Lightweight wood-based composites fall within the family of sandwich panels, layered elements formed by two thin skins bonded to a relatively thick core. These products achieve high mechanical performance and can fulfil other functions (e.g. thermal or acoustical) maintaining at the same time a limited density. Thanks to these peculiarities, today they are widely used in the transportation and construction sectors. In this context, the thesis reports the development and assessment of a new lightweight wood-based composite. This is made of okoumè (Aucoumea klaineana Pierre) plywood skins bonded to a new honeycomb core. Its distinctive feature is constituted by the new structure of the core, which is entirely made of okoumè plywood, lozenge-shaped cells. A further peculiarity of the honeycomb is represented by its potential aptitude for providing sound absorption in the low frequency range. In fact, its empty cells structure is suited for activating, in conjunction with a drilling of the composite skins, the Helmholtz resonance effect. The composite was set for use as a non-structural component in the marine industry. However, it is suitable for meeting the requirements of several other applications, e.g. floors in trucks and commercial vehicles, interior walls and furniture in caravans and motorhomes, ceilings and dividing walls in construction. On the basis of the performed laboratory tests, the composite resulted suitable for meeting the requirements of boatbuilding, in terms of lightness, bending strength, modulus of elasticity, shear strength, tension perpendicular to faces and dimensional stability. In addition, the impedance tube tests confirmed its potential aptitude for absorbing sound due to the Helmholtz resonance effect. To this day, the development can be considered concluded and the composite ready for the industrialization process. However, the product presents further opportunities if additional features are added: thermal insulation through a foam filling of the core and fire retardant properties through adequate surface treatments. Finally, besides the above-summarized activity, the research is enhanced by two additional strands: the study of a composite having an aluminum-foam core bonded to plywood skins, and the evaluation of the sound absorption properties for specific frequencies achieved by drilled plywood intended for use as composite skin for coverings and acoustic enhancement of enclosed spaces.
Development and assessment of new ligthweigth wood-based composites
NEGRO, FRANCESCO
2011-01-01
Abstract
Lightweight wood-based composites fall within the family of sandwich panels, layered elements formed by two thin skins bonded to a relatively thick core. These products achieve high mechanical performance and can fulfil other functions (e.g. thermal or acoustical) maintaining at the same time a limited density. Thanks to these peculiarities, today they are widely used in the transportation and construction sectors. In this context, the thesis reports the development and assessment of a new lightweight wood-based composite. This is made of okoumè (Aucoumea klaineana Pierre) plywood skins bonded to a new honeycomb core. Its distinctive feature is constituted by the new structure of the core, which is entirely made of okoumè plywood, lozenge-shaped cells. A further peculiarity of the honeycomb is represented by its potential aptitude for providing sound absorption in the low frequency range. In fact, its empty cells structure is suited for activating, in conjunction with a drilling of the composite skins, the Helmholtz resonance effect. The composite was set for use as a non-structural component in the marine industry. However, it is suitable for meeting the requirements of several other applications, e.g. floors in trucks and commercial vehicles, interior walls and furniture in caravans and motorhomes, ceilings and dividing walls in construction. On the basis of the performed laboratory tests, the composite resulted suitable for meeting the requirements of boatbuilding, in terms of lightness, bending strength, modulus of elasticity, shear strength, tension perpendicular to faces and dimensional stability. In addition, the impedance tube tests confirmed its potential aptitude for absorbing sound due to the Helmholtz resonance effect. To this day, the development can be considered concluded and the composite ready for the industrialization process. However, the product presents further opportunities if additional features are added: thermal insulation through a foam filling of the core and fire retardant properties through adequate surface treatments. Finally, besides the above-summarized activity, the research is enhanced by two additional strands: the study of a composite having an aluminum-foam core bonded to plywood skins, and the evaluation of the sound absorption properties for specific frequencies achieved by drilled plywood intended for use as composite skin for coverings and acoustic enhancement of enclosed spaces.
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