Chapter 5 -
Carpal Tunnel Syndrome
Chapter 5 -22
ISSUES TO ADDRESS...
• Stress and strain: What are they and why are
they used instead of load and deformation?
• Elastic behavior: When loads are small, how much
deformation occurs? What materials deform least?
• Plastic behavior: At what point does permanent
deformation occur? What materials are most
resistant to permanent deformation?
• Toughness and ductility: What are they and how
do we measure them?
Chapter 5 -3
Sections: 7.1 –7.4
•Define Engineering stress and strain
–Shear and torsion
•How the tests are performed
•Hooke’s law and conditions
•Suggested Reading pgs:187-196
Sections: 7. 1 7. 4: define engineering stress and strain. Shear and torsion: how the tests are performed, hooke"s law and conditions, suggested reading pgs:187-196. Elastic means reversible! bonds stretch return to initial. Plastic deformation (metals: initial, unload planes still sheared. Ao lb[= in original area before loading: shear stress, : N/m2 (pascal) or lbf/in2 often 106 pa = mpa. Common states of stress cable: simple tension: A o: torsion (a form of shear): drive shaft. Other common stress states (i: simple compression: Canyon bridge, los alamos, nm (photo courtesy p. m. anderson) Note: compressive structure member ( < 0 here). Other common stress states (ii: bi-axial tension, hydrostatic compression: Chapter 5 - 12: typical tensile test machine. Stress-strain testing: typical tensile specimen extensometer specimen. Moffatt, and j. wulff, the structure and properties of materials, Iii, mechanical behavior, p. 2, john wiley and sons, new york, 1965. )