ASTM D751 Tensile Testing of Coated Fabrics

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ASTM D751 is used to measure the tensile properties of coated fabrics. This includes the fiber content, coating type, and thickness of the coating on the fabric.

What Is ASTM D751?

ASTM D751 provides standard tests for a wide variety of mechanical properties of rubber and plastic coated fabrics that include rain wear, tarpaulins, and outdoor clothing. A coated fabric has at least one layer of textile with one layer of a rubber or polymeric coating. Our focus is on the sections of the standard that can be performed with a universal test machine. 

Why Perform ASTM D751?

Not all product testing is the same. As a manufacturer, you want to make sure your goods are safe and meet relevant standards. In order to ensure this, you need a reliable testing method like ASTM D751. This guarantees you and your buyers have peace of mind when it comes to quality and integrity.

ASTM D751 Test Method

ASTM D751 Breaking Strength & Elongation - Section 13

This test determines the breaking strength of the coated fabric by either the Grab Test Method (Procedure A) or the Cut Strip Test Method (Procedure B).

Preparing the Specimens

Gather two sets of 5 specimens each for longitudinal and transverse breaking strength.

  • Procedure A: 100 mm (3.9 in) wide x 150 mm (5.9 in) long cut from coated fabric
  • Procedure B: 25 mm (0.98 in) wide x 150 mm (5.9 in) long cut from coated fabric

Test Procedure

  • First, place the specimen symmetrically in the fixture clamps with the longer dimension parallel to the direction of the applied force.
  • Start the tension test at a rate of 5 mm/sec (0.19 in/sec).
  • Record the maximum force required by the universal test machine to break the specimen

ASTM D751 Bursting Strength - Section 18

The bursting strength test determines the bursting strength of the coated fabric. This test is characterized by a spherical plunger fixture.

Preparing the Specimens

Ten specimens should be cut with the smallest dimension at least 12.5 mm (0.49 in) greater than the outside diameter of the ring-clamp.

Test Procedure

  • First, mount the test specimen in the ring clamp.
  • Start the universal test machine at a rate of 5 mm/sec (0.19 in/sec) until a rupture occurs.
  • Record the force maximum force as the bursting strength of the specimen.

ASTM D751 Puncture Resistance - Section 22

This test determines the puncture resistance of the coated fabric. This test is different than the bursting strength test in that you operate the test machine at a faster rate and use a sharp plunger shaped fixture to puncture the fabric.

Preparing the Specimens

Five specimens should be cut with the smallest dimension at least 12.5 mm (0.49 in) greater than the outside diameter of the ring-clamp.

Test Procedure

  • First you should mount the test specimen in the ring clamp.
  • Start the universal test machine at a rate of 300 mm/min (11.8 in/min) until a puncture occurs
  • Record the maximum force recorded by the test machine as the puncture resistance of the specimen.

ASTM D751 Tearing Strength - Section 28

The Tongue Tear Method is more common than the Elmendorf test. It requires a universal testing machine. The trapezoidal test is a tear test method. 

Preparing the Specimens

Five specimens from each of the warp and filling directions should be tested. Specimens should be rectangular in shape and 75  x 200 mm (2.9 x 7.8 in) in size. Make a 75 mm (2.9 in) cut at the center of and perpendicular to a short side of the specimen to form the tongues.

Test Procedure

  • First center the specimen in the machine with one tongue fastened in each clamp
  • Start the machine with a uniform speed of 0.85 mm/sec (0.03 in/sec)
  • Record the force necessary to tear the cloth a distance of 75 -100 mm (2.9 - 3.9 in)
  • Tearing strength shall be the average of the 5 highest peak loads during the tearing.

ASTM D751 Adhesion of Coating to Fabric - Section 45

This test determines the adhesion of the coating to the fabric.

Preparing the Specimens

The peel adhesion of coating to fabric test in ASTM D751 requires two sets of two specimens each for the longitudinal and transverse direction. Your specimens should be rectangular and sized as 25 mm (0.98 in) wide x 200 mm  (7.87 in) long. After creating the specimens, separate the coating from the backing for a distance of 50 mm (1.9 in).

Testing Procedure

  • First clamp the separated portions of your sample in the jaws so that movement of the test machine will separate the coating from the backing.
  • Next run the test machine so that it separates the coating from the backing with a uniform speed of 0.85 mm/sec (0.03 in) or 5 mm/sec (0.19 in) for a minimum of 76 mm (3 in).
  • Record the force necessary to separate the coating from the backing.
  • Adhesion of coating shall be the average of the 5 highest peak loads during the test.

ASTM D751 Seam Strength - Section 66

This test and the dead load version of it (section 80) determines and compares the seam strength with the strength of the coated fabric. The seam strength test works great for lapped, lapped and bonded, and sewn seams using the modified grab test method.

Preparing the Specimens

Specimens should be in rectangle shapes and should be 50 mm (1.9 in) wide x 200 mm (7.8 in) long with the seam horizontally across the center.

Testing Procedure

  • First place the specimen symmetrically in the jaws of the grips with the seam centered between the jaws.
  • Start the test machine with a uniform speed of 5 mm/sec (0.19 in).
  • Record the force necessary for the sample to slip the seam or rupture the fabric.
  • Seam Strength shall be the median of all the individual results.

ASTM D751 Crush Resistance - Section 89

This test determines the crush resistance test of coated fabric. This test is applicable to diaphragm material cut from coated fabrics that will be used for automotive and regulator devices.

Preparing the Specimens

Three specimens should be tested. Specimens should be rectangles sized 50 mm (1.9 in) wide x 200 mm (7.8 in) long.

Testing Procedure

  • First you must place the specimen symmetrically on the base plate of your compression tester or universal testing machine.
  • Place the load button on the test specimen with the recessed end down and at least 12 mm (0.47 in) from any edge of the specimen.
  • Apply the force to the button with a uniform speed of 0.83 mm/sec (0.03 in/sec) until a deflection is noted by the test machine.
  • Record the force required to crush or cut the specimen.
  • The standard specifies that the test machine must be capable of producing a 1200 lb load.