Ultimate tensile strength of loblolly pine strands using stochastic finite element method

The purpose of the study was to predict the failure strength of different orientation of wood strands from different growth ring positions under tension loading. Stochastic models were constructed to account for the uncertainty of material properties. The Tsai-Hill criteria were used to predict the ultimate tensile strength (UTS). The UTS results from experimental testing were used to validate the results from models. The difference of UTS between experimental and SFEM ranged from 0.09 to 11.09%. Different stress distributions were found for different orientation strand models, whereas uniform stress distribution was found for homogeneous models. The magnitude of the stress distribution was greater for strands from the growth ring number 11-20. Sensitivity analysis showed that grain orientation and growth ring number influenced the UTS of strands. UTS of strands from growth ring number 1-10 showed strength indexes (X (t), Y (t), and S) as dominant factor, whereas UTS of strands from growth ring number 11-20 showed both strength indexes and stress components (sigma (1), sigma (2), and tau (12)) as dominant factors.