460
8. If El is known, calculate E2 using E12 from Equation F.1 and the
explicit form of Equation 6.8 which is
E (t +t ) -Et
E = 12 1 2 1 1 Eqn. F.3
t
2
9. If El is known, calculate E2 using E12 from Equation F.2 and the
explicit form of Equation 6.9 which is
(t + t )(E )/3 t (E )1/3
E2 = [ 2 12 1 1 ]3 Eqn. F.4
t
2
10. Compare E2 from steps 8 and 9; use an average, if possible.
11. If El is unknown, use an average value of E12 calculated from Equa-
tions F.1 and F.2, if possible, and t1 + t2 as composite layer
thickness.
12. Calculate E3 using Equation F.5.
E3 = 8.7451(D3 D )-1.0919 Eqn. F.5
13. Calculate E4 from Equation F.6.
E, = 5.40(D,)-1.0 Eqn. F.6
Note that in Equations F.1 through F.6 modulus Ei is in ksi,
deflection Di is in mils, and thickness, ti in inches.
14. Use E E2, or E12 ; E3 and E4 in an elastic layer computer program
to calculate Dynaflect deflections, Di through D5 with coordinates
corresponding to that of Figure F.1. Reasonable values of