Section Modulus calculation and optimization

Section Modulus:

Section modulus is the ratio of Area moment of inertia and the distance from neutral axis to an extreme end of the object. There are two types of section modulus is considered. One is Elastic Section modulus and Plastic Section modulus.

• Elastic section modulus is considered for a structural material such as, Beams, C-channel.
• Plastic section modulus is considered where the plastic behaviour is in acceptable limit.

What is the need of section Modulus:

Section modulus is calculated to find the stiffness of the object. The more value of the section modulus is has more resistance of bending. It changes according to the area moment of ineria. When, the area moment of inertia increaeas, It also increases the section modulus.

It is defined as,

S = I / Y

Where,

S - Section Modulus,

I - Area moment of inertia

Y - Disatnce from the neutral axis to an extreme end of the Object.

Here, I take the Section Modulus calculation for my Hood.

CASE - I:

Maximum Moment of Inertia (MOI) :- 4.838635363e+06 (mm^4) = 4838635.363 (mm^4)

Minimum Moment of Inertia (MOI) :- 1.417192338e+04 (mm^4) = 14171.92338 (mm^4)

The distance of Hood :- 879.5 mm

The distance from the neutral axis :- 879.5/2 = 439.75mm

Here, I considered Minimum Moment of Inertia.

S = I / Y

S = 14171.92338 / 439.75

S = 32.227 (mm^3)

CASE - II:

In order to increase the Section modulus Hood, we have to increase the Area moment of inertia. So that, I have offset the hood inner panel bottom edge by 2mm.

Here, I got the new Moment of Inertia Values.

Maximum Moment of inertia (MOI) :- 4.836077950e+06 (mm^4) = 4836077.950 (mm^4)

Minimum Moment of Inertia (MOI) :- 1.495189742e+04 (mm^4) = 14951.89742 (mm^4)

The distance from the neutral axis :- 439.75 mm

S = I / Y

S = 14951.89742 / 439.75

S = 34.000 (mm^3)

From the above calculations Case - II Section Modulus is Higher than Case -I Section Modulus.

So, The Resistance of Bending of Case - II Hood will be higher than Case - I Hood.