Section Modulus calculation and optimization

OBJECTIVE: To increase the Section Modulus of the hood by necessary changes using NX cad.

SECTION MODULUS:

It is termed as the ratio of the second moment of area and distance from N.A (Neutral axis) to the extreme fiber. Also, it is the measure of the strength of the given member. The stress in the outermost section of the beam is computed with the help of section modulus. It is indicated by S.

Section modulus is indicated as follows:

S-I/Y

Here, I is "moment of inertia" and y is the distance from the "neutral axis" to the top or bottom of fiber.

The Unit of a "section modulus" is in.3 (mm3)

Section modulus depends only on the cross-section shape of the structure. For symmetric sections, the value of "section modulus" is for both above and below of centroid of the fiber. An asymmetric section has two values for top and bottom of the fiber due to different distance from the centroid to the top and bottom of the material, the maximum "section modulus" is S max and the minimum section modulus is S min.

Importance:

. It is significant for beam and flexural member design.

• More the section modulus, the more the member is resistant to the bending of the beam.

. It is easier to calculate stresses in the beam and an exact measure of the strength of steel

• If two beams are made of the same material and comparing the "section modulus" of two beams, the beam with bigger section modulus will be tougher and more capable to withstand larger loads.

Section Modulus calculation of the Hood Design:

CASE 1: Initial Hood Design.

Area Moment of Inertia: (min)

MOI (Min):2.675961517e+05[mm]

CASE 2: Optimized Hood Design

Aim: Our Aim here is to increase the I(min)

MOI:(Min):2.822556776e+05[mm*] (increased)

Changes made: I increased the distance between the outer hood panel & the inner hood panel.

S-1/Y

S-2.822556776e+05 mm 4/476.5mm

S-11.2909636863

Schedule

Final result: Thus the stiffness of the car hood has been increased by increasing its area moment of inertia.

Conclusion:

Section modulus is directly dependent on the area moment of inertia and the distance from the neutral axis. Hence, to improve the geometry of the carry more bending load, the section modulus can be improved by increasing the area MOI of a given section. We can increase the section modulus just increasing the gap between the outer & inner panel.