Question

For an antifriction bearing, normal life is 14282 hours at some load, the life of the same bearing at the same load for 40% reliability is

• A. 28162 hour
• B. 48126 hour
• C. 54986 hour
• D. 14282 hour

Answer 1

The correct option is C 54986 hour

Given:
$L_{10}=14282hour$

We know that
$\frac{L_R}{L_{10}}={\left[\frac{lo{g}_e\left(\frac{1}{R}\right)}{lo{g}_e\left(\frac{1}{0.90}\right)}\right]}^{1/1.17}\frac{L_{40}}{L_{90}}=\frac{L_{60}}{L_{90}}={\left[\frac{lo{g}_e\left(\frac{1}{0.60}\right)}{lo{g}_e\left(\frac{1}{0.90}\right)}\right]}^{1/1.17}=3.85L_{40}=3.85\times 14282=54985.7hour\simeq 54986hour$