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D4964-96 – Standard Test Method Technical Guide
📐 Scope and Field of Application
ASTM D4964 – 96 (Reapproved 2020) establishes a standardized methodology for measuring the tension and elongation of elastic fabrics using a Constant-Rate-of-Extension (CRE) type tensile testing machine. The standard applies to both wide and narrow elastic fabrics made from natural or man-made elastomers, either alone or in combination with other textile yarns.
A critical requirement of this standard is the mutual selection of the loop tension(s) and elongation(s) at which the test results will be determined. If laundering procedures are part of the testing protocol, the temperature, number of washing cycles, and drying cycles must also be mutually agreed upon by the interested parties.
| 🟦 Parameter | 📐 Specification / Requirement |
|---|---|
| Standard Designation | D4964 − 96 (Reapproved 2020) |
| Fabric Types | Wide or narrow elastic fabrics |
| Machine Type | Constant-Rate-of-Extension (CRE) Tensile Testing Machine |
| Unit Systems | SI units or Inch-Pound units (must be used independently) |
💡 Key Differentiator: This standard is specifically for CRE-type machines. For testing using the Constant-Rate-of-Load (CRL) type machine, users must refer to the withdrawn Test Method D1775.
⚙️ Test Procedure and Extension-Recovery Cycles
The test method is centered on a defined mechanical cycle. A conditioned loop specimen is mounted in the CRE tensile testing machine. The specimen is subsequently extended at a specified rate to a specified loop tension, and then returned at a specified rate to zero tension. This constitutes a single extension-recovery cycle.
To stabilize the material and measure its performance characteristics, this cycle is performed a total of three times. During the execution of the test, extension-recovery curves may be plotted by an automatic recorder. The standard permits recording data for all three cycles or exclusively for the third cycle, providing flexibility while ensuring accurate characterization of the fabric’s elastic behavior.
| 🎯 Test Phase | ⚡ Specification / Action |
|---|---|
| Specimen Type | Conditioned loop specimen |
| Total Cycles | 3 (Extend to specified tension, return to zero tension) |
| Rate Application | Specified rate of extension and specified rate of return |
| Recording Options | Automatic plots of all cycles or only the third cycle |
📏 Referenced Standards and Key Terminology
ASTM D4964 integrates within a comprehensive framework of textile testing standards. The tensile testing machine itself must conform to Specification D76 (Tensile Testing Machines for Textiles). Specimen conditioning and testing must be performed in accordance with Practice D1776 (Conditioning and Testing Textiles).
Key terminology relevant to this standard is defined in Terminology D4850 (Fabrics and Fabric Test Methods) and Terminology D123 (General Textile Terms). Critical terms include constant-rate-of-extension, elastic fabric, extension-recovery cycle, loop tension, tension, and tension-recovery chart. These standardized definitions ensure clarity and consistency in the application of the test method across the industry.
⚠️ Compliance and Safety: This standard does not purport to address all safety concerns associated with its use. It is the responsibility of the user to establish appropriate safety, health, and environmental practices before use. The standard was developed in accordance with internationally recognized principles on standardization established by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
❓ Frequently Asked Questions
🔍 What specific parameters require mutual agreement under this standard?
ASTM D4964 mandates that the specific loop tension(s) and elongation(s) at which test results will be determined must be mutually agreed upon. Furthermore, if laundering procedures are included, the water temperature, number of washing cycles, and drying cycles must also be selected by mutual agreement between the interested parties.
💡 How many extension-recovery cycles does the test method require?
The standard specifies a total of three extension-recovery cycles. The specimen is extended to the specified loop tension and returned to zero tension for each cycle. An automatic recorder can plot the resulting curves for all three cycles or specifically for the third cycle for analysis.
⚡ Are SI and inch-pound units interchangeable in reporting results?
No. The values stated in either SI units or inch-pound units are regarded separately as standard. As the two systems may not be exact equivalents, each system must be used independently of the other. Combining values from both systems in any way is strictly prohibited by the standard.
📌 Which standards are referenced for machine specifications and conditioning?
The primary referenced standards include Specification D76 for tensile testing machines, Practice D1776 for conditioning and testing textiles, Terminology D123 for general textile terms, and Terminology D4850 for terms relating to fabric test methods.