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Fernandes, A., J. Lousada, J. Morais, J. Xavier, J. Periera, and P. Melo-Pinto. "Measurement of intra-ring wood density by means of imaging VIS/NIR spectroscopy (hyperspectral imaging)." Holzforschung. 67 (2013): 59-65. Abstract
Xavier, J., J. Morais, N. Dourado, and M. F. S. F. de Moura. "Measurement of mode I and mode II fracture properties of wood-bonded joints." Journal of Adhesion Science and Technology. 25 (2011): 2881-2895. Abstract
Catalanotti, G., P. P. Camanho, J. Xavier, C. G. Dávila, and AT Marques. "Measurement of resistance curves in the longitudinal failure of composites using digital image correlation." Composites Science and Technology. 70 (2010): 1986-1993. Abstract
Catalanotti, C., J. Xavier, and P. P. Camanho. "Measurement of the compressive crack resistance curve of composites using the size effect law." Composites Part A: Applied Science and Manufacturing. 56 (2014): 300-307. Abstract
Catalanotti, G., and J. Xavier. "Measurement of the mode II intralaminar fracture toughness and R-curve of polymer composites using a modified Iosipescu specimen and the size effect law." Engineering Fracture Mechanics. 138 (2015): 202-214. AbstractWebsite

Abstract A modified Iosipescu specimen is proposed to measure the mode İI\} intralaminar fracture toughness and the corresponding crack resistance curve of fibre reinforced composites. Due to the impossibility of scaling the specimen, a modification of the classical size effect method is proposed. The calculation of the crack driving force curves is performed using the Finite Element Method. The classical Iosipescu shear feature was used and tests were coupled with digital image correlation to support the proposed approach. Experiments were performed on IM7/8552 material system and the R-curve was obtained. The steady-state value of the fracture toughness of the ply is found to be equal to R 0 ss = 34.4  kJ/m2.

Xavier, J., M. Oliveira, J. Morais, and J. Pinto. "Measurement of the shear properties of clear wood by the Arcan test." Holzforschung. 63 (2009): 217-225. Abstract
Xavier, J., A. M. R. Sousa, J. J. L. Morais, V. M. J. Filipe, and M. Vaz. "Measuring displacement fields by cross-correlation and a differential technique: experimental validation." Optical Engineering. 51 (2012): 043602. Abstract
Xavier, J., J. R. A. Fernandes, O. Frazão, and J. J. L. Morais. "Measuring mode I cohesive law of wood bonded joints based on digital image correlation and fibre Bragg grating sensors." Composite Structures. 121 (2015): 83-89. Abstract

Abstract This work addresses the experimental identification of mode I cohesive law of wood bonded joints. The approach combines the double cantilever beam (DCB) test with both digital image correlation (DIC) and embedded fibre Bragg grating (FBG) sensors. The spectrum geometric mean of the \{FBG\} reflected spectral response was determined, and the wavelength evolution was used to define the fracture process zone (FPZ) development phase. This evaluation allowed a consistent selection of experimental range of over which the identification procedure of mode I cohesive law is build up. Mode I crack length, Resistance-curve and cohesive law parameters are characterised and discussed. The strain energy release rate (GI) is determined from the P�d curve by the compliance-based beam method (CBBM). The crack tip opening displacement (wI) is determined by post-processing displacements measured by DIC. The cohesive law in mode I (sI�wI) is then obtained by numerical differentiation of the GI�wI relationship.

Xavier, J., and F. Pierron. "Measuring orthotropic bending stiffness components of Pinus pinaster by the virtual fields method." The Journal of Strain Analysis for Engineering Design. 53 (2018): 556-565. AbstractWebsite

Orthotropic stiffness components of Pinus pinaster Ait. wood are simultaneously determined by means of a heterogeneous plate bending test. The proposed inverse identification approach couples full-field slope measurements provided by deflectometry with the virtual fields methods. Wooden plates oriented in the longitudinal–radial and longitudinal–tangential material planes were manufactured. A procedure was implemented to allow suitable specular reflective coating of the wooden plates, required in the deflectometry technique. Reconstructed curvature fields, applied load and plate dimensions were input in virtual fields methods for material parameter identification, assuming Kirchhoff–Love classical plate theory. Several virtual fields and load cases were analysed to address the identifiability of the method. The values of the orthotropic elastic constants obtained from the proposed approach were found in good agreement with regard to reference ones for the same species and determined from classical tensile, compression and shear mechanical tests.

Majano-Majano, Almudena, Antonio José Lara-Bocanegra, José Xavier, and José Morais. "Measuring the Cohesive Law in Mode I Loading of Eucalyptus globulus." Materials. 12 (2019). AbstractWebsite

Assessing wood fracture behavior is essential in the design of structural timber elements and connections. This is particularly the case for connections with the possibility of brittle splitting failure. The numerical cohesive zone models that are used to simulate the fracture behavior of wood make it necessary to assume a cohesive law of the material that relates cohesive tractions and crack opening displacements ahead of the crack tip. This work addresses the determination of the fracture cohesive laws of Eucalyptus globulus, a hardwood species with great potential in timber engineering. This study centres on Mode I fracture loading for RL and TL crack propagation systems using Double Cantilever Beam tests. The Compliance-Based Beam Method is applied as the data reduction scheme in order to obtain the strain energy release rate from the load-displacement curves. The cohesive laws are determined by differentiating the relationship between strain energy release rate and crack tip opening displacement. The latter is measured by the digital image correlation technique. High strain energy release rates were obtained for this species, with no big differences between crack propagation systems. The difference between the crack systems is somewhat more pronounced in terms of maximum stress that determines the respective cohesive laws.

Silva, F. G. A., M. F. S. F. de Moura, N. Dourado, J. Xavier, F. A. M. Pereira, J. J. L. Morais, and M. I. R. Dias. "Mixed-mode I+II fracture characterization of human cortical bone using the Single Leg Bending test." Journal of the Mechanical Behavior of Biomedical Materials. 54 (2016): 72-81. AbstractWebsite

Abstract Mixed-mode I+II fracture characterization of human cortical bone was analyzed in this work. A miniaturized version of the Single Leg Bending test (SLB) was used owing to its simplicity. A power law criterion was verified to accurately describe the material fracture envelop under mixed-mode I+II loading. The crack tip opening displacements measured by digital image correlation were used in a direct method to determine the cohesive law mimicking fracture behavior of cortical bone. Cohesive zone modeling was used for the sake of validation. Several fracture quantities were compared with the experimental results and the good agreement observed proves the appropriateness of the proposed procedure for fracture characterization of human bone under mixed-mode I+II loading.

de Moura, M. F. S. F., J. M. Q. Oliveira, J. J. L. Morais, and J. Xavier. "Mixed-mode {I/II} wood fracture characterization using the mixed-mode bending test." Engineering Fracture Mechanics. 77 (2010): 144-152. Abstract
Xavier, J., P. Monteiro, J. J. L. Morais, N. Dourado, and M. F. S. F. de Moura. "Moisture content effect on the fracture characterisation of Pinus pinaster under mode I." Journal of Materials Science. 49 (2014): 7371-7381. AbstractWebsite