Patent ID: 6813927
Filing Date: 2004-11-09
Classification: G01N

Abstract:
A apparatus for providing an indicator of or from which stiffness can be estimated for logs of length L, said apparatus comprisinga sensing device placed in contact with or in close proximity to a log end to detect at least part of a frequency spectrum of resonant plane acoustic waves f1, f2, . . . fn resulting from an induced disturbance that travels the length L and reflects at ends thereof, said induced disturbance being causable by a striking of one of the other log end and the log end, a processing device to derive the indicator from spectral information detected by said sensing device, and a display device to display said indicator received from said processing device, and wherein L is entered into said processing device, and wherein said processing device derives, as said indicator V2 and where V is the acoustic speed in a relationship MOE=densityÃ—V2 by reference to both L and f0, where f0 is a fundamental frequency of the acoustic spectrum f1, f2, . . . fn and where MOE is a dynamic modulus of elasticity, and wherein f0 is derived by the processing device using a best fit spectral analysis of the resonant plane frequencies of the at least part detected acoustic spectrum f1, f2, . . . fn.