Estimate the remaining life in revolutions of a 02-30 mm angular-contact ball bearing already subjected to 216000 revolutions with a radial load of 15 kN, if it is now to be subjected to a change in load to 25.05 kN. NOTE: This is a multi-part question. Once an answer is submitted, you will be unable to return to this part.

Respuesta :

Answer:

Radial load of 15 kN, remaining life is 2478519 rev

When load is 25.05, we have 485783 rev

Explanation:

For 02-30 mm angular contact bearing, then [tex]C_{10}=20.3 kN[/tex]

Since [tex] (F_1)^{a}L_1=K[/tex] then

[tex] (C_{10})^{a}L_{10}=K[/tex]

For a ball bearing, a=3 hence

[tex] (20.3)^{3}\times (10^{6})=K[/tex]

[tex]K=8.365\times 10^{9}[/tex]

Life at load 15 kN [tex]L_1=\frac {K}{F_1^{a}}=\frac {8.365\times 10^{9}}{15^{3}}=2478519 rev[/tex]

Life load at 25.05 kN [tex]L_2=\ frac {8.365\times 10^{9}}{25.05^{3}}= 532160.6 rev[/tex]

In such a scenario, the Palmgren-Miner cycle ratio summation rule is expressed as

[tex]\frac {I_1}{L_1}+\frac {I_2}{L_2}=1[/tex]

By substitution

[tex]\frac {216000}{2478519}+ \frac {I_2}{532160.6 }=1[/tex]

[tex]I_2=485783.4659 rev[/tex]