Weibull Analysis In Excel

The Facts For A Weibull Plot

i-values

1 37 0.109375 -2.15561601 3.610918 A Weibull function is provided in Excel for the CDF and PDF values2 63 0.265625 -1.17527042 4.1431353 69 0.421875 -0.60154355 4.2341074 73 0.578125 -0.14728704 4.290459 note x must be greater than zero5 108 0.734375 0.281917795 4.6821316 140 0.890625 0.794336831 4.941642

Excel Regression Stats2.361 0.632121

92.672 0.009373

0.9508

SuperSMITH Weibull Stats Given (change any value in the yellow boxes):2.361 b h

92.672 2.361 92.672

0.9500

Refer to The New Weibull Handbook, 5th edition, by Dr. Robert B. Abernethy for nomenclature

Data To Use For Excel Regression

Also refer to International Standard

X-age to failure sorted

Y-plot position

Use This Date For

X-axis

Use This Date For

Y-axis

Weibull(x,alpha,beta,trueWeibull(x,alpha,beta,false

note alpha in Excel is the Weibull slope note beta in Excel is the Weibull characteristic valueThe Weibull function in Excel

b= <--Using the Excel Weibull function for X-age to failure @ 92.672 we get the expected h= <--Using the Excel Weibull function for X-age to failure @ 92.672 we get the expected

R2 = The Weibull CDF = 1-exp(-(x/The Weibull PDF = (b/(

b=h=

R2 =

A Weibull function is provided in Excel for the CDF and PDF values

note x must be greater than zero

Weibull reliability R = 1-CDF

Given (change any value in the yellow boxes):x CDF PDF R H(t)

92.672 ----------> 0.632121 0.009372 0.367879 0.025477

The New Weibull Handbook, 5th edition, by Dr. Robert B. Abernethy for nomenclatureAlso refer to International Standard IEC 61649 Edition 2.0 2008-08 for the same nomeclature as The New Weibull Handbook

Weibull(x,alpha,beta,true) <--provides the cumulative distribution function, CDF, at the value of xWeibull(x,alpha,beta,false) <--provides the probablity density function, PDF, at the value for x

note alpha in Excel is the Weibull slope bnote beta in Excel is the Weibull characteristic value h

The Weibull function in Excel will not take a data set and return the b and h values!<--Using the Excel Weibull function for X-age to failure @ 92.672 we get the expected CDF<--Using the Excel Weibull function for X-age to failure @ 92.672 we get the expected PDF

The Weibull CDF = 1-exp(-(x/h)^(1/b))The Weibull PDF = (b/(h^b))*(x^(b-1))*exp(-1*(x/h)^b) Instanteous failure rate = H(t)=(b/h)*(x/h)^(b-1)