# Permissible dynamic bending stress

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The permissible dynamic bending stress is used to calculate the permissible dynamic radial load and a safety factor for the bending stress amplitude. The stress is considered at the point where the maximal stress occurs.

$\sigma_{max}= \sigma_{b, max} + F_t/A$

$\sigma_{min}= \sigma_{b, min} + F_t/A$

$\sigma_{m}= (\sigma_{max} +\sigma_{min})/2$

$\sigma_{a}= (\sigma_{max} -\sigma_{min})/2$

The input value is a permissible alternating stress with is reduced by the mean stress influence coefficient ψ. The safety factor is calculated as

$S_{dyn} =\frac{\sigma_{bDperm} - \Psi\cdot\sigma_m}{\sigma_a}$

The permissible dynamic radial load is calculated so that a safety factor of 1 is reached.