Study Of Finite Modeling Modeling Analysis For Pinus Sylvestris L.var. Mongolica Litv. Finger-jointed Lumber

Finger-jointed lumber production is widely employed in the utilization of small size and inferior wood. The processing technology is significant to the mechanical properties of finger-jointed lumber. So this study took lumber of Pinus sylvestris L. var. mongolica Litv. as subject, tested and determined the optimized process through experiments. Based on the experimental result, end-pressure range, MOE and MOR of finger-jointed lumber were modeled and analyzed by finite element method. It provides a new way in predicting finger-jointed lumber's properties, which has great value in research and it's popularization.The major conclusions are listed as below:(1) The result from end-pressure experiment showed that the end-pressure range for Pinus sylvestris L. var. mongolica Litv. structural-used finger-jointed lumber production is 2.6MPa-5.7MPa. Using fit ratio and end-pressure as factors in full factorial experiment, the test result indicated that when fit ratio is 0.1mm and end-pressure is 3.5MPa, the properties of the finger-jointed lumber is the best, of which the MOE is 14.4GPa, MOR is 75.9MPa, and parallel tension strength is 29.2MPa respectively.(2) Electrometric method and three point bending experiment with variable span method were performed to test Pinus sylvestris L. var. mongolica Litv. lumber's elastic constant. The results are:EL=9171MPa,μLR=0.472,μLTt=0.558, ET=460.4MPa,μTR=0.337,μTL=0.033, ER=831.6MPa,μRT=0.765,μRL=0.053, GRT=44.5MPa, GLT=521.7MPa, GLR=666.7MPa. It can be drew that the experiment result can characterize the lumber's material properties and can be used in finite element modeling.(3) The finite element modeling result of finger-jointed lumber's end-pressure shows the range is 2.0MPa～3.7MPa. It's slight smaller than the experimental result. But the full factorial experiment result showed that the optimized end-pressure is 3.5MPa, so it can be concluded that the finite element modeling process can be used to predict the optimal end-pressure for finger-jointed lumber.(4) Finite element modeling process can illustrate the deformation state correctly when finger-jointed lumber is still in elastic bending deformed state. The modeling results of MOE is 16.36GPa,18.40GPa and 16.73GPa respectively when fit ratio is 0mm,0.1mm and 0.3mm. Comparing with the experimental results, the modeling results were almost 30% higher. So the modeling result of finger-jointed lumber's MOE should be calibrated.(5) Finite element modeling method can be used to predict finger-jointed lumber's MOR while the production of the finger-jointed lumber is in perfect state. The modeling result of MOR were 78MPa,72MPa and 45MPa respectively when fit ratio is Omm,0.1mm and 0.3mm, and the deviation between experiment test result and modeling result is 21.3%,1.8% and 32.6% respectively which is mainly due to the decrease of fit ratio caused by shrinkage of lumber. So it's necessary for the model to be modified.