Unidirectional fibrous composites, like straight grained wood have the best longitudinal elastic-strength properties, but the problems of joining the composite elements cannot be solved effectively using «metal» approaches only. However, joining zones usually reduce the advantages of composites to zero. Experience of the Nature (for example, the structure of wood around a knot) shows the ways of a rational design of parts of quasi-unidirectional composites and zones of their joining preventing the «effects of cut fibers». There are three examples of solved problems in the report, connected with: 1) disorientation of fibers in shaped composite elements, 2) trajectories of fibers around a hole (modeling a knit) and «branch to trunk» connection,3) «Chinese lantern»-mode fracture of bamboo and composite tubes.
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