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Master Thesis - OUFTI-1

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4.3.5 Application of the global mass smearing method<br />

The second method to be applied is the global mass smearing method. In this method,<br />

the mass of each component is spread out over the entire area of the PCB. So, the global<br />

density is obtained by dividing the mass of the complete electronic card by the volume of<br />

the PCB. This calculation is realized in Equation 4.3.1.<br />

ρ global = m OBC 2 50.4607 × 10−3<br />

= = 3536.1388 kg/m 3 (4.3.1)<br />

V P CB 1.427 × 10 −5<br />

The results are presented in Table 4.4 and in Figure 4.19.<br />

Corresponding modes Frequency deviations (%)<br />

1 21.89<br />

2 30.07<br />

Table 4.4: Frequency deviations between corresponding modes using the global mass smearing<br />

method<br />

Figure 4.19: MAC matrix using the global mass smearing method<br />

It can be remarked that the results are better than the ones obtained using the simple<br />

method. So, this method is more accurate than the preceding one (which is in accordance<br />

with the theory).<br />

93

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