In peel, the load acts on only the first fraction of a millimeter of the bond at the edge, so even strong adhesives fail at low forces. Peel stress arises from flexible adherends, eccentric lap joints and bending. Designers keep adhesives in shear, add fillets, stiffen parts, taper ends, or use mechanical fasteners at the peel-prone end to reduce it.
Bracket keeps letting go at the top edge, that's peel stress from the offset load, not shear.
If a design depends on an adhesive in peel, add a fastener, a fillet or a stiffer part at the edge; more adhesive alone rarely helps.
Also heard as
- peel loading
Related terms
Peel
The force needed to strip a flexible bonded layer off a surface, given per unit width.
Cleavage
Loading that pries a rigid joint open from one end, concentrating stress along the leading edge of the bond.
Lap joint
A bonded joint where two parts overlap face to face, loading the adhesive mainly in shear.
Fillet
The bead of adhesive left around the edge of a joint, which smooths stress at the ends of the bond.
Toughened
Describing an adhesive modified with rubber or soft particles so the bond resists cracking, peel and impact.