ASTM C297
Flatwise Tensile Shear Fixture for Sandwich Constructions
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ASTM C297 – Standard Test Method for Flatwise Tensile Strength of Sandwich Constructions - PDF
ASTM C297 is the industry standard for determining the flatwise tensile strength of sandwich constructions, which are materials made up of two thin outer layers (faces) and a thicker core material. This test evaluates the bonding strength between the face sheets and the core, as well as the overall resistance of the sandwich panel to tensile forces applied in the plane of the faces.
This standard is essential for industries such as aerospace, automotive, construction, and marine, where lightweight and strong materials are required for structural applications. The test method is commonly used to evaluate the performance of composite sandwich panels, which offer a high strength-to-weight ratio ideal for such industries.
Test Specimen
The specimen for ASTM C297 testing is a sandwich panel, which consists of two face sheets (often made from composite materials) and a core material that provides strength without adding significant weight. The test sample is usually cut into either 1 x 1 inch (25.4 mm x 25.4 mm) or 2 x 2 inches (50.8 mm x 50.8 mm) squares to provide a manageable size for testing.
Sample Preparation:
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Cut the Sandwich Panel: The panel is cut into the required 1 x 1 inch or 2 x 2 inches squares to fit the testing machine grips.
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Clean the Specimen: The surface of the specimen must be clean and free from contaminants that might affect the adhesive bond between the face sheets and the core.
Test Equipment
To perform ASTM C297 testing, you will need a universal testing machine (UTM) equipped with the appropriate fixtures. The test requires a controlled tensile force to pull the face sheets apart from the core material.
Key Equipment:
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Universal Testing Machine (UTM): This machine must be capable of applying a constant tensile force at a standard rate of 0.05 to 0.2 in/min (1.27 to 5.08 mm/min).
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Grips or Fixtures: The sandwich specimen needs to be secured using specialized grips that can hold the material firmly while allowing for the application of tensile force.
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Data Acquisition System: This system records the force applied and displacement during the test, providing data for calculating tensile strength.
Test Procedure
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Specimen Mounting: Place the 1x1 inch or 2x2 inch specimen securely in the grips of the universal testing machine. Ensure the test specimen is properly aligned with the force application direction to avoid any angular misalignment during the test.
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Apply Load: The tensile load is applied slowly and steadily until failure occurs. This is usually the point at which the face sheets separate from the core material, or the core material fails. The standard tensile rate should be between 0.05 and 0.2 in/min (1.27 to 5.08 mm/min).
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Data Collection: Monitor the force required to separate the face sheets from the core and record the displacement as the specimen deforms.
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Failure Observation: Once the failure occurs, observe whether it’s a core failure (core material failure) or adhesion failure (failure of the bond between the core and face sheets).
Results Interpretation
The flatwise tensile strength is calculated by the formula:
Tensile Strength (psi) = Force (lb) / Area (in²)
Where:
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Force: This is the maximum load (in pounds) applied during the test.
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Area: The cross-sectional area of the core material exposed to the tensile force, in square inches.
For a 1x1 inch sample, the area would be 1 in², and for a 2x2 inch sample, the area would be 4 in².
Failure Modes:
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Core Failure: The core material fails, and the force needed to separate the face sheets exceeds the strength of the core.
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Adhesion Failure: The bond between the face sheets and core material fails, resulting in the face sheets separating from the core without damaging the core itself.
Applications
ASTM C297 is critical in various industries where sandwich panels are used:
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Aerospace: Sandwich constructions are common in aircraft fuselages, wings, and interiors, where the combination of strength and low weight is essential.
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Automotive: Sandwich panels are used for lightweight car body structures and automotive interiors to reduce overall weight and improve fuel efficiency.
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Construction: Sandwich panels are widely used for building facades, roofing, and insulation panels.
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Marine: Sandwich panels are utilized in shipbuilding for lightweight, durable structures.
Why Choose Our Galdabini Universal Testing Machines for ASTM C297?
Our Galdabini Universal Testing Machines (UTMs) are an excellent choice for performing ASTM C297 tests, offering precision, reliability, and ease of use. The Galdabini UTMs can provide the exact load control needed for testing the flatwise tensile strength of sandwich panels, ensuring accurate and reproducible results.
Key Features:
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Precision Load Application: Ensure accurate measurement of tensile forces for precise tensile strength calculation.
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Custom Fixtures: Our sandwich construction grips are designed to securely hold the specimen while minimizing the risk of specimen damage.
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Advanced Data Collection: Real-time force and displacement data ensure accurate test results, perfect for research, development, and quality control.
With Galdabini Universal Testing Machines, you can confidently test the performance of your sandwich constructions under the exacting standards of ASTM C297.
Conclusion
ASTM C297 is a crucial test method for determining the flatwise tensile strength of sandwich constructions. By measuring the bond strength between the face sheets and core material, this test ensures that sandwich panels can withstand the mechanical stresses they face in real-world applications. With Galdabini Universal Testing Machines, you can achieve precise, reliable results and ensure the performance and safety of your materials.
Contact us today to learn more about how Galdabini UTMs can enhance your material testing process for ASTM C297 and other industry standards.
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Similar Specifications:
ASTM D3354 - Blocking Load of Plastic Film
ASTM D1623 - Tensile Adhesion of Foam
EN 1607 - Tensile strength of Perpendicular faces of Thermal Insulation
EN 2243 - Tensile Testing of Structural Adhesives for Aerospace
DIN 53292 - Testing of Sandwiches - Tensile Testing
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