Section Modulus calculation and optimization

SECTION MODULUS CALCULATION AND OPTIMIZATION

AIM

Use the section from hood design and calculate the section modulus using the formula S=I/Y

S=Section modulus

I=Moment of Inertia

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

SECTION MODULUS

It is the ratio of moment of inertia (I) of the beam cross-section about the neutral axis to the distance (y _max) of extreme fibre from the neutral axis, Z =I/Y_{m a x}.

MOMENT OF INERTIA:

It is a measure of an object’s resistance to changes to its rotation.

• Also defined as the capacity of a cross-section to resist bending.
• It must be specified with respect to a chosen axis of rotation.

NEUTRAL AXIS:

The neutral axis is a line or plane through a beam or plate connecting points at which no extension or compression occurs when it is bent.

CALCULATING THE SECTION MODULUS FROM THE HOOD DESIGN:

Create a XY plane so that hood must part into two half and the force must be perpendicular to the plane.

• Find the intersection curve between the created datum plane and the hood.

• The section is to be made a closed section to calculated the SECTION INERTIA. First be project the intersection curve on plane and then connect the whole curve, so that it become a close loop, so that we can get actual MOI & section modulus.

• Take a point at both the extreme side of the hood, measure the distance between the points half of the distance will be ‘Y’ since we are taking the ‘O-Y’ axis as a neutral axis.

• Using the inertia analysis command calculate the moment of inertia of the section.

CALCULATION OF SECTION MODULUS.

MOI: 3.0396 X 10⁵ mm⁴

Y: 875.21/2 = 437.605 mm

SECTION MODULUS (Z) = I/Y_(MAX) = (3.0396 X 10⁵) / 437.605 = 694.599 mm³

MODIFICATION TO INCREASE THE MOI & SECTION MODULUS

For approaching in this way, I decrease the emboss with respect to outer surface of the inner hood plane. This lead to increase the MOI about the neutral axis which proportionally increase the ‘Z’.

Calculation of section modulus:

MOI ‘I’ = 3.2095 X 10⁵ mm⁴

Y: 875.21/2 = 437.605 mm

SECTION MODULUS (Z) = I/Y_(MAX) = (3.2096 X 10⁵) / 437.605 = 733.4468 mm³

CONCLUSION:

Hence after modification section modulus increases as compare to 1^st MOI. thus it increases the bending strength of the hood.