The failure or hazard rate of a component is given by (life is in hours):
h(t)= \begin{cases}0.015, & t \leq 200 \\ 0.025, & t>200\end{cases}Thus, the hazard rate is piecewise constant.
Find an expression for the reliability function of the component
Using Equation 2.18 or Equation 2.33, we have
R(t)=\exp \left[-\int_0^t h(\tau) d \tau\right]R(t)=\exp \left(-\int_{\tau=0}^t h(\tau) d \tau\right)=\exp (-H(t)) (2.33)
R(t)=e^{-\int_0^t h(\tau) d \tau} (2.18)
For
0 \leq t \leq 200: R(t)=\exp \left[-\int_0^t 0.015 d \tau\right]=\exp [-0.015 t] .
For
\left.t>200: R(t)=\exp \left[-\left(\int_0^{200} 0.015 d \tau+\int_{200}^t 0.025 d \tau\right]\right)\right] \\=[-(0.015(200)+0.025 t-0.025(200))]\\=\exp [-(0.025 t-2)]=\exp [2-0.025 t].