Core shear

Compressive collapse of a sandwich core, occurring either in service under concentrated loads or as a manufacturing defect when autoclave or press pressure drives the core inwards, typically at chamfered panel edges. It leaves a dished or wrinkled panel and reduces the structure's load-carrying capability.

Loss of adhesion between a sandwich panel's face sheet and its core, arising from manufacturing defects, impact damage, moisture ingress or fatigue. It removes the shear connection the panel relies on and can grow under load, so debonds are a key target of non-destructive inspection.

The mass per unit volume of a core material, used as the primary grade designation for structural foams and honeycombs. Higher densities generally bring higher strength and stiffness at the cost of weight, so cores are specified by density alongside thickness and cell or grain structure.