Springs Flashcards
Max normal stress in a coil spring
σmax = [+/- T d / 2 J] + [F / A]
What type of spring is good in high load situations
Leaf springs
What type of spring is good in rotational situations
Torsion spring
What do extension springs need to engage the spring
Initial tension force
What can compression springs be combined with for additional support
a shaft
Heavy duty springs go through the process of ….. after forming
heat treatment
L0:
free length
no load
L1:
installed length
preload
L2:
operating length
max. working load
Lc:
solid length
closed load
Closed length eqs
Lc = N d
N eqs in the closed spring length eqs
what are Na and E
N = Na + E
Na: num. of active turns
E: ends
PLAIN ENDS num. of active turns
N = Na
PLAIN GROUND-ENDS num. of active turns
N = Na + 1
SQUARED ENDS num. of active turns
N = Na + 2
SQUARED GROUND ENDS num. of active turns
N = Na + 2
Spring Index
C = D / d
What is D in the Spring Index eqs
Mean diam.
Outer diam. using Mean diam.
Do = D + d
Inner diam. using Mean diam.
Di = D - d
Hooke’s Law
F = kδ
Torsional stress eqs in terms of θ
θ = T Lw / J G
Deflection eqs
δ = (8 F D^3 Na) / (d^4 G)
Deflection eqs using C
δ = (8 F C^3 Na) / (d G)
Shear stress in a spring
τmax = (T r / J) + (F / A)
Ks is
shear factor
Kw is
Wahl factor
Why use Kw instead of Ks in a scenario
Because Wahl factor takes into account cyclic loading
Common sring index values
4 < C < 10
How to check for buckling
L0 < 5D
Relationship of max shear stress and Ultimate Tensile Strength
τmax < 0.55 Sut
