CRE Life Data Analysis 3

Question 1

In accelerated life testing (ALT) data analysis, the Arrhenius model relates failure acceleration to:

Accepted Answer

Temperature in Kelvin

Answer

The Arrhenius model uses absolute temperature (Kelvin) and an activation energy to model thermally-driven acceleration of failure rates.

Question 2

A Weibull probability plot shows data points curving upward (concave up) rather than forming a straight line. This most likely indicates:

Accepted Answer

A mixed population or two failure modes

Answer

Upward curvature on a Weibull plot often signals a mixed (competing) failure mode population, where two distinct subpopulations are present.

Question 3

The B10 life of a component refers to the time by which:

Accepted Answer

10% of units have failed

Answer

BX life (here B10) is the time at which X% of the population has failed, so B10 is the 10th-percentile failure time.

Question 4

Maximum Likelihood Estimation (MLE) is preferred over rank regression for life data analysis primarily because:

Accepted Answer

It handles censored data more rigorously and is asymptotically efficient

Answer

MLE properly incorporates censored observations into the likelihood function and achieves the Cramér-Rao lower bound efficiency for large samples.

Question 5

For a 3-parameter Weibull distribution, the third parameter γ (gamma) represents:

Accepted Answer

A guaranteed failure-free (location) period

Answer

The location parameter γ shifts the distribution so that no failures can occur before time γ, representing a failure-free period.

(CRE) Certified Reliability Engineer Practice Test