ASTM D7264 Flexural Properties of Composites

Scope:

ASTM D7264 method tests different materials that show different flexural properties according to varying temperatures, strain rate, and sample thickness. Hence it is desirable to evaluate different materials by Flexural properties ASTM D7264 testat varied influences. Flexural strength and rigidness are not basic characteristics of a material. These are the collaborated effects of a material’s core compressive, tensile, and shear properties. All three of the material’s elemental stress states are caused when the flexural properties of composites are considered upon loading. 

 Test procedure:

ASTM D7264 standard guides testing of flexural properties of polymeric composites with the aid of a bar of rectangular cross-section fixed on a beam and deviated at a constant rate. The test method states two methods. Method A provides a three-point loading system for central loading. Method B provides a four-point loading for two equal loading points. ASTM D7264 is structured for polymeric composites and uses a span to thickness ratio of 32 to 1. Fabric-supported composite materials (textile) are also quoted within the standard ASTM D7264.

Method A states a three-point loading system for central loading. The sample is placed on a support span, and impact is forced at the center by loading nose, procuring three-point bending at a certain rate. Method B states a four-point system for two equal loading references. The sample is placed on a span with uniformly distributed stress for the four-point flexural test amidst the loading noses.

Test procedure at non-ambient temperatures:

The universal test machine has an installed thermal machine. The chamber allows the test mounts from the base as well as the crosshead of the machine. It is done so that test mounts pass through the top & bottom of the chamber. Set test fixtures are installed inside the chamber. Testing is conducted inside an ambient temperature. The chamber has built-in heaters for elevating the temperatures. For reduced temperatures, the chamber uses CO₂ as a coolant.

Specimen size: 

The standard sample thickness is equal to 4 mm (approx 0.16 inches), the standard sample width is equal to 13 mm (0.50 inches), and the standard sample length is about 20 per cent longer than the support span. In case of the non-availability of a standard sample, alternate sizes may be used.

 Data:

Flexural Strength

Maximum Flexural Stress

Maximum Strain

Stress at Strain

Flexural Secant Modulus of Elasticity

Flexural Chord Modulus of Elasticity

Failure Mode & Location

Conclusion:

The flexural properties of polymeric composites are determined through ASTM D7264 test method which helps decide their industrial applications. The results aid in enhancing their quality keeping in view the global standards.