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.
Flatwise Shear Testing
Interfacial Strength
Experimental procedure used to determine the shear properties of a sandwich core in a direction parallel to the plane of the facings. Through flatwise shear testing, the shear modulus and shear strength are measured to ensure the core can effectively transfer loads between the top and bottom skins of a composite board. This method is the standard approach for evaluating the structural integrity of corrugated board and honeycomb panels.
It reveals how the internal structure resists sliding or deformation when the panel is subjected to bending.
Methodological Execution
Specimens are typically bonded to thick metal loading plates using a high strength adhesive to ensure the failure occurs within the core material. The test frame applies a force that creates a state of pure shear across the entire area of the specimen. For corrugated board, the results distinguish between the shear resistance provided by the fluting and the bond strength of the glue lines.
Accurate data collection requires sensitive sensors to record the minute displacements that occur before the structure yields. This information is essential for calculating the buckling resistance of large shipping crates.
Data Output
The primary outputs are the stress at failure and the slope of the stress strain curve.