Caracterização mecânica de madeiras deterioradas em campo por meio de ultrassom e flexão estática

Abstract

This study aimed to evaluate the natural resistance of four wood species exposed to field tests using ultrasound and static bending tests. Tectona grandis (teak), Azadaractina indica (neem), Inga sp. (inga) and Bagassa guianensis (tatajuba) logs with 1.2m length were subjected to field tests for 18 months, in the city of Sinop-MT. Samples were cut from healthy logs to characterize modulus of elasticity and modulus of rupture at static bending before the exposure in field test. After each period of exposure, samples were cut from the logs in three positions (in-ground contact, critical zone and above-ground). Nondestructive tests were performed using an ultrasound to determine the velocity of wave propagation in the decayed samples. Samples with lower velocities of wave propagation were subjected to the static bending tests. The results were compared with unexposed wood samples to characterize the degree of wood deterioration. Ultrasonic tests showed that samples collected from the critical zone of the logs presented lowest velocity of wave propagation. Among the species studied, teak and tatajuba wood presented the highest and the lowest natural resistance, respectively.

Comparison of Two Methods to Determine the Bending Modulus of Elasticity of Wood

“…The mean value of E m for the specie of Cambará was superior to that determined by other author [18]. Tatajuba presented E m greater than those found in others studies, for properties determined with wood moisture content of 12% [15,17,19].…”

Resistência e rigidez da madeira de espécies florestais submetidas a campo de apodrecimento

“…De acordo com Stangerlin et al (2015), a avaliação da durabilidade natural de madeiras pode ser realizada por inspeção visual da sanidade da peça em uso. Porém, para avaliar a resistência à deterioração da madeira a análise da perda de propriedades físicas e mecânicas configura-se como parâmetro essencial (Simsek et al 2010;Ali et al, 2011 ).…”

Ultrasound to determinate the modulus of elasticity of heat-treated woods subjected to field test

“…Heat treatment usage in Brazil has taken a prominent place in the strive for both sustainability and greater durability of the used wood without harming the environment, as it does not use chemicals that are harmful to it. Natural durability tests of wood in the field environment are important because it exposes the subject to various xylophagous organisms, as well as abiotic factors, emphasizing the visual health inspection of the service piece as an evaluation form (Stangerlin et al, 2015).…”