stress/strain

Question 1

equation for stress?

Answer 1

stress = force/cross sectional area

Question 2

stress is indépendant of material, but breaking points of materials can be used to determine strenghts

Answer 2

y

Question 3

stress = force/cross sectional area

Answer 3

y

Question 4

strain units?

Answer 4

none

Question 5

e=

Answer 5

delta l/l

Question 6

straight line in stress strain?

Answer 6

proportional limit

Question 7

elastic limit?

Answer 7

E

Question 8

what is the yield point?

Answer 8

material undergoes considerable elongation without an increase in stress (straight line)

Question 9

is there elastic recovery in the yield area?

Answer 9

no

Question 10

material begins to strain or work harden during yielding-what is this called?

Answer 10

strain hardening

Question 11

stiffnoess (k) =

Answer 11

f/delta l

Question 12

youngs modulus (E) =

Answer 12

stress/strain

Question 13

hookes law?

Answer 13

most materials have an initial region on thisr stress strain curve where they behave both elastically and linearly

Question 14

what is necking?

Answer 14

wasting in the material, cross sectional area is reduced, accounts for dip after ultimate strength where strain increases with decreasing stress

Question 15

units for E?

Answer 15

Pa - since strain has no units

Question 16

material with large YM?

Answer 16

steel

Question 17

rigidity =

Answer 17

EA

Question 18

A=

Answer 18

cross sectional area of bar

Question 19

therefore rigidity of bar will increase with increasing cross sectional area

Answer 19

y

Question 20

2 equations for stiffness?

Answer 20

f/delta l, or EA/l

Question 21

prefix G =

Answer 21

x10 ^9

Question 22

3 differences of viscous material?

Answer 22

does not deform instantaneously, does not return to same shape and size, stress is dependant upon strain

Question 23

co efficient of viscosity=? (n)

Answer 23

stress over strain rate

Question 24

strain rate is simply?

Answer 24

delta strain / delta time