Transverse Shear Deformation Limits in Structural Foamed High Yield Packaging Substrates
Low transverse shear modulus in foamed cores reduces effective bending stiffness and causes early compression collapse on short spans.
Core Apparent Density
Mass Distribution
Physical property defined as the total mass of a sandwich core material divided by its gross exterior volume, including all internal voids and cell spaces. This measurement of core apparent density differs from the true density of the base material, such as the solid cellulose or polymer, because it accounts for the air trapped within the honeycomb or foam structure. It acts as a primary specification for corrugated medium and structural cores used in transit packaging.
The value determines the overall weight of the finished composite panel.
Performance Relationship
Strength and stiffness in a sandwich panel are usually proportional to the amount of material present in the core. Increasing the core apparent density generally leads to higher shear strength and better resistance to localized crushing. However, the goal of sandwich construction is to maximize the moment of inertia while minimizing weight, so a lower density is often preferred if the load requirements are met.
Precise control over this property during the expanding or corrugating process ensures that the final board meets the structural demands of the intended application.
Calculation Protocol
Determining the value requires weighing a precisely cut specimen and measuring its length, width, thickness and mass. The result is expressed in kilograms per cubic metre.