Section Modulus calculation and optimization

S = I/y

Where,

S = Section Modulus

I = Moment of Inertia

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

Types of Section Modudlus

• Elastic Section Modulus
• Plastic Section Modulus

Elastic Section Modulus

Elastic section modulus is calculated when we are to use the material behavior till the yield point. For general design purposes, we use elastic section modulus.

Plastic Section Modulus

It is used for materials where the elastic yield is acceptable and the plastic behavior is considered to be an acceptable range. Plastic section modulus is the sum of the areas of cross-sections on each side of the plastic neutral axis that may or may not be equal and multiplied by the distance from the local centroid of the two regions to the plastic neutral axis.

Calculation and Analysis of the Section Modulus

Case 1

Calculation

MOI _(Max) = 9.124487966e+05 [mm⁴]

MOI _(Min) = 2.999718750e+03 [mm⁴]

y_max= 478 / 2 = 239

S = I/y

S = 2.999718750e+03 mm⁴ / 239 mm

S = 12.55 mm³

Case 2

Increased the gap between Hood outer panel and inner panel by emboss(stamping) to increase the cross sectional area.

Calculation

MOI _(Max) = 9.087444785e+05 [mm⁴]

MOI _(Min) = 3.597206132e+03 [mm⁴]

y_max= 478 / 2 = 239

S = I/y

S = 3.597206132e+03 mm⁴ / 239 mm

S = 15.05 mm³

^Conclusion

^{The Case 2 has high strength compared with Case 1 due to cross section of the Hood section area. By increasing the section area we can increase the strength of the section modulus.}