Failure Analysis

The weibull hazard analysis is determined by value of the shape parameter:
h(x) - B/0 (x-d)/0 (B-1)
when B<1, The hazard function is decreasing,this is known as  the infant mortality period.
when B=1,the failure rate is constant
when B>1,the failure rate is increasing,this is known as the wear rate period
where B= the shape parameter
          0 = is the scale parameter
          d= is the location parameter.
There are few observed failure rate that could be accurately modeled.
by the weibull distribution,some specific causes are:
-The breaking strenght of components or the stress required to factigue metals.
-The time to failure for electronic components,
-The time to failure for items that wear out,such as automobile tyres and  
-systems that fail when the weakest components in the system fails (Dolson,1994)