Modelagem e simulação da produtividade do forwarder em povoamentos de eucalipto

Abstract

The productivity gain of the machines in the wood extraction stages depends on the understanding of all variables and operational restrictions. This work aimed to evaluate, model and simulate the productivity of the forwarder in the extraction of wood in stands of Eucalyptus spp. under different operating conditions, subsidizing operations planning, increasing productivity and reducing production costs. The study was carried out in a forestry company located in the municipality of Três Lagoas, Mato Grosso do Sul, on stands of Eucalyptus spp. from 6 to 7 years. The management regime adopted by the company is clearcut, with the wood used in the production of cellulose, the wood extraction system used is the short cut (cut to length). Initially, an operational analysis of the extraction was carried out through time and motion study, using the continuous time method, characterized by the measurement of partial time without interruption of the timer, that is, continuously determining productivity, operational efficiency, mechanical availability and efficiency energy of the forwarder in plots with different average extraction distances (DME) and average individual tree volumes (VMI). Then, based on the data obtained, there was a correlation between these variables and the elements of the forwarder's operating cycle. A forwarder productivity curve was developed using the regression method studied step by step, while statistics and data models were processed using the R software. Subsequently, the sender's operational performance was divided into different conditions, partitioning plots using the geographic information system (GIS). The results showed that DME was the variable that most affected the forwarder's productive capacity under the conditions evaluated, and the greater the distance the machine travels, the lower its productivity. The mathematical model developed in the study explained 46% of the variation in forwarder productivity caused, judging by the complexity of the selected variables, the developed model presents an excellent forwarder productivity forecast. The adjusted model showed that, from the 0.36 m³ / tree VMI, the forwarder's productivity decreased, evidenced by the fact that it had exceeded the machine's operational capacity. The division of plots and the simulation of extraction scenarios allowed to optimize the DME by 14.15%, considering the alignment of planting and, consequently, the increase in productivity and the reduction of extraction costs with the forwarder was 2.7%.