Section Modulus Calculation and Optimization

Objective:

To calculate the Section Modulus of the Hood of a car (Already designed) for analyzing its strength.

Also altering the design of the hood to increase the value of section modulus, thus increasing the strength of the Hood by comparing both the values.

What is Section Modulus:

Sectional Modulus is the ratio of Moment of Inertia (I) of the beam cross section about the neutral axis to the distance (Y) of Extreme fiber from neutral axis. A beam that has a larger section Modulus than another will be stronger and capable of supporting greater loads.

Moment of Inertia is nothing but offering resistance against moment, twisting or bending. If any external load is applied on the body, how much resistance its offering to tend to deform. Higher the value of moment of inertia, higher the resistance to deform under certain load.

Question:

Use the Section from your Hood design and calculate the section modulus using the formula S = I/y

S = Section Modulus

I = Moment of Inertia

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

Come up with a new section that has improved the section modulus of the previous section and mention what change you made that has increased the strength.

By using the above principle, we are going to calculate the Section Modulus of the given Section from the Hood.

The values were obtained using Nx Cad Software.

I_MAX = 4.016e+06[mm^4]

I_MIN = 1.184e+04[mm^4]

Total Length Y =Y/2 = 828.9/2 = 414.45mm

• Section Modulus(S) = I/Y = 1.184x10⁴mm⁴/414.45mm

= 28.56 mm³ (Min Strength)

Hood Design Optimization:

Now increasing Depth by 0.5mm, we get

I_MAX = 4.032e+06[mm^4]

I_MIN = 1.257e+04[mm^4]

Total Length Y =Y/2 = 828.9/2 = 414.45mm

• Section Modulus(S) = I/Y = 1.257x10⁴mm⁴/414.45mm

= 30.33 mm³ (Min Strength)

Conclusion:

The difference can be seen as we increased the depth of the model, the Moment of Inertia increases and the strength also increases.