WOOD RESEARCH Volume 68, Number 3, 2023
Tamás Király and Zsolt Karácsonyi

Fracture Testing of Edge-Notched Timber Beams with Different Growth Ring Orientations

The purpose of this research is to test Norway spruce specimens with different growth ring orientations weakened by edge-notch until failure. In the experiments the specimens were subjected to 3-point bending, tension and compression tests. In addition, failure mode during loading is investigated using a high-resolution camera. Based on the measurement results the correlation between latewood ratio, ultimate force, ultimate elongation/deflection, calculated moduli, growth ring orientation and diameter of the growth ring at the edge-notch were obtained. Based on the population data of the three tests conducted, only one parameter pair, namely the ratio of latewood to calculated modulus, influences the measurement results to almost the same extent. The other parameter pairs show different values and correlations.

WOOD RESEARCH Volume 68, Number 1, 2023
Tamás Király, Zsolt Karácsonyi, and Rudolf Polgár

Modeling the earlywood and latewood growth rings of Norway spruce timber beams for finite element calculation

The purpose of this research is to determine the orthotropic material properties of the Norway spruce (Picea abies) and to develop a finite element modeling technique that, when applied to an individual specimen, can properly predict the outcome of the measurement results (i.e., deflection by a predefined loading) by simulation only. For the development of the finite element model of timber beams, their unique annual ring pattern is considered. The HSV color spectrum of picture of the end grain pattern is analyzed with a photo analytical algorithm in order to separate the phases, earlywood and latewood. The determined surface ratio of the phases is used to hypothesize that the volume and surface ratios are equal. For the description of wood as a material the rule of mixtures is used. The results of the compared measurements and FE models based on the introduced hypotheses show good agreement within the linear elastic limit.