Multi-layer Materials model parameters
The Multi-layer Materials models predict the performance of laminates constructed from a range of materials, thicknesses, and numbers of layers. These models are particularly relevant to multi-layer barrier laminates used in packaging.
The aim of multi-layer material design is to combine the properties of different materials into one structure. For example, to combine the strength and stiffness of one material with the permeability of another material, to produce a multi-layer material that is stiff, strong, and has a low permeability to air or water.
The relative position of the different layers can have a significant impact on the performance of the final laminate. For example, under bending, the bottom surface is subjected to tensile loads and the top surface to compressive loads. These loads, which are at a maximum at the outer surfaces, reduce to zero at the neutral axis. In contrast, shear loads, which are zero at the outer surfaces, reach a maximum at the neutral axis.
The level of shear loading is typically an order of magnitude lower than the tensile/compressive loads at the outer surfaces, and so the flexural performance of multi-layer laminates is generally dictated by the tensile and compressive properties of the outer layers. This is one of the reasons why EVOH (ethylene vinyl alcohol), which is an excellent barrier to oxygen, is often used as the central layer in multi-layer flexible packaging where its relatively high stiffness has minimal influence on the flexibility of the final laminate.
| Section | Parameter | Description |
|---|---|---|
| Source Records | Layer n | Specify the material record for each layer. Note: The order of materials is
important (for example, which face is the top material and which the bottom) as
the multi-layer will be anisotropic. The calculations for flexural modulus and
strength assume that Layer 1 is the bottom layer and that when loaded the top
face is in compression and the bottom face in tension. |
| Model Parameters | Thickness layer n | For each Layer, the Thickness. The current units are shown. |
| Record naming | Layer n | The abbreviated name. For example, if your source record is Aluminum, type Al. This is used to create the record names for the new materials. |
