Section Modulus calculation and optimization
SECTION MODULUS CALCULATION AND OPTIMIZATION FOR THE DESIGNED HOOD (by: pramod mamillapalli)
Introduction:
we do this approach to find out the rigidity of the hood while in frontal crash. It will also helps to chech the boundaries of pedestrian safety. By the end we can conclude with best design having the better saftey.
Definations of Section Modulus:
It is defined as the ratio between the area of moment of inertia to the distance between the neutral axis and the extreme end of the object. Section modulus is indicated with letter "S".
It is written as,
S=I/Y
Where,
S = Section modulus,
I = Area of moment of inertia,
Y = Distance between neutral axis to the extreme end of the object.
Moment of Inertia (I):
It is one of the many mass properties that describe an object's stability and the forces needed to alter its motion. Its units are kg.m^2.
Case Study & procedure:
Note: This case study is always study the frintal impact i.e., the section is always perpendicular to the impact.
For step one on your assembly we have to create a datum plane at the centre of the hood with the help of %arc length as shown.
Then we have to remove the design assembly by only taking the intersection curves for calculating the section modulus analysis for moment of inertia.
Now sketch on the datum for connecting and trimming the extra lines to get the outer boundary and hide the assembly.
Then use the section modulus analysis we have to note three different value and calculate the different modulus and finalize the better design having stiffness. Note: Values vary at distance of 0.5mm only below the inner panel each time.
1st MOI value:
Now the minimum MOI = 1.32*10^4.
whereas,
y= 876.8/2 = 438.4mm will be constant.
now section modulus S1 =I/Y
S1 =1.32*10^4/438.4
S1 =30.1095mm3.
2nd MOI value:
Now the minimum MOI = 1.35*10^4.
whereas,
y= 876.8/2 = 438.4mm will be constant.
now section modulus S2 =I/Y
S2 =1.35*10^4/438.4
S2 =30.78mm3.
3rd MOI value:
Now the minimum MOI = 1.372*10^4.
whereas,
y= 876.8/2 = 438.4mm will be constant.
now section modulus S3 =I/Y
S3 =1.374*10^4/438.4
S3 =31.34mm3.
Now as per the above suty we measure three different types of MOI by making minute measurement changes in the design to find out the better stiffness in the panel.
conclusion:
Now we got the three S1,S2 and S3 values for the section modulus as 30.1095,30.78 and 31.34 mm3 follows. So hereby i can conclude that after studying these three case studies among all the values S3 gives a better value of saftey and rigidity for the hood. So the third result says the increasing in strengh for the hood.