# ACME Example

### From ReliaWiki

ACME manufacturing has implemented an accelerated life testing program for their new product design. A total of 40 units were tested at four different pressure levels. The operating stress level is 170 psi. The following table shows the data from the test. Determine the parameters of the inverse power law Weibull model and obtain the use level probability plot with 90% 2-sided confidence bounds on time.

Stress Level, psi | 220 psi | 230 psi | 240 psi | 250 psi |
---|---|---|---|---|

165 | 93 | 72 | 26 | |

177 | 106 | 73 | 44 | |

238 | 156 | 99 | 63 | |

290 | 170 | 124 | 68 | |

Times-to-failure, hr | 320 | 185 | 134 | 69 |

340 | 214 | 150 | 72 | |

341 | 220 | 182 | 77 | |

380 | 236 | 186 | 96 | |

449 | 252 | 190 | 131 | |

544 | 288 | 228 | 140 |

The parameters of the IPL-Weibull model are estimated to be:

The use level probability plot is shown next.

In ALTA, the confidence bounds on time are the Type 1 bounds (Time Bounds).