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How to Measure the Tensile Properties of Materials Based on ISO527

If you want to know how much tensile force a material like plastic can withstand and how long it will remain intact, it's correct to measure according to the international standard ISO527.

I. Prepare the tools

1. Tensile testing machine: It can firmly pull the sample and accurately record the force applied and the extent to which the sample is elongated, just like a professional "tensile measuring instrument".

2. Clamping fixture: It is used to hold the sample firmly but without damaging it. Otherwise, if the sample is damaged before being pulled apart, it would be unacceptable.

3. Environmental chamber: If there are requirements for temperature and humidity, use it. The common setting is 23℃ and 50% humidity, providing a stable "microclimate" for the sample.

4. Extension meter: Placed in the middle of the sample, it is specifically used to measure the elongation of the sample. It is indispensable when calculating the "elasticity" of the material.

5. Ruler / caliper: Used to measure the length, width, and thickness of the sample. These dimension data are very important.

II. Prepare the samples

1. Make standard samples: Do not simply measure a piece of material randomly; it must be made into the prescribed shape. For example, for a common sample strip, the total length is 170 mm, the part used for testing is 50 mm long and 10 mm wide, and the thickness depends on the material, with no significant error allowed.

2. The quantity should be sufficient: At least 5 samples should be made, as the material may be uneven, and more tests will yield more reliable results.

3. The sample condition should be correct: Before testing, the sample should be placed in the standard environment (such as 23℃, 50% humidity) for 40 hours to adapt to the environment; otherwise, the environmental influence will be too significant, and the results will be inaccurate.

4. There should be no defects: The surface of the sample should have no cracks or scratches; otherwise, it may break at the defect first, affecting the test results.

III. Test steps

1. Calibrate the machine: First, let the tensile machine "warm up" and calibrate to ensure the accuracy of measuring tensile force and length, just like checking the accuracy of a ruler before use.

2. Measure the sample dimensions: Carefully measure the length (called the gauge length), width, and thickness of the middle testing part of the sample. Take the average of several measurements and calculate the cross-sectional area from start to finish.

3. Place the sample: Firmly clamp the sample in the fixture of the testing machine. Pay attention to alignment; do not be crooked; otherwise, the tension will be uneven, and the sample may break prematurely.

4. Set parameters: Select the tensile speed based on the material. For example, when measuring the "elasticity" of the material, it should be slower (1 - 5 mm/minute), and when determining when it breaks, it can be faster (such as 50 mm/minute).

5. Start the test: Start the machine. The machine will slowly pull the sample, simultaneously recording the tension force and the degree of sample elongation until the sample breaks. If the sample breaks near the jaw, this result is not valid; a new sample should be tested instead.

IV. Calculate the results

From the test record data, several key indicators can be calculated:

1. Tensile strength: The maximum tension force of the sample divided by the original cross-sectional area of the sample; the larger the value, the more "resistant to tension" the material is.

2. Yield strength: If the material is stretched to a certain point, the tension force does not increase but the sample is still elongating, at this time, the tension force divided by the original cross-sectional area is the yield strength, indicating that the material begins to "not withstand it".

3. Break elongation rate: The length elongated when the sample breaks divided by the original gauge length, multiplied by 100%, is the elongation rate; the larger the value, the more "able to elongate" the material is.

4. Elastic modulus: Observe the ratio of tension force and elongation when the sample is initially stretched; it can reflect the "elasticity" of the material. A large value indicates that the material is "hard" and is not easily elongated.

V. Record the test report

Finally, the test situation should be written down, including the material name, sample dimensions, test environment (temperature, humidity), tensile speed, and the results of each calculated indicator. The results of each sample and the average value should be written. If the sample breaks at an incorrect position during the test or if there are other abnormal situations, they should also be noted.

By following these steps, you can clearly understand the tensile properties of the material, and the results from different locations can also be compared with each other.