![ASTM SRJ-D638 Testing Fixture ASTM SRJ-D638 Testing Fixture](http://www.sophiahightech.com/wp-content/uploads/2016/07/ASTM-SRJ-D638-Testing-Fixture-e1475930671242.jpg)
ASTM D638 Â tensile tests measure the force required to break a plastic sample specimen and the extent to which the specimen stretches or elongates to that breaking point.
Tensile test procedure:
Specimens are placed in the grips of the universal tester at a specified grip separation and pulled until failure. For this fixture the test speed is determined by the material specification. An extensometer is used to determine elongation and tensile modulus.
![ASTM D638-B Testing Fixture - Drawing ASTM D638-B Testing Fixture - Drawing](http://www.sophiahightech.com/wp-content/uploads/2016/07/ASTM-D638-B-Testing-Fixture-Drawing-300x71.jpg)
Elevated or Reduced temperature test procedure:
A thermal chamber is installed on the universal test machine. The chamber is designed to allow the test mounts from the base and crosshead of the universal tester to pass through the top and bottom of the chamber. Standard test fixtures are installed inside the chamber, and testing is conducted inside the controlled thermal environment the same as it would be at ambient temperature. The chamber has internal electric heaters for elevated temperatures and uses external carbon dioxide gas as a coolant for reduced temperatures. The size of the chamber places a limitation on the maximum elongation that can be reached, and extensometers are generally limited to no more than 200° C.
Specimen size: The most common specimen for ASTM D638 is a Type I tensile bar.
![ASTM D638-B Testing Fixture - Assembly ASTM D638-B Testing Fixture - Assembly](http://www.sophiahightech.com/wp-content/uploads/2016/07/ASTM-D638-B-Testing-Fixture-Assembly-300x225.jpg)
Referenced DocumentsÂ
ASTM Standards
- D229Â Test Methods for Rigid Sheet and Plate Materials Used for Electrical Insulation
- D412Â Test Methods for Vulcanized Rubber and Thermoplastic Elastomers–Tension
- D618Â Practice for Conditioning Plastics for Testing
- D651Â Test Method for Test for Tensile Strength of Molded Electrical Insulating Materials
- D882Â Test Method for Tensile Properties of Thin Plastic Sheeting
- D883Â Terminology Relating to Plastics
- D1822Â Test Method for Tensile-Impact Energy to Break Plastics and Electrical Insulating Materials
- D3039/D3039MÂ Test Method for Tensile Properties of Polymer Matrix Composite Materials
- D4000Â Classification System for Specifying Plastic Materials
- D4066Â Classification System for Nylon Injection and Extrusion Materials (PA)
- D5947Â Test Methods for Physical Dimensions of Solid Plastics Specimens
- E4Â Practices for Force Verification of Testing Machines
- E83Â Practice for Verification and Classification of Extensometer Systems
- E132Â Test Method for Poissons Ratio at Room Temperature
- E691Â Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
- E1012Â Practice for Verification of Testing Frame and Specimen Alignment Under Tensile and Compressive Axial Force Application
- ASTM D638 A