Equivalent annual uniform costs of wood harvesting machines: a stochastic approach

Abstract

Determining the economic life of wood harvesting machines, time when the machine performed its functions at the lowest operating cost is associated with the lowest production cost. Thus, the objective was to determine the economic life of self-propelled machines that make up a mechanized lumber harvesting modulus with uncertainty conditions. Incurred operating costs over five years were considered, constructing mathematical models that associated the uncertainty intervals and allowed for assigning probability distributions. Subsequently, pseudorandom numbers were generated by Monte Carlo simulation to determine the probabilities of stochastic economic values. The results showed that, the optimal time to replace the set of machines composing the mechanized lumber-harvesting modulus occurred in the 4^th year of its useful life. Thus, the equivalent uniform cost of the harvesting base module increases 18.3% in the year subsequent the optimum replacement time, adding the costs of harvesting and processing the wood. Finally, the cost elements that most influence the determination of the economic life of the machines are the costs of replacing parts and of repairs and maintenance.