Material Joining and Beam Bending

1. Material Joining and Beam Bending Lab 5 Autumn Quarter

2. Beam Deflection • Every object acts as a spring – it will deflect when a force is applied • Extent of deflection depends on force applied, material properties and object shape Autumn Quarter

3. Although the beams have the same cross-sectional area, the moments of inertia are different Because the moments of inertia are different, the beams deflect different amounts Differences in Deflection Autumn Quarter

4. I = Area Moments of Inertia (depends on object shape) h b Moments of Inertia • A larger moment of inertia means that the beam will be more resistant to deflection Autumn Quarter

5. Strain: Stress: (lb/inch2) L (original length) P (applied force) A (cross-sectional area) d (deflection from original length) Stress and Strain: Simple Definitions Autumn Quarter

6. Strain: Stress: (lb/inch2) Stress vs. Strain Curves: Linear Portion (Hooke’s Law): Young’sModulus (slope of curve or material stiffness) Stress and Strain: Simple Definitions Autumn Quarter

7. y x P s L Cantilever Beam Bending Equation • In this lab, you will measure the deflection d for various loads P. Using this information and other measurements, calculate Young’s modulus E for each beam. Autumn Quarter

8. Material Joining • A separate demonstration will be given on the welding procedure • The final product will form a ‘T’ shape Autumn Quarter

9. Things to Consider: • How will joining the beams through welding affect the overall stiffness? • Is there any advantage to choosing a more flexible material such as aluminum over a stiffer material such as steel? • Hypothetically, if you were to design a 9x9” robot spring quarter, which materials do you feel would be most suited for use? • Which shapes would form a stiffer chassis? Autumn Quarter

10. Questions ? Autumn Quarter