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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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− |
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− | F= x
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− | 3 x E x J
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− | L³
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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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− |
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− | J=
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− | B x D³
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− | 12
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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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− |
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− | J=BD4/64
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− | D= Durchmesser
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− |
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− | To avoid plastic deformation of the spring the max bending force σ cannot be max
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− | exceeded
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− |
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− | Fmax= 3 x E x D xmax
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− | 2L²
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− |
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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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− |
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− | xmax= 2 x L ² Rp0,2
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− | 3 x D x E
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− |
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− | and/or
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− |
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− | Fmax= B x D ² Rp0,2
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− | 6L
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− |
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− |
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− | *'''Special Spring Shapes'''
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− |
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− | *'''Triangular spring'''
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− |
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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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− |
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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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− |
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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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− |
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− | *'''Trapezoidal spring'''
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− |
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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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− |
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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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− |
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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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