Fundamental investigations on acoustic emission are carried out for its application in the fields of materials science and safety engineering. Firstly, acoustic emission caused by plastic deformation and fracture of various types of metals and alloys is observed to study its physical properties. Secondly, aquantitative measuring method of acoustic-emission power and spectra is worked out. This method is applied to tension tests of monocrystals and polycrystals. Quantitative results are discussed in connection with microscopic mechanisms such as d islocation kinetics in the material. Thirdly, amulti-channel acoustic-emission source-location system is developed and is applied to hydrostatic tests of pressure vessels. Acoustice emission. is shown. to have a potential value for nondestructive inspection and safety moni-toring of structures.
This report describes the results obtained so far which are divided into the following. three: i) A wheel rolling resistance measuring device and the experimental results. The experimental apparatus used is explained and then the results of experiment are described. Thus, the various relations have been found between: (1) the resultant rolling resistance _??_ received by a wheel running on soft ground (S. G.) such as pulverulent substance, its vertical component V and horizontal component H, the direction θ, the coordinates (_??_, _??_) of the point Q to which the force is applied, the driving torque of wheel M, ect., on one hand; and (2) the breadth of wheel b, the wheel diameter 2r, the travelling velocity v, the angular velocity ω, the sinking depth at the lowermost end of wheel y0, the grain diameter of S. G. sample, the degree of moisture, etc., on the other hand. ii) Takahashi's theoretical equations for the resultant wheel rolling resistance based on the experimental results. The resultant rolling resistance of a wheel, _??_, consists of the wheel surface pressure from S. G., p=kyn, and the frictional force ƒ=μp (Here, y is sinking depth of wheel face into S. G., k and n are the constants concerning S. G.; and μ is the coefficient of friction between wheel surface and S. G.) It is also found that the values of R, H, V, θ, Q (_??_, _??_), etc. generally differ between the two different cases of wheel rolling, i.e. when the wheel is pulled and the wheel is driven by its own power. iii) Applications of the present studies and prospects to the future vehicles moving on themoon surface and the sea bottom.
Annealing behaviors of the damaged layers in silicon single crystal substrates implanted with the dose of some 1016ions/cm2 were investigated as a function of temperature, duration, and atmosphere of annealing, energy and species of ions, and surface conditions of the sub-strates. The nature, density, and distribution of the secondary defects, such as dislocation networks, dislocations both inside and outside of the implanted regions, and stacking faults were determined. The relations of such defects to the electrical and structural behaviors of the implanted ion species are discussed. Several sorts of implantation and annealing combinations were suggested to reduce secondary defects remaining in the substrates after annealing. These combinations were applied to form an emitter region of the npn planar transistors. Electrical characteristics of these transistors, like low frequency noise and current amplification factor at small collector current, were comparable to those of conventional transistors fabricated by the thermal diffu-sion process.
Silver particles formed in argon gas by the evaporation method were studied by electron microscopy. Particles of octahedron and truncated triangular bipyramid were found. Splitting of spots due to multiple refraction effect was observed for octahedral particles. An attempt was made to calculate the mean inner potential by analysing the separation of the split spots.
For explaining both the composition dependence of magnetization and the ferromagnetic region of each Mn-Al-X (X=Fe, Ni and Cu) system over a wide range of composition, a model has been proposed, which contains the concept of nonstoichiometric bond between Mn and Al. Here, formation of assumed phases and change of nonstoichiometric bond factor Kc are considered; when Kc=1, stoichiometric bond occurs, and when Kc>1, the quantity of Mn forming [Mn-Al] is larger than that of Al. By using this model, the experimental results can be reasonably well explained. It has been shown that the influence of Mn-Al binary system is strong in the region with π phase, and that it disappears in the region with κ phase, but a nonstoichiometric bond between Mn and Al exists. Moreover, interpretation of assumed phases on the basis of substitution, and estimation of atomic distribution of an alloy in Mn-Al-Cu system according to our model have been attempted.
An experiment on image distortion correction in acoustical holography was conducted. Scanned acoustical holography was used for imaging objects through a 5.06cm thick curved aluminum slab. Image distortion due to the curved slab was corrected in the reconstruction stage using two holograms; one, the hologram of the object, and the other, the hologram of the distortion media. A relatively good result has been obtained by the present experiment.
Positive ions impinging on a substrate in an rf sputtering system are observed by a quadrupole mass spectrometer with retarding grids to measure the ion energy. A spherical titanium target is used to avoid the edge effect of a planer one. The current of ion species is measured as a function of the rf power density and discharge pressure respectively. Argon is ionized by electron-impact ionization, being a main process of the discharge. The metal atoms, which are sputtered predominantly as neutral particles from the target, are ionized in the discharge by Penning ionization. The plasma potential estimated from the measurement of the ion energy varies from about 20 to 30 V positive to the ground potential in the region of 10-1 to 2×10-3Torr of the discharge pressure. It suggests that the effect of the resputtering during the film deposition is very small.
To improve the stability of a frequency stabilized laser, a double servo system consisting of a slow response loop and a fast response loop was designed, constructed and experimentally studied. In the faster response region, the phase lag of the servo system was mainly governed by the loop gain and the time constant of the fast response loop. This behavior was advantageously utilized in compensating the phase lag introduced by the integration element and, accordingly, in giving faster response to the total system. Frequency fluctuation of the laser in 1-10 Hz region was analyzed using the power spectrum density. The frequency variation, thus estimated, was smaller than several parts in 1011.