Converters & Calculators
ASTM D638: Tensile Testing For Plastics
Introduction to ASTM D638
ASTM D638 is a widely recognised standard developed by ASTM International for conducting tensile tests on plastics. This test method is essential for determining the tensile properties of plastics, which is critical for evaluating their strength and performance in various applications.
ASTM D638 Sample Dimensions and Specimen Type
|
Specimen Type |
Shape |
Dimensions (mm) |
Thickness |
Notes |
|
Type I |
Dumbbell |
165 × 19 × 3.2 |
3.2 |
Standard for most materials |
|
Type II |
Dumbbell |
50 × 13 × 3.2 |
3.2 |
For materials requiring smaller specimen sizes |
|
Type III |
Dumbbell |
40 × 6.4 × 3.2 |
3.2 |
For brittle and small materials |
|
Type IV |
Dumbbell |
60 × 6.4 × 3.2 |
3.2 |
For testing materials with limited elongation |
|
Type V |
Flat (rectangular) |
80 × 10 × 3.2 |
3.2 |
For thicker or more rigid materials |
ASTM Standards and Their Role
ASTM, formerly known as American Society for Testing and Materials, develops and publishes technical standards for a wide range of materials, products, systems and services. ASTM D638 describes the procedure for tensile testing of plastics and thereby ensures consistency and reliability of test results across different laboratories and industries.
Applications of Tensile Properties in Product Design
Understanding the tensile properties of plastics assists engineers and designers in selecting appropriate materials for their products. Whether the application involves automotive components, consumer electronics or packaging, the knowledge of how a plastic behaves under tensile load informs decisions that improve the durability and performance of the product.
Comparison of Plastics Based on Their Tensile Properties
|
Plastic Material |
Tensile Strength (MPa) |
Elongation at Break (%) |
Elastic Modulus (GPa) |
|
20-30 |
500-800 |
0.2-0.4 |
|
|
Polypropylene |
30-40 |
200-600 |
1.5-2.0 |
|
Polystyrene |
50-70 |
2-5 |
3.0-3.5 |
|
Polycarbonate |
60-70 |
60-80 |
2.3-2.4 |
|
ABS |
40-50 |
10-20 |
2.1-2.5 |
Factors Influencing Tensile Properties
Several factors can affect the tensile properties of plastics, including temperature, strain rate and material composition. Understanding these influences aids in predicting the behaviour of the material under various environmental conditions and loading scenarios.
Frequently Asked Questions
What is ASTM D638 used for?
ASTM D638 is used to determine the tensile properties of plastics, including tensile strength, elongation and elastic modulus, which are essential for evaluating material performance.
Why is tensile testing for plastics important?
Tensile testing provides critical data regarding the strength and flexibility of a plastic and assists engineers in selecting appropriate materials for specific applications, thereby ensuring product reliability.
How are specimens prepared for testing according to ASTM D638?
Specimens are prepared in accordance with the dimensions and specifications described in ASTM D638. This procedure ensures uniformity and consistency of test results.
Can ASTM D638 be used for all types of plastics?
ASTM D638 applies to a wide range of plastics. However, specific test conditions or alternative standards may be required for certain materials to obtain accurate results.
What factors can influence the outcome of a tensile test?
Factors such as temperature, strain rate and material composition can influence the tensile properties measured during a test according to ASTM D638.
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