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D2291 – Standard Test Method Technical Guide
This standard practice, D2291/D2291M, specifies a uniform procedure for fabricating ring test specimens from glass fiber and thermoset resin composites. It is used to prepare specimens for evaluating mechanical properties such as hoop tensile strength and short-beam strength, ensuring consistency in composite testing.
📐 Specimen Types and Configuration
The practice includes three final ring configurations for test specimens. These specimens are fabricated to be used in Test Methods D2290 for apparent hoop tensile strength of plastic or reinforced plastic pipe, and D2344/D2344M for short-beam strength of polymer matrix composite materials. The geometry is achieved through winding impregnated reinforcement on a mold or mandrel, followed by curing and machining.
⚙️ Fabrication Procedure and Apparatus
The fabrication involves using a winding machine to mount, tension, and collect wetted reinforcement on a mold or mandrel. A tension measuring system may be used optionally. The mold or mandrel surfaces must be treated to prevent sticking. Curing ovens must control temperatures within the specified tolerance.
| 🟦 Apparatus | 📏 Description | 🎯 Critical Requirement |
|---|---|---|
| Winding Machine | Superstructure for mounting, resin application, tensioning, and collection | Must be suitable for desired mold/mandrel size |
| Tension System | Device for measuring tension on wetted reinforcement | Use is optional; ensure trend consistency |
| Mold/Mandrel | Single-ring or cylinder fabrication mold | Surface coated to prevent specimen sticking |
| Curing Oven | Oven capable of controlled temperature curing | Temperature controlled within 69°F (65°C) |
📊 Temperature Control and Unit Requirements
Tight temperature control during curing and postcuring is critical. The standard requires that temperatures be maintained within 69°F (65°C). Additionally, values expressed in SI units or inch-pound units must be used independently; combining values from both systems can lead to nonconformance with the practice.
⚠️ Important: Always use SI or inch-pound units independently. Combining values from both systems may result in nonconformance with the standard.
💡 Tip: While tension measurement is optional, using a calibrated device can help ensure consistent specimen quality.
❓ Frequently Asked Questions
🔍 What is the intended use of this practice?
This practice is intended for fabricating ring-type test specimens for glass-resin composites to evaluate mechanical properties in composite structures.
💡 How are the ring specimens fabricated?
Specimens are fabricated by winding impregnated reinforcement on a mold or mandrel using a winding machine, followed by curing and optional machining to final configuration.
⚡ What temperature control is required for curing?
The curing and postcuring temperatures must be controlled to within 69°F (65°C) to ensure complete and uniform curing.
📌 What test methods are used with these specimens?
The fabricated ring specimens are used in Test Methods D2290 for apparent hoop tensile strength and D2344/D2344M for short-beam strength.