Ultrasonic Characterization of Horizontal Density Variations in Oriented Strandboard


  • Ronnie Y. Vun
  • Qinglin Wu
  • Charles J. Monlezun


Attenuation, horizontal density, OSB, velocity, quality control, ultrasonic


Random flake deposition in mat forming of oriented strandboard (OSB) results in inherent horizontal density variation that affects the panel strength quality. In this paper, a silicon gel coupled ultrasonic transmission (UT) was used to locate, map, and validate the horizontal density distribution in laboratory-made OSB. Two test boards were manufactured at each of three nominal density (ND) and three resin content (RC) levels. The UT variables velocity, attenuation, and root mean square voltage formed excellent complementary predictors of density for all RC and panel types. Based on the allowable ±10% variation in the average measured densities, both the general and polynomial models provided improved density prediction for boards at higher RC and ND levels. Using the contour and out-of-limits plots, the predicted horizontal densities gave a reasonable spatial approximation to the measured densities. All 6% RC panels with densities of 0.60 g/cm3 or greater conformed well to the limits, with declining conformity towards the lower RC panels.


Beall, C. F. 2002. Overview of the use of ultrasonic technologies in research on wood properties. Wood Sci. Technol. (36):197-212.nBucur, V., M. P. Ansell, C. Y. Barlow, J. Pritchard, S. Garros, And X. Deglise, 1998. Physical methods for characterizing wood composite. Holzforschung (52): 553-561.nChen, L-H, and F. C. Beall. 2000. Monitoring bond strength development in particleboard during pressing, using acousto-ultrasonics. Wood Fiber Sci.32(4):466-477.nKruse, K., C. Dai, and A. Pielasch. 2000. An analysis of strand and horizontal density distributions in oriented strand board. Holz Roh-Werkst.58(4):270-277.nJeong, H., and D. K. Hsu. 1995. Experimental analysis of porosity-induced ultrasonic attenuation and velocity change in carbon composites. Ultrasonics33(3):195-203.nJudd, N. C. W., and W. W. Wright. 1978. Voids and their effects on the mechanical properties of composites—An appraisal. SAMPE Journal, January/February: 10-14.nLenth, C. A., and F. A. Kamke. 1996. Investigations of flakeboard mat consolidation. Part I. Characterization the cellular structure. Wood Fiber Sci.28(2):153-167.nLu, C., and F. Lam. 2001. Random field representation of horizontal density distribution: I. Partially oriented strandboard mat. Wood Fiber Sci.33(3):437-449.nNeter, J., M. H. Kutner, C. J. Nachtsheim, and W. Wasserman. 1996. Applied linear statistical models. 4th Ed. Irwin McGraw-Hill, Chicago, IL. pp. 345-373.nOudjehane, A., and F. Lam. 1998. On the density profile within random and oriented wood-based composite panels: Horizontal distribution. Composites Part B 29B: 687-694.nRoss, R. J., and R. F. Pellerin. 1988. NDE of wood-based composites with longitudinal stress waves.Forest Prod. J.38(5):38-45.nSmith, C. D. 1982. Waferboard press closing strategies. Forest Prod. J.32(3):40-45.nSteiner, P. R., and C. Dai. 1993. Spatial structure of wood composites in relation to processing and performance characteristics: Part 1. Rationale for model development. Wood Sci. Technol. (28):45-51.nSuchsland, O. 1962. The density distribution in flakeboard. Q. Bull., Michigan Agric. Exp. Sta., Michigan State Univ.45(1):104-121.nSuchsland, and H. Xu. 1989. A simulation of the horizontal density distribution in a flakeboard. Forest Prod. J.39(5):29-33.nSuddarth, S. K. 1965. Detection of adhesive bond defects in the Polaris missile nose firing through mechanical impedance measurements. Pages 267-285 in 2nd Nondestructive Testing of Wood Symposium 1965. April, Washington State University, Pullman, WA.nVogt, J. J. 1986. Longitudinal stress waves as predictors of internal bonding strength. 12th Particleboard/Composite Materials Symposium, March, 1985. Washington State University, WA.nVun, R.Y-H, and F. C. Beall. 2002. Monitoring creep rupture in oriented strandboard using acoustic emission. In International NDT2002 Symposium, 19-21 August, 2002. University of California, Berkeley, CA.nVun, R.Y-H, Q. Wu, M. C. Bhardwaj, and G. Stead. 2003. Ultrasonic characterization of structural properties of oriented strandboard: Direct-contact vs. non-contact methods. Wood Fiber Sci. (in press). 35(2):29-33.n






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