CRE Design for Reliability 2

Question 1

In a Fault Tree Analysis (FTA), which gate represents an output event occurring only if ALL input events occur simultaneously?

Accepted Answer

AND gate

Answer

An AND gate in FTA produces the output event only when all of its input events occur, representing a situation where multiple failures must coincide to cause the top-level failure.

Question 2

Common Cause Failures (CCF) are particularly dangerous in redundant systems because they:

Accepted Answer

Can simultaneously defeat multiple redundant elements from a single shared cause

Answer

CCFs can simultaneously disable multiple redundant components due to a shared vulnerability (e.g., same environmental exposure, design flaw, or maintenance error), negating the benefit of redundancy.

Question 3

Highly Accelerated Life Testing (HALT) is primarily used during the design phase to:

Accepted Answer

Quickly find design weaknesses and operational/destruct limits by stressing beyond normal operating conditions

Answer

HALT applies stresses (thermal cycling, vibration, etc.) well beyond normal operating limits to rapidly precipitate and expose latent design weaknesses before production.

Question 4

Tolerance design (Taguchi method) in Design for Reliability focuses on making a design:

Accepted Answer

Robust and insensitive to variations in materials, manufacturing, and environment

Answer

Taguchi's robust design methodology aims to make product performance insensitive (robust) to noise factors such as manufacturing variation, component aging, and environmental conditions.

Question 5

Which reliability prediction standard is most commonly used for electronic components in US defense and aerospace applications?

Accepted Answer

MIL-HDBK-217

Answer

MIL-HDBK-217 is the most widely referenced US military handbook for electronic reliability prediction, providing failure rate models for a wide range of component types.

(CRE) Certified Reliability Engineer Practice Test

(CRE) Certified Reliability Engineer Practice Test

CRE Design for Reliability 2