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Berechnen Sie spring constant k aus wire diameter, coil diameter, and active coils. Design helical compression springs accurately.
Spring Constant (k)
5.139 N/mm
Spring Constant (k) vs Shear Modulus (G)
Formel
## Helical Spring Constant The stiffness of a helical compression or extension spring depends on material properties, wire size, and coil geometry. ### Formula **k = G d^4 / (8 D^3 Na)** where G is the shear modulus, d is wire diameter, D is mean coil diameter, and Na is the number of active coils. The spring index C = D/d should be between 4 and 12 for practical manufacturability.
Lösungsbeispiel
A steel spring with 3 mm wire, 25 mm mean coil diameter, 10 active coils, G = 79.3 GPa.
- 01G = 79,300 MPa (= N/mm^2)
- 02d^4 = 3^4 = 81
- 03D^3 = 25^3 = 15,625
- 04k = 79,300 x 81 / (8 x 15,625 x 10)
- 05k = 6,423,300 / 1,250,000 = 5.139 N/mm
- 06Spring index C = 25/3 = 8.33 (good, within 4-12 range)
Häufig Gestellte Fragen
What affects spring stiffness the most?
Wire diameter has the strongest effect because it appears as d^4. Doubling wire diameter increases stiffness 16 times. Coil diameter is next important (D^3 in denominator).
What is the shear modulus for spring steel?
For music wire and chrome silicon steel springs, G is approximately 79.3 GPa (11.5 Mpsi). For stainless steel springs, G is about 69 GPa.
How do I count active coils?
Active coils = total coils minus inactive end coils. For closed and ground ends, subtract 2. For closed ends only, subtract 2. For plain ends, active coils equal total coils.
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