Fatigue                 package:nlme                 R Documentation

Cracks caused by metal fatigue

Description:

     The 'Fatigue' data frame has 262 rows and 3 columns.

Format:

     This data frame contains the following columns:

     Path an ordered factor with levels '1' < '2' < '3' < '4' < '5' <
          '6' < '7' < '8' < '9' < '10' < '11' < '12' < '13' < '14' <
          '15' < '16' < '17' < '18' < '19' < '20' < '21' giving the
          test path (or test unit) number.  The order is in terms of
          increasing failure time or decreasing terminal crack length.

     cycles number of test cycles at which the measurement is made
          (millions of cycles).

     relLength relative crack length (dimensionless).

Details:

     These data are given in Lu and Meeker (1993) where they state ``We
     obtained the data in Table 1 visually from figure 4.5.2 on page
     242 of Bogdanoff and Kozin (1985).'' The data represent the growth
     of cracks in metal for 21 test units. An initial notch of length
     0.90 inches was made on each unit which then was subjected to
     several thousand test cycles.  After every 10,000 test cycles the
     crack length was measured.  Testing was stopped if the crack
     length exceeded 1.60 inches, defined as a failure, or at 120,000
     cycles.

Source:

     Lu, C. Joseph , and Meeker, William Q. (1993), Using degradation
     measures to estimate a time-to-failure distribution,
     _Technometrics_, *35*, 161-174

