Section Modulus calculation and optimization

Section modulus

Section Modulus is the geometric property of the given cross-section of any shaft or beam structures. It is the direct measure of the strength of the shaft section or the beam section. Higher the section modulus of a structure, the more the resistive it becomes to bending. Section modulus is defined as the ratio of polar moment of inertia to the radius of the shaft or the distance from the neutral axis to the outer fibres.

An object’s polar moment of inertia is its ability to resist deflection due to an applied torque. It is largely based on the cross-section of an object along the axis to which torque is applied. If we put it in simple terms polar moment of inertia is the resistance offered by a beam or shaft when it is being distorted by torsion. This opposition usually arises from the cross-sectional area and it should be noted that it does not depend on the material composition. If the polar moment of inertia is of higher magnitude then the torsional resistance of the object will also be greater. More torque will be required to turn the object at an angle.

The formula for section modulus is,

S = I/Y

Where,

S = Section Modulus

I = Moment of Inertia

y = distance between the neutral axis and the extreme end of the object.

Calculations

1st Section

Section modulus = Moment of inertia / distance between the neutral axis and the extreme end of the object

I = 160034.0253 mm^4 ; y = 1072.21 mm

Therefore, S = 160034.0253/1072.21 = 149.25 mm^3

2nd Section

Section modulus = Moment of inertia / distance between the neutral axis and the extreme end of the object

I = 172493.9589 mm^4 ; y = 1072.2313 mm

Therefore, S = 172493.9589/1072.2313 = 160.87 mm^3

Conclusion

We can see here that by increasing the distance between two panels we can increase the section modulus of the section. so the strength of the section will also increase evantually.