5. Ensuring specified tightness

Ensuring specified tightness or leakage rate is related to the determination of the force parameters f <sup>q</sup> or qσ. The sealing capacity of the SJ is evaluated by the permeability functional by Eq. (1). The contact characteristics—the relative contact area η and the gap density Λ, included in Eq. (1), are defined in the previous section. Included in Eq. (1), the probability vk of the medium flowing through the SJ is determined by the fusion of contact spots and is given in Ref. [3]. Two adjacent asperities will merge if η<sup>i</sup> > 0:5for each asperity.

Figure 11 shows the dependences for the elastic and elastic-plastic contacts.

The required permeability functional is determined by [3]

$$\mathbf{C}\_{\mu}^{\*} = \frac{2l\mu G l^{\*}}{R\_{\text{max}}^{3} \rho \Delta \mathbf{p}} \,\mathrm{}^{\prime} \tag{77}$$

6. Conclusion

developed and established:

is insignificant.

Author details

Using the proposed model of roughness as a result of the studies, methods for determining the contact characteristics and the conditions for ensuring a specified tightness of the joints were

Contact Mechanics of Rough Surfaces in Hermetic Sealing Studies

http://dx.doi.org/10.5772/intechopen.72196

23

Figure 11. The dependences of the permeability functional for the elastic (a) and elastic-plastic (b) contacts.

1. Contact characteristics and the permeability functional are determined depending on the introduced dimensionless power parameters fq for the elastic and q<sup>σ</sup> for elastic-plastic contacts.

2. The relative contact area and the gap density for elastic contact do not depend on the values of the parameters of the bearing curve p and q. To a large extent, the mutual influence of asperities affects, and at fq > 0.47, the determining factor affecting the perme-

3. To describe the elastic-plastic contact, Mayer's law and the relation between the hardening

4. In the case of elastic-plastic contact, the exponent of hardening n has a greater effect on the contact characteristics and to a lesser extent, the parameter ε<sup>y</sup> and the mutual influence of the asperities. For the considered range of the parameter qσ, the fusion of the contact spots

ability functional is the probability vk of the medium flowing (Figure 11).

exponent n and the Mayer index m were used.

Peter Ogar\*, Sergey Belokobylsky and Denis Gorokhov

\*Address all correspondence to: ogar@brstu.ru

Bratsk State University, Bratsk, Russia

where G� <sup>l</sup> is the specified tightness; r is the density of the sealed medium; p<sup>1</sup> and p<sup>2</sup> are the inlet and outlet pressures; μ is the dynamic viscosity; Δp ¼ p<sup>1</sup> � p2; and l is the compacting band width.

The force parameters <sup>f</sup> <sup>q</sup> or <sup>q</sup>σ, that providing a given level <sup>C</sup><sup>∗</sup> <sup>u</sup> are determined from the Cu f <sup>q</sup> or Cu q<sup>σ</sup> (Figure 11).

Contact Mechanics of Rough Surfaces in Hermetic Sealing Studies http://dx.doi.org/10.5772/intechopen.72196 23

Figure 11. The dependences of the permeability functional for the elastic (a) and elastic-plastic (b) contacts.
