Issue 47

L. Marsavina et al., Frattura ed Integrità Strutturale, 47 (2019) 266-276; DOI: 10.3221/IGF-ESIS.47.20 274 C ONCLUSIONS he paper presents the experimental results for mechanical and fracture properties of particleboard materials. Tab. 6 summarizes the obtained results for the two PB thicknesses corresponding to direction 2 of orientation. It could be observed that the PB with thickness of 16 mm has higher mechanical properties (Modulus of Rupture-MOR and Modulus of Elasticity-MOE); while the higher fracture toughness was obtained for PB with 25 mm thickness. Thickness MOR [MPa] MOE [MPa] K IC [MPa·m 1/2 ] K eff [MPa·m 1/2 ] 16 9.30 1406.7 0.736 0.631 25 9.24 1153.2 0.841 0.785 Table 6 : A comparison of mechanical and fracture properties for PB Using the experimental displacements measured by Digital Image Correlation (DIC) the Crack Relative Displacement Factor (CRDF) was estimated. The evaluation of CRDF allowing to evaluate the part of each mode in the fracture process. According to presented approach, all changes in material properties can be directly correlated with the displacement measurement and implicitly with the CRDF amplitude. As shown, the calculation of CRDF may be performed without knowledge of the material constitutive law. The values of CRDF show that even for an opening mode loading, the crack path and experimental boundary conditions induce a mixed mode configuration. Even if the value of CRDF corresponding to mode II is small, the results show the presence of the mode II during the crack propagation in opening mode. As shown in Tab. 4, the relationship between the CRDF corresponding to mode I and II of fracture, and the relationship between the Stress Intensity Factor (SIF) show some similarities to the shear test. This observation allows consideration of the calculated phase angle. Moreover, the fracture energy was evaluated from the CRDF and the SIF values. It should be noted that this approach allows evaluation of the fracture parameters without the knowledge of the properties of material. Classical fracture criteria (Maximum Tensile Stress and Minimum Strain Energy Density) provide a good prediction of fracture of particleboard (see Fig. 5). A CKNOWLEDGEMENT art of the experimental work was carried out in the framework of the grant from the Romanian National Authority for Scientific Research, CNCS – UEFISCDI, project code PN-III-P1-1.1-MCD-2016-0076, contract number 41/8.11.2016, which supports the mobility of Dr. Pop at the University Politehnica Timi ș oara. The authors are grateful to Mr. Robert Moscaliuc for specimen preparation and his contribution to experimental program. R EFERENCES [1] Beer, P., Sinn, G., Gindl, M., Stanzl-Tschegg, S. (2005). Work of fracture and of chips formation during linear cutting of particle-board, Journal of Materials Processing Technology 159, pp. 224–228. [2] Beer, P., Gindl, M., Stanzl-Tschegg, S. (2008). Wedge splitting experiments on three-layered particleboard and consequences for cutting, Holz als Roh- und Werkstoff 66, pp. 135-141. [3] ANSI A208.1 (1998). Particleboard and MDF For Shelving, American National Standard, Composite Panel Association, Gaithersburg, MD. [4] Johnson, J. A., Ifju, G., Rogers, H.W. (1976). The performance of composite wood/particleboard beams under two point loading, Wood and Fiber, 8(2), pp. 85-97. [5] Norvydas, V., Minelga, D. (2006). Strength and Stiffness Properties of Furniture Panels Covered with Different Coatings, Materials Science, 12(4), pp. 328-332. T P