Renault D41 1048 Flexible and Semi-Rigid Cellular Materials - Tear Strength (Example: Trouser Type)

The standard "Renault D41 1048 Flexible and semi-rigid cellular materials - Tear strength (example: trouser type)" developed by the French automobile company Renault describes a procedure for determining the tear strength characteristics of flexible or semi-rigid cellular materials in the form of flat sheets or pieces thicker than 10 mm. The method to be used in cases where the thickness is 10 mm or less is specified in the standards.

In principle, this test method consists of measuring the average load required to propagate a tear in a “trousers” type test specimen.

Major test equipment used in these tests includes:

• The tensile testing machine must meet the following conditions:
  • There should be a device that records the load-elongation curve.
  • It must have a load sensor suitable for the measuring range of the materials being tested. For tear tests on polyurethane foams, the sensor must have a maximum load of 1000N.
  • The moving jaw travel speed shall be 50 mm/min plus/minus 5 mm/min or any other speed specified in the reference documents.
  • In order to secure the test specimen without possible slipping, the jaws and jaws must have jaws such that the clamping of the jaws does not require a preload applied to the test specimen (such as screw-clamping jaws and jaws with saw-tooth grooves). The width of the jaws must be greater than the width of the test specimens.
• Band saw (toothless).
• The punch consists of steel blades representing a rectangle (50 mm plus/minus 1 mm x 12,5 mm plus/minus 1 mm) with a 50 mm blade along the length for the formation of the legs of the “trousers” type specimen with dimensions of 125 mm plus/minus 1 mm x 25 mm plus/minus 1 mm.
• The conditioned room should have a temperature of 23 degrees plus/minus 2 degrees and a relative humidity of 50 percent plus/minus 5 percent.
• The climate chamber should have a temperature of 23 degrees plus/minus 2 degrees and a relative humidity of 50 percent plus/minus 5 percent.
• Small ruler.

For seat foams, the “trousers” type specimen shall be a rectangular parallelepiped with the following dimensions: 125 mm plus/minus 1 mm x 25 mm plus/minus 1 mm x 25 mm plus/minus 1 mm. For materials with a thickness of less than 10 mm, the method specified in the reference documents shall be used. When the thickness of the material is between 10 mm and 25 mm, test specimens of the same thickness as the material shall be used.

Samples are taken from the test samples using a band saw or punch.

The orientation of the test specimens in the part is determined by the position of the tear plane relative to the direction of expansion of the foam. 5 specimens are taken for each of the following orientations:

• Rupture plane parallel to the expansion direction of the foam
• Rupture plane perpendicular to the expansion direction of the foam

For pillows, the direction of expansion of the foam is assumed to be perpendicular to the plane of the bearing area.

For foams delivered in sheets, one of the two plane directions is assumed to correspond to the direction of expansion of the foam and, if unknown, the direction is determined by rotating the test specimen so that its thickness corresponds to the thickness of the sheet.

In the case of special foam with an automatically formed skin, test samples shall be taken from the centre. In particular, for test samples where the tear plane is parallel to the direction of expansion of the foam, at least 4 mm of the skin shall be removed.

Test samples are conditioned in the conditioning chamber or climate chamber for at least 16 hours.

Among the numerous tests, measurements, analyses and evaluation studies carried out for businesses in various sectors, our organization also provides testing services defined in the “Renault D41 1048 Flexible and semi-rigid cellular materials - Tear resistance (example: trouser type)” standard with its trained and expert staff and advanced technological equipment.