Section Modulus calculation and optimization

Section modulus is the ratio of the total moment resisted by the section to the stress in extreme fiber.In easy language it is a geometric property for a cross-section used in design of beams or flexural members.It is also used to calculate bending stresses in a structural members.

Section Modulus(S) = Moment of Inertia(I)/distancebetween neutral axis and extreme end of the object(y)

Larger is the section modulus greater is the load bearing capacity.

I have calculated the section modulus of the hood design and given the details  :

1.Original Hood design

.

here M1 (minimum)=1.862*10^6 mm⁴ 

and M2(maximum)=1.47410^8 mm⁴

and the distance between end points is 478.281 mm hence the distance between the end point and the neutral axis is:

y=239.125mm.

Now 

Section Modulus(S1)=I/y=1.862*10^6/239.125=7786.722 mm 

This is the original section modulus of the hood design.

2.Modified Section Modulus

In the modified section modulus:

M1=2.018*10^6 mm⁴ 

M2= 1.586*10^8 mm⁴  

and the distance between end points is 478.166 mm hence the distance between the end point and the neutral axis is:

y= 239.083mm

Now 

Section Modulus(S2)=I/y= 2.018*10^6/239.083= 8440.689mm

Thus,S2>S1

Since this section modulus is greater than the original section modulus hence its correct to say that this design is able to sustain more loads and is more reilable.

This is the modified section modulus of the hood.