Figure 2.

(a) Models of interweaving and non-interweaving architectures with collagen volume fractions ranging from 36% to 91%. For all models, the matrix surrounding the fibers had the same dimensions (1000 μm by 1000 μm by 200 μm). Fibers within the matrix were arranged in the x (white) and y (blue) directions. The number of fibers was the same in both directions. In the non-interweaving models, the fibers were straight, and there were no interactions between the fibers. In the interweaving models, the fibers were undulated in a zigzag manner, and we considered the interactions between them. For the mechanical simulation, we assigned an equi-biaxial stretch of 2.18% in the x-y plane as displacements at the edge of the fiber-matrix assembly (black arrows). Note that the fibers are continuous. However, because of software limitations, they appear as if they have a “gap” on the exterior side of a curve. (b) Fiber period and tortuosity were measured for all the interweaving models. As collagen volume fraction increased, (c) the period decreased, and (d) the tortuosity period increased, both smoothly and nonlinearly. For the non-interweaving models, since all fibers were straight, the tortuosities were all equal to 1.00 and the periods are ill-defined.