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Created page with "====6.4.7 Contact Spring Calculations==== Fig. 6.20: One side fixed contact bending spring L = Length of spring E = Modulus of elasticity B = Width of spring F = Spring force..."
====6.4.7 Contact Spring Calculations====
Fig. 6.20:
One side fixed contact bending spring
L = Length of spring
E = Modulus of elasticity
B = Width of spring
F = Spring force
D = Thickness of spring
x = Deflection
max = maximum bending force
The influence of the dimensions can be illustrated best by using the single side
fixed beam model (Fig. 6.20). For small deflections the following equation is valid:
F= x
3 x E x J
L³
where J is the momentum of inertia of the rectangular cross section of the beam
J=
B x D³
12
For springs with a circular cross-sectional area the momentum of inertia is
J=BD4/64
D= Durchmesser
To avoid plastic deformation of the spring the max bending force σ cannot be max
exceeded
Fmax= 3 x E x D xmax
2L²
The stress limit is defined through the fatigue limit and the 0.2% elongation limit
resp.
xmax= 2 x L ² Rp0,2
3 x D x E
and/or
Fmax= B x D ² Rp0,2
6L
*'''Special Spring Shapes'''
*'''Triangular spring'''
Deflection
x= L³
F
2 x E x J
= x L³
D³
6 x F
E x B
Max. bending force
Fmax= 1 8 x F x L
B x D²
*'''Trapezoidal spring'''
Deflection
x= x L³
E x J
F
(2 + B /B )
x= x L³
E x B x D³
12 x F
(2 + B /B ) min ma
Max. bending force
Fmax= 1 8 x F x L
(2 + B /B ) x B x D² min max max
==References==
[[Application Tables and Guidance Data for the Use of Electrical Contacts#References|References]]
Fig. 6.20:
One side fixed contact bending spring
L = Length of spring
E = Modulus of elasticity
B = Width of spring
F = Spring force
D = Thickness of spring
x = Deflection
max = maximum bending force
The influence of the dimensions can be illustrated best by using the single side
fixed beam model (Fig. 6.20). For small deflections the following equation is valid:
F= x
3 x E x J
L³
where J is the momentum of inertia of the rectangular cross section of the beam
J=
B x D³
12
For springs with a circular cross-sectional area the momentum of inertia is
J=BD4/64
D= Durchmesser
To avoid plastic deformation of the spring the max bending force σ cannot be max
exceeded
Fmax= 3 x E x D xmax
2L²
The stress limit is defined through the fatigue limit and the 0.2% elongation limit
resp.
xmax= 2 x L ² Rp0,2
3 x D x E
and/or
Fmax= B x D ² Rp0,2
6L
*'''Special Spring Shapes'''
*'''Triangular spring'''
Deflection
x= L³
F
2 x E x J
= x L³
D³
6 x F
E x B
Max. bending force
Fmax= 1 8 x F x L
B x D²
*'''Trapezoidal spring'''
Deflection
x= x L³
E x J
F
(2 + B /B )
x= x L³
E x B x D³
12 x F
(2 + B /B ) min ma
Max. bending force
Fmax= 1 8 x F x L
(2 + B /B ) x B x D² min max max
==References==
[[Application Tables and Guidance Data for the Use of Electrical Contacts#References|References]]
