薄肉球殻に小さな集中荷重が作用した場合の強度に関する研究(第2報)

抄録

Factors which are seemed to affect on the strength of thin sphere under little concentrated load are radius of sphere, height or length of chord, thickness and mechanical properties of material (elastic and plastic properties), etc. In these factors, that resulted from the shape of the test-piece were already reported in the part 1 of this paper. Then, in this report, we will discuss about the effects of thickness and material.
The typical thickness of test-pieces are 0.6, 0.8, 1.0 and 1.2mm. On each test-pieces, relation between deflection (δ) and load (P) is examined by the same method as used in the Part 1 of this paper. The results are as follows.
(1) The relation between deflection (δ) and load (P) is shown by the parabolic curve. When the sheet is thinner than 0.5. 0.6mm, the relation is shown by the single parabolic curve. When the sheet is thicker than 0.5 0.6mm, however, it is shown by one parabolic curve up to the certain` value of load which varies with the thickness, and then, when load passes over this value it is shown by the other parabolic curve which differs from the former.
(2) In each curve, the angle of inclination (tanα) is proportional to thickness (t), and the value which is compensated identically for the shape of test piece and the material-property (a/rh/tanα) is inversely proportional to the second power of thickness (t²). After all, the relation between deflection and thickness is generally shown by the following experimental formula.
δ=AγhP^b/Ept³
In the range in which load is light and the sheet is thin, b is approximately 1. Then diflection (δ) is shown as follows.
δ=AγhP/Ept³
(3) When the sheet is thicker than 0.6mm, a jump phenomenon is revealed. We desire to study on this jump phenomenon still more.
(4) The above formula may be applied even for aluminum alloys.