The Prediction Of Strength Of Parallel Strand Lumber

This paper was focused on using energy principle in elasticity and the theory of laminated panel in composite mechanics to establish the mechanical model of parallel strand lumber. Based on the different elastic constant of poplar veneer tested in the experiment, we can achieve the purpose of forecasting the strength of materials. The results as follows:The single-factor anova showed that the effect of hot-pressing pressure on veneer compression ratio was very obvious, second is the initial moisture content of veneer and hot-pressing temperature. The effect of hot-pressing time on veneer compression ratio was neglectable.Tests of multiple factors showed that the effect of hot-pressing pressure, hot-pressing temperature and the initial moisture content of veneer on the compression ratio of veneer was very obvious. Compared with any single factor, the effect of interaction between any two or three factors on the compression ratio of veneer was not obvious. We can get the conclusion that each factor was independent.The model of compressed-board density by single factor analysis as follow: When the hot-pressing pressure is lower than 5MPa, we could get the model of compressed-board density by single factor analysis more precise.When the PSL pressed without glue, each layers of veneer density showed normal distribution. Especially, the pressure is 5MPa, the density of veneer gradient become obviously. Relationship between the modified compressed-board density and the main factors equation is: In this paper, we use the strain foil to be pasted up on the veneer to measure coefficient of elasticity. Test results showed that the coefficient of elasticity of the lumber is accurate.Verification test results showed, based on the elasticity energy principle, we can receive a highly precision of the prediction range which the mechanical model of parallel strand lumber was established by the laminated plate theory.