1. A specimen is loaded to a stress of 15,000 psi, and held, at  constant strain, for 4000 hours. Find the actual stress during the stress relaxation mode, at 100 hour increments, and plot it versus time.

For this material:

    a_r = 400
    n_r = 0.01
 
For reference,

    s = s_o - a_r Ln ( 1 + n_r t)        t is in hours, s in psi

2. Another specimen of the same material is loaded to a stress of 15,000 psi. Its initial elongation is 0.006". It is held, at constant load for 10,000 hours. Its creep deformation during this time is 0.004" (producing a total elongation of 0.01"). The load is then released and the elongation recorded for the next 4000 hours. Find the actual (total) elongation during the anelastic aftereffect mode, in 100 hour increments, and plot it versus time.

For this material:

  a_R = 0.001

For reference,

    e = a_R Ln ( 1 + n_r t)        t is in hours, e in inches

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