Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lab 7P. 1Autumn Quarter Material Joining and Beam Bending Lab 7

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lab 7P. 2Autumn Quarter Beam Deflection Every object acts as a spring – it will deflect when a force is applied Extent of deflection (δ) depends on: –Force applied –Object geometry –Material properties F δ

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lab 7P. 3Autumn Quarter Object Geometry: Moments of Inertia A larger moment of inertia means that the beam will be more resistant to deflection Area Moments of Inertia (I) depends on object shape b1b1 b2b2 h1h1 h2h2 b h

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lab 7P. 4Autumn Quarter Differences in Deflection - Geometry 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

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lab 7P. 5Autumn Quarter Strain:Stress:(lb/inch 2 ) A (cross-sectional area) F (applied force) L (original length)  (deflection from original length) Stress and Strain: Simple Definitions

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lab 7P. 6Autumn Quarter Strain:Stress:(lb/inch 2 ) Material Property: Young’s Modulus (E) Note that Young’s modulus does not depend on the geometry of the object. units: Young’s modulus (or the modulus of elasticity) is the ratio of stress to strain in a material:

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lab 7P. 7Autumn Quarter Stress vs. Strain Curves: Young’s Modulus (slope of curve or material stiffness) Linear Portion (Hooke’s Law): Strain:Stress: Stress, Strain, and Young’s Modulus

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lab 7P. 8Autumn Quarter Cantilever Beam Bending Equation In this lab, you will measure the deflection δ for various loads F. Compare experimental deflection to theoretical for each case. F δ s L dial indicator Theoretical deflection:

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lab 7P. 9Autumn Quarter Welding Consists of heating the joints and adding a filler material Different from brazing and soldering Alternative to fasteners like nuts and bolts More permanent way to join materials

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lab 7P. 10Autumn Quarter Material Joining The final product will form a ‘T’ shape

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lab 7P. 11Autumn Quarter 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?

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lab 7P. 12Autumn Quarter Lab Reports Individual lab report Include sketch of experimental set-up Detailed lab-specific requirements not given: determine what is appropriate based on write-up and data gathered.

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lab 7P. 13Autumn Quarter Questions ?