Difference between revisions of "Contact Spring Calculations"

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===6.4.7 Contact Spring Calculations===
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<figure id="fig:Oneside_fixed_contact_bending_spring">
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[[File:One side fixed contact bending spring.jpg|right|thumb|One side fixed contact bending spring]]
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</figure>
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The influence of the dimensions can be illustrated best by using the single side fixed beam model <xr id="fig:Oneside_fixed_contact_bending_spring"/> <!--(Fig. 6.20)-->. For small deflections the following equation is valid:
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:$F = \frac{3 \cdot E \cdot J}{L^3} $
  
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where J is the momentum of inertia of the rectangular cross section of the beam
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:$J = \frac{B \cdot D^3}{12}$
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For springs with a circular cross-sectional area the momentum of inertia is
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:$J=\pi D^4/64$
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:$D= Durchmesser$
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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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:$\sigma_{max} = \frac{3 \cdot E \cdot D}{2L^2}\cdot_{max}$
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The stress limit is defined through the fatigue limit and the 0.2% elongation limit resp.
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:$\times_{max} = \frac{2 \cdot L^2}{3 \cdot D \cdot E}R_{p0,2}$
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<br />and/or<br />
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:$F_{max} = \frac{B \cdot D^2}{6L}R_{p0,2}$
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<li>'''Special Spring Shapes'''</li>
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<ul>
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<li>'''Triangular spring'''</li>
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Deflection
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:$ \times = \frac{F}{2 \cdot E \cdot J}L^3$
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:$= \frac{6 \cdot F}{E \cdot B}\cdot \frac{L^3}{D^3}$
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Max. bending force
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:$\sigma_{max}= \frac{18 \cdot F \cdot L}{B \cdot D^2}$
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<li>'''Trapezoidal spring'''</li>
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Deflection
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:$ \times = \frac{F}{(2 + B_{min} /B_{max})}\times \frac{L^3}{E \cdot J}$
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:$\times= \frac{12 \cdot F}{(2 + B_{min} /B_{max})}\cdot \frac{L^3}{E \cdot B \cdot D^3}$
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Max. bending force
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:$\sigma_{max}= \frac{18 \cdot F \cdot L}{(2 + B_{min} /B_{max}) \cdot B_{max} \cdot D^2 }$
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</ul>
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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 12:04, 14 May 2014

6.4.7 Contact Spring Calculations

One side fixed contact bending spring

The influence of the dimensions can be illustrated best by using the single side fixed beam model Figure 1 . For small deflections the following equation is valid:

$F = \frac{3 \cdot E \cdot J}{L^3} $

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

$J = \frac{B \cdot D^3}{12}$

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

$\sigma_{max} = \frac{3 \cdot E \cdot D}{2L^2}\cdot_{max}$

The stress limit is defined through the fatigue limit and the 0.2% elongation limit resp.

$\times_{max} = \frac{2 \cdot L^2}{3 \cdot D \cdot E}R_{p0,2}$


and/or

$F_{max} = \frac{B \cdot D^2}{6L}R_{p0,2}$


  • Special Spring Shapes
    • Triangular spring

      • Deflection

      $ \times = \frac{F}{2 \cdot E \cdot J}L^3$


      $= \frac{6 \cdot F}{E \cdot B}\cdot \frac{L^3}{D^3}$


      Max. bending force

      $\sigma_{max}= \frac{18 \cdot F \cdot L}{B \cdot D^2}$
    • Trapezoidal spring

      • Deflection

      $ \times = \frac{F}{(2 + B_{min} /B_{max})}\times \frac{L^3}{E \cdot J}$


      $\times= \frac{12 \cdot F}{(2 + B_{min} /B_{max})}\cdot \frac{L^3}{E \cdot B \cdot D^3}$


      Max. bending force

      $\sigma_{max}= \frac{18 \cdot F \cdot L}{(2 + B_{min} /B_{max}) \cdot B_{max} \cdot D^2 }$

    References

    References

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