A New Apparatus For Compression Testing Of Wood

Authors

  • Jozsef Bodig
  • James R. Goodman

Abstract

Discussion is presented concerning the nature of stress distribution in a compression block. Two major factors, the mismanufacturing of specimens and the misalignment in respect to the center of the loading axis, are shown to be the major causes of eccentric loading in compression. The authors have desiged a new compression apparatus which was proved by both theoretical consideration and by experimental data to be better than the presently used single spherical bearing block. Using two spherical bearing blocks reduces considerably the undesirable side effects in comparison to the one spherical block system, but neither of these two techniques is designed for accurate specimen centering. The effect of the three loading systems in creating distortion in a compression specimen was evaluated. Six basic measured strain properties proved to be affected by these testing techniques.

References

American Society For Testing And Materials. 1965. Standard method of testing small clear specimens of timber. ASTM Designation D 143-52.nBodig, J. 1966. Stress-strain relationship of wood in transverse compression. J. Materials 1(3): 645-666.nEllwood, E. L. 1954. Properties of American beech in tension and compression perpendicular to grain and their relation to drying. School of Forestry Bulletin No. 61, Yale University.nKobayashi, S. 1962. Restraint in compression test of orthotropic materials. Forest Prod. J. 12(10): 489-492.nStieda, C. K. A. 1968. Computer evaluation of strain gage rosette readings. Instrument & Control Systems 41(11): 73-74.n

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Published

2007-06-22

Issue

Number 2 / Summer 1969

Section

Research Contributions

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