Abstract
Acoustic emissions were measured during the swelling of southern yellow pine (Pinus sp.). The acoustic emissions are generated by swelling pressures which cause tissue movement and microfracturing within the samples during hydration. The samples were cycled through five wet/dry cycles and the acoustic emissions were measured during the wetting portion of the cycle. The level of acoustic emissions decreased exponentially with each cycle. Simultaneously, the estimated void volume within the samples increased slightly with each cycle. The results suggest that microfracturing is occurring within wood during swelling and increasing the void volume available for moisture penetration. The pattern indicates that the amount of microfracturing decreases with each cycle. The data also indicate that dimensional stability treatments for wood must effectively prevent moisture penetration of the microvoid areas within the wood.
Zusammenfassung
Während des Quellens von Kiefernholz wurden Schallemissionen gemessen. Diese entstehen durch den Quellungsdruck, der Gewebebewegungen und Mikrorisse während der Wasseraufnahme verursacht. Die Proben wurden einem fünfmaligen Zyklus von Befeuchten und Trocknen unterworfen, wobei die Schallemissionen während der Wasseraufnahme gemessen wurden. Die Stärke der Schallemissionen nahm dabei exponentiell ab. Gleichzeitig erhöhte sich das geschätzte Porenvolumen der Proben leicht mit jedem Zyklus. Die Ergebnisse lassen vermuten, daß Mikrorisse während des Quellens entstehen und das Porenvolumen für weitere Wasseraufnahme Die Anzahl der Mikrorise verringert sich mit jedem Zyklus. Für die Dimensionsstabilisierung von Holz ergibt sich daraus, daß vor allem das Eindringen von Wasser in die Mikroporen verhindert werden muß.
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This research was begun while the primary author was employed at the Mississippi Forest Products Utilization Laboratory
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Rice, R.W., Peacock, E. Acoustic emissions resulting from cyclic wetting of southern yellow pine. Holz als Roh-und Werkstoff 50, 304–307 (1992). https://doi.org/10.1007/BF02615358
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DOI: https://doi.org/10.1007/BF02615358