Section Modulus calculation and optimization

Section Modulus

It is termed as the ratio of second moment of area and distance from N.A (Neutral axis) to the extreme fibre. Also, it is a measure of the strength of a given member. The stress in the outermost section of beam is computed with the help of section modulus. This is indicated by S.

Section modulus is indicated as follows: S = I/Y (mm^3)

Where,

I -- Moment of inertia.

Y -- Distance from neutral axis to extreme end of the section.

Importance:

• It is significant for beam and flexural member design.
• The more section modulus, the more the member is resistant to bending of the beam.
• It is easier to calculate stresses in beam and an exact measure of strength of steel.
• If two beams are made of the same material and comparing the “section modulus” of two beams, the beam with bigger section modulus will be tougher and more capable to withstand larger loads.

Section modulus calculation

A horizontal section of the hood was taken on the plane and neutral axis was drawn.

Distance from neutral axis to the extreme end of the section was measured.

i.e. Y = 430mm.

To that section ‘Section Inertia Analysis’ was applied and Moment of Inertia was noted down.

Section--1

MOI (min) = 1.11*10^4 mm^4

S = 1.11*10^4/430 = 25.81 mm^3

Section--2

Now, by increasing the area of the section and then calculated

MOI (min) = 1.3*10^4 mm^4

S = 1.3*10^4/430 = 30.23 mm^3

Conclusion

Comparing the values of the area and the section modulus of both the sections.

By increasing the area, section modulus of the section increases. Which automatically increases strength.