Bending Strength of Materials

These resources, from the STEM Guitar project, include a PowerPoint presentation and an activity on the strength of guitar materials. The purpose of the presentation is to learn about "... materials testing and relate that information to how luthiers create bended sides for guitars." The presentation goes through the following six common forces that materials may be exposed to: tensile, compression, shear, bending, hardness, and torsion. The presentation also discusses stress-strain curve, Young's Modulus (Modulus of Elasticity), proportional limit, elastic limit, yield point, ultimate strength, rupture, and more. 

The 6-page Strength of Materials activity covers the concepts discussed in the presentation and has students apply bending force to a wood sample. The activity has the following learning objectives: 

1. Students will learn about materials testing.
2. Students will be able to recognize stress/strain curve
3. Students will be able to define stress as a ratio of force to surface area
4. Students will be able to define strain as a ratio of deformation to original size
5. Students will be able to define Young’s Modulus as a ratio of stress-to-strain
6. Students will be able to define elastic limit and locate on stress/strain curve
7. Students will be able to define yield strength as 0.2% more than elastic limit
8. Students will be able to define ultimate strength and locate on stress/strain curve
9. Students will be able to explain what needs to occur to successfully bend guitar sides using terms elastic limit, yield strength, ultimate strength.