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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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| − |
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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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| − |
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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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| − |
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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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| − |
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| − | The stress limit is defined through the fatigue limit and the 0.2% elongation limit resp.
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| − | :<math>x _{max} = \frac {2 x L^2}{3 x D x E}R_{p0,2}</math>
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| − |
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| − | <br />and/or<br />
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| − | :<math>F _{max} = \frac {B x D^2}{6L}R_{p0,2}</math>
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| − |
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| − |
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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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| − |
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| − | Deflection
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| − | :<math>x = \frac {F}{2 x E x J}L^3</math>
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| − |
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| − |
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| − | :<math>= \frac {6 x F}{E x B}x \frac{L^3}{D^3}</math>
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| − |
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| − |
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| − | Max. bending force
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| − | :<math>\sigma _{max}= \frac {18 x F x L}{B x D^2}</math>
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| − |
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| − | <li>'''Trapezoidal spring'''</li>
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| − |
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| − | Deflection
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| − | :<math>x= \frac {F}{(2 + B_{min} /B_{max})}\times \frac{L^3}{E x J}</math>
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| − |
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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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| − |
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| − | Max. bending force
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| − |
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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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| − | </ul>
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| − |
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| − | ==References==
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| − | [[Application Tables and Guideline Data for Use of Electrical Contact Design#References|References]]
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