Monitoring Acoustic Emissions to Predict Modulus of Rupture of Finger-Joints from Tropical African Hardwoods
Keywords:Acoustic emission, finger-joints, tropical African hardwood, modulus of rupture
The acoustic emission patterns generated from bending tests of finger-joints from three tropical African hardwoods, Obeche (Triplochiton scleroxylon), Makore (Tieghemella heckelii), and Moabi (Baillonella toxisperma) were evaluated to determine the possibility of using them to predict finger-joint modulus of rupture.
The patterns of acoustic emissions generated from the bending tests were observed to differ, depending on the type of finger profile and wood species. The regression coefficient of the regression of cumulative acoustic emission count on applied stress squared also varied with the profile and species type. When modulus of rupture was correlated with this regression coefficient, for stresses applied up to 50% of mean ultimate strength, the logarithmic regression model developed could predict modulus of rupture of the finger-joints accurately to ±10%. ±12%, and ±21% for Obeche, Makore, and Moabi, respectively. The models developed also seemed sensitive to the quality of the finger-joints from the three tropical African hardwoods.
The results of the study gave an indication that this acoustic emission monitoring procedure could be useful for nondestructively predicting modulus of rupture of finger-joints from the three tropical African hardwoods.
American Society for Testing and Materials. (ASTM). 1994. Standard method of static tests of timber in structural sizes. ASTM D198-84. ASTM, West Conshocken, PA.nAnsel, M. P. 1982. Acoustic emission from softwood in tension. Wood Sci. Technol. 16(1):35-58.nAyarkwa, J., Y. Hirashima, and Y. Sasaki. 1999. Predicting static bending modulus of elasticity of tropical African hardwoods from density using a model based on longitudinal vibration. Ghana J. Forestry 8(2000):1-8.nAyarkwa, J., Y. Hirashima, and Y. Sasaki. 2000. Predicting tensile properties of finger-jointed tropical African hardwoods using longitudinal vibration. Ghana J. Forestry 9:(in press).nAyarkwa, J., Y. Hirashima, and Y. Sasaki. 2000. Effect of finger geometry and end pressure on the flexural properties of finger-jointed tropical African hardwoods (in press). Forest Prod. J. 50(11/12).nBeall, F. C., and W. W. Wilcox. 1987. Relationship of acoustic emission during radial compression to mass loss from decay. Forest Prod. J. 37(4):38-42.nBeaulieu, C., C. Verreault, C. Gosme, and M. Samson. 1997. Experimental assessment of the effect of length on the tensile strength of structural finger-joined lumber. Forest Prod. J. 47(10):94-100.nBodig, J., and B. A. Jayne. 1982. Mechanics of wood and wood composites. Van Nostrand Reinhold Company. New York, N.Y. Pp. 247-269; 645-650.nChristensen, R. H. 1962. Cracking and fracture in metals and structures. Crack Propagation Symposium, Coll. Aeron., Cranfield, England. Pp. 326-374.nDeBaise, G. R., A. W. Porter, and R. E. Pentony. 1966. Morphology and mechanics of wood fracture. Mater. Res. Stand. 6(10):493, 499.nDedhia, D. D., and W. E. Wood. 1980. Acoustic emission analysis of Douglas-fir finger-joints. Mater. Eval. November 1980:28-32.nDunegan, H., and D. Harris. 1968. Acoustic emissions a new nondestructive testing tool. Lawrence Radiation Lab., Livermore, CA. UCRL-70750.nDunegan, H., and D. Harris. 1969. Ultrasonics. ULTRA 7:160-166.nFisette, P. R., and W. W. Rice. 1988. An analysis of structural finger-joints made from two northeastern species. Forest Prod. J. 38(9):40-44.nHartbower, C. E., W. E. Reuter, C. F. Morais, and P. P. Crimmins. 1972. Use of acoustic emission for the detection of weld and stress corrosion cracking. ASTM Spec. Tech. Pub. 505: 187-221.nHoneycutt, R., C. Skaar, C., and W. Simpson. 1985. Use of acoustic emissions to control drying rate of red oak. Forest Prod. J. 35(1):48-50.nJapanese Industrial Standards. 1977. Methods of test for wood. JIS Z 2101. Tokyo, Japan.nKnuffel, W. E. 1988. Acoustic emission as strength predictor in structural timber. Holzforschung 42(1988): 195-198.nKohler, G. 1981. Finger-jointing of unseasoned sawn timber for pallet manufacture. Holz-Zentralblatt 107(130):2015-2016.nKollman, F., and H. Krech. 1960. Dynamic measuring of elastic wood properties and damping. Holz Roh-Werkst. 2:41-45.nLembke, C. A. 1977. Finger-jointing increases value 5700%. Australian Forest Ind. J. 43(1):5-11.nNoguchi, M., K. Nishimoto, Y. Imamura, Y. Fujii, S. Okumura, and T. Miyauchi. 1986. Detection of very early stages of decay in western hemlock wood using acoustic emissions. Forest Prod. J. 36(4):35-36.nNoguchi, M., R. Ishi, Y. Fujii, and Y. Imamura. 1992. Acoustic emission monitoring during partial compression to detect early stages of decay. Wood Sci. Technol. 26(4):279-287.nOfosu-Asiedu, A., J. M. Nani-Nutakor, and J. Ayarkwa. 1996. Kumasi base-line survey - data collection for a finger jointing plant. Research Report of the Forestry Research Institute of Ghana, Kumasi, Ghana. Pp. 1-3.nOno, K. 1973. Present studies on acoustic emission for iron and steel. Iron and Steel 59:1338-1359.nOnogami, M., K. Yamaguchi, H. Nakasa, K. Sano, E. Isono, and T. Watanabe. 1979. Acoustic emission - Bases and applications. Japan Corona Pub. Co. Pp. 125.nPollock, A. A. 1971. Acoustic emission methods of NDT. Brit. J. NDE 13:85-89.nPorter, A. W. 1964. On the mechanics of fracture in wood. Ph.D. Thesis, Suny College of Forestry. Syracuse, NY.nPorter, A. W., M. L. El-Osta, and D. J. Kusec. 1972. Prediction of failure of finger-joints using acoustic emissions. Forest Prod. J. 22(9):74-82.nPrah, E. A. 1994. Environment and recovery in industrial processing of timber. Seminar on "The Environment and the Utilization of Wood Waste". Assoc. Ghana Industries and the Friedrich Naumann Foundation. Kumasi, Ghana. Pp. 5-10.nRice, R. W., and C. H. Skaar. 1990. Acoustic emission patterns from the surface of red oak wafers under transverse bending stress. Wood Sci. Technol. 24(2):123-129.nSamson, M. 1985. Potential of finger-joined lumber for machine stress-rated lumber grades. Forest Prod. J. 35(7/8):20-24.nSato, K., T. Okano, L. Asano, and M. Fushitani. 1985. Application of AE to mechanical testing of pages 240-243 wood. Proc. 2nd Int. Conf. on Acoustic Emission. Lake Tahoe, CA.nStrickler, M. D. 1980. Finger-jointed dimensioned lumber-Past, present and future. Forest Prod. J. 30(9):51-56.nStrickler, M. D., R. F. Pellerin, and J. W. Talbott. 1970. Experiments in proof loading structural end-jointed lumber. Forest Prod. J. 20(2):29-35.nSuzuki, M., and A. P. Schniewind. 1987. Relationship between fracture toughness and acoustic emission during cleavage failure in adhesive joints. Wood Sci. Technol. 21:121-130.nUlasovets, V. G., and L. A. Makerova. 1988. Standardizing factors in the manufacture of single-layer parquet panels. Derevoobrabatyvayushchaya-Promyshlennost 11:14-15.n
The copyright of an article published in Wood and Fiber Science is transferred to the Society of Wood Science and Technology (for U. S. Government employees: to the extent transferable), effective if and when the article is accepted for publication. This transfer grants the Society of Wood Science and Technology permission to republish all or any part of the article in any form, e.g., reprints for sale, microfiche, proceedings, etc. However, the authors reserve the following as set forth in the Copyright Law:
1. All proprietary rights other than copyright, such as patent rights.
2. The right to grant or refuse permission to third parties to republish all or part of the article or translations thereof. In the case of whole articles, such third parties must obtain Society of Wood Science and Technology written permission as well. However, the Society may grant rights with respect to Journal issues as a whole.
3. The right to use all or part of this article in future works of their own, such as lectures, press releases, reviews, text books, or reprint books.