Properties Of Materials

Question 0

What is stress?

Answer 0

Force/Area

Question 1

What two things can we measure to assess the tensile stress of a material?

Answer 1

Stress and strain

Question 2

What is stress measured in?

Answer 2

PA

Question 3

What is strain?

Answer 3

Change in length/lengt

Question 4

What arête typical stress for a lad compared to premolar?

Answer 4

30 Mpa

Question 5

Why do some materials elongate more than others?

Answer 5

Difference in elsstic modules or Young’s modulus

Question 6

T/F

Young’s modulus is a measur of how flexible or rigid a materialis

Answer 6

T

Question 7

How can we measure elastic modules?

Answer 7

By looking at stress strain curves

Question 8

What are the two regions on the stress strain curves?

Answer 8

Elastic and plastic region

Question 9

What does the elastic region suggest?

Answer 9

When the material is released and returned back To its original shape

Question 10

What does the plastic region mean?

Answer 10

The material has been permanently deformed

Question 11

What values can be seen on stress strain curves?

Answer 11

Proportional limit
Yield stress
Proof stress
Fracture stress

Question 12

Below the proportional limit what does this mean?

Answer 12

The material deforms elsstically and is proportional

Question 13

What happens below the proportional limit and yield stress?

Answer 13

The elastic deforms but not proportionally

Question 14

What is the boundary been elastic and plastic?

Answer 14

Yield stress

Question 15

What is often used instead of proportional limit and why?

Answer 15

Proof stress since proportional limit is hard to measure

Question 16

What is the definition of the fracture stress?

Answer 16

0.2% plastic strain

Question 17

Where does the material fracture?

Answer 17

At f

Question 18

What is the elastic modules?

Answer 18

Stress / strain

Question 19

A high gradient on the stress strain curve indicates what?

Answer 19

The elasticity the higher the gradient the more rigid there lower the gradient the more flexible

Question 20

T/F a ductile material cannot be drawn easily into a wire?

Answer 20

F

Question 21

For a material to be ductile, what happens to the layers of atoms?

Answer 21

They slide past each other

Question 22

Which part of the stress strain graph represents a ductile material?

Answer 22

The length of the plateau

Question 23

A strong material can absorb little force before breaking. T/F

Answer 23

F

A weak material breaks at little force