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Spring Shear Stress Calculator

Shear Stress Helical Linear Spring Calculator

This calculator will determine the shear stress in a helical spring as well as maximum allowable torsional stress

shear stress in a helical linear spring
Eq. 1
τ = Ks 8 F D / ( π d3 )

where

d = wire diameter, (in, mm)
F = applied force, (lbs, N)
D = mean spring diameter, (in, mm)
Ks = (2C + 1)/(2C),
C = D/d.

The deflection and force are related by F = kx where the spring rate (spring constant) k is given by

Eq. 2
k = d4 G / ( 8 D3 N )

where

G = shear modulus of elasticity, (N/mm2, lbs/in2)
N = number of active coils, #

Spring Material: The minimum tensile strength of common spring steels may be determined from

Eq. 3
Sut = A / dm

where

Sut = tensile strength in MPa,
d = wire diameter in millimeters,

A and m are listed in the table

 Material ASTM m A Music wire A228 0.163 2060 Oil-tempered wire A229 0.193 1610 Hard-drawn wire A227 0.201 1510 Chrome vanadium A232 0.155 1790 Chrome silicon A401 0.091 1960

Maximum allowable torsional stress for static applications may be approximated as

Ssy = τ = 0.45 Sut cold-drawn carbon steel (A227, A228, A229)

Ssy = τ = 0.50 Sut hardened and tempered carbon and low-alloy steel (A232, A401)

Related:

Source

Fundamentals of Engineering Supplied Reference Handbook, Fifth Edition
National Council of Examiners for Engineering and Surveying