The rule of mixtures is used in the mechanical design of composite structures to estimate the elastic modulus (Ec) based on the following properties:
Based on these values, the lower-bound estimate of elastic modulus is calculated by:
Ec = 1 / (ff / Ef + (1 – ff) / Em).
On the other hand, the upper-bound (linear) estimate of elastic modulus is calculated by:
Ec = ff * Ef + (1 – ff) * Em.
Write a function to calculate the weighted Ec between both bounds, based on the provided weighting (wt) of the upper bound. (The lower bound will have the remainder of the weighting, or 1–wt.)