Section Modulus calculation and optimization

AIM:-

To calculate the section modulus of the given hood panel for analyzing its strength and also optimizing the design to see differences in the bending strength of the hood.

Section modulus

Section modulus is defined as the ratio of moment of inertia and distance from the Neutral axis to the extreme fiber. Section modulus is a geometric property for a given cross-section used in the design of beams or flexural members. Other geometric properties used in the design include an area for tension and shear, the radius of gyration for compression, and the moment of inertia, and the polar moment of inertia for stiffness.

S=I/Y

S= Section Modulus

I= Moment of Inertia

Y= Distance between the neutral axis and the extreme fiber

Moment of inertia of different shapes

There are two types of section modulus

• Elastic section modulus
• Plastic section modulus

Sectional modulus analysis

Here we calculate the elastic sectional modulus

Case 1

• Take the intersection of the hood with the YZ plane.

• Then the curve needs to be closed one so take the top surface to intersect the hood outer panel and lower surface of the hood inner panel. Then trim all the intersect and line to create a close curve. Finally, fill the curve.

As per the section modulus equation

S=I/Y

Where Moment of inertia(M1)= 1.668*10^6 mm^4

Moment of inertia(M2)= 1.853*10^8 mm^4

Distance between the neutral axis and the extreme fiber(Y)= 489.595/2 =244.7975 mm

So S= 1.668*10^6/ 244.7975 = 6.813 *10^3 mm^3

Therefore Section modulus(S)= 6813.79 mm^3

Case 2

• The hood inner panel curve is offset by 0.5 mm outwards and section inertia analysis is done the same as in case 1 for a close curve.

S=I/Y

Where Moment of inertia(M1)= 1.734*10^6 mm^4

Moment of inertia(M2)= 1.9*10^8 mm^4

Distance between the neutral axis and the extreme fiber(Y)= 489.595/2 =244.7975 mm

So S= 1.734*10^6/ 244.7975 = 7.083*10^3 mm^3

Therefore Section modulus(S)=7083.4 mm^3

Result

Case 1: S= 6813.79 mm^3

Case 1: S= 7083.4 mm^3

By changing the distance of the inner panel to 0.5 mm the section modulus value also increases. So we can by ching the distance to 0.5 mm the section modulus also increases.

Conclusion:-

Section modulus is successfully determined and improved by section area.