1. Forging new generations of engineers
Stress
Principles of EngineeringTM
Lesson 5.2 – Strength of Materials
Forging new generations of engineers
Project Lead The Way, Inc.
Copyright 2007

2. Stress

3. Stress:
Stress in a structure is calculated once the applied forces are known and the shape or geometry of a part is chosen.
Stress in a part must be below the allowable stress of the material, or the part fails. Allowable stress depends on several factors which will be shown later in this lesson.

4. Stress:  Before After Axial   Shear
Twisting, bending, & torsion forces also factors in (but require the Calculus).   

5. Stress:
Axial
Shear

6. Types of Loading Formula Axial  = P / A
where: A is the cross section area
Shear  = P / A
Formulas shown can be used to calculate average stress on the cross section P

7. Stress:
Twisting
and
Torsion

8. Pure Bending Compression M M Tension
M is a moment or torque. M creates axial compressive (-) stress on the top surface and axial tensile (+) stress on the bottom surface. The axial stress crosses through zero at the location of the centroid of the cross section, this location is called the neutral axis.