Spring Rate (Spring Constant)
Definition
The force required to compress or extend a spring by one unit of length. Denoted as k, it is calculated as k = Gd⁴/(8D³n) for helical springs, where G is shear modulus, d is wire diameter, D is mean coil diameter, and n is active coils.
Practical Note
Spring rate is measured in N/mm or lbf/in. Higher values mean stiffer springs requiring more force for the same deflection.