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Round wire helical spring (given the force on spring)

Round wire helical spring D d
Round wire helical spring

Values for calculation

$ d $ $ \mathrm{mm} $
$ D $ $ \mathrm{mm} $
$ n $
$ E $ $ \mathrm{GPa} $
$ G $ $ \mathrm{GPa} $
$ F $ $ \mathrm{N} $
$ S_y $ $ \mathrm{MPa} $

Calculation

Shear admissible stress

$$τ_{adm}=\cfrac{S_y}{\sqrt{3}}$$

Spring deflection

$$f=\cfrac{64\cdot n\cdot\left(\cfrac{D}{2}\right)^3\cdot F}{d^4\cdot G\cdot 10^3}$$

Spring stiffness

$$k=\cfrac{F}{f\cdot 10^{-3}}$$

Energy stored

$$E_p=\cfrac{F\cdot f\cdot 10^{-3}}{2}$$

Spring index

$$C=\cfrac{D}{d}$$

Wahl factor

$$K_W=\cfrac{4\cdot C-1}{4\cdot C-4}+\cfrac{0.615}{C}$$

Shear stress

$$τ_S=\cfrac{8\cdot F\cdot D\cdot K_W}{π\cdot d^3}$$

$$τ_S\le τ_{adm}$$

Safety factor

$$S_F=\cfrac{τ_{adm}}{τ_S}$$