We made axial stress fatigue tests about the specimens which have circumferential notches, made of 0.13%C and 0.63%C steels, under the conditions σ_m/σ_a=0, 1, 3, 5, etc., where σ_m denotes the tensile mean stress and σ_a the stress amplitude.
The summary of the results is as follows:
(1) About the notched specimens, the endurance limit line in the endurance limit diagram under axial stress is given by a straight line which passes the two points, the one represents the value of σ_w on the ordinate and the other represents the value of σ_T on the abscissa, where σ_w denotes the endurance limit under completely reversed tension and compression and σ_T denotes the breaking strength on final area about the notched specimen.
(2) About the notched specimen, the inclinations of S-N curves, when the ordinate represents σ_max=σ_m+σ_a and the abscissa represents number of stress cycles N in logarithmic scale, and each S-N curve is drawn at σ_m/σ_a=const., become parallel.
(3) Using the conclusions above mentioned, we suggest a method of construction of σ_max-σ_m-N diagram, which gives the safe region of materials under axial load.

View full abstract

Results of an investigation of the hydraulic property, compressive strength and heat of hydration of the ternary system BaO-Al₂O₃-SiO₂ are reported.
From these measurement it was found that the clinkers whose compositions lie within the field of triangles BaO·Al₂O₃-2BaO·SiO₂-3BaO·3Al₂O₃·2SiO₂, BaO·Al₂O₃-BaO·6Al₂O₃-3BaO·3Al₂O₃·2SiO₂ are stable and have relatively strong strength.

View full abstract

Constructing the similar type apparatus which was employed by H. Green and his co-workers to measure the flow properties of paintlike materials, observations upon the viscosity of clay slips were made at various solid concentrations, and the magnitude of “thixotropic break down” and “thixotropic set up” of these suspensions was decided.

View full abstract

Comparing the several air permeability methods, i. e., the Lea Nurse, Sub Sieve Sizer and Blaine methods for measuring the particle size of the raw materials of cemented carbides, we recognized that the Blaine type are the most suitable and usefull one for routine testing.
The values obtained by this method showed fair coincidence with the electron microscope observations for W, WC powders, but for oxides, i. e., WO₃, TiO₂ etc. coarser. The method have the tendency to give the size of aggregated powders. Mr. Rose introduced the new correction method for revising the defects of Carman equation, but from our experiments it is suggested that the corrected values obtained by his method for the fine powders are too small.

View full abstract