Adhesives, Sealants & Industrial Bonding worked example

Lap Shear Strength Estimate at 99% surface-prep effectiveness: a worked example

This scenario runs the lap shear strength estimate calculation on the strong side: 99% surface-prep effectiveness, with every other input held at its documented default. a product designer needs an early estimate of lap shear capacity for a bonded joint

The inputs for this scenario

  • Lap overlap area: 2.5 in² or mm² (unchanged)
  • Adhesive shear strength: 2,800 psi or MPa (unchanged)
  • Surface-prep effectiveness: 99 % (raised for this scenario; the documented default is 88)
  • Cure/process yield: 92 % (unchanged)

Working through the calculation

  • Applying the documented formula (Theoretical lap shear capacity = lap overlap area × adhesive shear strength) to the inputs above produces each figure below.
  • At this operating point the engine returns 6,376 lbf or N for effective lap shear capacity, the number this scenario is built around.
  • At this operating point the engine returns 7,000 lbf or N for theoretical lap shear capacity.
  • At this operating point the engine returns 70 lbf or N for surface-prep loss.
  • At this operating point the engine returns 554 lbf or N for cure/process loss.

How this compares with the baseline

  • Against the tool's baseline example, where surface-prep effectiveness sits at 88% and the headline result is 5,667 lbf or N, this scenario comes in 12.5% above the baseline at 6,376 lbf or N.
  • Use it for early joint sizing, adhesive candidate screening, or setting a realistic proof-load target before physical pull testing. Treat this as a target state: the delta against the baseline quantifies what the improvement is worth before you commit to chasing it.

Results at a glance

  • Effective lap shear capacity: 6,376 lbf or N (headline result)
  • Theoretical lap shear capacity: 7,000 lbf or N
  • Surface-prep loss: 70 lbf or N
  • Cure/process loss: 554 lbf or N

Run it with your numbers

  • Every input above is editable in the live Lap Shear Strength Estimate calculator, which recalculates instantly and can be shared with the inputs intact.

Last reviewed 2026-05-12.