Section Modulus calculation and optimization
SECTION MODULUS CALCULATION AND OPTIMASATION:
OBJECTIVE:
- To calculate the section modulus for the hood design designed previously, and increse the moment of resistance comparatively.
SECTION MODULUS:
- Section modulus is the ratio of total moment resisted in section of hood to the stress in outermost fibre. It gives a clear understanding of load that can be withheld by the hood structure designed. It varies when the value of moment of resistance or the distance changes. In order to increase the section modulus, the moment of resistance should be increased.
- The formula for finding Section modulus is, S-l/y
- S is the Section moudulus,
- I is the moment of inertia and
- y is the distance from neutral axis to outermost fibre.
- Y is shown in above picture
Section Calculations:
Before the optimisation:
The minimum value of moment of inertia (1) = 7.569 10^-7 m^4
=756900 mm^4
The distance from the neutral axis to the outermost fibre (y) = 240.701 mm
Section modulus (S) =756900/240.701
=3144.565 mm^3
The maximum value of moment of inertia = 1.598*10^4 m^4
= 15980000 mm^4
The distance from the neutral axis to the outermost fibre (y) =240.701 mm
Section modulus (S) =15980000/240.701 mm
=5608.618mm^3 mm^3
After the Optimisation:
The minimum value of moment of inertia (I) = 7.959 10^-7 m^4
= 795900 mm^4
The distance from the neutral axis to the outermost fibre (y) =240.701 mm
Section modulus (S) =795900/240.701
=3306.59 mm^3
The maximum value of moment of inertia (I) = 1.35 *10^4 m^4
= 1350000 mm^4
The distance from the neutral axis to the outermost fibre (y) = 240.701 mm
= 240.701 mm
Section modulus (S) =1350000/240.701
= 66389.420 mm 3
COMPARISON:
The section modulus before optimisation = 3144.565mm 3 (Min)
=5608.618mm^3 (Max)
The section modulus after optimisation = 3306.59mm^3 (Min)
= 66389.420mm 3 (Max)
Section modulus before optimisation< Section modulus after optimisation
The inner panel of hood is offseted to 0.5mm to its downside and the section modulus after optimisation is comparetively higher than before. So, when the distance between the outer and inner panel decreases, the section modulus increases Which means it can with hold more pressure than the previous case.
CONCLUSION:
- The section modulus has been calculated for the hood design for both before and after optimisation. After optimisation the value of resistance seems better and would recommend to decrease the gap between two panels.