CRE Failure Analysis & Testing 3

Question 1

A Weibull plot of field failure data shows a shape parameter (β) of 0.5. This indicates the failures are most likely due to:

Accepted Answer

Infant mortality or early-life failures

Answer

A Weibull shape parameter β < 1 indicates a decreasing failure rate, characteristic of infant mortality failures caused by latent defects.

Question 2

In failure mode and effects analysis (FMEA), the Risk Priority Number (RPN) is calculated as:

Accepted Answer

Severity × Occurrence × Detection

Answer

RPN = Severity × Occurrence × Detection, where each factor is rated on a scale (typically 1–10) to prioritize corrective actions.

Question 3

Which failure analysis method uses dye to reveal cracks and surface discontinuities in non-porous materials?

Accepted Answer

Liquid penetrant testing

Answer

Liquid penetrant testing (PT) uses capillary action to draw dye into surface-breaking discontinuities, which is then revealed with a developer.

Question 4

The Inverse Power Law model in accelerated testing is typically applied when the accelerating stress is:

Accepted Answer

Voltage or mechanical load

Answer

The Inverse Power Law relates life to non-thermal stresses such as voltage, pressure, or mechanical load, where life is inversely proportional to stress raised to a power.

Question 5

During failure investigation, a 'witness mark' on a bearing component most likely indicates:

Accepted Answer

Contact or impact with another component during operation

Answer

Witness marks are impressions or rub marks left on a surface by contact with another component, indicating improper clearance or misalignment.

(CRE) Certified Reliability Engineer Practice Test

(CRE) Certified Reliability Engineer Practice Test

CRE Failure Analysis & Testing 3