タイトル（掲載誌）航空宇宙技術研究所報告 = Technical Report of National Aerospace Laboratory TR-676
一般注記In order to study strength characteristics at room temperature and the strength evaluating-method of ceramic materials, bending-tests of bars, tensile tests of rectangular plates and spin-tests of disks with a hole in the center were conducted on hot-pressed Silicone Nitride (Si3N4) specimens. The results can be summarized as follows: 1.The mean strengths of the specimens as shown by either the tensile or the spin tests, agreed well with the values predicted from the results of the mean strength and the Weibull’s modules by bending-tests of the material and the effective volume. 2.The mean strength generally decreased with increasing effective volumes of the specimens when said effective volumes were not very small. However, they approached a certain value independent of the effective volumes when they were small enough, as in the case of fracture tests of notched specimens. The limit value of the effective volumes in the present study was about 1mm3. 3.Good test-results were obtained without showing any eccentric load effects that might exist in the present tensile test, where the specimens received the loads through cross pin connectors at both ends of the test-pieces to which steel attachments were fixed with adhesive. 4.For the following reasons spin-testing is considered to be a useful method of testing the strength of ceramics. i)The only force acting on the test-piece is the centrifugal body-force created by the specimen itself. As it is not necessary to consider any reaction force from the test-instrument in spin-testing, stress concentrations caused by misalignment of the test-pieces are expected to be negligeble. ii)Large effective volumes can be tested by this method because only tensile stresses are created in the specimens. iii)Disk spin-tests can also provide useful data on the dual-axial tensile strength of materials because the forces created in the disk under spin-testing are tensile stresses, both in tangential and in radial directions. iv)Much information about the mechanical characteristics of material that is necessary for use in designing rotating parts of machine can be obtained from rather few spin-tests for the avobe reasons. 5.Observations of the fracture origins and of propagation on the fracture surfaces were made. When the effective volumes were large as in the case of spin-testing, two or more fracture origins were sometimes observed. Locations of the fracture origins did not necessarily coincide with that site where maximum stress was predicted to occur, and the discrepancies between the actual and predicted sites were generally great when stress-gradients on the fracture surface were small.
資料番号: NALTR0676000
レポート番号: NAL TR-676
一次資料へのリンクURLhttps://jaxa.repo.nii.ac.jp/?action=repository_action_common_download&item_id=44933&item_no=1&attribute_id=31&file_no=1
連携機関・データベース国立情報学研究所 : 学術機関リポジトリデータベース（IRDB）（機関リポジトリ）
提供元機関・データベース宇宙航空研究開発機構 : 宇宙航空研究開発機構リポジトリ