Today's KNOWLEDGE Share:Notched testing of sandwich composites

Today's KNOWLEDGE Share:

Notched testing of sandwich composites: The sandwich open-hole flexure test!

"A primary reason for having two notch sensitivity test methods for composite laminates is the difference in failure modes and resulting notch sensitivities under tension and compression loading. Sandwich composites are commonly subjected to flexural loading, resulting in a tension-loaded facesheet and a compression-loaded facesheet. When using fiber-reinforced composite facesheets, the compression-loaded facesheet typically fails first." 

"Additionally, sandwich composites are used in compression-loading applications, and their notched strengths under compression and flexural loading are typically not the same. Therefore, even though failure primarily occurs in compression-loaded facesheets, two separate test methods are desired." 

"The new sandwich OHF test standard is designated as an ASTM standard practice, as it provides only supplemental instructions for modifying the sandwich long beam flexure test method, ASTM D72495, for use with open-hole sandwich specimens. As in all other ASTM notch sensitivity tests for composite laminates and sandwich composites, a specimen width-to-hole diameter ratio of 6:1 is used. This ratio has been widely accepted in the aerospace composites community for producing acceptable notched strength reductions while minimizing the interaction between the centrally located open through-hole and the specimen edges." 

Source:#managingcomposites/#thenativelab

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