Lap joint
Lap joint turns up in 2 fields: adhesives, woodworking. Here is what it means to the people in each one.
Lap joint in adhesives
A bonded joint where two parts overlap face to face, loading the adhesive mainly in shear.
The overlap is the simplest and most common adhesive joint because it puts a large bond area in shear, where adhesives are strongest. Stress is not uniform: it peaks at the two ends of the overlap, and an offset load path adds peel there. Lengthening the overlap helps only up to a point, after which the extra middle area carries almost nothing. Tapering the ends or adding fillets reduces the peaks.
"Make it a lap joint with a 25 mm overlap, the butt joint you drew will never hold."
Lap joint in woodworking
A joint formed by overlapping two pieces of wood, often with half the thickness removed from each.
A fundamental woodworking joint where two pieces of material overlap. In a half-lap joint, half of the material thickness is removed from the mating face of each piece, allowing them to sit perfectly flush when assembled. It provides a massive amount of face-grain gluing surface, making it exceptionally strong against racking forces.
"I used a simple half lap joint for the cross braces on the workbench legs so they sit flush."