Cobra clips: physical testing


Our clips are subjected to extreme physical testing conducted in partnership with both the Cetim Cermat Laboratory and the ICAM Laboratory.

Cobra® clips are tested to determine in a precise manner the maximum allowable stress and constraints.

Two types of tests were conducted to measure the constraints linked to clip tearing: clip alone and clip in a wood decking platform

Between dry periods (summer or dry season) and wet periods (winter or rainy season), wood is subject to swelling and shrinkage, and decking boards can twist or warp. As a consequence, this applies a tensile force of more or less importance on the clip head.


Tensile testing on Cobra stainless steel 20 and 24 clips

Test n°1

Test d'arrachement d'un clip Cobra Test d'arrachement d'un clip Cobra

Measure the limit tensile (pull-out) value on a clip screwed into a treated pine sleeper, conducted by the Certim Cermat laboratory.

The average value obtained is 225kg (2.5kN)

Test n°2

test mécanique cobra 20 arrachement - banc d'essai arrachement du clip sur une terrasse en bambou thermochauffé sur lambourde aluminium

Tensile (pull-out) measurement of a clip on a thermally modified bamboo on an aluminum sleeper

The break value obtained is 250kg (2.5kN) but only after breakage along the wood board groove.

The weak point is the board groove which splits and tears before the breakage or distortion of the clip.

The test was also conducted on Ipé board with a thickness of 20mm and the results were identical.




Tensile testing on Cobra stainless steel 20 and 24 clips

Test de cisaillement des clips Cobra Test de cisaillement des clips Cobra Test de cisaillement des clips Cobra

The second test concerns shear strength.
It measures the resistance of a clip and fastening screw on a Northern pine sleeper to a lateral force applied to the board.

The average value obtained is 650kg (6.5kN)

Detailed test results available upon request.




Cobra D-Lock clip tensile (pull-out) tests

test mécanique dlock - le banc d'essai test mécanique clip dlock arrachement 250 kg

Test conducte, on an exotic wood (bangkirai) decking module and on treated pine sleepers.

The clip distorts without retaining its original shape at a force of 250kg (2.5kN).

Clip breakage occurs from 3.5kN. The stainless steel fastening screws distort at this stage.