Calibration of Acoustic Emission Parameters in Relation to the Equilibrium Moisture Content Variations in a Pinus sylvestris Beam

Abstract

Under constant temperature conditions, air relative humidity variations affect hygroscopic objects, such as wood, modifying their moisture content and provoking, at low values, damages and fractures. The parameters (amplitude, counts, and energy) derived from the acoustic emission non-destructive technique are calibrated with respect to equilibrium moisture content values using 14 samplings of Pinus sylvestris. The experimental procedure uses multi-technique approaches involving a universal testing machine, digital image correlation, and acoustic emissions, and notes that the three parameters of acoustic emission strictly depend on the equilibrium moisture content. For a better interpretation, a statistical approach is applied to model the equilibrium moisture content variations radially and longitudinally. Amplitude, counts, and energy are calibrated as a function of the equilibrium moisture content, indicating that all three parameters are necessary to have an integral vision of the conservation of a wooden material. Moreover, the shape of the macro-fractures that occur at the surface can be associated with the level of moisture or dryness of the sample. Finally, the proposed method can be used in situ because, through acoustic emission monitoring, it is possible to quantify the fingerprint of the state of conservation of a material.

Sustainable management of heritage buildings in long-term perspective (SyMBoL): current knowledge and further research needs

“…The threshold value of 51.9 dB was found as an early warning indicator for Scots pine samples with mixed mode fractures; while in the case of Mode I fracture, as cracks occurred instantaneously, the oncoming fracture was not predicted. Then, the main experimental task at NTNU was the development of a novel Risk Assessment Tool (RAT) for determining the level of risk of mechanical decay on a cylindric Pine element resembling a stave (diameter of circa 16 cm) when subjected to (natural and artificial) environmental hygric change similar to those existing in the SCs of Ringebu and Heddal (Bertolin et al, 2020a(Bertolin et al, , 2020bBertolin et al, 2021aBertolin et al, , 2021bKarvan et al, 2021;Bartolucci et al, 2020;Bartolucci et al, 2021;Califano et al, 2023).…”

Discrimination between softwood and hardwood based on hemicellulose content obtained with portable nuclear magnetic resonance

“…Moisture affects all properties of wood. While moisture in the cell lumens only produces an increment of weight (Tsoumis 1991), moisture contained in cell walls influences the mechanical and thermal properties of wood (Bartolucci et al 2021). Moisture content (MC) of wood also affects its resistance to decay and insects as well as its preservative treatment (Tsoumis 1991).…”

Discrimination between Softwood and Hardwood based on Hemicellulose Content obtained with Portable Nuclear Magnetic Resonance

“…Moisture affects all properties of wood. While moisture in the cell lumens only produces an increment of weight (Tsoumis 1991), moisture contained in cell walls in uences the mechanical and thermal properties of wood (Bartolucci et al 2021). Moisture content (MC) of wood also affects its resistance to decay and insects as well as its preservative treatment (Tsoumis 1991).…”