EXPERIMENTAL INVESTIGATION OF MIXED-MODE CRACK GROWTH PROCESS IN WOOD MATERIAL Due to the complex wood anatomy and the loading orientation, the timber elements are subjected to a mixed-mode fracture. In these conditions, the crack tip advance is characterized by mixed-mode kinematics. In order to characterize the fracture process function versus the loading orientation, a new mixed-mode crack growth timber specimen is proposed. In the present paper, the design process and the experimental validation of this specimen is proposed. Using experimental results, the energy release rate is calculated. The calcul consists on the separation of each fracture mode. The design of the specimen is based on the analytical approach and numerical simulation by finite element method. The specimen particularity is the stability of the crack propagation under a force control.
INVESTIGATII EXPERIMENTALE ALE PROCESULUI DE PROPAGARE A FISURII IN LEMN (MODUL MIXT).

PRO LIGNO

Volum 6 | Număr 1 | Publicat la 15/03/2010 | ISSN  1841-4737 | eISSN  2069-7430

Autori:
Rostand Moutou PITTI [1] | Frederic DUBOIS [2]
[1] Universitatea Polytech'Clermont Ferrand, France - [2] Universitatea Limoges - GEMH Laboratory, France
Rezumat
 Ca urmare a anatomiei lemnului si a orientarii incarcarilor, ruperea elementelor din lemn este caracterizata printr-o propagare a fisurilor in mod mixt. In aceste conditii avansarea frontului de fisura este caracterizat printr-o cinematica de propagare mixta. In vederea caracterizarii procesului de fisurare in functie de evolutia incarcarii, o noua epruveta, adaptata propagarii fisurilor in mod mixt, este propusa (2MCG - Mixed Mode Crack Growth). In cadrul acestui articol sunt prezentate procesul de realizare a epruvetei si validarea sa experimentala. Utilizand masuratorile experimentale, energia procesului de rupere va fi calculata in functie de evolutia frontului de fisurare. Conceptia epruvetei este bazata pe un calcul analitic si o modelare prin metoda elementelor finite. Particularitatea epruvetei consta in faptul ca propagarea fisuri este stabila. 
Cuvinte cheie:
lemn, mecanica ruperii, energia de fisurare, mod mixt, metode optice.

Bibliografie

Conservation Laws in Elasticity of the J-integral Type - CHEN, F.H.K., SHIELD, R.T. - , Journal of Applied Mechanics and Physics , 1977
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