DMS - stress/strain Flashcards
How can the curve at point A be described
linear
What does the linear region of the stress strain diagram represent
elastic deformation
What is meant by elastic deformation
If the stress is removed, the material will return to the original shape
What happens to the curve at point B
it stops being linear
What is point B referred to as
the yield stress / the proportional limit
What is meant by yield stress
this is the point that plastic deformation starts to occur
When the graph goes from being linear to being curved, what does this tell us about the material
it has now exceeded its elastic limit
What happens to a material when it exceeds its elastic limit
it will now begin to deform permanently
Once a material has exceeded its elastic limit, if you remove the stress, will the material return back to its original shape?
no
this is known as plastic flow
What is point C called?
ultimate strength
What is the ultimate tensile strength
It is the maximum stress the specimen can withstand - this is different from the fracture strength
What is point D
This is where the stress has lead to fracture
What important information does point D give us?
the fracture strength
What region of the graph is the elastic modulus calculated from
A
What is the formula for Young’s modulus
stress/strain
What is the units for Youngs modulus
MPa
What information about the material does Young’s modulus give us
rigidity/flexibility
What does a high Young’s modulus mean
rigid
What does a low Young’s modulus mean
flexible
What is meant by ductility
amount of plastic strain produced in the specimen at fracture
How is ductility measured
by drawing a line from the point of fracture which is parallel to that of the elastic region
where the line meets the strain axis, this is the measurement
shown by a red line on the graph
What is the opposite of ductile
brittle
What is the definition of stress
force per unit cross-sectional area
What is the definition of strain
change in length/original length
