Parameters of logging machines are determined by the characteristics of the subject of labour, in particular the size of trees. In stands the sizes of trees vary and have stochastic character. This leads to the difficulty of determining the design tree for the felling machine or calculating the weight of the wood moved by the transport machine. The problem is complicated by the fact that the design of the forest machine should ensure the efficiency of work in different stands. The solution of the problem of determining the calculated characteristics of the subject of labour (characteristics that determine the values of external forces acting on the forest machine) can be based on the analysis of regularities in the structure of stands by thickness. The purpose of this study is to describe a method of constructing stochastic models of the structure of the stand by thickness in the design of forest machines and an example of its application. The proposed method makes it possible to form a stochastic model of the tree stand structure by thickness for the forest area under study and covers procedures from the collection of initial data to the generation of the tree diameter algorithm. Generation algorithms obtained by the method can be used in the development of simulation models for computer experiments aimed at calculating the optimal parameters of forest machines.

Keywords: forest machines designing, stochastic simulation, stand structure by thickness, tree diameter distribution, simulation modeling, computational experiment on the computer