Using the Multi-layer Materials model
- Multi-layer Materials: Assumptions and calculations
- Multi-layer Materials: Derivation of calculations
About the Multi-layer Materials model
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.
Using the Multi-layer Materials model
Click on Synthesizer on the main toolbar and under 
Multi-layer Materials, click one of the models:
- 2-layer
- 3-layer
- 4-layer
- 5-layer
- 6-layer
- 7-layer
Source records
To select materials for each layer, click . This displays the full MaterialUniverse tree for the active database. Browse the tree, highlight the material of interest and click .
The order of materials is important (i.e. 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
For each Layer, type a Thickness. The current units are shown to the right of the box.
Record naming
For each Layer, type an abbreviated name. For example, if Layer 2 is Polypropylene, type PP. These are used to create the record names for the new multi-layer materials.
Viewing synthesized records on a chart
The synthesized records can be plotted on a chart for easy comparison with existing materials in the database.
- Creating synthesized records
- Highlight a synthesized record on a chart
- Edit a synthesized record
- Delete a synthesized record
Example datasheet
