Research On The Elastic Model And Technology Of Composite Poplar LVL

In recent years. Laminated veneer lumber(LVL) has been developed rapidly in western, Japanese and other developed countries. But in home, the production of LVL is still small and the quality of LVL can not meet the international standard. On the other hand, there is great space for the development of LVL.In the mechanics of composite material , the objects of this paper research: Poplar LVL Enhanced with Wire Net and Poplar LVL composited with resin impregnated veneer. The former can be regarded as by orthogonality anisotropy layer ( Poplar veneer ) with isotropy layer( metal net); the latter is layed only by orthogonality anisotropy, Poplar veneer. In the foundation of classical layer theory and corresponding assumptions, paper have put forward the rigidity model of this composite layer. And through the technology research for this composite Poplar LVL, on the one hand, the effect of complex strengthens has been discussed; on the other hand, experiment data has been offered to test the rigidity model.In the research of Poplar LVL Enhanced with Wire Net, Wire net and Poplar veneer with 3 kinds of adhesives(phenol formaldehyde resin(PF)^ polyurethane adhesive(PU) and epoxy resin adhesive), were composited to enhanced LVL in which different wire nets and different layers of wire nets were included .The results from experiments showed that wire net improved remarkably Poplar LVL on modulus of rupture(MOR),modulus of elasticity(MOE),and among all the factors ,the mesh of wire net is the most effective.In the research of Poplar LVL complexed with resin impregnated veneer, the effect of different volume of resin impregnation of veneer and different reinforcement methods on mechanical properties has been investigated. Results from experiments showed that the mechanical properties will be enhanced by resin impregnation of the veneers, moreover, the more the numbers of the veneers which were impregnated by resin, the higher the mechanical properties of the LVL were. Various resin impregnation volume have remarkable effect only on thickness swelling of CLVL(one LVL had all veneers impregnated) after 24-hour water-soak, besides, thickness swelling increased with the reduction of the resin impregnation volume.The model is tested by the comparison between actual data of MOE and theoretical data. It is showed that the relative errors were less than 15% between prediction and trial values, when composite lumbers have low peel rate and classical lay theory is tenable.