T
1
=
Nmm
u
=
β
m
=
grade
z
1
=
Σ =
δ
1
=
K
A
=
K
v
=
K
Fα
=
K
Fβ
=
Y
Fa1
=
Y
Fa2
=
Y
Sa1
=
Y
Sa2
=
Y
β
=
Y
ε
=
Ψ
d
=
σ
FP1
=
MPa
σ
FP2
=
MPa
m
eF
=
mm