15 November 1996 Use of phase-plot to evaluate damping of free vibration in wood-based materials
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Classical log-decrement techniques have been used to evaluate the damping property of materials. However, the consistency and repeatability of the method when applied to wood and wood-based materials has been found lacking. A different way to view the free vibration of a single-degree- of-freedom system in the (chi) -(chi) (DOT) plane is presented. When (chi) and (chi) (DOT)/(omega) d are used to describe the free vibration, it will plot as a spiral curve asymptotically approaching the origin. The radius R of the spiral curve, when plotted in the time domain,is the same as the decay profile curve of the free vibration. Since every sample point has its associated radius, all points of the free vibration can be used to calculate the damping property. This method does not require a knowledge of the initial conditions and is easy to use. Preliminary results show that the new method is more consistent and repeatable in measuring damping than the classical method for wood- based materials.
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Zhiyong Cai, Zhiyong Cai, Michael O. Hunt, Michael O. Hunt, Kenneth J. Fridley, Kenneth J. Fridley, David V. Rosowsky, David V. Rosowsky, } "Use of phase-plot to evaluate damping of free vibration in wood-based materials", Proc. SPIE 2944, Nondestructive Evaluation of Materials and Composites, (15 November 1996); doi: 10.1117/12.259072; https://doi.org/10.1117/12.259072

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