Ultrasonic Characterization of Structural Properties of Oriented Strandboard: A Comparison of Direct-Contact and Non-Contact Methods<sup>1</sup>


  • Ronnie Y. Vun
  • Qinglin Wu
  • Mahesh C. Bhardwaj
  • Gary Stead


Densification, direct-contact, non-contact ultrasound, quality control, OSB, velocity, attenuation


A through-thickness ultrasonic transmission (UT) in oriented strandboard (OSB) was done to compare the performance of direct-contact (DC) and non-contact (NC) ultrasonic systems. The DC measurements produced a higher velocity than the NC system for a given board type, possibly due to transducer's compression over liquid couplant in the DC method. The UT responses correlated nonlinearly to sample density. The responses were not affected by the panel shelling ratio for the threelayer boards. Viable correlations between panel properties and UT parameters were board-specific for either method. Attenuation and root means square voltage (RMS) parameters were suitably used as density predictors if the flake alignment level is known; otherwise, velocity parameter could be used. In the single-layer boards, internal bond strength, bending stiffness, and breaking resistance were highly correlated to attenuation and RMS, a calibration importance. A density of 900 kg/m3 marked the transition point for the UT responses. The point showed the transition between the diminishing physical effects of the interspatial voids in the lower density half and the increasing plastic-strain hardening modifications in the higher density half. The high correlations of DC-Velocity and NC-Attenuation to density and strength properties attest a feasible application of both methods in wood composite research and in a real-time quality control system for fiber-based facilities.


American Society for Testing and Materials (ASTM). 1996. Annual Book of ASTM Standard D1037-96, American Society for Testing and Materials, Philadelphia, PA.nBeall, C. F. 1996a. Application of ultrasonic technology to wood and wood-based materials. In Ferenc Divos, ed. Proc. 2nd University of Western Hungary International Conference on the Wood Science/Technology and Forestry. Sopron, Hungary.nBeall, C. F. 1996b. Future of nondestructive evaluation of wood and wood-based materials. Keynote pages 409-413 in Proc. 10th International Conference on NDE of Civil Structures & Materials, Boulder, CO.nBeauchamp, K. G., and C. K. Yuen. 1979. Digital methods for signal analysis. George Allen & Unwin Ltd., Boston, MA.nBenson, H. 1991. University physics. John Wiley & Sons, New York, NY. pp. 663-672; 962 pp.nBhardwaj, M. C. 1997. Innovation in non-contact ultrasonic analysis: Applications for hidden objects detection. Mat. Res. Innovation1:188-196.nBhardwaj, M. C., I. Neeson, and G. Stead. 2000. Introduction to contact-free ultrasonic characterization and analysis of consolidated materials. Technical report at the Application of Nondestructive Evaluation in Powder Metals Seminar. Iowa State Univ., Ames, IA. 13 pp.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.nDickens, J. R., D. A. Bender, and D. E. Bray. 1996. A critical-angle ultrasonic technique for inspection of wood parallel-to-grain. Wood Fiber Sci.28(3):380-388.nErmolov, I. N. 1998. Major ultrasonic inspection problem. Russian J. Nondestructive Testing34(1):35-37. Plenum Publishing, New York, NY.nFuruno, T., C-Y. Hse, and W. A. Cote. 1983. Observation of microscopic factors affecting strength and dimensional properties of hardwood flakeboard. Pages 297-312 in T. M. Maloney, ed. Proc. 17th Washington State University International Symposium on Particleboard- Composite Materials. Pullman, WA.nGeimer, R. L. 1979. Data basic to engineering design of reconstituted flakeboard. Pages 105-125 in T. M. Maloney, ed. Proc. 13th Washington State University International Symposium on Particleboard/Composite Materials. Pullman, WA.nJeong, H. 1997. Effects of voids on the mechanical strength and ultrasonics attenuation of laminated composites. J Composite Mater.31(3):276-292.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.nLee, N. J., and Q. Wu. 2002. In-plane dimensional stability of three-layer oriented strandboard. Wood Fiber Sci.34(1):77-95.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.nSas Institute Inc. 2000. SAS User's Guide version 8.0. SAS Institute Inc., Cary, NC.nVun, R. Y-H. 1998. Monitoring creep rupture in oriented strandboard using acoustic emission FPL rep. 36-01-138, University of California Forest Product Laboratory, Richmond, CA. 87 pp.nVun, R. Y-H., Q. Wu, M. C. Bhardwaj, and G. Stead. 2000. Through-thickness ultrasonic transmission properties of oriented strandboard. Pages 77-86 in Ferenc Divos, ed. Proc. 12th University of Western Hungary International Symposium on Nondestructive Testing of Wood. Sopron, Hungary.nWu, Q. 1999. In-plane dimensional stability of oriented strand panel: Effect of processing variables. Wood Fiber Sci.31(1):28-40.n






Research Contributions