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Numerical prediction of checking during timber drying and a new mechano-sorptive creep model

Quantitatives Vorhersagen der Rißbildung bei der Holztrocknung und ein neues Modell des mechanisch-sorptiven Kriechens

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Abstract

The dependence of the amount of checking on shrinkage induced stress level during timber drying is considered. This relationship is investigated by comparing theoretically calculated maximal stress with observed amount of checking in a set of drying tests. Different ways of modelling wood creep behaviour are included. It is found that a correlation exists in all the cases studied, except when creep is described with the traditional equation for mechano-sorptive creep. It is shown that this exception is due to a special mathematical property of the equation. A new mechano-sorptive creep model is thus proposed and briefly investigated. Using this model, a method for predicting the amount of checking in timber drying is developed.

Zusammenfassung

Die Abhängigkeit des Ausmaßes der Rißbildung aufgrund von Schwindungsspannungen während der Holztrocknung wird untersucht. Diese Beziehung wurde ermittelt durch Vergleichen von theoretisch berechneten maximalen Spannungen mit tatsächlich beobachteten Rißbildungen. Verschiedene Modelle des Kriechverhaltens wurden einbezogen. Es ergaben sich für alle untersuchten Fälle gute Korrelationen, außer bei Anwendung der traditionellen gleichung für mechanisch-sorptives Kriechen. Die Ausnahme wurde auf spezielle mathematische Eigenschaften dieser Gleichung zurückgeführt. Deswegen wird ein neues Modell für mechanisch-sorptives Kriechen vorgeschlagen und kurz untersucht. Auf der Grundlage dieses neuen Modells wird eine Methode entwickelt, um das Ausmaß der Rißbildung während der Holztrocknung vorherzusagen.

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  1. CTS Consulting Ltd., Ekono Corporation, P.O.B. 27, SF-00131, Helsinki

    J. -G. Salin

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Salin, J.G. Numerical prediction of checking during timber drying and a new mechano-sorptive creep model. Holz als Roh-und Werkstoff 50, 195–200 (1992). https://doi.org/10.1007/BF02663286

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