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ASTM D412 Tensile Strength of Rubber | Unuo Instruments

ASTM D412 is used to measure the tensile(tension) properties of rubber and elastomers. This test standard includes 2 kinds of test methods for different shapes of samples and needs universal testing machine to perform the test.

1. What is the tensile strength test?

Tensile strength is the max tensile stress or force that the tested sample can withstand before breaking. Tensile strength test is used to measure a material’s tensile strength resistance ability. It is a very useful test to know material properties.

2. ASTM D412 Tensile strength test standard for rubber and elastomers

ASTM D412 tests samples in the shape of dumbbells, rings, or straight pieces of uniform cross-sectional area. It tends to measure rubber/elastomers tensile stress, tensile stress at a given elongation, tensile strength, yield point, and ultimate elongation. ASTM D412 contains 2 kinds of test methods. Method A for dumbbell and straight shape sample; Method B for ring shape sample. Both test methods need a universal testing machine to perform the test. And its test samples should not be prestressed.


3. Requirement for tensile strength tester(UTM) of ASTM D412

1) Constant rate of extension type(CRE)
2) Speed 500±50mm/min(20±2 in./min)
3) Extensometer
4) Suitable grip
Check recommended tensile strength tester

4. ASTM D412 method A for dumbbell and straight shape samples

Method A is the most widely used method of ASTM D412.
1)Sample preparation
Dumbbell: Use die C shape cutting die to cut sample. Unuo Instruments can supply the cutting die and cutting machine.
Straight: only applied when eight dumbbell or ring shape samples is not practical to cut
2)Fix the dumbbell or straight sample on the UTM. Please be careful to place specimen as per regulated.
Tensile stress, tensile strength and yield point: Set the speed to 500±50mm/min. Run the test. Record the force aT the elongation specified for the test and break. To test the elongation, extensometer is a must-needed device for UTM. Although the extensometer is an optional accessory for UTM, but we do suggest customer to purchase it with UTM especially for customer who will need to test rubber.
Tensile set: place the sample as regulated; set the grip at a constant speed for 15s for reach the specified elongation. Then, hold the specimen at the specified elongation for 10 min, release quickly without allowing it to snap back and allow the specimen to rest 10min.
Set after break: after the sample is broken, test it for 10 min, fit the 2 pieces together and make them in good contact over the full area of the break.

5. ASTM D412 method B for ring sample

1) Sample preparation
Use ring shape die with drill press to cut the sample.
2) Adopt speed 500±50mm/min, run the test and record the ultimate(breaking) elongation and the tensile(force) strength.

6. Unuo Instruments UI-1100 Universal Testing Machine Features

Unuo Instruments’ UTM adopts servo motor to ensure the constant speed of test and high precision load cell to measure the force. With specially designed software, users can easily observe the dynamic test data of the test procedure. Before delivery, we will pre-set the ASTM D412 test program so that users can save time on the program setting. Except for ASTM D412, UI-1100 can still perform many tests like tear, shear and etc. Besides, we can customize the test grips. If you are looking for ASTM D412 related testing machine, why not contact us today or just give us a call?


7. Recommended Testing Machine for ASTM D412

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