Creep Equations

Question 1

What does a creep graph look like ?

Answer 1

Question 2

What does a stress relaxation graph look like?

Answer 2

Question 3

What does a creep function consist of ?

Answer 3

Question 4

At what temperature for metals and ceramics does creep start to be pivotal ?

Answer 4

Question 5

What relates density and temperature?

Answer 5

Question 6

What equation relates Youngs Modulus and temperature ?

Answer 6

Question 7

What is the steady state creep strain rate ?

Answer 7

Question 8

What is the creep exponential steady-state creep strain rate ?

Answer 8

Question 9

What is the Arrhenious equation ? ( dependency between creep rate and temperature)

Answer 9

Question 10

What is the creep rate combining the exponential law and the Arrhenious equation?

Answer 10

Question 11

What is the stress with relation to time for creep relaxation ?

Answer 11

Question 12

What is the Kelvin-Voigt viscoelastic model?

Answer 12

Question 13

What is Maxwell’s Viscoelastic model?

Answer 13

Question 14

What is Fick’s law?

Answer 14

Question 15

What is the diffusion coefficient?

Answer 15

Question 16

What happens to density as a material is heated up?

Answer 16

It decreases

Question 17

What happens to the volume of a specimen as it is heated up?

Answer 17

Volume decreases

Question 18

What happens to the Young’s Modulus of a material as it is heated up?

Answer 18

It decreases

Question 19

What is creep?

Answer 19

Creep is a time-dependant deformation at high temperatures at a constant stress below the yield stress of a material.

Question 20

What are the 3 stages of a creep graph?

Answer 20

Primary creep, secondary creep and tertiary creep

Question 21

What happens during primary creep?

Answer 21

Creep rate decreases with time as mobile dislocations become steady

Question 22

What happens during secondary creep?

Answer 22

Dislocation creation and annihilation are balanced

Question 23

What happens during tertiary creep?

Answer 23

Creep rate accelerates, leading to fracture

Question 24

What is the gradient of a creep graph?

Answer 24

Creep rate

Question 25

What happens if we plot log strain against log stress?

Answer 25

We get a linear line ln strain = strain^n X B

Question 25

What happens if we plot ln strain against 1/T?

Answer 25

A linear relationship is obtained.

Question 26

What happens during relaxtion?

Answer 26

Strain is kept constant, and in time stress reduces

Question 27

Is plastic recovery larger in concrete or polymers under creep?

Answer 27

Plastic recovery is far larger in polymers, as concrete has a large plastic deformation

Question 28

When will atoms only ever diffuse?

Answer 28

When energy is put into the system

Question 29

Why do materials deform more at higher stresses?

Answer 29

Atoms start to diffuse between the grains themselves, resulting in very high deformations

Question 30

What is a dislocation glide?

Answer 30

When dislocations move along slip planes overcoming barriers by thermal activation

Question 31

What is a dislocation climb?

Answer 31

Involves dislocation movement to overcome barriers by diffusion of vacancies or institials

Question 32

What is diffusion creep?

Answer 32

The flow of vacancies under an applied stress

Question 33

What is grain boundary sliding?

Answer 33

Involves the sliding of grains past each other