Torsion Spring Design
Mufaddal Rasheed 
A short article on key parameters for torsion spring design
Torsion springs are essential mechanical components used to store and release rotational energy, making them crucial in applications ranging from garage doors to automotive systems. Designed to work by resisting twisting forces.
Torsion Springs are Helical coil springs subjected to end torsion like a shaft .
The key design parameter for torsion spring is the End Deflection and Bending stress developed on the inside of the coil .
Total number of turns in the coil is given by
Bending Stress in the wire is key limitation for design .
d is the wire diameter in mm
F is the Force applied in N at a distance ‘l’ from the center of coil in mm
Ki is the Wahls factor
E is the Youngs modulus in N/mm^2
Wahls Factor :
Wahl's factor is a correction factor used in spring design to account for the additional stress caused by curvature in helical springs, particularly in compression and torsion springs
Where C is
D - Coil diameter
d - Wire diameter
Spring rate of a Torsion spring is measured by its angular rate
How much Torque or Force is required to rotate the end of torsion spring for unit angle
Otherwise called torsional stiffness
The Angle of deflection for a given force can be calculated using the formula.
Categories: : Mechanism and Machine design