Flexural test on flat sandwich constructions by beam flexure ASTM C393.

The test method ASTM C393 determines flexural strength, core shear strength and facings compressive and tensile strengths in the direction the core would be placed in a structural construction.  Core materials applicable include continuous (foams) and discontinue bonding surfaces (honeycomb).

Test procedure:  Install the conditioned specimens (if required) into a 3-point or 4-point loading fixture on the Universal Test Machine and initiate at a specified grip separation significant enough to produce failure within 3 to 6 minutes. The standard speed is 6 mm/min [0.25 in/min].  The standard loading configuration is a 3-point configuration with a support span of 150 mm [6.0 in]. The 4-point configuration is considered modified.

Specimen size: Five rectangular specimens, 75 mm [3.0 in] x 200 mm [8.0 in] tested at thickness.

Data: From 3-point loading results the following calculations can be made:

  1. Core Shear Ultimate Stress
  2. Core Shear Yield Stress
  3. Facing Stress
  4. Failure type/mode

**Please note that this test description is intentionally generic in nature and aimed at providing a descriptive summary to enhance test understanding. Standards can be obtained from appropriate standard authorities. 

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