Section Modulus calculation and optimization

Aim: To calculate the section modulus of Hood and its optimizaition of Hood for better section modulus.

Section modulus:

Section modulus is defined as the ratio of moment of inertia of the cross section about the nutral axis to the distance of extreme fiber from the nutral axis. If a section has high section modulus than compare to others it has higher strength and supports great loads. It is denoted by S

Here,

S=I/Y

S= section modulus

I= moment of inertia

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

Here, calculating the section modulus of hood which is taken from the Hood challange. So here we take the section of our hood design for calculation, we take the section along the length of the hood and find the moment of inertia using inertia anaiysis tool in NX cad.

Procedure:

From hood design take the intersection curves of hood outer and inner pannel using intersection curve tool.

No take outer curve of the outer pannel and outer curve of the inner pannel using composit curve tool.

create the points on the ends of the outer pannel curve and Trim the edges, join them using lines.

using the join command join all the curves as a single curve and make it smooth using smooth tool.

Now using inertia analysis tool select the curve to find the moment of inertia. 

Here, the values are

I(max)=  4.7385e+05[mm^4] 

I(min)= 544.2860[mm^4]

Y = 488.325 mm

Calculations:

S(section modulus)= I/Y

Y = 488.325/2=244.162

S(max)=`4.7385x10^5mm^4`/244.162mm`

S(max)= `19.40x10^2 mm^3`

S(min)= `544.2860mm^4/244.162mm`

S(min)= `2.22 mm^4`

Optimization:

In optimization we modify the the section by reducing the gap between the outer pannel and inner pannel curve by 1mm and joined the together to find the moment of inertia, then we compare the both the section value to find which section has better strength and load baring capacity compare to the perivous section.

Here, the modified section values

I(max)= `4.7386x10^5 mm^4`

I(min)=`544.371mm^4`

Y= 488.325 mm

Calculation:

S=I/Y

Y=488.325/2=244.162

S(max)= `4.7386x10^5mm^4`/244.162mm`

S(max)= 19.40x10^2mm^3

S(min)= `544.371mm^4/244.162mm`

S(min)= 2.22mm^4

Comparsion table:

The values are taken for section before modification and after modification 

section	values	modified section	values
I max	4.7385x10^5mm^4	I max	4.7386x10^5mm^4
I min	544.2860mm^4	I min	544.371mm^4
S max	19.40x10^2mm^3	S max	19.40x10^2mm^3
S min	2.22mm^4	S min	2.22mm^4
Y	488.325mm	Y	488.325mm

Conclusion:

In this project the section modukus is same for the both the sections. After modification of section by reducing the gap by 1mm between the 2 pannels the monent of inertia is little bit changed that is I (max) is 4.7385x10^5mm^4, I (min) is 544.2860mm^4 and  I(max)= `4.7386x10^5 mm^4, I(min)=`544.371mm^4`. In my case monent of inertia is increased from perivous section and section modulus is same, So the there is no increase in strength of hood.