Knockdown factors for edge distance and countersink depth (if applicable) are applied to the laminate strengths for the determination of the final failure margins. The edge distance knockdown factor is calculated using a polynomial fit to experimental data that varies based on the edge distance to bolt diameter ratio e/d.
The knockdown factor is determined using Eqs. 39-41 [49].
The countersink depth knockdown factor is taken from Heslehurst and is shown graphically below [42].
