Yield criterion of the softwood under conditions of variable humidity

• Autorzy: Kowal M. , Mielniczuk J.
• Języki publikacji: EN

Abstrakty

EN

Wood is a porous material. In a dry state the unit volume of wood consists of water-free volume of the wood substance, the so-called wood skeleton, and of the air-filled pores. The variable humidity produces the internal forces within the loaded wood bulk loading to destruction in the form of loosening wood fibers, cracks and twists. In the paper the yield criterion or the transition of the softwood into the plastic state is discussed. The outset of yielding is examined in accordance with the Hill criterion for anisotropy with various ratios of humidity. The case of plane stress with the orthotropic structure is used as an example for which the material constants are identified, resulting in a special form of the yield criterion.

Słowa kluczowe

EN

yield criterion; softwood; humidity

PL

kryterium plastyczności; drewno miękkie; wilgotność

• Wydawca: Instytut Podstawowych Problemów Techniki PAN
• Czasopismo: Engineering Transactions
• Rocznik: 2001
• Tom: Vol.49, iss.4
• Strony: 529--535
• Opis fizyczny: Bibliogr. 7 poz., rys., tab., wykr.

Twórcy

autor

Kowal M.

• Institute of Technology Pedagogical U niversity of Zielona Góra, Poland

autor

Mielniczuk J.

• Institute of Technology Pedagogical U niversity of Zielona Góra, Poland

Bibliografia

• 1. M.P. ANSELL, Acoustic emission from softwood in tension, Wood Sci. and Techno!., 16, 1982.
• 2. T. BEDNARSKI, Outline of plastic yielding mechanics, PWN, Warsaw 1995.
• 3. R. HILL, Mathematical theory of plasticity, Oxford University Press, 1950.
• 4. M. KOWAL, S.J. KOWALSKI, Material constants for wet pine sapwood, Studia Geotechnica et Mechanica, 20, 3-4, 1998.
• 5. R. MISES, Mechanik der plastischen Formanderung von Kristallen, ZAMM, 8, 3, 161-185, 1928.
• 6. W. MoLINSKI, Deformations of wood tensed crosswise to wood fibres at humidity variation in higroscopy range [in Polish], Ph. D. Thesis Agric. Acad., Poznan 1984.
• 7. J. RACZKOWSKI, Der Einfluss von Feuchtigkeitsanderungen auf das Kriechverhalten des Holzes, Holz als Roh- und Werkst, 27, 6, 1969.