Section Modulus calculation and optimization

Briefly Explain the Section Modulus :

it is the ratio of the moment of inertia of a section about the neutral axis to the distance of the outermost layer from the neutral axis

The elastic section modulus is defined as S = I / y, where I is the second moment of area (or moment of inertia) and y is the distance from the neutral axis to any given fiber. It is often reported using y = c, where c is the distance from the neutral axis to the most extreme fiber, as seen in the table below.

is denoted by S:

Formula: S=I/Y

where,

S = Section modulus

I= Moment of Inertia (Unit mm 4)

Y= Distance from the Neutral axis to the extreme end (unit mm)

The Unit of a “section modulus” is (mm3)

SECTION #1

• I have taken my design hood, for the calculation.
• To calculate the moment of inertia, I have taken the hood section along the length of the hood & find the inertia using the 'section inertia analysis' tool in NX CAD.
• Then, the section modulus is calculated using the given formula i.e.

S = I/y

Where,

S = Section Modulus

I min = moment of inertia(min.) = 2.892209129*10^⁵ mm^4

Y = distance from neutral axis to extreme end =(L/2)= 876.4625/2 = 438.23125

S = 2.8922 x 10^⁵ / 438.23125

S = 659.973mm^³

I have optimized the hood section Area by offsetting downward 0.5mm of the hood inner panel for the calculation to get

more strengthen the hood panel.

SECTION #2

• I have taken my design hood, for the optimized calculation.
• To calculate the moment of inertia, I have taken the hood section along the length of the hood & find the inertia using the 'section inertia analysis' tool in NX CAD.
• Then, the section modulus is calculated using the given formula i.e.

S = I/y

Where,

S = Section Modulus

I min = moment of inertia(min.) = 2.940410025x10^⁵

Y = distance from neutral axis to extreme end =(L/2)= 876.4625/2 = 438.23125

S = 2.940410025x10^5 / 438.23125

S = 670.972mm^³

section#1

S = 659.973mm^³

section#2

S = 670.972mm^³

1. The section modulus value of section#2 is higher than section#1

2. after we have increased the section area by 0.5mm, the moment of inertia & section modulus values increase. which means strength and load material also increases.