Difference between revisions of "Contact Spring Calculations"

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===6.4.7 Contact Spring Calculations===
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[[File:One side fixed contact bending spring.jpg|right|thumb|One side fixed contact bending spring]]
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Fig. 6.20:
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One side fixed contact bending spring<br />
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L = Length of spring<br />
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E = Modulus of elasticity<br />
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B = Width of spring<br />
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F = Spring force<br />
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D = Thickness of spring<br />
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x = Deflection<br />
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max = maximum bending force
  
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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:
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:<math>F = \frac {3 x E x J}{L^3} x</math>
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where J is the momentum of inertia of the rectangular cross section of the beam
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:<math>J = \frac {B x D^3}{12}</math>
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For springs with a circular cross-sectional area the momentum of inertia is
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:<math>J=\pi D^4/64</math>
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<math>D= Durchmesser</math>
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To avoid plastic deformation of the spring the max bending force σ<sub>max</sub> cannot be exceeded
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:<math>\sigma _{max} = \frac {3 x E x D}{2L^2}x_{max}</math>
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The stress limit is defined through the fatigue limit and the 0.2% elongation limit
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resp.
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xmax= 2 x L ² Rp0,2
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3 x D x E
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and/or
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Fmax= B x D ² Rp0,2
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6L
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*'''Special Spring Shapes'''
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*'''Triangular spring'''
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Deflection
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x= L³
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F
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2 x E x J
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= x L³
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D³
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6 x F
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E x B
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Max. bending force
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Fmax= 1 8 x F x L
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B x D²
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*'''Trapezoidal spring'''
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Deflection
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x= x L³
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E x J
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F
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(2 + B /B )
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x= x L³
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E x B x D³
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12 x F
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(2 + B /B ) min ma
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Max. bending force
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Fmax= 1 8 x F x L
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(2 + B /B ) x B x D² min max max
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==References==
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[[Application Tables and Guideline Data for Use of Electrical Contact Design#References|References]]

Revision as of 13:49, 2 April 2014

6.4.7 Contact Spring Calculations

One side fixed contact bending spring

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 = \frac {3 x E x J}{L^3} x

where J is the momentum of inertia of the rectangular cross section of the beam

J = \frac {B x D^3}{12}

For springs with a circular cross-sectional area the momentum of inertia is

J=\pi D^4/64

D= Durchmesser

To avoid plastic deformation of the spring the max bending force σmax cannot be exceeded

\sigma _{max} = \frac {3 x E x D}{2L^2}x_{max}

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

References

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