Abstract
When we design a prosthesis we must consider its dynamic movement, in particular, stress-distribution.
Recently, the strain gauge method, the photoelastic method, and the finite element method are applied to measure for prosthesis stress analysis.
By any way, on the assumption that dynamic property of test pieces, especially, Young's modulus and Poisson's ratio are necessary to be known in advance.
We will measure the principal stress-distribution of plate denture finally, we used foil strain gauge and digital strain measuring equipment to measure Young's modulus and Poisson's ratio primarily.
When we measured them, we made the 12 rectangular rectangular test pieces as materials which were the heat curing acrylic resin for denture plate “Acron”(G-C's dental industrial Co., Ltd.) and took compressive test by using Amsler testing machine.
And we measured displacement by foil strain gauge which type was KFR-02-Cl-16 (KYOWA electronic instruments Co., Ltd.).
We searched for maximam compressive unit stress, Young's modulus, and Poisson's ratio, about 12 kinds of test pieces which sizes were 3×3×3mm, 3×3×6 mm, 3×3×9mm, 4×4×4mm, 4×4×8mm, 4×4×12 mm, 5×5×5mm, 5×5×10mm, 5×5×15mm, 6×6×6 mm, 6×6×12mm, and 6×6×18mm.
The strain which was on the point of breaking was caliculated the recurrent expression by method of least squares, from the data.
We did fundamental close examination, we gained the evaluation from the piece which size of 5×5×10 mm, because of stability of data and efficiency of standard-sized test piece, as shown followings.
Maximum compressive unit stress
11.66 S. D.±0.19kg/mm2Young's modulus 190.1 S. D.±6.3kg/mm2Poisson's ratio 0.313 S. D.±0.032kg/mm2
