Section Modulus calculation and optimization

OBJECTIVE : To increase section modulus of the hood design by doing necessary changes.

SECTION MODULUS:

• It is the ratio of second moment of area and distance from neutral axis to the extreme fiber.
• It shows the stiffness of the given member.
• Section modulus is a geometric property of cross-section used in the design of flexural members or beams.
• The stress in the outermost section of the beam is calculated by section modulli method.
• Other geometric properties useful in design calculations areas follows

1. Area ---> Tension and Shear calculation
2. Radius of gyration ----> Compression calculation
3. Moment of inertia and polar moment of inertia ----> Stiffness calculation

• There are two types of section moduli, the elastic section modulus and the plastic section modulus.
• The elastic section modulus is defined as S = I / y

where I = Second moment of inertia

y = Distance from the neutral axis to extreme fibre

• The unit of sectional modulus is cubic millimeter.
• The bodies having more shear modulus are tougher & can withstand more load.

Section Modulus Calculation of Hood Design:

METHODOLOGY:

1. Create a datum plane at the centre of the Hood Assembly.
2. Use the Intersection Curve option.
3. Project the 2D sketch From given 3D Sketch
4. Use trim option & studio spline option to get required closed geometry.
5. Apply section inertia modulus command to get section modulus.

Case 1: Initial Hood Design

Area Moment of Inertia:

MOI(Max)= 4.760238725e+06 mm^4

MOI(Min)=1.475443151e+04 mm^4

Y distance:439.9395 mm

S=I/Y

S=1.475443151e+04 mm^4/439.9395 mm

S=33.53 mm^3

Case 2: Optimized Hood Design

Our Target is to increase the I(Min)

MOI(Max):4.776063999e+06 mm^4

MOI(Min): 1.513886836+04 mm^4 (INCREASED)

Changes Made:

1. Increase the distance between the outer panel & inner panel.
2. Add the Embosses in the structure.

Y distance:439.9395 mm

S=I /Y

S=1.513886836+04 mm^4/439.9395 mm

S=34.411 mm^3

CONCLUSION:

1. The area moment of inertia of the hood is directly proportional to the section modulus.

2. As the section modulus of hood increases it can bear more load & get stiffer.

3. So we can increase the distance between outer & inner panel. As well as we can provide embosses to get more area moment of inertia which will result into more section modulus.