Rubber seals : Analyze the effectiveness of the rubber seals using Finite element method.

Rubber seals are designed for the prevention of leakage of fluid. The stress relaxation properties of rubber seals is a factor indicating the performance of the rubber seals. This article provides an example of analyzing the performance of rubber seals and comparison between the two compound by using the Finite element method. Shape of the rubber seals that are used in this article has a shape that axisymetric. as shown in Figure 1.

Figure 1. Finite element model of Rubber seals

Rubber materials model
Choose a neo-Hookean is strain energy function of hyperelastic model , while pronie’ series n = 1 is used as a model viscoelastic properties . The properties of rubber materials which both display Table 1.

Table 1 . Rubber material properties

Material name	Hyperelastic Model	Pronie’	series
	Neo Hookean (C10)instantaneous (MPa)	gi	ti (sec)
Rubber1	2	0.3	1
Rubber2	2	0.4	1

Stress relaxation behavior of rubber material in Table 1 are shown in Figure 2. It was found that the shear modulus of the Rubber1 is higher than Rubber2 (stress reduced to less than Rubber2).

Figure 2. Shear Modulus (G(t)) of rubber compound

Defined boundary conditions.
To simulate events of rubber seals (as O-Ring) will begin from the engagement Housing and Groove, which will simulate the speed of compression of Housing and Groove at 22.5 mm/s .The next step is to compare the pressure of the rubber seals (as O-Ring) compression with the Housing and Groove at the time of 10 seconds.

Simulation results.

Distribution of stress components in the radial direction.

Figure 3. Stress component in the radial direction of the back rubber seals (as O-ring).

Figure 4. Stress component in the radial direction of the rubber 1 material

Figure 5. Stress component in the radial direction of the rubber 2 material

From Figure 3 it was found that the stress in the radial direction is negative, represents the pressure rubber seals (as O-Ring) with Groove and Housing act to prevent leakage of fluid. It was found that the pressure rubber seal (as O-Ring) are similar, both rubber. (arising from the G (0) of these two materials are equal) over time. Pressure in these areas has decreased, as shown in Figure 4 and 5.

Considering the reactions of the rubber seals (as O-Ring), which acts on Groove and Housing will be found that compound Rubber 1 the reactions above, as shown in Figure 6. which is shown to be effective in preventing leaks better.

Figure 6 Reaction force from the rubber seals (as O-Ring) in the radial direction.

Simulation results show that viscoelastic properties affect the performance of the rubber seals to prevent leakage significantly. Although Hyperelastic properties of rubber compound is like a Viscoelastic properties that must be considered is the relaxation of the shear modulus (G (t)), as shown in Figure 2. At the same time improving efficiency of rubber seals also depend on other factors such as instantaneous modulus, operating temperature and seal friction.