Section Modulus calculation and optimization

Section Modulus calculation and optimization

OBJECTIVE:

• To calculate the section modulus for the previously designed hood and optimized hood.
• To come up with the new section that has improved section modulus of the previous section.

Section Modulus is given by the formula:-

S = I/y

Where,

S = Section Modulus

I = Moment of Inertia

Y = distance between the neutral axis and the extreme end of the object

Stainless steel AISI 302 is considered as material for the hood which is cold rolled with y = 520 MPa.

Cross-section of Hood: DESIGN 1

From the above analysis, following minimum and maximum moment of inertia are obtained

I_max = 5314.1438 mm⁴

I_min = 16.7511 mm⁴

y = 440 mm

S_max = I_max / y = 5314.1438 / 440 =12.0775 mm³

S_min = I_min / y = 16.7511 / 440 = 0.03807mm³

DESIGN 2:

Outer panel with 5mm offset towards inner panel with no geometry changes.

From the above analysis, following minimum and maximum moment of inertia are obtained

I_max = 5122.6735 mm⁴

I_min = 13.0259 mm⁴

y = 440 mm

S_max = I_max / y = 5122.6735 / 440 =11.1424mm³

S_min = I_min / y = 13.0259 / 440 = 0.0296 mm³

CONCLUSION:

• By comparing the values we can say that section modulus of the optimized hood of Design 2 is increased by 1 %.

From the formula we can see that the Section modulus is directly proportional to its Moment of Inertia.

Moment of Inertia is given as the “sum of the product of mass” of each particle with the “square of its distance from the axis of the rotation”.

Thus to increase the Moment of inertia we have to increase the gap between the outer and inner panel.