Abstract
The authors laid the grain of hulled rice (stiffix L) and the grain of milled rice (suffix R) of long grain variety on the two fulcra, gave a concentrated load in the center of them, and messured the breaking load in bending WAm, WRm and the breaking deflection in bending δLm, δRm under various moisture contents γ.
The authors calculated the deflection in bending δLm, δRm by taking out the penetrating quantity into each fulcrum in loading time from the transforming quantity, namely the apparent deflection εLm, εRm. From the results of measurements, the authors came to following conclusions.
(1) Irrespective of moisture contents γ, the authors concluded that a grain of rice could not be regarded as an elastic body. Accordingly, from the results of bending test, a breaking strength and a coefficient of elasticity could not be calculated, but the relation of the breaking load WLm, WRm and the ratio of a deflection to load WLm/δLm, WRm/δRm in relation to the moisture content γ could be clarified for the branny part and the starchy part in grain and also for grains tested, (shown in Fig. 8 and 9).
(2) The relation of breaking load in grain of hulled rice WLm to the moisture content γ was the relation of an exponential function. As the unprocessed grain was used, this deviation seemed to show the differrence among the individuals, but when the abnormal grains which seemed to have been injured were excluded the correlativity was remarkable.
(3) The relation of breaking load in grain of milled rice WRm to the moisture content γ was the relation of two different exponential functions which were connected at the point of γ≈14.5%, and at γ<14.5% the change of WRm was remarkable. And the deviation of which cause seemed to be in a process to mill rice and to adjust moisture was large.
(4) At the moisture content γ>14.5% the ratio of breaking load in grain of hulled rice and milled rice WLm/WRm showed almost the fixed value (WLm/WRm=7), and at γ<14.5% this ratio approached 1 rapidly, So at γ≈14.5%, the remainder WLm-WRm was the maximum value. And the ratio of tensional strength of rice to δLm/δRm was more remarkable. At γ>14.5% this value was more than 24.
(5) The ratio of load to deflection WLm/δLm, WRm/δRm, was of a similar relation in the breakig loat WLm, WRm. But those deviations were large.
