Patent Number: 6,308,571

Title: Method for determining crook potential in wood

Abstract: A method for determining crook potential of wood is described. One embodiment comprises nondestructively obtaining lengthwise shrinkage rates (from a third party or by direct measurement) of wood and then determining crook potential of the wood based on the lengthwise shrinkage rates. Where the wood comprises lumber, lengthwise shrinkage rate measurements typically are made on at least one major planar surface of the lumber. The method typically comprises determining lengthwise shrinkage rates two or more measuring points separated by a predetermined distance, such as at substantially one-foot intervals along the lumber. Particular embodiments of the present invention determine lengthwise shrinkage rates using infrared radiation, microwave radiation, electricity, ultrasound energy, and combinations thereof Working embodiments of the method use ultrasound energy to determine lengthwise shrinkage rates. For example, one working embodiment measures the speed of an ultrasound pulse through wood to determine the modulus of elasticity (MOE) of the wood which can then be correlated to the lengthwise shrinkage rate. In another example, lengthwise shrinkage rate can be determined from the speed of an ultrasound pulse using an empirically derived formula, such as an exponential formula. Another embodiment of the present invention comprises determining crook potential of wood based on non-averaged lengthwise shrinkage rates. Another embodiment of the present invention comprises determining crook potential is determined using a finite element model (FEM). The method the present invention provides can determine crook potential that correlates with actual measured crook with an R.sup.2 value of at least 0.5.

Inventors: Stanish; Mark A. (Seattle, WA), Floyd; Stan L. (Enumclaw, WA), Cramer; Steven M. (Lodi, WI)

Assignee: Weyerhaeuser Company

International Classification: G01N 29/44 (20060101); G01N 29/07 (20060101); G01N 29/04 (20060101); G01N 33/46 (20060101); G01N 029/18 (); F26B 013/10 ()

Expiration Date: 10/30/2018