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The initiation of failure in
composite sandwich beams is heavily dependent on properties of the core material.
Several core materials, including PVC foams and balsa wood were characterized. The
various failure modes occurring in composite sandwich beams are described and their
relationship to the relevant core properties is explained and discussed. Under flexural
loading of sandwich beams, plastic yielding or cracking of the core occurs when
the critical yield stress or strength (usually shear) of the core is reached.
Indentation under localized loading depends principally on the square root of the
core yield stress. The critical stress for facesheet wrinkling is related to the
core Young’s and shear moduli in the thickness direction. Experimental
mechanics methods were used to illustrate the failure modes and verify analytical
predictions.