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.
Also heard as
- single lap
- overlap joint
Related terms
Lap shear
The standard strength test for adhesives, pulling apart a single overlap joint and reporting load over bond area.
Butt joint
A joint where two parts are bonded end to end, with only the small end area carrying the load.
Scarf joint
A joint where both parts are tapered to long matching slopes and bonded along the taper.
Peel stress
Tension pulling one adherend away from the other at the edge of a bond, concentrated along a thin line.
Fillet
The bead of adhesive left around the edge of a joint, which smooths stress at the ends of the bond.