INTERACTION TERM OF TSAI-WU THEORY FOR LAMINATED VENEER

A stochastic-based method of evaluating the interaction parameter (F-1 2) of the Tsai-Wu strength theory has been presented in this paper. Tr eating all strength parameters of the strength theory as random variab les, the mean and standard deviation of F-12, under plane stress condi tions, have been estimated for Douglas-fir laminated veneer. This esti mation has been managed through a nonlinear least-squares fit of the p arameters to a cumulative probability distribution of off-axis tensile data. For the purpose of comparison, a sample evaluation of F-12 usin g deterministic methods has been presented. This evaluation showed str ong dependence of F-12 on angle to grain. A subsequent sensitivity ana lysis of the off-axis tests on the value of F-12 indicated that data f rom 15 degrees off-axis tensile tests were more stable in establishing F-12 than that of other angles tested: 30 degrees, 45 degrees, and 60 degrees.