Basics of Reliability Modeling

Question 1

Reliability, Availability, Maintainability

Answer 1

• Reliability: the system’s ability to perform its function without failures in a given period of time
• Availability: the system’s ability to be operational at a given point in time
• Maintainability: the system can be repaired within a certain period of time

Question 2

Safety assessment methods

Answer 2

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Question 3

Simplification Safety assessment methods

Answer 3

• For reliability calculations we can assume to operate the components in the constant failure rate regime, therefore we can use λ = const., then also λ = 1/MTBF holds true
• Since failure rates are usually small and are oftentimes based on a flight time of one hour, we can also state that λ*t «1. We can further assume that the component works properly in the beginning of the analysis (Pc,0= 1, Pf,0= 0)
• f the components of a system are assembled in a series, then the following expression can be used: 𝜆𝑠𝑦𝑠=𝜆𝐴+𝜆𝐵

Question 4

Mean Time Between Failures (MTBF)

Answer 4

This quantity describes the arithmetic mean between failures of a technical system T4 F7