A New Approach to Determine and Evaluate the Poisson's Ratio of Wood

Modern timber engineering requires increasing application of the finite element method (FEM). In such analyses, the elastic constants including the Poisson´s ratios are required. The latter have mostly been neglected so far, since these vary to a great degree in related literature. Hence, an experimental method based on compression tests was developed and benchmarked on numerous preliminary tests in order to determine the Poisson´s ratios on spruce wood (Picea Abies). For the first time, the extended measurement uncertainty was taken into account. On the basis of these values, a comparison with values from literature was conducted. Several observations indicate that, in addition to the
wood properties, the load application as well as the test setup have a significant influence on the Poisson´s ratios. In summary, all obtained values lie in the medium range of the literature values. Consequently, the developed test method
for determining the Poisson´s ratios is considered to be suitable. In addition, an expanded Poisson's ratio was determined taking into account the measurement uncertainty in order to obtain a symmetrical compliance matrix.