Section Modulus calculation and optimization
Section Modulus calculation and optimization
The main objective of this challenge is to calculate the section modulus of the hood design. The section modulus of the car hood is calculated using the tools and commands available in the NX cad, buy calculating the section modulus of the car hood we can know the strength of the car hood by section modulus formulae.
SECTION MODULUS It is defined as a direct measure of the strength of any cross-sectional area of an object about a reference axis.
Section Modulus - I/Y
I- Moment of inertia.
Y - Distance between the neutral axis and the extreme end of the object.
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 second moment of inertia, and polar second moment of area for the stiffness. Any relationship between these properties is highly dependent on the shape in question. Equations for the section moduli of common shapes are given below. There are two types of section moduli, the elastic section modulus, and the plastic section modulus. The section moduli of different profiles can also be found as numerical values for common profiles in tables listing properties of such.
There are many section modulus formulas available for different sections some of them are mentioned below-
| Cross-sectional shape | Figure | Equation | |
|---|---|---|---|
| Rectangle |  |
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| doubly symmetric (major axis) | 
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| doubly symmetric(minor axis) |  |
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| Circle |  |
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| Circular hollow section |  |
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The hood design that we are going to check the section modulus is -
From the center of this car hood, we can calculate the section modulus by following the ways
Apply the intersection curve command for the hood's inner panel and outer panel, we can get separate lines for that both, and then we have to join them in a proper way and then apply the section modulus and calculate the strength for that hood.
After we get the intersection curves we use the sketch option to join them to create a closed body and then the section inertia analysis function is used to obtain the values of moment of inertia of the body
CASE 1 -
Calculating the section modulus of original one without any changes
Given data
Maximum moment of inertia =1.55485*10^7 mm^4
Minimum moment of inertia = 7.3740*10^4 mm^4
Distance of the entire hood = 483.20mm
Y = 483.20/2
= 241.60mm
section modulus =minimum moment of inertia / Y
= 7.3740*10^4/ 241.60
=305.21 mm
Section modulus for the case 1 =305.21 mm
CASE 2
In this case we offset the inner panel to 3mm and provide with more embosses on the inner panel to test the section modulus under new scenario.
Given data
Maximum moment of inertia =1.585017*10^7 mm^4
Minimum moment of inertia = 1.046639*10^5 mm^4
Distance of the entire hood = 483.20mm
Y = 483.20/2
= 241.60mm
section modulus =minimum moment of inertia / Y
= 1.046639*10^5/ 241.60
=433.211 mm
Section modulus for the case 1 =433.211 mm
Conclusion - In these 2 cases we got to know that in case 1 we got a value of 305.21mm and when compared to the case which is when the inner panel is offsetted by 3mm along with aditional embosses we get 433.211 mm, so we can conclude that the when the value is increased the strength is also increased.