Abstract:The paper aimed at studying the potential of two nondestructive methods to estimate the wood mechanical properties and mass loss due to thermal treatments. In this study, a low-density tropical hardwood species Simarouba amara (marupá) was used. Forty small beams with dimensions of (25 × 25 × 400) mm (width × thickness × length) were cut from this species. Initially, the beams were nondestructively tested using stress wave and ultrasound methods. Stress wave velocity (Swv), ultrasound velocity (V LL), dynamic … Show more
“…In the heat treatment of wood up to approx. 200 • C, the increase in the ultrasound velocity, especially in the longitudinal direction of the wood, which is equivalent to a specific modulus of elasticity (E/ρ), is also indicated by other studies [41,42]. Elastomechanical anisotropy of heat-treated wood has not been widely studied so far.…”
The use of heat-treated timber for building with wood is of increasing interest. Heat treatment improves the durability and dimensional stability of wood; however, it needs to be optimized to keep wood's mechanical properties in view of the possible structural use of timber. Therefore, dry vacuum heat treatment varying the maximum temperature between 170 • C and 230 • C was used on fir (Abies alba Mill.) structural timber, visually top graded according to EN 338, to analyze its final weight loss, hygroscopicity, CIELAB color, and dynamic elastomechanical properties. It turned out that weight loss and total color difference of wood positively correlates with the increasing intensity of the heat treatment. The maximum 40% reduction of the hygroscopicity of wood was already reached at 210 • C treatment temperature. The moduli of elasticity in longitudinal and radial direction of wood, determined by ultrasound velocity, increased initially up to the treatment temperature of 210 • C, and decreased at higher treatment temperature. Equally, the Euler-Bernoulli modulus of elasticity from free-free flexural vibration of boards in all five vibration modes increased with the rising treatment temperature up to 190 • C, and decreased under more intensive treatment conditions. The Euler-Bernoulli model was found to be valid only in the 1st vibration mode of heat-treated structural timber due to the unsteady decrease in the evaluated moduli of elasticity related to the increasing mode number.
“…In the heat treatment of wood up to approx. 200 • C, the increase in the ultrasound velocity, especially in the longitudinal direction of the wood, which is equivalent to a specific modulus of elasticity (E/ρ), is also indicated by other studies [41,42]. Elastomechanical anisotropy of heat-treated wood has not been widely studied so far.…”
The use of heat-treated timber for building with wood is of increasing interest. Heat treatment improves the durability and dimensional stability of wood; however, it needs to be optimized to keep wood's mechanical properties in view of the possible structural use of timber. Therefore, dry vacuum heat treatment varying the maximum temperature between 170 • C and 230 • C was used on fir (Abies alba Mill.) structural timber, visually top graded according to EN 338, to analyze its final weight loss, hygroscopicity, CIELAB color, and dynamic elastomechanical properties. It turned out that weight loss and total color difference of wood positively correlates with the increasing intensity of the heat treatment. The maximum 40% reduction of the hygroscopicity of wood was already reached at 210 • C treatment temperature. The moduli of elasticity in longitudinal and radial direction of wood, determined by ultrasound velocity, increased initially up to the treatment temperature of 210 • C, and decreased at higher treatment temperature. Equally, the Euler-Bernoulli modulus of elasticity from free-free flexural vibration of boards in all five vibration modes increased with the rising treatment temperature up to 190 • C, and decreased under more intensive treatment conditions. The Euler-Bernoulli model was found to be valid only in the 1st vibration mode of heat-treated structural timber due to the unsteady decrease in the evaluated moduli of elasticity related to the increasing mode number.
“…Stress waves can identify internal defects because the defects can change the characteristics of stress wave propagation. The stress wave has been widely used in non-destructive testing in the field of geology [125][126][127], tree damage diagnosis [128][129][130], and composites [131][132][133][134][135]. Han et al [111] used the stress wave to detect online the internal defects during the AFP process, where continuous loading induced by the process itself was used as an excitation source without another external excitation (see Figure 12).…”
Automated fiber placement (AFP) is an advanced manufacturing method for composites, which is especially suitable for large-scale composite components. However, some manufacturing defects inevitably appear in the AFP process, which can affect the mechanical properties of composites. This work aims to investigate the recent works on manufacturing defects and their online detection techniques during the AFP process. The main content focuses on the position defect in conventional and variable stiffness laminates, the relationship between the defects and the mechanical properties, defect control methods, the modeling method for a void defect, and online detection techniques. Following that, the contributions and limitations of the current studies are discussed. Finally, the prospects of future research concerning theoretical and practical engineering applications are pointed out.
“…Em outros estudos, Del Menezzi et al (2014) trabalharam com Simarouba amara tratada termicamente e concluíram através do teste T-pareado que no T1 Embora esses estudos apontem conclusões distintas, há concordância em que o tratamento térmico ou termomecânico altera as propriedades da madeira e de painéis, o que ratifica os resultados aqui encontrados.…”
Section: Variação Da Cor (δE*) Classificaçãounclassified
RESUMOA pressão concentrada em pequeno grupo de espécies tropicais torna necessário maior investimento em estudos e técnicas de melhoramento em espécies menos conhecidas na tentativa de direcioná-las para usos múltiplos. Este trabalho tem por objetivo avaliar a influência do tratamento termomecânico nas propriedades colorimétricas e no modulo de elasticidade da madeira de marupá, com a finalidade de utilizá-la no segmento de pisos. Os resultados mostraram uma mudança significativa, com efeito da temperatura na cor e na propriedade de elasticidade da madeira. Em geral, houve uma melhora no módulo de elasticidade dinâmico, enquanto a velocidade variou de acordo com cada tratamento apresentado, tendo-se valores mais baixos para os tratamentos com maior pressão. A madeira escureceu (menores valores L* e maiores valores de a*) com a aplicação da temperatura. As cores da madeira de marupá após os tratamentos, aliadas à propriedade de elasticidade potencializam essa espécie como opção para a indústria de pisos.Palavras-chave: madeira, termodensificação, colorimetria.
Thermomechanical Treatment and the Effects on the Properties of Simarouba amara (Aubl.)
ABSTRACTThe pressure concentrated in a small group of tropical species necessitates greater investment in research and breeding techniques in lesser known species in an attempt directs them to multiple uses. This work aims to evaluate the influence of thermomechanical treatment on colorimetric properties and modulus of elasticity of timber marupá, in order to use it on the floor segment. The results showed a significant change with temperature effect on the color and the property of elasticity of wood. In general, an improvement in dynamic elastic modulus as the speed varied with each treatment shown, having lower values for the treatments with high pressure. The dark wood (lower L * values and higher values of a *) with application of temperature. The colors of wood marupá after treatments, combined with property of elasticity enhances this species as an option for the flooring industry.
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