Reliability+Engineering

=What is it?= According to Wikipedia, "Reliability engineering is an engineering field that deals with the study, evaluation, and life-cycle management of reliability: the ability of a system or component to perform its required functions under stated conditions for a specified period of time. Reliability Engineering is a sub-discipline within Systems Engineering. Reliability is often measured as probability of failure, frequency of failures, or in terms of availability, a probability derived from reliability and maintainability. Maintainability and maintenance are often important parts of reliability engineering.

=The Problem= Reliability Engineering is a necessary evil that many refer to as an art more than a science particularly because it relies on opinion and experience rather than hard testing. in my experience most engineers that I have worked with shy away from doing any sort of reliability analysis which has forced me to learn a little about the field so that I may contract a firm to perform teh analysis for us.

=The Tools=

Mean Time Between Failure (MTBF).
According to Wikipedia "MTBF is the predicted elapsed time between inherent failures of a system during operation".

Failure Modes Effect and Criticality Analysis (FMECA)
According to Wikipedia, "FMECA is an extension of failure mode and effects analysis (FMEA). FMEA is a bottom-up, inductive analytical method which may be performed at either the functional or piece-part level. FMECA extends FMEA by including a //criticality analysis//, which is used to chart the probability of failure modes against the severity of their consequences. The result highlights failure modes with relatively high probability and severity of consequences, allowing remedial effort to be directed where it will produce the greatest value.



Fault Tree Analysis (FTA)
The FTA is another tool used for anticipating potential failures and their effects to the system. According to Wikipedia FTA is defined as "A top down, deductive failure analysis in which an undesired state of a system is analyzed using boolean logic to combine a series of lower-level events. This analysis method is mainly used in the field of safety engineering and Reliability engineering to determine the probability of a safety accident or a particular system level (functional) failure.

I find the FTA to be the ost usefull tool since it gives you a structured representation of the relationship of a piece part failure to the system as a whole. Below is an example of a FTA.

=Why is it important?= Doing reliability analysis early in the design process helps to identify things that need to be designed out of the system or mitigated some how. As an example my last project we identified that under a tension load if the product were to separate it would cause the pilot to lose control of the Yaw controls and could result in a fatal scenario. To mitigate the risk we did extensive testing on the fasteners holding the assembly together, and in the end doubled the number of fasteners to bring the risk down.

= TEM Degree Focus = I believe this needs to be part of both the electrical and mechanical degree programs. Depending on the discipline the engineer should have the ability to perform reliability analysis on their preliminary designs. I believe both of these programs contain the core classes required to perform this analysis, mainly advanced mathematics and mechanical / electrical theory. The current programs should be expanded to include a class on reliability analysis.

= Additional Reading = = = [] No MTBF is a website with the mission of the missuse and misunderstanding of reliability engineering. = =