Section Modulus calculation and optimization
TITLE: SECTION MODULUS OF CAR HOOD
INPUTS: CAR HOOD PANEL
EXPLANATION :
The car hood panel is a very important part, which plays a crucial role in safety and Maintainance, Car has a great history and based on different studies performance and Design evolved frequently.
Now different parameters are Depends on the Design which Directly improves CAR hood Design and Maintains International Manufacturing standards.
A car hood Usually Plays a Vital Role, In most of Front Drive engine car Hood Protects the engine and its parts, As well as other Components like the radiator, Air Intake, Electrical Components and Sensors, Power steering system, brake system Battery, etc.
Car hood panel design Made with the Following Parameters
1. Material Selection
2. Thickness of Metal sheet
3. Lightweight
4. Pedestrian Safety
5. Easy Assembly
6. Aerodynamic Performance
7. Heat dissipation and Cooling
8. Noice and Vibration Control
9. Maintenance Ease, Etc.
Above are a few Parameters on behalf of the multiple aspects to be considered in CAR hood Design.
Section Modulus:-
Section Modulus is the way to define the Toughness of a Hood Which needs to be maximum in its conditions to satisfy all Design Aspects, Generally, Engineers always try to improve the Section modulus Value to make the Hood Stronger. It's a Structural Cross section that resists Bending.
Role of Section Modulus :
1. Bending Resistance.
It relates to the bending stiffness of the panel. Higher the value higher the resistance to Bending. it Prevents Excessive Deflection of the Hood due to External Load. such as wind loads, impacts, or weight.
2. Structural Strength
The section modulus is directly proportional to the strength of the hood panel. A higher section modulus Means a greater ability to withstand bending stresses, distribute loads, and resist deformation.
3. Impact Absorption
A higher value gives Better Protection in Safety and Protects The Engine Compartment From accidents, the hood can be designed to act as a crumple zone, absorbing energy and reducing the severity of the impact transferred to the passenger cabin.
Image 3.1 Crumple of Hood Panel
4. Weight optimization
Section Modulus Where needs to improve Which Directly Depends on the Weight and Design of the Panel, Minimum Material Usage, and Improve Stiffness this is an Important Task Given to the engineer which Directly Maintains balance between strength and weight reduction.
5. Manufacturing consideration.
Manufacturing of panels should involve standard processes. If the Car design is complex or the structure may involve multiple manufacturing processes directly increases the cost of manufacturing, which means while improving the Section modulus we need to manage all aspects which should not increase the cost, weight, or manufacturing process.
CALCULATION OF SECTION MODULUS
Caluculation formula :- S= I/Y
S= Section Modulus
I = Moment of Intertia
Y= Length of extreme fiber from the neutral axis
Step 01:-
Create Plate at Middle of Outer Hood Panel Along with Crumple Zone
Step 02: -
Intersect with Outer panel and inner panel
Step 03: -
Create a Sketch For Calculating Y Value and Make a surface With Intersect Geometry.
Note:- Perform Trim operation to Obtain a Close Surface which will help to calculate the Moment of inertia.
Y = 882.831/2 = 441.4 mm
Step 04:-
Calculate the Minimum Moment of Inertia, "I".
I = 909700000 mm4
Step 05:-
Calculate The Section Modulus
S = I/Y
S = 909700000mm4/441.4mm
S = 20,60,942.45 mm3
Step 06:-
Select the Material and Calculate the Yield Stress of Material
Selected Material for Car Hood is:-
For Stainless steel 304 Grade Tensile Strength is 540 Mpa ( N/mm2)
Step 07: -
Calculate Yield Moment:- My = S x Tensile Strength
My = 20,60,942.45 mm3 X 540 N/mm2
My = 1.11e9 N.mm
Step 08: -
Modify the Moment of inertia.
I = 941700000 mm4
Y = 441.4 mm
S = I/Y = 9417e5 /441.4 = 22,72,442.084 mm3
My = S * Tensile Strength = 1.227e9 N.mm
Conclusion:- Initial Value For "I" and Modified Value For "I" is Increased by 3.4%, Due To small Offsetting of the inner panel by 0.5mm Improving the Value of Section modulus by 3.4 %.
There are no. of ways to improve the Section Modulus
1. Thickness increase
2. Modify Inner panel Cutouts (Most recommended)
3. Material Change
4. Manufacturing Process Change (Improve stiffness)
5. Detailed study with FEA (Finite Element Analysis)