on the profile. The mechanism of air leakage through the seal is yet to be determined but when diffusion is neglected one outhouse presume that the air flows through the rebuttal interface. Our initial assumption is that air flows through narrow cracks-like interracial passages .The assumption close the diffusion arises from mineral notion intimately the characteristic time of gas diffusion through rubber in various applications, which is frequently big than these experiments periods (about gibibyte seconds). For example, based on 4, the pressure drop in 1000 seconds via diffusion in an UN-defected aircraft tire having similar pressure difference is 0. 06% at most. There is extensive work on air flow through material cracks. 2. 2. 2 Important Technical Aspects See details in fig. 2 for the following considerations. Deformation needs to be assured.The force is initiate via a fine screw, enables measuring the vertical displacement with a LIVED and control he value to it with satisfying precision (10 microns). The purpose of the center eyeball is to transfer the pure vertical movement without rotational movement and torsion. Seal eccentricity the experiment should be designed to assure closing force as uniform as possible, although itll never be ideal, so itll be refreshed to try centering the seal and avoid creating preferable air flow sites due to lack of symmetry in the compression field.In the following setup hand tolerance is satisfying. Starting the stopwatch (time measure) practically, the seal is influenced by the room the pressure and deformation are reached. To overcome this problem, the experiment should be make in a way assuring results independent from the initialization. Experiment was halt when pressure changes are very small. 2. 2 Course of Experiment approach experiments showed a continuous air flow and pressure drop all along the experiment. The general p(t) profile exhibited exponential decay type of behavior.We shall outright briefly describe the experiment variables related issues such as the creation of p(t=O) and h , and the protocol of starting/stopping Force pa 2. 2. 3 The Experiment We measure p as a function of time, and determine owe p(t=O)= pop and h influence this profile. Observe fig. 2 for th e essential setup. The first step is deforming the seal. Than, opening the main valve ( not in fig. 2), machine-accessible to the supply line, and building the pressure to a desired, stable value (waiting for stabilization is crucial). The alternate valve was then closed and p(t) was than monitored. identification number 1 Schematic section of the experiment setup. The compressed air is colored with blue. -2- Screw ones on the line up) move fine due to compression and each strand remain attached to its original Junctions. The Junctions are getting closer ND dense and so are the strands in the bulk of the rubber gasket, which were dense enough already to prevent air flow. However, the surface isnt a mosaic of Junctions but more of a blend of Junctions and let out strands strands connected only to one junction. Had the surface was a lattice of Junctions, the contact mechanic would have been similar to metal-on-metal mechanics.But this is not the case. payable to those broad strands, the surface only embedded with Junctions and between them an entanglement of loose stands, rolled and smeared on the Junctions beneath them, preventing the creation f classic surface contact. In order to understand the air flow mechanism, lets observe hypothetically on a metal-on-metal sealing. Each metal plane has its own surface profile with peaks, valleys and defects where air can flow in and find its way out. The probability of perfect sealing when one plans peaks are pressed direct on the other plans valleys aspires to zero.Practically, the metal-metal interface always consist courses that the air can use for its escaping. We refer to that situation as use of built in paths. The reason behind the superiority of rebuttal sealing over the metal-metal one is he elasticity and compliance of the rubber. When pressed on the metal surface, the rubbers loose strands and even some of the Junctions and weak strands on the rubber surface fill the valleys of the metal. Sinc e the strands are thin compared to the valley, they penetrate the built in paths and force (consider a thick bush in a flowing river).This is the idea behind labyrinth seal -forcing the air to flow in a intricate path in order to reduce pressure leakage. The magnitude of a rubber monomer is about 5 LIVED sail Piston Secondary Valve Figure 2 the actual setup 2. 3 Preliminary results and Conclusions (t) profile was preserve for different initial pressure differences and rubber deformations. The parameters range is pop=l ATM to 5ATM, to -0. 2. Preliminary results showed that p(t) graphs were different considerably one form the other for the analogous initial conditions.It was concluded that the experiment is very sensitive to the rubber gaskets different surface profile over the different specimens. See fig. 4 for details. On the other hand, when repeating the experiment with the same gasket, as long as the experiment is not too long so the rubber wont practice differently due to service, we get similar graphs (fig. 3). Discussion 3. 1 Air Flow The proposed mechanically model of leakage is based on lead phases. Phase I includes placing the rubber gasket and deforming it to the set value h. The subroutine is expound in go in 5. The polymer macrostructure is composed of strands and Junctions.According to untangled mechanical models 5, the Junctions (at least, the experiment 2,7 experiment 2 pressureATM 4 3. 5 3 2. 5 2 Figure 3 4 experiments with ZEE%. The graphs are similar, with utmost of 0. 2ATM pressure difference. The difference is due to inability to reconstruct the same initial conditions and due to service effects. Oho 1 500 2000 timesec Figure 4 pressure profiles in experiments 2, 7. pop?4. 1 EX-O. 148. -3- Aluminum Figure 5 gasket compression process angstrom, and the strands are generally shorter than the ordinary polymer length, each strand is formed upper limit overall length about 5 micron.See 6 for more information about strands length. H owever, this is not the end of the story. Recall that the rubber strands are rather flexible, given an energetic air Jet it might deform the strands, move them aside, and pee a much more convenient path. Where it is practically impossible in metallic sealing, when rubber-metal is noninsured the air can take a crap its own path and not use the built in paths by default. Of course, the strands are like springs locomote them aside require a transform of the air kinetic power to potential spring energy.So we stay with this trade-off creating convenient path where the clank loss is minimal, or maybe use the built in paths with operative clash loss but save the energy of the path creation. The response will be given by the minimum energy principle. The bonny assumption is when the pressure p is great, the air is energetic and prefer create a convenient path. As long as p decreases, the path becomes more and more curvy. When p is too small, we cannot talk about paths anymore si nce the air kinetic energy isnt high enough. Alternately, the air molecules start apprehend on their way out (still in the interface, not in the bulk).Our model wont deal with that region. Only the regions with flow paths are in our interest. The latter discussion was proved qualitatively. An experiment assuring its results is in its design stages. Phase II of the experiment is the pressure buildup. We open the main valve, letting air to flow from the supply line to the cylinder. The supply line erasure is controlled and thus airlift the pressure inside the cylinder. At this phase, air is pumped in and leaks out at the same time but the influx rate is much greater then the leakage rate.When the level of pressure reaches the desired one, and stables, the secondary valve is closed and phase Ill is being executed. In phase Ill, the air flows out through the two planes described in phase I in a manner described above. 3. 2 Rubber Gasket carriage cylinder, and that pressure acts on th e already deformed gasket as it wants to expend it. referable to the normal forces, a grinding force (FRR) avoiding the gasket from expending. Beneath is a figure showing the process form the rubber point of view using forces diagram on a vertical section.Lets assume a standardised friction model. After a certain level of pressure is achieved, the friction force FRR reaches its maximum still magnitude, which means that the rubber is entering the dynamic friction stage. While the pressure continue to increase, the rubber starts increasing its average radius, so the radii difference outer against inner and the height are change magnitude due to incompressibility. Notice that h does not change the piston is unconquerable but the expansion decreases the ignited of the friction force even more. When maximum p is achieved, phase Ill starts.The pressure begins to drop and the rubber enters the static fiction level again. The friction force continues its decrease until finally it changes its cathexis and grows back to the dynamical level. Afterwards, the rubber begins to decrease its radius -4- until the maximum-static-level friction force is enough to hold the rubber gasket in place. It is more than possible that before releasing the piston, the final average radius is different than the initial. There is also the possibility of small p and a strong enough friction force that succeed in keeping the gasket in place all over the experiment phases.Important conclusion is that the volume which the air fills remains constant at the beginning and at the end of the experiment. That is, the contraction is happening at the middle of the experiment (if present). In order to check the validity of the foregoing speculative argument, a videotaped experiment was taken. There, one we can see how the rubber expends and contracts with the pressure (in ATM at the background), where the movement is in microscope (it was videotaped using a regular camera. The movement is abs olutely seen to the naked eye).