Application of a bending vibration method without weighing specimens to the practical wooden members conditions

Abstract

Abstract A vibration test to measure the mass of a specimen without weighing it using the difference between the resonance frequency with an additional mass and that without it (vibration method with additional mass, VAM) was applied to small, clear, and wooden specimens assuming practical situations. An apparatus that provided various end conditions by compressing the ends of the specimens was used in the tests. Bending vibration tests were performed on the specimens installed in the apparatus with/without an additional mass. Because the mass ratio (estimated mass by VAM/measured mass), namely, M VAM/M 0, which represents the estimation accuracy of VAM, was stable when the compressive strength was sufficiently large, VAM could be adequately used when the specimen was properly installed in the apparatus. The end condition at maximum compressive stress by the apparatus was an imperfect fixed condition. The M VAM/M 0 value greatly deviated from 1 in the specimens with a large height. The deviation in M VAM/M 0 from 1 was due to the introduction of the measured resonance frequencies with/without a concentrated mass into the frequency equation that required resonance frequencies under an ideal fixed–fixed condition. A correction method for M VAM/M 0 was then proposed.

Keywords

• Additional mass
• Fixed–fixed condition
• Mass
• Rotatory inertia
• Semi-rigid
• Shear