Section Modulus calculation and optimization

Section Modulus

Section modulus is a geometrical property related to the cross-section area of a flexural member. Section modulus is of two types, elastic section modulus, and plastic section modulus.

The expression to calculate the elastic section modulus is,

Where ‘s’ is the section modulus of a cross-section, ‘I’ is the moment of inertia of a cross-section, and ‘y’ is the distance from the neutral axis.

Section Modulus of an Automobile Hood.

Case-1

Substitute the values in the above expression of section modulus,

The section modulus for the given cross-section area is 399.5mm³.

Case-2

The cross-section area is changed by changing the height of the emboss and outer hood.

Substitute the values in the above expression of section modulus,

The section modulus for the given cross-section area is 399.6mm³.

Case-3

The cross-section area is changed by changing the height of the emboss and outer hood.

Substitute the values in the above expression of section modulus,

The section modulus for the given cross-section area is 4mm³.

Conclusion

The section modulus greatly depends on the moment of inertia and the distance from the neutral axis. For better strength, the section modulus has to be higher, and it greatly depends on the cross-section area since the distance from the neutral axis can not shorten much.