What is ASTM D 638 standard test method for tensile properties of plastics?

 

In the ASTM D 638 test, a standard specimen of a specified size is stretched to fracture. The following is an overview of the general steps:

 

1. Sample Preparation: A specimen is prepared to meet the standard size requirements according to the specifications in ASTM D 638. Typically, the specimen is long and has a protective edge to prevent localised stress concentrations.

 

2. Clamping the specimen: Clamp the specimen in the fixture of the tensile testing machine. Ensure that the specimen is clamped uniformly and that there is no damage or cuts.

 

3. Applying Tensile Force: Begin to apply tensile force to the specimen. The rate of force application is usually fixed and defined. 4.

 

4. Record force and deflection: With the aid of a tensile testing machine, record the tensile force and corresponding deflection on the specimen. Usually, the loading curve will show the relationship between force and strain. During the test, the maximum load (maximum force) and the fracture position can be recorded.

 

5. Analysing the results: The results of the tensile test are analysed according to the required indicators. Commonly used metrics include tensile strength (maximum tensile force on the specimen), elongation at break (ductility of the specimen before tensile fracture), and modulus of elasticity (stiffness of the material).

 

The ASTM D 638 test method provides important information about the tensile properties and mechanical characteristics of plastic materials. These data have important applications in engineering design, material selection and quality control.