This is a

law applicable to composite materials. It allows for the prediction of properties when
two materials or more are put into a system. e.g. in Fibre Reinforced Polymer matrices. The

equation is as follows: -

X_{c}=X_{m}V_{m} + X_{f}V_{f}

where: -

- X represents the property of the material, e.g. Density
- V represents the Volume fraction of the material
- m represents the matrix material, e.g. Epoxy
- f represents the reinforcement
- c represents the composite material