4.1 Unidirectional micromechanics results

In addition to Density, unidirectional micromechanics has pages to calculate 6 moduli, 4 hygrothermal properties, 9 transport properties, 6 strengths, and 2 fracture toughness. That is 35 properties. In addition, each property can be calculated with several methods. If you expand the links for each property (by clicking the \includegraphics[width=14pt]{./Images/expand.png} sign), you can see that each property can be calculated by several methods:

Why several methods? Well, for starters there is the need to reproduce other people’s work, which may have used some of the older methods. Then, there is the need to teach the older, simpler methods to give insight into how things work. But at the end of the day, if you just want the best prediction, then use the Periodic Microstructure Method (PMM) for everything.

Unlike older methods, PMM can take into account the transverse isotropy of Carbon fiber. With PMM, a single method can compute all the properties, while with older methods you have to pick and choose different methods for different properties because no single method is good for everything. Also, PMM does not use adjustable parameters. Some of the older methods, such as Halpin-Tsai, have incorporated empirical parameters that were adjusted decades ago by forcing the method to compare well to experiments or finite element simulations that were done for specific materials of that age (not your material today). Let me know how it goes trying to find out if those fitting parameters are still valid for modern materials today!

Anyway, you can use any method you like in this chapter, but in the rest of CADEC, when CADEC needs a micromechanics calculation, it does it using PMM.