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Journal of Materials Science

, Volume 41, Issue 21, pp 7247–7259 | Cite as

The fracture of wood under torsional loading

  • Zheng Chen
  • Brian Gabbitas
  • David Hunt
Article

Abstract

A series of experiments have been carried out on hardwood (red lauan) and softwood (sitka spruce) test pieces using static and cyclic torsional loading under displacement control. Measurements of the applied torque, the corresponding angle of twist and the number of cycles to failure were recorded. It was found that under static torsional loading, the strength of both hardwood and softwood reduced as the grain orientation of the sample to the axis of twist increased from 0° to 90° with a corresponding decrease of elastic modulus. Hardwood is stronger than softwood. In the fatigue test, when the torsional load is plotted against cycle number, the results showed that under displacement control stress relaxation occurs. The SN curve for softwood has a shallower gradient than that of hardwood, indicating that the torsional strength of softwood is less affected by fatigue loading than hardwood. In both static and cyclic torsional loading tests, the failure mode of hardwood is slow and incomplete, whereas, softwood fails suddenly and completely. The crack growth is along the tangential direction in the hardwood cross-section and in the radial direction in the cross-section.

Keywords

Fatigue Hysteresis Loop Tangential Direction Test Piece Grain Orientation 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Notes

Acknowledgements

The authors wish to thank Dr P. Bonfield, of the Building Research Establishment(UK), for supplying the Sitka spruce and Scots pine used in this work.

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Copyright information

© Springer Science+Business Media, LLC 2006

Authors and Affiliations

  1. 1.University of TorontoTorontoCanada
  2. 2.University of WaikatoHamiltonNew Zealand
  3. 3.London South Bank UniversityLondonUK

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