This data record should only be input for installed tethers.

     2   5  7   11          21         31         41
    - --- -- ---- ---------- ---------- ---------- ----------
   |X|XXX|  |TIFL|XXXXXXXXXX|XXXXXXXXXX|          |          |
    - --- -- ---- ---------- ---------- ---------- ----------
          |   |                             |          |
          |   |                             |          |
          |   |                             |          |_(2) Half Life (E10.0)
          |   |                             |
          |   |                             |_(1) Impact Factors (E10.0)
          |   |
          |   |_Compulsory Data Record Keyword (A4)
          |
          |_Optional User Identifier (A2)

(1) The stress impact factor.

The initial stress caused by tether impact is assumed to be proportional to the velocity of impact. The stress impact factor is the constant of proportionality, in other words.

initial axial stress = (stress impact factor)(impact velocity)

(2) The half life duration of the impact.

As the shock wave is reflected at the vessel and anchor ends it is assumed that the decay is exponential.

If the half life input above is t2, the axial stress due to the impact at a time t after impact is given by:

axial stress = initial axial stress * exp ( -0.69315 t/t2)