a

Crack length, spherical radius

m

a _m

Permissible crack size

m

b

Weibull slope

nd

B

Basicity index

nd

Specimen width

m

C

Constant

nd

C _p

Specific heat at constant pressure

J kg ^?1 K ^?1

C _v

Charpy impact energy

J

d

Weld width

m

D

Coefficient of diffusion

m ² s ^?2

E

Modulus of elasticity

MN m ^?2

G

Strain energy release rate

J m ^?2

I

Current

A

J

Current density

A m ^?2

Strain energy around a crack

J m ^?2

J _Q

Provisional value of J

J m ^?2

K

Absolute temperature

K

Stress intensity factor

K MN m ^? or N mm ^?3/2

K ₁

Stress intensity factor in the opening mode (I)

MN m ^? or N mm ^?3/2

K _IC

Critical value of K _I for unstable crack extension

MN m ^? or N mm ^?3/2

K _n

Modified Bessel function of the second kind of order n

nd

ln

Logarithm to base e

nd

log

Logarithm to base 10

nd

l, L

Length, distance

m

m

Mean interval between failures

s

M

Any metal

nd

n

Any numerical factor

nd

Operating parameter

nd

n, N

Number of cycles

nd

P

Probability

nd

q

Rate of heat or energy flow

W

Cumulative number of failures

nd

Q

Quantity of...