Section Modulus calculation and optimization

 

SECTION MODULUS OF HOOD

 OBJECTIVE:

To find the section modulus of the hood and optimisation to improve the overall section modulus.

SECTION MODULUS:

Section modulus is a direct measure of strength of any sectional area of an object about a reference axis. This strength can be measured directly from Section modulus formula.

Formula of Section Modulus: It may be defined as the ration of total moment resisted by the section to the stress in the extreme fibre which is equal to yield stress.

 

S = I / Y

Where,

            S - Section modulus.

            I   -Moment of inertia.

            Y -The distance from the reference line (neutral axis) to one of the extreme ends of an object.

MOMENT OF INERTIA:

            Moment of inertia is nothing but offering resistance against of moment, bending or twisting.

FOR EXAMPLE

If we applied any external load on the body, how much resistance its offering to tend to deform. So, the higher value of moment of inertia, have higher resistance to deform under certain load, hence we can say that moment of inertia directly proportional to the strength of the material, and strength of the material can be calculated with the help of section modulus.

CASE 1:

 

Here I’m going to implement the same principle for my generated hood,

Fig 1

 

Fig 2

 

Here is the moment of inertia was calculated by using the NX-software,

Imax = 4.888374121e+006 [mm⁴]

Imin =  1.419703789e+004[mm⁴]

TOTAL LENGTH :

Total length = 874.4700mm

Y = TOTAL LENGTH / 2

Y = 874.4700 / 2

Y = 437.235mm

For  Imax

            S = I /Y

            S = 4.888374121e+006 [mm⁴]  / 437.235mm

            S = 11180.1985mm³

For Imin

            S = I /Y

            S = 1.419703789e+004[mm⁴] / 437.235mm

            S =  32.47 mm³

CASE 2 :

            Here I offset the inner panel by 1mm to outside, the results shown in below,

Fig 1

 

Fig 2

 

            Total length = 874.4700mm

Y = TOTAL LENGTH / 2

Y = 874.4700 / 2

Y = 437.235mm

For  Imax

            S = I /Y

            S = 4.885883389e+006 [mm⁴]  / 437.235mm

            S = 11174.502mm³

For Imin

            S = I /Y

            S = 1.477448040e+004[mm⁴] / 437.235mm

            S =  33.790 mm³

CONCLUSION:

            For Imax from the above calculations, the section modulus value decreased from 11180.1985mm³ to 11174.502mm³.

 

For Imin From the above calculations, I got an improvement in section modulus from 32.47 mm³ to 33.790 mm³.