Section Modulus calculation and optimization

SECTION MODULUS CALCULATION AND OPTIMIZATION CHALLENGE

Objective:

Use the Section from your 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

Come up with a new section that has improved the section modulus of the previous section and mention what change you made that has increased the strength.

Designed Hood:

Hood Inner Panel

Hood Outer Panel

Section Modulus Calculation:

• I have taken the section perpendicular to neutral axis as shown in below figures.
• Now I have separated the section curve and taken the outer most curves of hood inner and outer panel and closed the open curves to make a complete closed section

Section Curve closed loop

Section Modulus Obtained Values

As per the formula I have calculated the section modulus of the hood.

S= I/y

I= Moment of Inertia (Min)

I= 1.549 X 10^4 mm^4

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

y= 443mm

S= 1.549 X 10^4/443 mm^3

S= 0.00349 X 10^4 mm^3

Section Modulus Calculated value before optimization

Section Modulus Calculation after Optimization

Case-1: Increasing the distance between hood inner and outer panel

• I have taken the same section of the hood which is designed and increased the distance between hood inner and outer panel by offsetting only the inner panel curves by 2.5mm.
• The result is shown below.

Section after offsetting the inner panel curves by 2.5mm

Section Modulus obtained values

Calculation:

S= I/y

I= 1.705 X 10^4 mm^4

y= 443mm

S= 1.705 X 10^4 mm^4/443mm

S= 0.003848 X 10^4 mm^3

Section Modulus Calculated value after optimization-Case1

Observation:

• After optimizing the section as explained above the section modulus values has increased to

0.00035 X 10^4 mm^3 more as compared to before optimization.

• I have offset the section curve to 2.5mm to increase the distance between hood inner and outer panel.
• More we increase the distance between hood inner and outer panel, the section modulus value increase accordingly (Anyway we can increase the distance only till some extent as per the design and other components assembly constraints).

Case-2: Increasing the distance between hood inner and outer panel and adding embosses to hood inner panel section curve

• I have taken the same section of the hood which is designed and increased the distance between hood inner and outer panel by offsetting only the inner panel curves by 1.5mm.
• Then i have edited the inner panel section curve to add emboss section to the existing section curve.
• The result is shown below.

Section after offsetting 1.5mm and adding emboss section curves to inner panel

Section Modulus obtained values

Calculation:

S= I/y

I= 1.649 X 10^4 mm^4

y= 443mm

S= 1.649 X 10^4 mm^4/443mm

S= 0.003722 X 10^4 mm^3

Section Modulus Calculated value after optimization-Case2

Observation:

• After optimizing the section as explained above the section modulus values has increased to

0.000232 X 10^4 mm^3 more as compared to before optimization.

• I have offset the section curve to 1.5mm to increase the distance between hood inner and outer panel and I have added emboss curves to the hood inner panel section curve.
• More we increase number of embosses such that that dissipates or resists the crash forces reaching the persons inside the car thus the strength of hood can be increased.

Table showing Section Modulus Calculation before and after optimization

NOTE:

• WE CAN INCREASE THE STRENGTH OF THE HOOD BY ADDING EMBOSSES OUTSIDE OF THE HOOD OUTER PANEL PROVIDED IF THE ERGONOMICS AND AERODYNAMICS AND OTHER FACTORS WHICH INFLUNCES THE PROJECT ARE NOT AFFECTED