Section Modulus calculation and optimization

Section Modulus:
Section modulus is geometric property of a given cross section which is used in design of flexural members and also determines the strength of the steel.It can be increased by improving the geometry rather than adding additional material.
Section modulus (S): I/Y(max)
I-Area of moment of Inertia
Y(max)-Distance of extreme layer from neutral axis.
M/I = σ/Y
M = σ* S
σ = Yield strength
S = Section Modulus
Material Data- SS Steel AISI-302 cold rolled
Y = 520Mpa
1) Distance between inner & outer panel-13.76 mm (original design)

I(Max):4.96 * 1000000 mm4; Y-445.7mm
S= I/Y= 11128.5
M= 11128.5* 520
M=5786820 Nmm
2) Distance between inner & outer panel-17.76 mm (4 mm increase in distance)

I(Max):4.98 * 1000000 mm4; Y-445.7mm
S= I/Y= 11173.4
M= 11173.4* 520
M=5810168 Nmm
3) Distance between inner & outer panel-20.76 mm (7 mm increase in distance)


I(Max):5.0 * 1000000 mm4; Y-445.7mm
S= I/Y= 11218.3
M= 11218.3* 520
M=5833516 Nmm

Conclusion: Increase in the distance between the inner & outer panel results in slight increase of bending moment whereas the addition of new geometric feature will increase the stiffness drastically.