1. A method for structurally analyzing and printing a part, comprising: (a) receiving, in computer memory, a model of the part for three-dimensional printing from a material comprising a matrix and fiber material; (b) receiving, in computer memory, one or more properties for the material; (c) using the model, determining a print head tool path for use during the three-dimensional printing of the part; (d) generating a virtual mesh of analytic elements within the model of the part and determining a trajectory of at least one stiffness-contributing portion of the material based at least in part on the print head tool path, wherein the trajectory of the at least one stiffness-contributing portion is determined through each of the analytic elements in the virtual mesh; (e) using one or more computer processors to determine a performance of the part based at least in part on the one or more properties received in (b) and the trajectory of the at least one stiffness-contributing portion determined in (d); (f) electronically outputting the performance of the part determined in (e); and (g) using a print head to print the part along the print head tool path.