Mechanical Testing Flashcards
Review of mechanical testing; in particular, tensile strength
When did the idea of mechanical testing occur?
1830s when early steam boilers started to explode under the greater pressures demanded of them
What was decided to be done about mechanical testing?
Committee of engineers recommended steels should be tested to determine strength, using a reproducible and standard test
What mechanical properties are tested?
Ductility, strength, wear, stiffness, tension, fatigue, shear, hardness, creep, impact, torsion
What is tension?
Pulling apart slowly until it cracks; force is experienced in the gauge length
Why are tension tests not great?
They don’t duplicate in real life
What is the gauge length?
Region with smallest diameter; becomes longer and thinner
What does the International Standards Organisation do?
Outline standardised dimensions, diameter, gauge length, part to be gripped, surface finish, strain rate, precise direction of the application of the load, slack in the machine
What is the initial graph produced by tension testing?
Force-extension curve; converted to stress-strain curve
What law does the curve follow in the elastic region?
Hooke’s law
How is force converted to stress?
Force/CSA
What is the sign for stress?
σ (Sigma)
How is extension converted to strain?
Change in length/original length
What is the sign for strain?
ε (Epsilon)
What is the UTS and where would it be found on a stress-strain curve?
Ultimate tensile strength; peak of curve
What does it mean that the material acts elasticly?
Returns to original length after load is removed
