Propiedades elásticas de Pinus sylvestris l. y Picea abies (l.) h. karst. usando métodos vibratorios no destructivos

Abstract

In this investigation elastic properties of Picea abies and Pinus sylvestris species from Austrian high-latitude forest were obtained. Another factor, the visual classifying influence in elastic properties, was determined. In order to assess this classifying influence, 210 wood blocks from homogeneous dimensions (40x40x300) mm3 were arranged; 60 blocks from Picea abies, and 150 from Pinus Sylvestris. In Wood laboratories of Universidad Distrital Francisco José de Caldas, in Bogotá, these wood pieces were weighted and measured. After these latter data was gathered and analyzed, vibratory tests setting accomplishment was proceeded to carry out. After that, each block was hitted, and its different frequencies obtained in Hz, were collected and processed by means of applying FFT ANALYZER Software (belonged to FAKOPP Inc.), turning time wave domain into frequency domain through Fourier transform. Once these values were obtained and considering a math model established, Dynamic Elasticity Modulus (DEM) was calculated. Furthermore, visual classifying into three groups (A, B, C), in accordance with defects, and its weighted influences in DEM was developed. With the purpose of data analysis and their normality confirmation, Kolmogorov-Smirnov and Shapiro-Wilk tests were accomplished. In the outcomes null hypothesis was corroborated, therefore data distribution was normal. Concatenating with the above, it was devised two analysis among each one of species group, in the following order: the first one comprehend Varianza (ANOVA), and the last one related to HSD (Honestly-Significant-Difference) Tukey test. As a result, the average DEM from both wood species (Picea abies and Pinus Sylvestris) was obtained; from which Picea abies presented 10415 MPa, whereas Pinus Sylvestris obtained 12399MPa. The before mentioned brings as consequence that P. Sylvestris has greater elastic behavior when comparing to Picea abies; this result due to by the density of specie, where P. abies had an mean density of 454Kg.m-3, and P. Sylvestris mean density was 580Kg.m-3. Regarding to classified groups by defects (A, B, C), the findings demonstrated that P. abies species DEM mean values in A group were 11730 MPa; in B, 10540 MPa, and in C, 9706 MPa. In consideration of P. Sylvestris species mean values, the outcomes were: To the A group, 13319 MPa, to the group B, 12661 MPa, and to C group, 10269 MPa. The outcomes reflect that from mean value, the relationship between classifying by defects and DEM is identified; however, in ANOVA accomplishment, only P. Sylvestris presented meaningful differences among A, B, C groups, as demonstrated in HSD Tukey analysis. In this manner, it was confirmed the technical efficiency of non-destructive tests, and its importance as useful wood classifying tool, allowing this way its execution in national scenes. Finally, It has to be suggested to deepen in quantitative investigations about defects and its incidence in elastic properties from this two wood species, in accordance to its destination to Colombian trading.