Composites · Worked example
A two-pass screen for a laminate with a fastener hole
Two layups share the same hole, edge distance and restraint. The first pass checks global displacement; the second checks local bearing and delamination indications.
The comparison
The plate has a 6 mm hole, a 12 mm centre-to-edge distance and a 1,600 N tensile load. Tip displacement is limited to 1.2 mm, with a 5% mass-reduction target.
The baseline is [0/+45/-45/90]s; the candidate is [0/+45/0/-45]s. Material data, outer geometry, restraint and load direction remain unchanged.
What would stop the proposal
The first pass checks directional stiffness and displacement. A separate local pass covers the bearing zone, free edge and layup termination.
A lighter candidate does not move forward if bearing damage or a delamination indication appears first at the hole. The global stress plot cannot overrule that local failure condition.
The record handed to test
Material inputs, ply thickness, local mesh, fixture coverage, measurement points and the damage criterion travel together. If the criterion is still open, the candidate stays under review.
Physical testing sits outside this screen; the revised layup remains unverified.