1. Tensile Test
The most common static test is the uniaxial tensile test, which provides information about a variety of properties.
As a load is applied to a test specimen, the elongation is recorded.
The ordered pairs are graphed in a stress/strain curve.

2. Specimen
mounting
Universal Testing Machine

3. Schematics of the Process

4. Units of Strength: Stress
Strength of materials are recorded in units of Force/Area, and are referred to as various stresses.
The symbol for stress is the Greek letter sigma:
Stress is synonymous with strength 

5. Examples of Normal Stress
Cables on suspension bridges.
Legs of chairs: dent the pine floors? (compressive strength of pine vs oak)
Skyboxes at the ball park.
Cutting tool operations.
Forming and fabricating operations.

6. Units of Deformation: Strain
Tension equates to elongation
Units of elongation are Strain:
Note that strain is dimensionless: merely a ratio 

7. The Stress-Strain
Diagram
(fig A.5)

8. Region I
The modulus of Elasticity (E) is calculated in stress/strain up to the proportional
limit.
Designers live here

9. Young’s Modulus (E)
Is in the Elastic region: strain is directly proportional to stress. (Hooke’s Law)
Units are in psi or MPa
Yield stress is the strength of the material when permanent deformation takes place.
The larger value of E, the more resistant a material is to deformation. This is a measure of material stiffness in response to an applied load: a quantified property: E

10. Elastic Deformation Airplane wings: sway with fracture
1950’s accident: B17 into Empire State building: swayed 12’?
Bridge swaying
glass vs steel
Design safety factors

11. Region II: Plastic Deformation
Ductility: the ability to plastically deform in tension without breaking
Malleability: the ability to plastically deform in compression without breaking
Fabrication processes: forming

12. Region III: Failure Material thins from the stress, work-hardening
leads to fracture
Cutting processes occur in this region

13. Specific Tensile Properties
Modulus of Elasticity E
Yield stress (strength)
Ultimate Tensile strength (stress)(UTS)
Ductility: elongation percentage

14. Strength of Materials
Strength is the property determined by the greatest stress the material can withstand prior to failure, as failure is determined by the designer. It may be defined by the proportional limit, the yield point, or ultimate strength. No single value is adequate to define strength, since the behavior under load differs with the kind of stress, and the nature of the loading.

15. Stiffness
The property that enables a material to withstand high stress without great strain (elongation). It is a resistance to any form of deformation, and is a function of the modulus of elasticity.

16. Elasticity & Ductility
Elasticity is the property of material enabling it to regain its original dimensions after removal of a deforming load.
Ductile materials can undergo considerable plastic deformation under tension, before breaking. % elongation is the measurement. Wires, extrusions as examples
Malleability is material ability to deform plastically in compression

17. Brittleness
Brittleness implies the absence of any plastic deformation prior to sudden failure. This means the breaking strength (UTS) is usually equal to the yield stress. In general, poor in tension, and tested in compression: concrete, cast iron, ceramics.

18. Toughness & Resilience
Toughness is that property enabling it to endure high impact loads or shock loads. A body that can be both highly stressed, and greatly deformed without failure is tough.
Resilience is that property enabling it to endure high impact loads without inducing a stress in excess of the elastic limit (yield).

19. Creep Permanent deformation at stress less than yield.
Materials with higher resilience are more susceptible to creep.
Temperature is the most contributing environmental factor.
For example: Creep limit for LEXAN at 73oF is 2000psi. (GE, p.5)
Easiest to beat by adding reinforcing materials.

20. Comparison of Materials

21. The Nature of the Load Determine the stress on the 1.0” Ø rod.
If, by design, the stress on the rod cannot exceed 10,000psi determine the minimum diameter
Shear Loads
Shear Stresses
Shear strengths can be approximated from tensile strengths

22. Torsion Stress

23. Brazing Application L
0.75
6 ton load
Determine L