Section Modulus calculation and optimization

Objective:

• To calculate the section modulus using the section of the hood designed.

• To make a change in the cross-section and to come up with a better section modulus value .
Introduction

Section modulus:

Section modulus is a geometric property for a given cross-section used in the design of beams or flexural members, it is also referred to as the Polar Modulus or the Torsional Sectional Modulus. 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. Any relationship between these properties is highly dependent on the shape in question. Equations for the section moduli of common shapes are given below. There are two types of section moduls, the elastic section modulus and the plastic section modulus.

S=I/Y

Here, S = Section modulus I= Moment of Inertia (Unit mm 4)

Y. Distance from Neutral axis to the extreme end (unit mm)

The Unit of a "section modulus" is (mm3)

Section modulus equations:

Design study for first time:

In this case we have the results,

Max. MOI = 4.70768 * 10^6 mm^4

Min. MOI = 1.30948 * 10^4 mm^4

y=869.64/2= 434.82 mm

Max. S= 4.70768 * 10^6/434.82 = 1.08267 * 10^4 mm^3

Min. S= 1.30948 * 10^4/434.82 = 30.115 mm^3

After optimization by increasing the thickness of Hood by 0.5 mm:

In this case we have the results,

Max. MOI = 4.70186 * 10^6 mm^4

Min. MOI = 1.3259 * 10^4 mm^4

y= 434.82 mm

Max. S= 4.70186 * 10^6/434.82 = 1.0813 * 10^4 mm^3

Min. S= 1.3259 * 10^4/434.82 = 30.493 mm^3

Conclusion:

Thus the section modulus of the Front Hood of a car was calculated and compared with the optimized hood and found the better result. Hence I'm concluding that when the sectional area of the hood increases the stiffness and resistance of the hood strength will also be increased.
From the result, we can conclude and say that off-setting the cross-section of the inner panel 0.5 mm downward(Optimized) would give a better section modulus and this would help in increasing the strength of the hood.