A coupon cut across the seam is gripped by the top sheet on one side and the bottom sheet on the other and pulled apart. A good seam is stronger than the sheet, so the sheet yields and stretches before the weld gives way. Results are reported as strength per width and elongation, against spec minimums for each sheet thickness.
Shear test numbers are fine on that machine, it's the peels that keep failing.
Also heard as
- shear
- bonded seam strength
- seam shear
Related terms
Peel test
Seam test that pulls the top sheet away from the bottom sheet across the weld to check how well they fused.
Tensiometer
Portable tensile tester used on site to pull geomembrane seam coupons in peel and shear.
Coupon
Narrow strip cut across a seam sample for peel or shear testing, usually one inch wide.
FTB
Film tear bond: a seam coupon that breaks in the sheet beside the weld rather than through the weld itself.