Requirements for the diameters of round timber to ensure the rigidity of a flat raft unit

Ensuring the effective functioning of transport and technological schemes for the supply of timber to consumers requires the improvement of well-known flat raft units in terms of simplifying their design and ensuring the possibility of manufacturing in raft machines. The purpose of the study is to determine the permissible range of variation in the diameters of round timber in the rows of a flat raft unit relative to the accepted (nominal) diameter to ensure its rigidity. Rows of round timber of an improved design of a flat raft unit (RF Patent No. 210485) are the object of research. To reduce costs, all experiments of the experiment were carried out on models of flat raft units, the scale of which is 1 : 10. The models were subjected to a stiffness test. During all the experiments, the data obtained were entered into a table, where each zero-level diameter was assigned an established permissible range of variation in the diameter of round timber in the rows of a flat raft unit. Using experimental data that were obtained for models of flat raft units, we determined the permissible range of variation in the diameters of round timber, from which rows of flat raft units of natural sizes are assembled. It is established that for each accepted (nominal) diameter of round timber in the upper segment, from which rows of a flat unit are assembled, there is a change up and down by 1.0 cm. This condition is valid when changing the nominal diameter from 10.0 to 70.0 cm. In practical conditions, in order to ensure the greatest rigidity of a flat raft unit, it is necessary to use round timber with minimal fluidity. It is not allowed to use round timber in rows with a thickness of more than 1.0 cm by 1.0 m in length. At the same time, flexible ties should be carried from the ends of round timber laid in rows by at least 1.0 m. Compliance with the established variation in the diameters of round timber in the upper segment from which rows of improved flat raft units are assembled will make it possible to produce raft units of this design that will have sufficient rigidity, and as a result, wave resistance.