Spring rate
Category: Forces & performance
The force required to compress or extend the spring by one unit of length — the spring's stiffness (N/mm).
Also called stiffness. It depends on the material's shear modulus, the wire diameter, the mean diameter and the number of active coils: k = G·d⁴ / (8·Dm³·Na).
A higher rate means a stiffer spring; a lower rate, a softer one.
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