Section Modulus calculation and optimization
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.
Answer:
Section Modulus:
- It is defined as the ratio of the moment resisted by the section to the stress in the extreme fibre.
- It gives an idea that most of the work in bending is being done by the extreme fibres of the beam, i.e the top and bottom fibres of the section.
- The distance of the fibres from top to bottom is therefore built into the calculation.
- If the section modulus increases and hence its load bearing capacity.
- A section that has longer section modulus than another will be stronger and capable supporting greater loads.
Calculation of Section Modulus:
- In this challenge I have taken my designed hood for calculation.
- To calculate the moment of inertia , I have taken the hood section along the length of hood & find the inertia using section inertia analysis tool in NX CAD.
- Then , the section modulus is calculated using the given formula i.e.
S = I/Y
Where,
S = Section Modulus
I = Moment of Inertia
Y = Distance between the neutral axis and the extreme end of the object.
Overall Distance of Hood Section
Moment of Inertia of Hood Section:
Moment of inertia with normal condition:
From the given above section we can calculate the section modulus from the formula,
s = i/y
I = moment of inertia(moi) = 3.1226*10^5mm^4
Y = Distance from neutral axis to extreme end = 439.7mm
Hence , S = 7.10mm^5
Similarly I have prepared a chart to optimize the section modulus , by extending the lowermost edge of inner panel and then calculated the moment of inertia for each extension of inner panels edge:
From the given above section we can calculate the section modulus from the formula,
s = i/y
I = moment of inertia(moi) = 4.3264*10^5mm^4
Y = Distance from neutral axis to extreme end = 439.7mm
Hence , S = 9.83mm^5
CONCLUSION:
- The section Modulus of my hood section is 7.10mm^5.
- After extending the lowermost edge of the inner panel & calculating the section modulus , we found that witn the extent of lowermost edge of inner panel by 0.5mm.
- Thus the extension section modulus is 9.83mm^5.
- As the largest section modulus has the better capability to withstand the load.