Lap shear coupons, peel strips and wedge specimens are cut from the same material and given the same surface prep as production parts. Lines often bond witness coupons alongside real parts in each shift or batch, then break them to prove the process. Coupon results drive acceptance of film adhesive lots, primer batches and surface treatments.
Bond six coupons with every batch and drop them in the oven with the parts, quality wants them broken by Friday.
Also heard as
- test coupon
- witness coupon
- specimen
Related terms
Lap shear
The standard strength test for adhesives, pulling apart a single overlap joint and reporting load over bond area.
Dog bone
A cast or cut tensile specimen with wide ends and a narrow middle, used to test bulk adhesive properties.
T-peel
A peel test where two flexible strips bonded face to face are pulled apart in a T shape.
Cohesive failure
A break that runs through the adhesive itself, leaving adhesive on both parts.
Same word, different worlds
A small test piece sprayed alongside production parts to stand in for them in destructive tests.
Printed Circuit BoardsSmall test pattern built on the production panel and measured or sectioned to prove the boards meet spec.
GeosyntheticsNarrow strip cut across a seam sample for peel or shear testing, usually one inch wide.