Determination of the elasto-plastic material characteristics of Norway spruce and European beech wood by experimental and numerical analyses

Abstract

Experimental and numerical analyses are presented concerning of compression tests parallel and perpendicular to the grain, three-point bending, and double-shear joints in compliance with the relevant test standards (ASTM D2395, BS 373, EN 383 and EN 26891). Woods of Norway spruce (Picea abies L. Karst.) and European beech (Fagus sylvatica L.) were tested to describe their non-linear behavior. Elasto-plastic material models were the basis for the finite-element (FE) analyses with the input of own experimental data and those of the literature. The elasto-plastic material model with non-linear isotropic hardening was applied based on the Hill yield criterion in regions of uniaxial compression. The material characteristics were first optimized and validated by means of basic 3D FE models under the same conditions as applied for the experiments. Afterwards, the validated material models were implemented into the solver with more complex numerical analyses of wooden dowel joints. Concurrently, the digital image correlation (DIC) served for verification of the numerical wooden joint models. A good agreement (with a relative error up to 16%) was found between numerically predicted and experimentally measured data. The differences may be mainly attributed to some natural characteristics of wood which were not considered in the proposed material models. The proposed elasto-plastic material models are capable of predicting the wood’s ultimate strength, and therefore could contribute to a more reliable design of wood structures and their performance.

Determination of Elastic Properties of Beech Plywood by Analytical, Experimental and Numerical Methods

“…The modulus of elasticity differs very little between individual specimens, as do the shear moduli. Likewise, the mean principal out-of-plane modulus of elasticity from flexural vibration differs from the in-plane modulus of elasticity from longitudinal vibrations in the L and T directions by only 3.5 and 2.5%, respectively, and it is comparable to values from the literature [52][53][54][55]. Due to the small differences, it was decided that three samples are sufficient for determination of the basic mechanical properties in the main tissue directions (L, T, R), therefore the number of samples was not increased.…”

Wood-adhesive bond loaded in mode II: experimental and numerical analysis using elasto-plastic and fracture mechanics models

“…FE prediction of force-displacement response in the elastic part of the test is sufficient compared to polynomial fit (blue line); only the PRF group shows a certain bump in the middle of the elastic part due to using arithmetic average as the base for polynomial fit. An agreement of FE model with the experiments regarding stiffness is determined by an orthotropic material model taken from the literature (Milch et al 2016). This implies that wood used in this work had very similar properties as one in the Milch et al (2016), despite the fact that both woods came from different growing positions within the region of Central Europe.…”

“…Within the FE analyses, three material models of beech wood (Table 1) were employed: (i) orthotropic elastic model (Elas); (ii) orthotropic elasto-plastic model with the same compression and tension yield stresses (EP) and (iii) orthotropic elasto-plastic model with different compression and tension yield values (EP+). The first two models were taken from Milch et al (2016). The third one was developed based on the second model using a procedure that aimed to extend the difference between compression and tension yield values while preserving Hill plasticity conditions (Hill 1983).…”

Comparison of Finite Element Models for Particle Boards with Homogenous and Three-Layer Structure

“…No data that would defi ne the elasto-plastic behaviour of particle boards have been found in available literature and this signifi cantly complicates the prediction of their properties. Unlike particle boards, when predicting elasto-plastic behaviour of solid wood, useful data could be obtained regardless whether the tensile, compression or bending load is applied, with 16% deviation between the FE model and experimentally obtained values (Milch et al, 2016). If only the predictions of the results in elastic portion of the load-defl ection curve and in the fi eld of shear behaviour are determined, the deviations are even smaller as they are only around 7 % for Norway spruce and 0.5 % for European beech (Milch et al, 2017).…”