Reliability

It is defined as the probability that a given system will perform it’s function adequately for it’s specified period of lifetime under specified operating conditions.

Common measures are :

1. Failure rate.

2. Mean time between failures(MTBF)

3. Survival percentage.

Failure Rate:

Rate which components of population fail.

R(t)=N_s(t)/N_f(t)

Where,

N_s(t)- No. of components that survived during time ’t’

N_f(t) – No. of failures that occurred during the same time.

Mean time between Failures(MTBF):

The reciprocal of the failure rate(1/λ).

Where

λ —-Failure rate.

Failure rate = (No.of failure )/(Time period during all components were exposed to failure)

 

Reliability Analysis:

Failure Mode and Effect Analysis(FMEA)

Purpose :

1. To recommend design changes.

2. To identify design weakness.

3. To help in choosing alternatives.

Four Stages:

I^st Stage – System boundaries and the scope of the analysis is decided.

II^nd Stage – Data Collection

Ex: Specification,Operating Procedure,Working Conditions.

III^rd Stage– Preparing the component or parts list.

IV^th Stage – Failure frequency and the functions of the part identified,causes of       failures,Failure detection.

 

 

 

Explore posts in the same categories: MMM

Tags: common measures, design changes, failure detection, failure mode and effect analysis, failure rate, failure time, lifetime, mean time between failures, nbsp, nf, probability, reliability analysis, scope, stage data, stage system, survival, system boundaries, time period, time t, working conditions

You can comment below, or link to this permanent URL from your own site.