Section Modulus calculation and optimization

Aim:

To find the section modules of the hood design and optimization of the design.

Section modulus:

1. Section modulus is the geometrical property for a given cross-section used in the design of beams or flexural members
2. If the section modulus increases the moment of resistance increases and hence it's load bearing Capacity
3. There are two types of section modulus, the elastic section modulus and the plastic section modulus.

Elastic section modulus.

For general design, the elastic section modulus is used, applicable up to the yield point for most metals and other common materials.

Formal of section modules is below

S=I/Y

S-section modulus

I-Moment of inertia

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

Plastic section modulus.

The plastic section modulus is used for materials where elastic yielding is acceptable and plastic behavior is assumed to be an acceptable limit. Designs generally strive to ultimately remain below the plastic limit to avoid permanent deformations, often comparing the plastic capacity against amplified forces or stresses.

How we have to find the section modulus of our designed hood??

As our NX we have to find moment of inertia of our designed hood by using NX cad software following comments are used

Step-1

We have to convert our hood geometrical drawing buy using inter section curve command

(We have choose entire assembly and we go with body face we have to choose mirror plane)

Now we get combined cross section of our hood design

Step-2

We Required closed section for the hood to find the moment of inertia

We have to edit our geometrical cross section by crating a plane a parallel to the mirror plan (the we sketch the sketch work bench)

Then we project the inter section curve and edit our hood and Mack closed the design and finish the sketch (we have to use the comment trim, and quick extend)

Step-3

After the we have to choose the section inertia command in analysis tab the we have to choose existing section and hole in section inertia tab

The we get the moment of inertia:

Step-3

Then we find the distance of x axis by using measure command

S=I/Y

I=7884.191 mm^4(Minimum MOI consider)

Y=488 mm

S=16.156mm^3

Step-4

The hood inner panel’s curve is offset by 5mm outwards and section inertia analysis is done same as case 1 for a closed curve.

S=I/Y

I=10440.68mm^4(Minimum MOI consider)

Y=488 mm

S=21.39mm^3

Conclusion;

To comparing the case 1 and 2

• The section modulus of value of case 2 is more than the case 1
• As we increase the section of area the MOI and SMI which means strength and load material also increase. which the MOI directly proportional to the strength of materials