1	Stress Analysis Mechanics: Stress and strain
2	Topics Free Body Diagrams (Review) Stress Strain Deformation Hooke’s Law Stress-Strain Diagrams Design: The Safety Factor
3	Free Body Diagrams Shows all external forces acting on the body Procedure Identify the isolated body and draw it At all force locations draw the vectors Supports Connections Contacts Add the Weight force Label forces with their value or a letter for unknowns Add a coordinate system Add geometric data (Lengths, angles, … )
4	Examples 1
5	Examples 2
6	Examples 3
7	Stress Internal Forces Reaction to external forces Distributed throughout volume of material Stress Normal stress Acts at right angles to a selected plane The axial direction in a rod or cable Shear stress: stays in the selected plane (advanced topic: Strength of materials course) Can a structure withstand the forces applied to it?
8	Stress 2 s = P/A (Pascals) s: Average stress P: Applied force A: Cross section area Tension / Compression
9	Strain Strain: deformation due to stress e = d / L e: Normal strain d: Change in length L: Original (unstressed) length
10	Hooke’s Law Springs F = kx F: Applied Force k: Spring constant x: displacement Stress-Strain s = Ee s: Stress E: Modulus of Elasticity e : Strain
11	Stress-Strain Diagram
12	Example 6 200 kg engine block Cables 0.7 m long 4 mm diameter E = 200 GPa Find Normal Stress Axial Deformation