Section Modulus calculation and optimization

TITLE: Section Modulus calculation and optimization.

SECTION MODULUS:

Section modulus is a geometric property for a given cross-section used in the design of beams or flexural members. Other geometric properties used in design include area for tension and shear, radius of gyration for compression, and moment of inertia and polar moment of inertia for stiffness.

The section modulus of the cross-sectional shape is of significant importance in designing beams. It is a direct measure of the strength of the beam. A beam that has a larger section modulus than another will be stronger and capable of supporting greater loads.

It includes the idea that most of the work in bending is being done by the extreme fibres of the beam, ie the top and bottom fibres of the section. The distance of the fibres from top to bottom is therefore built into the calculation.

The ratio of Area Moment of Inertia to the Distance from the Neutral Axis to the Point where the Bending Normal Stress is determined.

Section modulus (S) = I/Y

SECTION TAKEN: (HOOD)

CONDITION 1:

The Maximum and minimum moment of inertia obtained are

I(max) = 4.85 x 10^6 mm^4

I(min)= 1.35 x 10^4 mm^4

y= 445 mm

The Section modulus is calculated,

S(max)= 1O.9 x 10^3 mm^3

S(min)= 30.33 mm^3

CONDITION 2:

The Maximum and minimum moment of inertia obtained are

I(max) = 4.95 x 10^6 mm^4

I(min)= 1.33 x 10^4 mm^4

y= 445 mm

The Section modulus is calculated,

S(max)= 11.13 x 10^3 mm^3

S(min)= 29.88 mm^3

CONCLUSION:

FROM ABOVE,

It can be noted that increasing the Sectional Area of the cross section increases the Moment of Inertia thereby increasing the Section Modulus.

The Section modulus optimization reveals that the Emboss defined in the hood panels provide better Moment of Inertia hence the strength of the sheet metal is significantly improved.

Thus Section Modulus carried out on BIW Structures provide better undertanding of the Load bearing capcity. bending resitance and forces and stress exerted in the beam and has wider significance of reducing the weight and cost for Automotive OEM's.