Section Modulus calculation and optimization

AIM:-

Use the Section from our Hood design and caliculate the Section Modulus using the formula S = I/y

Section Modulus:-

• It is the ratio of area moment of inertia about the neutral axis and to the distance of outermost fiber from the neutral axis.
• Section Modulus is the ratio of total moment resisted by the section to the stress in the extreme fiber.
• Section modulus give us idea about how much of load the given structure can take.
• If the Section Modulus increases the moment of resistance increses and hence its load bearing capacity.
• S = I/y

Where,

S = Section Modulus

I = Moment of Inertia

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

Above the Hood challenge Section Modulus value of the part was caliculated after finding out the minimum moment of inertia value(I) and dividing it with the value of y.

Initially a datum plane was created to pass through the part's cross section there by showing us the cutsection of the part while using the ''Intersection curve'' command. then this was projected on to a sketch plane(outer curve of hood outer panel, outer curve of the hood inner panel) and joining to create a closed section.

Then ''section inertia analysis'' was performed on the existing section to find out minimum moment of inertia value.

We can say S is directly proportional to I. So when I increases S also increases which means bending resistance of the part increases. We know I = length*(depth^3)/12. So when we increase depth value, the value of S increases.

CASE 1

The following picture shows minimum MOI value for existing cross section of hood.

Moment of inertia(max) = 9.0165*10^4

Moment of inertia(min) = 2.6811*10^4

Value of y = 440mm

section Mod us = Moi (min)/y

=2.6811*10^5/440

= 609.34*10^3

CASE 2

The following picture shows minimum MOI for hood when innerpanel(outer layer) is offset by 0.5mm on dowmward direction to increase overall cross section.

Therefore S=I/y

=2.7531*10^5/440

= 625.70*10^3.

In this case optimisation was done by increasing cross section area of the part.

CONCLUSION

• By comparing the values we can clearly say that the section modulus of the optimized hood increases by 5.5%
• Moment of inertia increases by increasing depth of hood.
• It seems if we increase the gap between inner and outer panel also increases.