Contact Physics – Formulas
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6.4.2 Contact Physics – Formulas
- Constriction resistance
(Single spot contact according to Holm; circular touching spot between clean contact surfaces)
(Multi-spot contact according to Holm without influence between the N individual spots)
(Multi-spot contact according to Greenwood considering the influence between the spots)
- Contact resistance
- Path resistance
- Contact resistance and contact force
(According to Holm model for film-free spherical contact surfaces with plastic deformation of the contact material; Fk < 1 N for typical contact materials)
(According to Holm model for film-free spherical contact surfaces with plastic deformation of the contact material; Fk > 5 N for typical contact materials)
- Dynamic contact separation (without considering magnetic fields caused by the current path)
(Rule of thumb with FA in N and l in kA)
- Contact voltage and max. contact temperature
- Contact resistance at higher contact forces (according to Babikow)
For FK between 10 and 200 N
c = material dependent proportionality factor
m = shape dependent exponent of the contact force
Material combination | c |
---|---|
Copper - Copper | (0.08 bis 0.14) x 10-3 |
Aluminium - Aluminium | Copper and copper alloys for springs and connectors |
DIN EN 1758 | Copper and copper alloys in strip form for system component carriers |
ASTM B 103/B103M-10 | Spec. for Phosphor Bronce Plate, Sheet, Strip, and Rolled Bar |
ASTM B 36/B36M-95 | Spec. for Brass Plate, Sheet, Strip, and Rolled Bar |
ASTM B 122/B122M-08 | Spec. for CuNiSn-, CuNiZn-, and CuNi-Alloy |
ASTM B 465-09 | Spec. for Copper-Iron-Alloy Plate, Sheet, and Strip |
ASTM B 194-08 | Standard Spec. for CuBe-Alloy Plate, Sheet, Strip and Rolled Bar |
ASTM B 534-07 | Sec. for CuCoBe-Alloy and CuNiBe-Alloy Plate, Sheet, Strip, and Rolled Bar |