Surface deformation of walnut burl veneer on aircraft sandwich panels assessed by three-dimensional digital image correlation
The three-dimensional digital image correlation method (3D-DIC) was used to study the surface deformation of aircraft interior sandwich panels as a result of a water vapor adsorption treatment. The effects of a fire-retardant treatment and wood burl structure were evaluated. Unvarnished and varnished panels made with walnut burl veneer (Juglans hibdsii L.) were selected and analyzed separately. Half of the samples from each type of panel received a fire-retardant treatment (phosphate based) on all three layers of the decorative plywood. The other half had the two inner layers treated and the outer layer untreated. Swirl grain and bud traces areas were identified on the burl pattern of veneer surfaces. Samples preconditioned to 20 °C and 40% relative humidity underwent an adsorption (25 °C, 90% RH) treatment. Changes in moisture content were measured after adsorption. Full-field swelling strains (in-plane) and Z-displacements (out-of-plane) were obtained from each figure type in samples after the adsorption conditioning. The application of the 3D-DIC method revealed that the fire-retardant treatment increased the swelling strains and Z-displacements on unvarnished and varnished surface panels. This treatment also caused a significant differentiation of Z-displacements on swirl zones compared to bud trace zones in varnished panels. Thus, the degree of surface deformation depended on the burl wood structure and the fire-retardant treatment. The 3D-DIC method was suitable for evaluating local swelling strains and Z-displacements on unvarnished and varnished wood veneer surfaces.
The authors gratefully acknowledge Jean Ouellet and Luc Germain for valuable assistance. This research was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC), the Mitacs accelerate program, Bombardier Aerospace, 3M Canada Company, and the Consortium for Research and Innovation in Aerospace in Québec (CRIAQ).
- Ayrilmis N, Dundar T, Candan Z, Akbulut T (2009) Wettability of fire retardant treated laminated veneer lumber (LVL) manufactured from veneers dried at different temperatures. BioResources 4:154–1535Google Scholar
- Booth CF (2008) Aircraft veneer catalog. http://boothveneers.com/veneers. Accessed 16 January 2017
- Candan Z, Ayrilmis N, Akbulut T (2011) Dimensional stability of OSB. BioResources 6:308–316Google Scholar
- Cintron R, Saouma V (2008) Strain measurements with the digital image correlation system Vic-2D. Department of Civil Environmental and Architectural Engineering, University of Colorado, DenverGoogle Scholar
- Dundar T, Ayrilmis N, Candan Z (2008b) Evaluation of surface roughness of laminated veneer lumber (LVL) made from beech veneers treated with various fire retardants and dried at different temperatures. For Prod J 58:71–76Google Scholar
- Dünisch O (2012) Influence of the wood structure on water uptake and swelling and its significance for surface finishing of high quality furniture. In: International union of forest research organizations conference, division 5 forest products, July 8–13, Estoril, PortugalGoogle Scholar
- El Mouridi M, Laurent T, Famiri A, Kabouchi B, Alméras T, Calchéra G, El Abid A, Ziani M, Gril J, Hakam A (2011) Physical characterization of the root burl wood of thuja (Tetraclinis articulata (Vahl) M.). Phys Chem News 59:57–64Google Scholar
- Govorčin S, Sinković T, Sedlar T, Šefc B, Ištok I (2012) Properties of trunk and briarwood of tree heath (Erica arborea L.) from island Rab. In: 5th conference on hardwood research and utilisation in Europe, May 17–18, Sopron, HungaryGoogle Scholar
- Kang HY, Kang SG, Kang CW, Matsumura J (2013) Measurement of strain distributions in white oak boards during drying using a digital image correlation method. J Fac Agric Kyushu Univ 58:55–59Google Scholar
- Liu Y, Jehanathan N, Yang H, Laeng JJ (2007) SEM observation of the orange peel effect of materials. Mater Lett 61:143–1433Google Scholar
- Pan P, Qian K, Xie H, Asundi A (2009) Two-dimensional digital image correlation for in-plane displacement and strain measurement: a review. Meas Sci Technol IOPscience 20:1–17Google Scholar
- Peng M, Ho CH, Wang WC, Chui YH, Gong M (2012) Measurement of wood shrinkage in jack pine using three-dimensional digital image correlation. Holzforschung 66:639–643Google Scholar
- SAS Institute Inc. (2013) Procedure guide, 2nd edn (SAS/AF® 13.2) SAS Institute, Cary, NCGoogle Scholar