Section Modulus calculation and optimization

AIM - Calculation and Optimization of section modulus for hood design

OBJECTIVES - 

• To increase the strength of a hood

THEORY - 

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 second moment of area (or area moment of inertia) and y is the distance from the neutral axis to any given fibre. It is often reported using y = c, where c is the distance from the neutral axis to the most extreme fibre, as seen in the table below. Below image shows section modulus for commonly used sections.

• Section modulus depends on orientation of geomerty. Below image shows how change in orientation can increase the section modulus followed by moment of Inertia.

MAIN  CONTENT -

• Below image shows given hood design
• It consists of hood inner panel as well as hood outer panel

Front View

Back View

Hood Section

CASE 1 - First Hood Design study

• Section of given hood design have been studied.
• We have used section inertia analysis tool to find out moment of inertia for the given section.

• Minimum moment of inertia - 2.51291 x 10^5 (mm^4)
• Y = 4.857599/2 = 242.8799 mm
• S= I/Y, , Section Modulus formula
• S = 2.51291 x 10^5 / 242.8799 = 1034.63 mm^3 
• Minimum Strength = 1034.63 mm^3

CASE 2 - Optimized Hood design study

• To optimize the hood design, inner panel is increased by 0.5 mm distance.

• Minimum moment of inertia - 2.55664 x 10^5 (mm^4)
• Y = 4.857599/2 = 242.8799 mm
• S= I/Y , Section Modulus formula
• S = 2.55664 x 10^5 / 242.8799 = 1052.63 mm^3 
• Minimum Strength = 1052.63 mm^3

CONCLUSION - 

• From the above results, it can be concluded that strength of hood is directly proportional to the moment of Inertia. With increase in moment of inertia,  strength of hood increases.
• Moment of inertia can be changed by changing the shape and size of the hood section.