Construction of Trajectories of the Fibers Which Bypass a Hole and Their Comparison with the Structure of Wood in the Vicinity of a Knot

Attachment fittings remain a weak point of composite structures owing to traditional techniques of drilling holes for rivets or bolts. An alternative version is suggested by Nature by creating a "branch-trunk" connection without fiber cutting. Two methods for numerical construction of rational trajectories of fibers that "bypass" a hole in a composite plate are proposed. The methods implement the condition of the absence of tangential stresses along these trajectories that is almost equivalent to the conditions of equal tension of fibers. The constructed trajectories are compared with the structure of wood in the vicinity of a knot. It is shown that the "bypass" of fibers around inclusions or inhomogeneities (holes or recesses) yields a decrease in the influence of the stress concentrations as compared to an ordinary structure of reinforcement with rectilinear fibers.