Section Modulus calculation and optimization

Aim

To calculate section modulus of hood and optimize the design to have improved section modulus.

Section modulus:-

Section modulus is a direct measure of a strength of any cross sectional area of an object about an reference axis.

The formula of section modulus is given by,

S=I / Ymax

Where,
I = Moment of inertia (mm^4)
Y = Distance between neutral axes and outermost fiber (mm)

Steps to calculate section modulus:-

• Step 1:- Find location of centroid of given cross section.
• Step 2:- Find moment of inertia about neutral axis (INAINA)
• Step 3:- Find Ymax Ymax from neutral axis.
• Step 4:- Find elastic section modulus using the formula provided above.

Moment of inertia is nothing but offering resistance against the moment, bending or twisting. So higher the moment of ineria higher will be its resistance to deform is higher.

Here the sectional modulus of hood design before optimization

Momemt of inertia is calculated by NX-CAD software

I_max – 4.206967 x e^7 = 4613.288 (mm^4)

I_min – 1.296803 x e^5 = 7.882 (mm^4)

Y = Total length / 2

= 878.51/2

=439.255 mm

section modulus = 4613.288 / 439.255

= 10.5025 mm^3

Optimized design

Inorder to increase the sectional modulus, cross sectional area has to be increased. So here the optmized design:

I_max – 9.340214 x e^7 = 10242.7884 (mm^4)

I_min – 3.63918 x e^5 = 540.1022(mm^4)

Y = Total length / 2

= 878.51/2

=439.255 mm

section modulus = 10242.7884 / 439.255

= 23.3185 mm^3