Variation in Mechanical Properties within Individual Annual Rings in the Resonance Spruce Wood (Picea abies (L.) Karst.)

This paper shows results of specific elastic modulus and specific tensile strength in the resonance spruce wood [Picea abies (L.) Karst.] in relation to its heterogeneity within individual annual rings. It also presents changes in the average values of microfibril angle in S2 layer measured in tangential walls of tracheids (MFA) within individual annual rings. On the grounds of the results, it can be concluded that specific modulus of elasticity and specific tensile strength of wood are strongly influenced by the position of the sample in annual rings. Generally, the values of these parameters increase along the width of annual rings. It is also noted that the specific modulus of elasticity and specific tensile strength depend on MFA. As MFA decreases, the values of these parameters increase.