As an example, calculate the torque and stress in the following case using the values as follows.
E：2.06×10⁵  (N/mm²)　b：10 (mm)
t：1.0 (mm)　l：1200 (mm)
In the case of the values above, the spring constant k can be calculated using the following formula.

Therefore, the torque delivered (M) per turn (360°) is expressed by the following formula, where 360° is represented as 2π.

Stress at that point is as the following formula.