Analysis and Design of Machine Elements

2 Strength of Machine Elements

Nomenclature

b

cylinder length, mm

E

elastic modulus, MPa

F

force, N

K _A

service factor, or application factor

K _σ

combined influence factor

k _f

fatigue stress concentration factor

k _t

geometric stress concentration factor

k _σ

fatigue stress concentration factor in tension

k _τ

fatigue stress concentration factor in shear

m

material constant

N

number of load cycles

N ₀

critical number of cycles

N _v

equivalent number of cycles

q

notch sensitivity factor

r

stress ratio

S

safety factor

S _ca

calculated safety factor

[S]

allowable safety factor

β _q

intensify factor

β _σ

surface condition factor for tension

ε _σ

size factor for tension

μ

Poisson's ratio

ρ

radius of curvature, mm

σ

tensile stress, MPa

σ ₋₁

endurance limit of a material at r = −1, MPa

σ _−1e

endurance limit of an element at r = −1, MPa

σ _−1Nv

endurance strength at r = −1 and N = N _v , MPa

σ ₀

endurance limit at r = 0, MPa

σ _1,2,3

principal stresses, MPa

σ _a

stress amplitude, MPa

σ _b

ultimate, or tensile strength, MPa

σ _ca

calculated tensile stress, MPa

σ _e

equivalent stress, MPa

σ _lim

material strength, MPa

σ _m

mean stress, MPa

σ _max

maximum stress, MPa

σ _min

minimum stress, MPa

σ _r

endurance limit at stress ratio r, MPa

σ _rN

endurance strength at r and N, MPa

σ _r∞

endurance limit, ...