1. BODY STRUCTURAL ELEMENT
SMC 4133 AUTOMOTIVE STRUCTURES
BODY STRUCTURAL ELEMENT
Consists of frames and panels
Made of thin-walled structural elements
Non-symmetrical section
Forms of several pieces using spot weld
All materials in this slide are taken from Donald E Malen Fundamentals of Automobile Body Structure Design, SAE International.

2. Structural Requirements
SMC 4133 AUTOMOTIVE STRUCTURES
CLASSICAL BEAM BEHAVIOUR
Structural Requirements
All materials in this slide are taken from Donald E Malen Fundamentals of Automobile Body Structure Design, SAE International.

3. Structural Requirements
SMC 4133 AUTOMOTIVE STRUCTURES
BEAM STIFFNESS
Structural Requirements
INSPIRING CREATIVE AND INNOVATIVE MINDS
All materials in this slide are taken from Donald E Malen Fundamentals of Automobile Body Structure Design, SAE International.

4. Structural Requirements
SMC 4133 AUTOMOTIVE STRUCTURES
EXAMPLE 1
Structural Requirements
Does the given section size meets both requirements?
Answer: Stress = 208N/mm^2, Deflection = 5.6 mm
INSPIRING CREATIVE AND INNOVATIVE MINDS
All materials in this slide are taken from Donald E Malen Fundamentals of Automobile Body Structure Design, SAE International.

5. Structural Requirements
SMC 4133 AUTOMOTIVE STRUCTURES
AUTOMOTIVE BEAM SECTIONS
Beam sections in a body structure are commonly non-symmetrical
Deflection of the beam generally will not be collinear with the applied load
Use principle axis to find deflection that collinear with the load
Structural Requirements
Deflection
Resolve the load
Solve for the resulting deflection
Calculate the resultant deflection
Stress
- Resolve the moment
Solve for the resulting stress
- Find the resultant stress
All materials in this slide are taken from Donald E Malen Fundamentals of Automobile Body Structure Design, SAE International.

6. Structural Requirements
SMC 4133 AUTOMOTIVE STRUCTURES
EXAMPLE 2
Structural Requirements
Determine the tip deflection and the stress at point A. y x
INSPIRING CREATIVE AND INNOVATIVE MINDS
All materials in this slide are taken from Donald E Malen Fundamentals of Automobile Body Structure Design, SAE International.

7. Structural Requirements
SMC 4133 AUTOMOTIVE STRUCTURES
Point loading of thin-walled sections
Structural Requirements
All materials in this slide are taken from Donald E Malen Fundamentals of Automobile Body Structure Design, SAE International.

8. Structural Requirements
SMC 4133 AUTOMOTIVE STRUCTURES
EXAMPLE 3
Structural Requirements
Determine latch structure stiffness.
Answer: K system = 33.2 N/mm
INSPIRING CREATIVE AND INNOVATIVE MINDS
All materials in this slide are taken from Donald E Malen Fundamentals of Automobile Body Structure Design, SAE International.

9. Structural Requirements
SMC 4133 AUTOMOTIVE STRUCTURES
TORSION OF THIN-WALLED MEMBERS
Structural Requirements
Closed section
INSPIRING CREATIVE AND INNOVATIVE MINDS
All materials in this slide are taken from Donald E Malen Fundamentals of Automobile Body Structure Design, SAE International.

10. Structural Requirements
SMC 4133 AUTOMOTIVE STRUCTURES
Structural Requirements
Non-uniform thickness
Uniform thickness
INSPIRING CREATIVE AND INNOVATIVE MINDS
All materials in this slide are taken from Donald E Malen Fundamentals of Automobile Body Structure Design, SAE International.

11. Structural Requirements
SMC 4133 AUTOMOTIVE STRUCTURES
EXAMPLE 4
Structural Requirements
Determine the angle of rotation and the shear stress under the pure torque
of T =250 kNmm. Take shear modulus G = 78 Gpa.
Answer: Angle = degree, Shear stress = 25 N/mm^2
INSPIRING CREATIVE AND INNOVATIVE MINDS
All materials in this slide are taken from Donald E Malen Fundamentals of Automobile Body Structure Design, SAE International.

12. Structural Requirements
SMC 4133 AUTOMOTIVE STRUCTURES
Open section
Structural Requirements
EXAMPLE 5
Recalculate EXAMPLE 4 but now using open section as shown below
and comment on the result.
Answer: Angle = 803 degree, Shear stress = 2197 N/mm^2
All materials in this slide are taken from Donald E Malen Fundamentals of Automobile Body Structure Design, SAE International.

13. Structural Requirements
SMC 4133 AUTOMOTIVE STRUCTURES
BUCKLING OF THIN-WALLED MEMBERS
Structural Requirements
Most of the failure modes are caused by plate buckling of section elements
Buckling stress of the rocker:
INSPIRING CREATIVE AND INNOVATIVE MINDS
All materials in this slide are taken from Donald E Malen Fundamentals of Automobile Body Structure Design, SAE International.

14. Structural Requirements
SMC 4133 AUTOMOTIVE STRUCTURES
Critical compressive plate buckling stress (simply supported):
Structural Requirements
a/b > 1
a/b < 1
Plate flexural rigidity
INSPIRING CREATIVE AND INNOVATIVE MINDS
All materials in this slide are taken from Donald E Malen Fundamentals of Automobile Body Structure Design, SAE International.

15. Structural Requirements
SMC 4133 AUTOMOTIVE STRUCTURES
Buckling Stress
Structural Requirements
k = buckling constant
All materials in this slide are taken from Donald E Malen Fundamentals of Automobile Body Structure Design, SAE International.

16. Structural Requirements
SMC 4133 AUTOMOTIVE STRUCTURES
Techniques to prevent buckling
Structural Requirements
Reducing width by adding a bead
Reducing width by chamfering corners
Reducing width by adding corners
INSPIRING CREATIVE AND INNOVATIVE MINDS
All materials in this slide are taken from Donald E Malen Fundamentals of Automobile Body Structure Design, SAE International.