Section Modulus calculation and optimization of HOOD design
Section Modulus
Section modulus determines how much of load the section can withstand without failure .It is defined as the ratio of total moment resisted by the section to the stress in the extreme fiber. It is calculated by,
S = I/Y
Where, S - Section modulus (mm^3)
I - Min area Moment of inertia (mm^4)
Y – Distance between the neutral axis to the extreme end of the object (mm)
The moment of inertia (I) is a measure of a cross-section’s resistance to bending. It is calculated by integrating the area of the cross-section with respect to the square of the distance from the neutral axis.
The distance from the neutral axis to the outermost fiber (Y) is also known as the section modulus constant. It is the measure of how far the material is from its neutral axis to its farthest point.
Therefore, if the section modulus increases the moment of resistance increases thus the load bearing capacity increases. So, it is essential to calculate the section modulus for any structure before building it to ensure its safety and stability.
By calculating the section modulus, it is easy to evaluate the strength and deflection of a structural member under various loading conditions.
Case I (before Optimization)
The Hood which is already designed is imported and section inertia analysis is done.
As per the section modulus equation,
S = I/Y
( For I, MOI (min) value is considered and Y is Total distance/ 2 = 440.77995 mm )
Therefore,
S = 277825.15 (mm^4) / 440.78 (mm)
= 630.30 mm^3
S = 630.30 mm^3
Case II (After Optimization)
Hood inner panel’s curve is offsetted by 0.5 mm outwards and the section inertia analysis is done.
As per the section modulus equation,
S = I/Y
( For I, MOI (min) value is considered and Y is Total distance/ 2 = 440.77995 mm )
Therefore,
S = 281561.84 (mm^4) / 440.78 (mm)
= 638.78 mm^3
S = 638.78 mm^3
RESULT
Here, the section modulus value of case I is higher than the case II. Which means the strength of load material increased since the moment of inertia directly proportional to the strength of the material.