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.
this image shows the complete values.
i)CASE -1
Calculating the section modulus of original one without any changes-
The entire length of the intersection is shown below -
Given data
Maximum moment of inertia =4.776048*10^6 mm^4
Minimum moment of inertia = 1.4995099*10^4 m^4
Distance of the entire hood = 877.07mm
Y = 877.07/2
=438.53mm
section modulus =minmum moment of inertia / Y
= 1.4995099 * 10^4/ 438.53
=34.19 mm
Section modulus for the case 1 =33.23mm
CASE 2
In this method, we have to offset the inner panel to 0.5 mm outward and check the inertia for this one as same as, we did for the previous one-
GIVEN DATA-
MAXIMUM moment of inertia = 4.76934 * 10^6 mm^4
MINIMUM moment of inertia = 1.52064 * 10^4 mm^4
Distance of the entire hood = 877.07mm
Y = 877.07/2
=438.53mm
Section modulus S = Minimum moment of inertia / Y
= 1.52064 * 10^4 / 438.53
= 34.67 mm
CASE - 3
We are going to add some more embosses at the hood inner panel this is how it looks..
values obtained from this changed car hood panel
Given data =
max. Moment of inertia = 4.784296 * 10^6 mm^4
Min. Moment of inertia = 1.505336 *10^4 mm^4
Distance of the entire hood = 877.07mm
Y = 877.07/2
=438.53mm
Section modulus S = Minimum moment of inertia / Y
= 1.505336 * 10^4 / 438.53
= 34.32 mm
NOTE- In all the three cases we got to know that in case 1 we got a value of 33.23 mm and when compared to the case which is offsetted by the distance of 0.5 of inner panel towards downwards, then the value obtained was 33.36 mm so we can conclude that the value was increased so that we can say that the strength is also increased.
and in the case 3 we have added more embosses then the previous one so we have got another value which is different from the case 1 inner panel.
Conclusion: Section Modulus of Hood of the car was calculated and optimized section modulus with some changes or optimization and found some better results.