Acoustic tomography is based on the velocity variation inside the inspected element. However, wood is heterogeneous and anisotropic, which causes natural velocity variations. In wood, the great challenge to apply this technology is to interpret and differentiate the natural variations of the material from those caused by deterioration. This study aimed to evaluate the interference caused by knots, the wave propagation direction, and the effect of juvenile and reaction wood on the velocities determined via ultrasonic tomography. The tests were performed using 40 disks of Pinus elliottii. From the results it was concluded that intrinsic orthotropy of the wood was reflected in the wave propagation on the disks with radial velocities greater than the tangential ones, higher velocities in the knot zones, and different velocities in the zones of compression and opposition wood. In the measurements using the diffraction mesh, the edge velocities (tangential direction with the maximum angle from the radial direction) were always lower than all of the other velocities in the disk. More significant variations in the velocity were obtained in the juvenile wood. These results contribute to quantifying some interferences associated with tomography images, such that the misinterpretation can be minimized.

Wood-processing industries must be able to estimate the properties of wood to properly manage the wood production chain. For this estimation, changes in certain characteristics over time must be identified so that they can be used to rapidly differentiate a clone or species. Of interest are acoustical, geometrical, physical, and mechanical properties, all measurable in seedlings. Thus, the objective of this research was to analyze the evolution of the ultrasonic wave propagation velocity, diameter, height, basic density, strength, and stiffness starting in nursery seedlings at 3 months of age to trees at 6 years of age, which is the cutting age used by the pulp and paper industry in Brazil. The experiment was conducted in 121 seedlings and 270 trees of three Eucalyptus clones. Within the age range analyzed, the results indicated that all parameters have the potential to be used in a predictive model to estimate the future quality of clones, although the predictive value of these parameters varies. The ultrasonic wave propagation velocity was the only property that maintained the coherent differences among clones from the seedling to the cutting age (6 yr old). The strength, stiffness, diameter, and height maintained coherence from 12 months to the cutting age, whereas the basic density was maintained from the age of 24 months to the cutting age. We hope that these results will contribute to improving the methods to select clones.

Anticipate the knowledge of wood properties using tests in earliest ages is very important for the forest sector. So, we need to find properties that, measured in early ages, can be used in prediction models of trees properties. The objective of this research was to analyze if strength and stiffness, obtained in seedlings, are different in different clones and if this differences are maintaining in trees during the years, until the cutting age. Using the data obtained so far, we verify that there are statistical differences in strength and stiffness obtained in seedlings from different clones. This result is important to make these properties candidates to be used in prediction models. We expect that the differentiation obtained in seedlings remain up to 6 years old that is the cutting age of the trees.

A identificação da condição interna de árvores é um problema atual importante, tanto para o setor urbano quanto florestal. Equipamentos de tomografia acústica permitem obter imagens da condição interna de árvores. No entanto os existentes no mercado são importados e muito onerosos, fazendo com que a tecnologia seja muito limitada em nosso país. Esse projeto de iniciação científica está incorporado a esforço do grupo de pesquisa em Ensaios Não Destrutivos da FEAGRI/Unicamp, visando o desenvolvimento de tomografia ultrassônica com tecnologia nacional. O objetivo deste projeto de IC foi caracterizar o nível de interferência da presença de medula e de nós nas imagens de tomografia ultrassônica geradas. Os resultados preliminares indicam que zonas de madeira de reação tendem a apresentar velocidades inferiores (cerca de 30% da máxima), enquanto regiões com nó velocidades máximas. No entanto não é esperado que tais variações interfiram na identificação de deteriorações, já que as velocidades em discos íntegros, com presença apenas de nós ou medula deslocada, em geral apresentaram velocidades sempre superiores a 70% da velocidade máxima obtida no proprio disco. Palavras-chave: ensaio não destrutivo, inspeção de árvores, tomografia ultrassônica.