材料
Online ISSN : 1880-7488
Print ISSN : 0514-5163
ISSN-L : 0514-5163
21 巻 , 228 号
選択された号の論文の10件中1~10を表示しています
  • 田代 仁
    1972 年 21 巻 228 号 p. 817-825
    発行日: 1972/09/15
    公開日: 2009/06/03
    ジャーナル フリー
  • 山口 章三郎, 関口 勇, 杉山 勝俊, 鈴木 順雄
    1972 年 21 巻 228 号 p. 826-831
    発行日: 1972/09/15
    公開日: 2009/06/03
    ジャーナル フリー
    Two kinds of fillers, such as carbon fibre and PTFE powder, were used for the present study of their effects on the friction etc. of polyacetal.
    The contents of those fillers are 5, 10 and 25%, and length of carbon fibre are 1, 3 and 5mm, respectively.
    The friction and wear tests were carried out by using the Suzuki type friction tester and Ito's sliding wear tester.
    The results obtained are as follows;
    (1) The kinetic frictional coefficient of polyacetal decreases with content of fillers, such as PTFE powder and carbon fibre.
    (2) The sliding wear amount of polyacetal containing PTFE powder is about 0.5∼0.7 times as much as that of unfilled polyacetal.
    (3) The value of limiting pv of polyacetal containing the fillers increases with the increase of the contents of both fillers, PTFE powder and carbon fibre, and with that of length of carbon fibre.
    The pv value of polyacetal containing PTFE powder is about 1.2∼2.2 times as much as that of unfilled polyacetal, and that containing carbon fibre is about 1.1∼1.6 times as much as that of unfilled polyacetal.
  • 池尻 忠夫
    1972 年 21 巻 228 号 p. 832-838
    発行日: 1972/09/15
    公開日: 2009/06/03
    ジャーナル フリー
    In view of the fact that synthetic resin is extensively used as materials for making electric apparatuses and instruments, the important problem in this connection is about arc resistance, when arc takes place in that part of the apparatuses and instruments where the resin is used, or in those parts adjacent to such. Accordingly theoretical studies were made of initiation of arc with respect to chemical structure of insulating materials, and of the means of strengthening arc resistance by loading it with fillers from the standpoint of correlation between deteriorativity and molecular structure. In the theoretical studies the method used by D.J. Parr et al. to appreciate the tendency of tracking deterioration was adopted. It was thought that the tendency of carbonization or formation of organic semi-conductor was then expressed as the ratio of the sum of bond energies tending to produce carbon or organic semi-conductor to the total amount of energy in the molecule, ΔHcHs. According to this method arc resistance is found in experimental result to be nearly in proportion to ΔHcHs, the proportional constant standing in minus. It is to be noticed that the coefficient in correlation of arc resistance and ΔHcHs stood at -0.978. It is observed in this way that the assumption of possibility for arc resistance in resins in their chemical structure is justified to a certain degree. It is to be added that for measurement of arc resistance ASTM D 495-61 standard test method was adopted, and that for test materials such thermosetting resin and thermoplastic resin were used, as phenol resin, epoxy resin, polyester resin, polyvinyl chloride, etc. It is shown also, and is mechanically proved in the light of correlation between deteriorativity and molecular structure, that synthetic resin can be used to advantage by reinforcing it by loading it with fillers, to promote its arc resistance about three times as strong. It is not whatever kind of resin, however, that has property of arc resistance that can be strengthened by loading it with diluent fillers, no matter in what large quantity.
  • 勝山 邦久, 佐々 宏一, 伊藤 一郎
    1972 年 21 巻 228 号 p. 839-845
    発行日: 1972/09/15
    公開日: 2009/06/03
    ジャーナル フリー
    It is no easy task to get an analytical solution of the dynamic stress around a hole of whatever shape in a material. A report of studies is presented in this paper made of the dynamic stress in two materials with holes, one circular, and the other square, both caused by the propagation of pulsive cylindrical stress wave. The stress was analysed by a numerical technique which involved the fine difference approximation to the momentum equations. The main results obtained are as follows.
    (1) Stress concentration factors on the surface of the circular hole obtained by this numerical analysis agree fairly well with the analysis worked by M. T. Jakub and C. C. Mow.
    (2) The state of stress distribution around the circular hole changes with the ratio of λ/d, where λ is a wave length of the stress wave and d is a diameter of the hole. When the value of λ/d is greater than 2 or 3, the disturbance of the stress due to the existence of the hole becomes similar to that obtained under quasi-statical stress field. When the value of λ/d is smaller than 2 or 3, on the other hand, the stress wave reflects on the surface of the circular hole as if it reflected on a plane surface and the reflected waves from the surface of the hole had a dominant effect on the stress distribution.
  • 菅野 幹男, 小島 公平
    1972 年 21 巻 228 号 p. 846-851
    発行日: 1972/09/15
    公開日: 2009/06/03
    ジャーナル フリー
    Coarse grained polycrystalline aggregates of high-purity iron (99.996 at. %) have been fatigued in alternating bending at room temperature, and the behavior of individual grains has been studied by the X-ray technique together with optical microscopy. The fatigue deformation of the grains in the aggregates is found as fairly influenced by the crystal orientation. A grain possessing the orientation near the <001>-<011> side of stereographic triangle shows slip traces, while another grain near the <111> corner gives no trace of slip. In particular cases, the traces are exhibited also on the {001} plane when the crystallographic conditions are favorable for cleavage fracture. Because of the constraints of the surrounding grains, the microstructural change of deformation is much more complicated in the grain sited in the central part of the specimen than that located in the fringes of the specimen, even when both the grains possess resembling orientations. Localized slip zones are formed in the grain with definite orientation. The mechanism of fatigue deformation of b. c. c. metals is discussed in connection with crystallographic observations.
  • 藤谷 景三, 元津 彰夫
    1972 年 21 巻 228 号 p. 852-858
    発行日: 1972/09/15
    公開日: 2009/06/03
    ジャーナル フリー
    In this paper is presented a report of tests of constant strain low cycle torsional fatigue that were carried out on 0.81% C piano wires at room temperature and at elevated temperatures 270°C, 300°C and 400°C respectively, with a view to the investigation of the plastic fatigue phenomena. Three kinds of torsions were worked for the tests, completely reversed, fluctuating and pulsating, under the test speed of 1rpm. The main results obtained are as follows.
    (1) There is larger effect of temperature on the fatigue life than that of the mean strain. Let the strain amplitude stand as it is, there is longer fatigue life at 270°C and shorter fatigue life at 400°C than room temperature, the former case being considered to be the annealing effect.
    (2) The time-strength diagram shows linear decrease in strain amplitude γa against increase in the mean strain γm which the latter represents the number of cycles from the initiation of macrocrack N'=50 to its fracture N=200 or N=1000.
    (3) The test result shows that there exists linear relationship between, the total plastic strain γp.total and N' or N, when they are plotted on a log-log scale. It is found also that the same relationship holds for the total hysteresis energy W, the not-total hysteresis w' and the strain amplitude γa. In the completely reversed tests, γp.total and W are defined as γp.total=4ΣNn=1γpmf and W=w·N, in which γp and γmf are the plastic strain amplitude and the mean strain just before fracture, respectively.
  • 北川 正義
    1972 年 21 巻 228 号 p. 859-863
    発行日: 1972/09/15
    公開日: 2009/06/03
    ジャーナル フリー
    The fatigue crack growth rate dc/dN can be represented in the power law of the stress intensity range ΔK as follows:
    dc/dN=a1(ΔK)m
    where m is the material constant and a1 is considered as a function of ΔK according to Forman et al.'s law. It has been pointed out that a1 and m, which have important physical meanings, are functions of several factors, stress ratio R, frequency, temperature, environment and so on.
    In investigating the mechanism of fatigue crack growth, it is necessary that the effect of those factors will be systematically studied. Not so many studies have hitherto been made on the fatigue crack growth in high polymers as have been made on those in metals. The mechanism of their fatigue crack growth has been left in the dark in this way.
    In the present paper, therefore, it is pointed out that the effect of stress ratio on the fatigue crack growth rate will act as a link in the chain of the study on the fatigue of high polymers.
    The results obtained are summarized as follows:
    (1) The fatigue crack growth period is strongly influenced by stress ratio.
    (2) The fatigue crack growth rate follows the relation as follows:
    dc/dN=a5eαR(ΔK)m/(1-R)KIc-ΔK
    where KIc is the fracture toughness, and a5, α and m are material constants.
    (3) From the microscopic observation, the fatigue crack tip deformation process at loading is found to be different from that at unloading. This difference will lead to the formation of striation.
    (4) From the measurement that was made on the surface roughness meter, the striation height is found to be proportional to the striation spacing.
  • 菅野 昭
    1972 年 21 巻 228 号 p. 864-868
    発行日: 1972/09/15
    公開日: 2009/06/03
    ジャーナル フリー
    In his previous report, the author mentions success in preparing an available brittle lacquer coating which always presented strain sensitivity to circ. 800 micro strain under whatever condition of temperature and humidity without resorting to heat treatment. The difficulty in lacquer coating lies in maintaining its thickness perfectly even. It was particularly the case when the body for coating happened to be engineering structures to be analysed and of complicated construction. Since cracking on the lacquer coating develops in consequence of the strain transmitted from the top surface of the structures to the coating, the properties of crack formation on it will be markedly influenced by the thickness of the coating. The author has investigated, therefore, into the effect of the thickness on both the strain sensitivity and the crack density which are very important factors in practical use.
    As the result of the study, the following facts have been proved.
    The thickness of the coating need not be precisely even, since there is scarcely any change either in the strain sensitivity or in the crack density so long as it is restricted within 0.08-0.12mm. Moreover, the behavior of the strain sensitivity under curing process which has been hitherto held as inconceivable is now found as has been caused by fine crystallization of abietic acid used as a basic ingredient of the lacquer coating.
  • 山口 梅太郎, 奥村 誠
    1972 年 21 巻 228 号 p. 869-875
    発行日: 1972/09/15
    公開日: 2009/06/03
    ジャーナル フリー
    A laboratory measurement of the attenuation constant of sound waves travelling through rock was carried out. The so-called free vibration method was employed for this purpose. The travelling and oscillating longitudinal sound waves were excited in a long boring-core specimen of rock by means of an impact of small steel ball tied at one end of the specimen which was horizontally suspended by strings. The fundamental frequency of the oscillating waves was decided by the length of the bar. Observation was also enacted of the damped free oscillation of the sound waves.
    The reasonable attenuation constants and Q values have been obtained from several rock specimens. The Q's which have been directly calculated from the attenuation constants are substantially independent of frequency, but the Q of the Kuzuu (in Tochigi Prefecture) limestone is evidently dependent on the wave frequency.
  • 後藤 徹
    1972 年 21 巻 228 号 p. 876-881
    発行日: 1972/09/15
    公開日: 2009/06/03
    ジャーナル フリー
feedback
Top