$$ \begin{array}{l}{\text { Maximum bending stress }\left(\sigma_{b}\right)=\frac{M}{I} \times Y} \ {\text { Where, } M=\text { Maximum Bending Moment ( } \mathrm{kN} . \mathrm{m}) \text { or (N.mm) }} \ {\qquad \begin{array}{l}{\mathrm{I}=\text { Moment of Inertia }\left(\mathrm{mm}^{4}\right)} \ {\mathrm{Y}=\text { Distance of neutral axis from top or bottom (mm). }}\end{array}}\end{array} $$