What canvas, canvas (canvas) is a thicker cotton fabric or linen fabric, named after it was originally used for sails. Generally, plain weave is used, a small amount of twill weave is used, and multi-strand threads are used for warp and weft yarns. Canvas is usually divided into two categories: coarse canvas and fine canvas.

1. Terms and definitions related to canvas tensile test

1) Standard atmosphere

A controlled relative humidity and temperature environment at which textiles are conditioned and tested. The standard atmosphere used for the test is a temperature of 20.0 °C ± 2.0 °C and a relative humidity of 65.0% ± 4.0%.

2) Fabric length length of piece

The distance from the start to the end in the longitudinal direction of the fabric.

3) Fabric width width of piece

The distance between the outermost edges of the fabric perpendicular to the length of the fabric.

4) fabric density fabric count

The number of yarns contained in a 10 cm length in the warp or weft direction of the fabric.

5) strength at breaking

The maximum force, expressed in Newtons (N), measured in a test in which a specimen is stretched to break.

6) Elongation at breaking

In a tensile test, the elongation at which the specimen is stretched to break, expressed in percent.

7) Nominal clamping length length within two clamps

Under the specified pretension, the initial distance between the two jaws held by the clamp, the unit is mm.

2. Canvas tensile testing machine:

1) Steel ruler: its length is greater than the measured part of the fabric, and the graduation value is mm.

2) Isokinetic elongation type tensile testing machine: The operating speed of the movable clamp of the testing machine is 100 mm/min~110 mm/min. The testing machine is equipped with a vise-type gripper or a winding gripper. Grip distance: 200 mm±l mm.

3) Workbench: The surface is smooth and flat, and its length and width should be larger than the measured part of the placed fabric. 4.8 Cutting knife.

3. Principle of canvas tensile test:

1) Determination principle of breaking strength and breaking elongation of canvas fabric:

Elongate the specimen by applying progressively increasing force by suitable mechanical means until fracture occurs, indicating the maximum force and elongation at fracture.

4. Canvas tensile test steps:

1) Swatch preparation

Three canvases are randomly selected each time, and each canvas is more than 1 m away from the rolling head, and a whole cloth sample with a length of 1 m is cut out.

2) Moisture conditioning of fabric samples

The layout samples were equilibrated in the standard atmosphere specified in GB/T 6529 for 24 h.

3) Sample preparation

① Cut at least 5 warp samples and 5 weft samples from each cloth sample at least 100 mm away from the edge of the cloth, and add several preparatory samples. The effective width of the samples is 50 mm, generally at least on both sides of the sample. Leave 5 mm burrs; the length of the specimen should meet the nominal clamping length of 200 mm.

② Pull off the yarns on both sides of the sample to make the width of the sample 50 mm. For canvas with more than 5 warp threads, remove the yarns on both sides of the test warp strength cloth strip before the test, so that the two sides of the cloth strip are 50 mm wider than each other. 4 more yarns (not clamped by the clamps), see picture below.

4) Zero calibration

Before the test, correct the zero position of the strength testing machine; then adjust the distance between the clamping distances of the strength testing machine, and make the clamps align and parallel to each other to ensure that the sample will not be skewed after being stressed; select the running speed of the movable clamp of the strength testing machine 100 mm/min~110 mm/min.