Evaluation on non-linear viscoelastic bending deflection of wood

Summary

The viscoelastic deflection resulting from load increasing continuously from 30% stress level (linear range) to 60% stress level (non-linear range), i.e., within the proportional limit was measured over a period of 10 h. The experimental deflection could be predicted by a numerical method using model element constants which were an experimentally determined function of stress level. An 8-element model consisting of a Maxwell model and three Voigt models in series was used. The upper limit of stress level where a linear relation between creep strain and stress holds ranged from about 35% to 40%. Calculated deflections agreed well with experimental deflections.