# Reliability | Reliability Analysis | Methods | Failure Rate | Mean Time Between Failures | MTBF | Failure Mode Effective Analysis | FMEA

## Reliability Analysis

Reliability Analysis is defined as the probability that a given system will perform its function adequately for its specified period of a lifetime under specified operating conditions.

## Reliability Analysis Common measures are :

1. Failure rate.

2. Mean time between failures(MTBF)

3. Survival percentage.

### Failure Rate:

The rate at which components of the population fail.

R(t)=Ns(t)/Nf(t)

Where,

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

Nf(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)

## Failure Mode and Effect Analysis(FMEA)

### The purpose of FMEA:

1. To recommend design changes.
2. To identify design weaknesses.
3. To help in choosing alternatives.

## Four Stages of Reliability Analysis:

Ist Stage – System boundaries and the scope of the analysis are decided.

IInd Stage – Data Collection

Ex: Specification, Operating Procedure, Working Conditions.

IIIrd Stage: Preparing the component or parts list.

IVth Stage – Failure frequency and the functions of the part identified, causes of failures, Failure detection.