Section Modulus

Aim

To determine the section modulus, utilize the section from your Hood design and provide a brief explanation of the concept.

Introduction

About section modulus:

It's a theory that evaluates a cross-section's capacity to bend. Flexural members are designed with this geometric characteristic in mind. The bending resistance of a structural part increases with section modulus. Section modulus often comes in two varieties: elastic and plastic.

We need to grasp cross-sectional dimensions (height, breadth, etc.) to calculate the section modulus before we can talk about how to do so. Cutting a 3D structural object, such as a beam, column, slab, etc., perpendicular to its length yields the cross-section of that object.

Calculation of The Section Modulus:

W: section modulus

I: area moment of inertia

Y: distance from the neutral axis to any given fibre of the cross-section

Just like the section modulus, the moment of inertia is a geometric property of a cross-section. Any point within a cross-section is essentially a fiber of that cross-section.

the picture's designated point P The fiber is above.

The section modulus is computed for the fiber in structural design that experiences the maximum stress since it is typically the one that is located furthest from the neutral axis (y and z).

In the case of a rectangular cross-section, those would be the fibers on the top or bottom edge.

And, in a rectangular cross-section for the z-axis, it is the outermost fibres on the left and right.

Let's now compute the cross-sectional area modulus of a rectangle.

The moment of inertia (Iy) and the distance from the neutral axis (Yz) are required to compute the section modulus.

The equation for the area moment of inertia for a rectangle shape

Iy= h3 * w12

The farthest point from the neutral axis, y, is represented by half of the cross-section height.

Y=h2

Analysis

Section modulus of the Hood design:

Creating a cross-section for the section modulus analysis of the frontal impact.

• Create a datum plane in the middle of the hood.

• Take the intersection along the datum plane.

• Create a sketch along the datum plane and using the project curve, project the intersection curve to the sketch and complete the sketch.

Section Inertia analysis of the primary Cross section.

• Select the Section inertia analysis option and opt existing section option.

• Select the sketch, provide the hollow thickness of 0.75 and do the analysis.

• For calculation, we utilise the MOI(Min) value.

• I(Min)=2.806563925*105mm4

• Y is the distance from the Neutral axis to the end which is half of the total length.

• Y= (876.8065/2)mm =438.40325mm

Wp =IMinY=2.806563925*105mm4(438.40325)mm= 640.178631203 mm3

Section Inertia analysis of the Modified Cross section.

• Edit the Primary cross-section and create a downward offset of 0.5mm.

• Create a new sketch and project on the upper section and the offset section and create a new closed sketch.

• Select the Section inertia analysis option and opt existing section option.

• Select the sketch, provide the hollow thickness of 0.75 and do the analysis.

• For calculation, we utilise the MOI(Min) value.

• I(Min)=2.842146909*105mm4

• Y is the distance from the Neutral axis to the end which is half of the total length.

• Y= (876.8065/2)mm =438.40325mm

Wp =IMinY=2.842146909*105mm4(438.40325)mm= 648.295127602 mm3

Conclusion

The section from the Hood design has generated a 640.178631203 mm3 section modulus. Which also improved to 648.295127602 mm3 by offsetting the below surface’s section by 0.5mm.