Modelling in Multi-material Systems

The speed at which heat or mass is transferred through a material is of great importance to engineers and manufacturers. Depending on the application it may be desirable to have a slow transfer of heat, for insulating purposes, or a fast transfer of heat, for increased productivity in moulding applications or for higher efficiency heat exchangers. Mass diffusion is important in such processes as moisture permeability of paint films or the degradation of the matrix in polymer composite laminates and some packaging material. Plastic products are increasingly being made as layered designs so the manufacturer has the freedom to tailor the products properties to a particular application.

To better understand how a material is performing under service conditions or during manufacturing it is desirable to use modelling and visualisation techniques to predict the material response. Transport modelling refers to the modelling of heat and mass transfer as both are considered as transport processes that originate from molecular activity. Heat transfer is initiated by a temperature difference in a medium while mass transfer is initiated by a difference in the concentration (chemical potential for more complex systems with stress gradients) of some chemical species in a mixture.

NPL has been developing software tools for modelling transient heat and mass transport in multi-material systems. The software tool TherMOL has been used for determining various materials, boundary and transport properties for polymers, adhesives, composites, metals and biomaterials.

For more information, please contact Jim Robinson