The simplest OTF model, in the following named OTF1, assumes to be small,
to be small compared to
and
, and
as constant (
)
[36, 49]. Equation (A.1) then simplifies to
![]() | (A.2) |
With only contributing to the total differential
![]() |
and by approximating yields
![]() | (A.3) |
Equating (A.2) with (A.3) finally gives
![]() | (A.4) |
Note the similarity to (2.9) in (A.4). Hence, OTF1 only requires the
determination during stress but neglects the mobility reduction described
by
and
.