Design calculators

First-pass sanity checks for the rules the selector flags. Representative rules of thumb — verify against MMPDS, the OEM process spec, and your stress group before release.

Edge distance & pitch

Minimum hole-to-edge and hole-to-hole spacing from the fastener diameter.

Nominal diameter

Composite edge (3D + 0.05)0.8"

Metal edge (2D)0.5"

Hole pitch (4D)1"

Composites need more room than metals: matrix-dominated shear is weaker and stress concentrations interact more severely.

Bearing stress check

Bearing stress = load / (diameter × thickness), vs the material's representative allowable.

Load (lbf)

Diameter (in)

Thickness (in)

Material

Within allowable40 ksi

allowable 50 ksimargin +25%

Composite allowables (CFRP ~50, GFRP ~40 ksi) are conservative hot/wet. Metal values are representative ultimate bearing — confirm with MMPDS.