Material Vocabularly 2

Question 1

What is strain?

Answer 1

The change in length per unit length

ε = x/L

No units as it is a ratio

Question 2

What is the young modulus?

Answer 2

The stiffness of a material (stress/strain)

E = σ/ε
Or E = FL/xA

Units: Pa

Question 3

What is stress?

Answer 3

The force applied / cross-sectional area it is applied to

σ = F/A

Units: N/m² or Pa

Question 4

What is elastic behaviour?

Answer 4

A property of a material that enables it to regain its original shape after being distorted by stress

Question 5

What is plastic behaviour?

Answer 5

When a material has a low elastic limit, and permanently changes shape when stress is applied

Question 6

What is yield?

Answer 6

The point at which elastic limit is reached and the material ‘gives’ a little although no added force is applied- stress drops slightly

Question 7

What is UTS?

Answer 7

Ultimate Tensile Stress

The point at which a material is strongest, it cannot withstand more stress

Question 8

What is breaking strength?

Answer 8

The maximum stress needed at the time of breakage

Past the UTS, wire becomes thinner so stress increases locally- it snaps

Question 9

What is the yield strength?

Answer 9

The maximum stress needed to reach yield point

Question 10

What is stiffness?

Answer 10

A measure of difficulty in stretching or bending the material