A BALANCED LAMINATION CONCEPT FOR DIMENSION LUMBER

LOWER QUALITY LUMBER PRODUCTS ARE USED WITH INCREASING REGULARITY DUE TO THE CONTINUOUSLY SHRINKING HIGH QUALITY TIMBER RESOURCE. THE USE OF LOWER QUALITY LUMBER RESULTS IN ADDITIONAL PROBLEMS DUE TO A POTENTIALLY EXTENSIVE WARPING, BOTH DURING STORAGE AND CONSTRUCTION. INCREASED WARPING IS EQUATED TO UNSATISFACTORY PERFORMANCE AND ECONOMIC LOSSES DUE TO NEEDED REPAIR AND REPLACEMENT. THE PROPOSAL REPRESENTS A RESEARCH EFFORT TO DETERMINE THE FEASIBILITY OF APPLICATION OF A THEORETICAL ORTHOTROPIC ELASTICITY. MIRROR IMAGE LAMINATION OF TWO ANISOTROPIC LAMINAE PRODUCES A MEMBER WITH ORTHOTROPIC CHARACTERISTICS. THIS CONCEPT TRANSLATED TO LAMINATED LUMBER SHOULD PRODUCE A RELATIVELY WARP-FREE MEMBER DUE TO THE MINIMIZATION OF THESHEAR COUPLING PHENOMENON WHICH IS DOMINANT IN LOWER QUALITY LUMBER. FURTHER BENEFIT IS EXPECTED TO BE DERIVED FROM INCREASED STRENGTH OF THE LAMINATE RESULTING FROM DEFECT DISPERSION AND AN INCREASED RESISTANCE TO CRACK PROPAGATION. THE PROPOSED RESEARCH WILL PROVIDE QUANTIFIABLE INFORMATION ON THE RELATIVE IMPROVEMENTS IN DIMENSIONAL STABILITY AND STRENGTH OF MIRROR IMAGE LAMINATEDLUMBER (MIRROR LAMINATE) MEMBERS OVER THOSE OF THE SAME QUALITY MADE OF SOLID SAWN LUMBER.