Materials Flashcards
A1 mocks
Why would you use digital measurements?
To reduce the risk of error
What graph shows a material that doesn’t obey Hookes law?
A Force- extension graph that isn’t straight
What do you call forces that squash the material?
Compressive
How do you calculate a strain ratio?
F/A ×100
What’s different about compressive forces?
They’re negative
Define stress
The ratio of load to cross-sectional area
What is the breaking stress?
The smallest stress to break the material
Give the enery transferes when a spring js stretched
Kinetic-> elastic strain which is stored in the spring
Give the energy transferes when the string is released
Elastic strain-> kinetic
Give the energy transferes when it plastically deforms
Kinetic–> some elastic potential, some to sepate atoms and dissapates as heat
What does the are under a stress strain graph represent?
Strain energy (energy stored per unit volume)
Define the yeild point
Material stretches/extends without any extra load or even with a reduced load. Large amounts of plastic deformation takes place.
What graphs look the same and different for the same material but different dimentions?
Stress-strain will always look the same
Force-extension will look different
Why are brittle materials brittle?
They have a rigid structure
What is a fracture?
A stress applied to a brittle material to cause tiny cracks on the surface, which get bigger and bigger until it breaks completely
