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.The elastic section modulus is defined as S = I / y, where I is the area moment of inertia and y is the distance from the neutral axis to any given fibre. The section modulus indicates the resistance to deformation and bending.It is highly dependent on the shape of the cross section of object by changing the cross section section modulus can be varied.Higher the section modulus higher the resistance to bending and deformation.

Section Modulus (S) = I(MIN) / y

I(MIN)-MINIMUM AREA MOMENT OF INERTIA

Y - DISTANCE FROM THE NEUTRAL AXIS TO THE OUTER EDGE

The above equation is obtained from Flexural formula M/I = σ/y

σ - Bending stress, M - Bending moment

SECTION MODULUS CALCULATION ON HOOD PANNEL

CASE-1

Section modulus  of actual hood pannel 

                                   

                                                           I(min) = 1.40529*10^4 mm^4

                                                                  y = 878mm/2 = 439mm

                                                                 S = I/y = 32.011mm^3

CASE-2

Section modulus of hood with of 0.5mm offset innerpannel upwards. 

                 

                                                             I(min) = 1.42352^4 mm^4

                                                                    y = 878/2 = 439mm

                                                                   S = I/y =  32.426mm^3 

CASE-3

Section modulus of hood with 1mm offset innerpannel downwards

                                                                                                                                       

                                                          I(min) = 1.44303*10^4 mm^4

                                                                 y = 878/2 = 439mm

                                                                 S = I/y = 32.8mm^3 

CASE-4

                             

                                                                 I(min) = 1.38264*10^4 mm^4

                                                                        y = 878/2 = 439mm

                                                                       S = I/y = 31.49mm^3

CONCLUSION

 From the observation it is evident that the section modulus is changing with change in cross sectional area and change in geomertic shape.

 Increasing the cross sectional area by offsetting the inner pannel cause a slight increase in the section modulus.

 By removing  embosses from the actual design result in decrease of the section modulus.

 Thus it can be inffered that to increase the section modulus we can either increase the cross sectional area or introduce more embosses in the inner pannel.