In order to compare various material options for a particular structural application, it is convenient to formulate criteria that can help us rank the relative performance of different materials. This can be accomplished through the following steps:

• Idealizing the structure to a simple representative geometry (i.e.: a flat plate for a wing skin)
• Identifying relevant characteristic equations relating the performance of the idealized geometry to material properties and structural capabilities
• Rearranging the characteristic equations to form ratios comparing one material to another in terms of weight, cost, or other design constraints.

It is important to remember that this process is not perfect. It is based on the first step, which typically over-simplifies the structure. But it provides an excellent first step to narrow down material options to clear leading options, or a few options for further design studies.

In order to compare various geometry options, a similar process can be taken whereby the material option is fixed, and the influence of geometry within the characteristic equations is explored.