Fatigue                 package:nlme                 R Documentation

_C_r_a_c_k_s _c_a_u_s_e_d _b_y _m_e_t_a_l _f_a_t_i_g_u_e

_D_e_s_c_r_i_p_t_i_o_n:

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

_F_o_r_m_a_t:

     This data frame contains the following columns:

     _P_a_t_h 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.

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

     _r_e_l_L_e_n_g_t_h relative crack length (dimensionless).


_D_e_t_a_i_l_s:

     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.

_S_o_u_r_c_e:

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