MECH466-Lecture-5 - 1 MECH 466 Microelectromechanical...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 1 MECH 466 Microelectromechanical Systems University of Victoria Dept. of Mechanical Engineering Lecture 5: Stress and Strain Mechanics of Beams May 24th, 2007 Mech 466, N. Dechev, UVic 2 Stress and Strain Bending of Beams Overview Mech 466, N. Dechev, UVic 3 Graphical Relation Between Stress and Strain Mech 466, N. Dechev, UVic Linear Region Ceramics, Crystal Silicon, Polysilicon Metals, Gold, Aluminum, Certain Plastics Linear Region 4 Movie of Tensile Testing of Steel The relationship of stress and strain for steel can be observed in the following movie: Mech 466, N. Dechev, UVic Tensile Testing A36 mild steel, (speed = 4X), [Civil Engineering, University of New Mexico] 5 Values for E (modulus of elasticity) Some typical values for E for common MEMS materials are listed below: Note: Appendix A lists numerous material properties for typical MEMS materials. Mech 466, N. Dechev, UVic Material E (GPa) Yield Strength (MPa) Fracture Strength (MPa) Single Crystal Silicon: <100> <110> <111> 130 168 187 N/A 600 to 7700 Polysilicon 120 to 175 N/A 1000 to 3000 Silicon Nitride (SiN) <100> <110> 385 254 N/A 6400 to 14000 Silicon Oxide 73 N/A 8400 Silicon Carbide (SiC) 700 N/A 21000 Stainless Steel 200- 2100 Gold 78 250- Aluminum 70 170- When you strain a body along one axis, it will change shape along the other axes. For example, consider the rectangular body below: If it is in tension, its cross-sectional area will become reduced. We can define Poissons ratio as: Note for Si: (See Appendix A for other materials) 6 DeFnition of Poissons Ratio Mech 466, N. Dechev, UVic 7 Defnition oF Stress Tensor Consider a solid body (as shown below) with an arbitrary shape, subjected to a set of arbitrary forces....
View Full Document

This note was uploaded on 02/02/2010 for the course MECH 466 taught by Professor Dechev during the Summer '07 term at University of Victoria.

Page1 / 15

MECH466-Lecture-5 - 1 MECH 466 Microelectromechanical...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online