How is the bending coefficient of sheet metal calculated

The calculation formula is as follows:

L=0.5π ×( R + K coefficient × T) ×(θ/ 90)

L: Unfold length of sheet metal
R: Inner radius of bend
T: Material thickness
θ: Bending angle
Y factor: a constant determined by the position of the neural bend line. Its default value is 0.5 (the so-called “bend line”).

In the practice of sheet metal design, the commonly used sheet metal flattening calculation formula is based on the K coefficient, which ranges from 0 to 1, indicating the resistance of the material to stretching during bending.

The relationship with the y coefficient is as follows:
Y coefficient = (π / 2) × K coefficient