Tensile Strength is a measure of a material’s ability to resist forces that try to stretch or pull it apart. It is the maximum tensile stress sustained by a material during a tensile test.
Why is the Tensile Strength Important?
Tensile strength is a key mechanical property because it helps determine how a material will perform when subjected to pulling, stretching, or mechanical loading.
It is commonly used to evaluate:
- Thermoplastics
- Thermosets
- Reinforced plastics
- Polymer composites that meet ASTM D638 specimen requirements
A material with high tensile strength is generally better able to resist cracking, tearing, and mechanical failure.
How is the Test Performed?
ASTM D638 uses a standardized specimen, often called a dog-bone specimen, which has a reduced cross-sectional area in the center.
- The specimen is placed in a tensile testing machine.
- The machine grips both ends of the specimen.
- A tensile force is applied at a controlled rate.
- The specimen is stretched at a controlled rate while load and elongation are measured until yielding and/or fracture occurs.
- The applied load and elongation are continuously recorded.
What Does the Result Mean?
Tensile Strength is the maximum tensile stress reached before the material breaks.
The result is typically reported in:
- MPa (Megapascals)
- psi (Pounds per Square Inch)
A higher value indicates greater resistance to pulling forces.
Additional Properties Measured
The ASTM D638 test can also provide information about:
- Yield Strength – the stress at which permanent deformation begins.
- Elongation – how much the material stretches before breaking.
- Modulus of Elasticity – the stiffness of the material.
Example
If Material A has a tensile strength of 70 MPa and Material B has a tensile strength of 35 MPa, Material A can withstand approximately twice the tensile stress before failure.
Summary
ASTM D638 is a tensile test used to determine a material’s resistance to pulling forces. A standardized specimen is stretched until failure, and the maximum stress achieved is reported as the tensile strength. The test is widely used to evaluate the strength, stiffness, and deformation behavior of materials.
Source: Chesterton ARC Manuals, astm.org
Please note:
Despite thorough research, our description may contain inaccuracies regarding the most current ASTM procedures.
Our description should be considered solely as an overview for informational purposes.